LED driver series for LCD back light
White LED dri ver f or medium sized
and large sized LCD back li ght
BD9470AEFV・BD9470AFM
●General Description
BD9470AEFV and BD9470AFM are high efficiency
driver for white LED. They are designed for large sized
LCD. BD9470AEFV and BD9470AFM are built-in
DCDC converter that supply appropriate voltage for
light source.
BD9470AEFV and BD9470AFM are also built-in
protection function for abnormal state such as OVP:
over voltage protection, OCP: over current limit
protection of DCDC, SCP: short circuit protection, open
detection of LED string.
Thus they are used for conditions of large output
voltage and loa d cond itions.
●Features
6ch LED constant current driver
LED maximum output cur ren t 250mA
Individual PWM dimming modulation allowed for
LEDs
±2% LED current accuracy (when each LED is set
to 130mA)
Built-in LED feedback voltage automatic adjustment
circuit according to LED current
Built-in start-up circuit independent of PWM light
modulation
built-in VOUT・FB voltage maintenance function
when PWM=Low（0%）
Built-in LED current stabilization circuit while
scanning operation is performed
Built-in VOUT discharge circuit while shutdown
Built-in LED protection (OPEN / SHORT protection)
Individual detection and individual LED OFF for
both open and short circuit
Adjustable LED short-circuit protection threshold
PWM-independent LED protection
VOUT over voltage protection (OVP) and reduced
voltage protection (SCP) circuit
Built-in failure indication function
Built-in ISET pin short-circuit protection circuit
●Key Specifications
VCC supply Voltage range: 9.0V～35.0V
LED minimum output current: 40mA
LED maximum output cur ren t: 250mA
DCDC oscillation frequency: 150KHz(RT=100Kohm)
Operation cir cuit curre nt: 6mA(typ.)
Operating temperature range: -40℃～85℃
●Applications
■ LED driver for TV, monitor and LCD back light
●Package
W ( Typ.) x D(Typ.) x H(Max.)
HSOP-M28 18.50mm x 9.90mm x 2.41mm
HTSSOP-B28 9.70mm x 6.40mm x 1.00mm
●Typical A pplication Circuit
Figure 3. T ypical A pplicatio n C ircuit
Figure 1. HSOP-M28
Figure 2. HTSSOP-B28
STB
VCC
REG58
GND
FB
SS
RT
LED6
PWM4
PWM6
DCDC_GND
N
ISET
CS
PWM1
PWM2
LSP
PWM3
PWM5
FAIL
OVP
LED5
LED4
LED_GND LED3
LED2
LED1
UVLO
VIN
STB
PWM
FAIL
○Product structure：Silicon monolithic integrated circuit ○This product is not designed protecti on against radioact i ve rays
1/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・14・001
Datashee
t
BD9470AFM・BD9470AEFV
1. Specificati o n for BD9470AEFV・BD9470AFM
●Absolute Maximum Ratings (Ta=25°C)
Parameter Symbol Rating unit
OVP Detect Voltage (DCDC Stop) VCC -0.3~36 V
LED1~6 pin voltage LED1~6 -0.3~40 V
STB・FAIL・UVLO・OVP pin voltage STB,FAIL,UVLO,OVP -0.3~36 V
ISET・FB・SS・
CS・N・REG58・RT pin voltage ISET・FB・SS・CS・N・REG58・RT -0.3~7 V
PWM1~6
・
LSP
PWM1~6
・
LSP
Power dissipation (HSOP-M28)*1 Pd 5208 mW
Power dissipation (HTSSOP-B28)*2 Pd 4700 mW
Operating temperature range Topr -40～+85 ℃
Storage temperature range Tstg -55～+150 ℃
Maximum junction temperature Tjmax +150 ℃
*1 Decreases -41.7mW/°C at Ta=25°C or higher (When mounting a four-layer 70.0mmx70.0mmx1.6mm board)
*2 Decreases -37.6mW/°C at Ta=25°C or high er (When mounting a four-layer 70. 0m m x7 0.0m mx1.6m m board)
●Recommended Operating Ratings
Parameter Symbol Rating unit
Supply voltage VCC 9.0 ～ 35.0 V
LED1-4 pin minimum output current ILED_MIN 40 mA*1
LED1-4 pin maximum output current ILED_MAX 250 mA*1*2*3
LSP input voltage range VLSP 0.3～2.5 V
DC/DC oscillation frequency fsw 100 ～ 500 kHz
Min. on-duty for PWM light modulation PWM_MIN 30 μS
*1 The amount of current per channel
*2 If LED makes significant variations in its reference voltage Vf, the driver will increase power dissipation, resulting in a rise in package
temperature. To avoid this problem, design the board with thorough consideration given to heat radiation measures.
*3 The LED current can be set up to 250mA
● Pin Configuration ( TOP VIEW ) ●Outline Dimension Diagrams/Sign Diagrams
LOT No.
BD9470AFM
BD9470AEFV
LOT No.
Figure 4. Pin Configuration
（
TOP VIEW
）
Figure 5. Outline Dimension Diagrams/Sign Diagrams
GND
LED6
PWM4
PWM6
ISET
PWM1
PWM2
PWM3
PWM5
FAIL
OVP
LED5
LED4
LED_GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14 15
16
17
18
19
20
21
22
23
24
25
26
27
28
STB
VCC
REG58
FB
SS
RT
DCDC_GND
N
CS
LSP
LED3
LED2
LED1
UVLO
7.SS
1.REG58
2.CS
3.N
4.DCDC_GND
5.RT
6.FB
8.ISET
9.PWM1
10.PWM2
11.PWM3
12.PWM4
13.PWM5
14.PWM6 15.GND
16.FAIL
18.LED6
17.OVP
19.LED5
21.LED_GND
20.LED4
22.LED3
24.LED1
23.LED2
25.UVLO
27.STB
26.LSP
28.VCC
2/35 TSZ02201-0F10C1002000-1-2
© 2013 ROHM Co., Ltd. All rights reserved. 19.Oct .2 013 Rev.003
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
Contents
1. Specification for BD9470AEFV・BD9470AFM P2～P9
●Absolute Maximum Ratings P2
●Recommended Operating Ratings P2
●Pin Configuration P2
●Outline Dimension Diagrams/Sign Diagrams P2
●Electrical Characteristics P4,P5
●Pin Numbers, Names, and Functions P6
●External Component Recommended Range P6
●Internal Equivalent Circuit Diagrams P7
●Block Diagram P8
●Characteristic date P8,P9
2. Understanding BD9470AEFV・BD9470AFM P10～P12
●Pin Functions P10～P12
3. A p plicati on of BD9470AEFV・BD9470AFM P13～P32
3.1 BD9470AEFV, BD9470AFM examination for application P13～P27
●Start-up and SS capacity setting explanation P13,P14
●The setting of REG58 capacity and shutdown procedure P15
●VCC series resistance setting procedure P16
●The necessity for holding output voltage and FB voltage while PWM=Low P17,P18
●Ex planat ion of VOUT（OVP） voltage holding function when PWM=Low P19,P20
●FB current Source mode・Sink/Source mode P21,P22
●LED Current setting P23
●DC/DC converter drive frequency setting P23
●UVLO setting procedure P24
●OVP/SCP setting method P25
●LSP setting procedure P26
●Timer latch function P27
3.2 Selection of DCD C components P28～P30
●OCP setting procedure/DCDC component current tolerance selection procedure P28,P29
●Selection of Inductor L P30
●Selection of switching MOSFET transistors P30
●Selection of rectifier diodes P30
3.3 Timing chart P31
3.4 List of protection function P32
4. Caution on use P33
5. Ordering Information P34
6. Revision history P35
3/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
●Electrical Characteristics (unless otherwise specified, Ta = 25°C, VCC=24V )
Parameter Symbol Specification unit Condition
Min Typ Max
【
Whole Device
】
Operation Circuit Icc － 5.5 8.5 mA STB=3V, PWM1-6=3.3V
Standby current IST － 40 80 μA STB=0V
【
UVLO Block
】
Operating voltage (VCC） VUVLO_VCC 6.5 7.5 8.5 V VCC=SWEEP UP
Hysteresis voltage （VCC） VUHYS_VCC 150 300 600 mV VCC=SWEEP DOWN
UVLO release voltage VUVLO_U 2.88 3.00 3.12 V VUVLO=SWEEP UP
UVLO hysteresis voltage VUHYS_U 250 300 350 mV VUVLO=SWEEP DOWN
UVLO pin leakage current UVLO_LK -2 0 2 μA VUVLO=4V
【
DC/DC Block
】
Error amp. Reference voltage
(Min)
VLED 0.36 0.40 0.44 V
LEDx Terminal ILEDx =
40mA
Error amp. basic voltage
(ILED=130mA)
VLED 0.428 0.450 0.472 V
LEDx Terminal ILEDx =
130mA
Oscillation frequency FCT 142.5 150 157. 5 KHz RT=100kohm
Max. duty cycle of output N NMAX_DUTY 90 95 99 % RT=100kohm
RT short protection range RT_DET -0.3 - VRT×90% V RT=SWEEP DOWN
On resistance on N pin source
side
RONSO 1.5 3 6 Ω
On resistance on N pin sink side RONSI 1.5 3 6 Ω
RT pin voltage VRT 1 1.5 2 V RT=100kohm
SS pin source current ISSSO -2.6 -2.0 -1.4 μA VSS=2V
Soft start completion voltage VSS_END 3.52 3.70 3.88 V SS=SWEEP UP
FB source current IFBSO -115 -100 -85 μA VLED=0V, VFB=1.0V
FB sink current IFBSI 70 100 130 μA
VLED=5.0V(ALL_CH),
VFB=1.0V,VSS=4V
FB source mode
SS pin input voltage range
FB_SO_SS 4.9 - - V SS=SWEEP UP
FB sink/ sou rce mode
SS pin input voltage range
FB_SOSI_SS 3.9 - 4.4 V SS=SWEEP DOWN
Over current detect voltage VCS 372 400 428 mV CS=SWEEP UP
CS source current ICS 15 30 60 μA VCS=0V
【
DC/DC protection Block
】
OVP Detect Voltage (DCDC
Stop)
VOVP 2.90 3.00 3.10 V VOVP SWEEP UP
OVP protection timer release VOVP_CAN VOVP-0.14
VOVP-0.1
VOVP-0.04
V VOVP SWEEP DOWN
Short protection detect voltage VSCP 0.05 0.1 0.15 V VOVP SWEEP DOWN
OVP pin leakage current OVP_LK -2 0 2 μA VOVP=4V
4/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
●Electrical Characteristics (unless otherwise specified, Ta = 25°C, VCC=24V)
Parameter Symbol Specification unit Condition
Min Typ Max
【
LED Driver Block
】
LEDｘ pin current ac cura cy 1 ⊿ILED1 -2 - 2 % ILED=130mA
LEDｘ pin current ac cura cy 2 ⊿ILED2 -2.5 - 2.5 % ILED=150mA
LEDｘ pin leakage curre nt ⊿ILED3 -3.5 3.5 % ILED=250mA
ISET pin voltage ILLED -0.8 - 0.8 uA
STB=H, PWMx=L,
LEDx=40V
LEDｘ pin current ac cura cy 1 VISET 1.3 1.5 1.7 V RISET=30kΩ
【
LED protection Block
】
ISET short circuit protection range ISET_DET -0.3 - VISET×90%
V ISET=SWEEP DOWN
LEDｘSHORT protection voltage VLSP 8.5 9 9.5 V
LEDx=SWEEPUP,
LSP=OPEN
LSP pin resistive divider(Higher
R)
RULSP 1860 3100 5580 kΩ LSP=0V
LSP pin resistive divider(Lower R) RDLSP 540 900 1620 kΩ LSP=4V
LEDｘ OPEN detect voltage VOPEN 0.15 0.20 0.25 V LEDx=SWEEP DOW N
【
REG58 BLock
】
REG58 output voltage 1 REG58_1 5.742 5.8 5.858 V IO=0mA
REG58 output voltage 2 REG58_2 5.713 5.8 5.887 V IO=-15mA
REG58 max output current | IREG58 | 15 － - mA
REG58_UVLOdetect voltage REG58_TH 2.1 2.4 2.7 V
STB=ON
REG58=SWEEP DOWN
REG58_UVLO Hysteresis REG58_HYS 100 200 400 mV
STB=ON->OFF
REG58=SWEEP DOW N
REG58 Discharge current REG58_DIS 3.0 5.0 7.0 uA STB=ON->OFF REG58=4V
【
STB Block
】
STB pin HIGH voltage STBH 2 - 35 V STB=SWEEP UP
STB pin LOW voltage STBL -0.3 - 0.8 V STB=SW EEP DOWN
STB pin Pull Down resistance RSTB 600 1000 1800 kΩ VSTB=3.0V
【
PWM Block
】
PWMｘ pin HIGH voltage PWM_H 1.5 - 15 V PWMｘ=SWEEP UP
PWMｘ pin LOW voltage PWM_L -0.3 - 0.8 V PWMｘ=SWEEP DOWN
PWMｘ pin Pull Down resistance RPWM 1200 2000 3600 kΩ PWMｘ=3.0V
【
FAIL Block
（
OPEN
DRAIN
）】
FAIL Pin Ron RFAIL 250 500 1000 Ω VFAIL=1.0V
FAIL Pin Leakage current ILFAIL -2 0 2 μA VFAIL=5V
5/35 TSZ02201-0F10C1002000-1-2
© 2013 ROHM Co., Ltd. All rights reserved. 19.Oct .2 013 Rev.003
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
●Pin Numbers/Names/Functions
Pin No.
HSOP-M28 Pin Name
HTSSOP-B28 Symbol Function
1 8 ISET LED current setting resistor connec tion pin
2 9 PWM1 PWM light modulation signal input pin for LED1
3 10 PWM2 PWM light modulation signal input pin for LED2
4 11 PWM3 PWM light modulation signal input pin for LED3
5 12 PWM4 PWM light modulation signal input pin for LED4
6 13 PWM5 PWM light modulation signal input pin for LED5
7 14 PWM6 PWM light modulation signal input pin for LED6
8 15 GND Ground pin for analog block
9 16 FAIL Error detection output pin
10 17 OVP Overvoltage protection detection pin
11 18 LED6 LED output 6
12 19 LED5 LED output 5
13 20 LED4 LED output 4
14 21 LED_GND Ground pin for LED
15 22 LED3 LED output 3
16 23 LED2 LED output 2
17 24 LED1 LED output 1
18 25 UVLO Detection pin for Under voltage Lockout prevention
19 26 LSP LED short-circuit protect io n vol tage sett ing pin
20 27 STB Enable pin
21 28 VCC Power supply pin
22 1 REG58 5.8V regulator output pin / Shutdown timer pin
23 2 CS
DC/DC output current detection pin
OCP detection pin
24 3 N DC/DC switching output pin
25 4 DCDC_GND DC/DC GND pin
26 5 RT DCDC Drive frequency setting connection pin
27 6 FB Error Am p output pin
28 7 SS
Slow start/
LED protection masking time setting pin
●External Component Recommended Range
Parameter Symbol Specification unit
VCC pin connecting capacity
CVCC
～
μF
VCC pin connecting resistance
RVCC
～
kΩ
REG58 pin connecting capacity
C_REG
～
μF
Soft start setting capacity
CSS
～
μF
RT pin connection resistance range
RRT
～
kΩ
ISET pin connecting resistance range
RISET
～
kΩ
The operating conditions listed above are constants for the IC alone. To make constant setting with practical set devices, utmost attention shoul d be paid.
*1 Please ref er to 【3.2 function explanatiob and selection of external components for thes election of VCC
series resistance.
6/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
●Internal Equivalent Circuit Diagrams
REG58 / N / CS / DCDC_GND SS FB
REG58
N
DCDC_GND
CS
SS
FB
OVP ISET RT
OVP
100k
2k
4k
5V
ISET
RT
STB FAIL UVLO
STB
1M
1M
5V
FAIL
500
UVLO
1M
5V
LED1-6/LED_GND PWM LSP
LED1-6
LED_GND
PWM1-6
2M
100k
5V
LSP
4V
3.1M
900k
5V
100k
Figure 6. Internal Equivalent Circuit Diagrams
7/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
VREG
OVP
Control
Logic
Current
Sence
+
-
+
-
-
-
-
PWM COMP Driver
ERR AMP
Current driver
VCC
STB
FB
DCDC_GND
CS
N
FAIL
OVP
UVLOREG58
Rpc
Cpc
C
VCC
VCC
COUT
LED4
LED3
LED2
LED1
Timer
LOGIC
OSC
RT
AGND
UVLO
(VCC) UVLO
CREG
+
Open-Short
Detect
ISET
OSDET
+
V
IN
C
IN
ISET
LEDGND
TSD SCP
PWM1
PWM2
LSP
4V
3V
SS
PWM3
PWM4
OS DET
SS
Css
SS FB
Clamp SS_END
SS_END
LED5
LED6
-
-
PWM5
PWM6
1.5V
0.9V
+
REG58
Use at
At sink source mode
● Block Diagram
●Characteristic date(reference date)
Figure 8. ICC[mA] vs V CC[V]
Figure 9. REG58[V] vs VCC[V]
Figure 7. Block Diagram
3
4
5
6
7
8
9
10
914 19 24 29 34
VCC[V]
ICC[mA]
5.0
5.5
6.0
6.5
7.0
914 19 24 29 34
VCC[V]
REG58[V]
8/35 TSZ02201-0F10C1002000-1-2
© 2013 ROHM Co., Ltd. All rights reserved. 19.Oct .2 013 Rev.003
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
Figure 10. ILED[mA ] vs Temp[
℃
]
Figure 11. IFB[uA] vs LEDx[V]
( @ILED=130mA)
Figure 12. ILEDx[mA] vs RISET[kohm]
Figure 13. FCT [kHz] vs RRT[kohm]
120
122
124
126
128
130
132
134
136
138
140
-40 -20 0 20 40 60 80
Temp[℃]
ILED[mA]
-160
-120
-80
-40
0
40
80
120
160
0.0
0.2
0.4
0.6
0.8
1.0
LEDx[V]
IFB[uA]
10
100
1000
10 100
RISET[kohm]
ILEDx[mA]
10
100
1000
10 100 1000
RRT[kohm]
FCT [ kHz ]
9/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
2. Understanding BD9470AEFV・BD9470AFM
●Pin Functions
○ISET （HTSSOP-B28:8PIN/HSOP-M28：1PIN）
The ISET pin is a resister value of output current setting. The output current ILED vary in inverse proportion to resister
value. The relation of the output current ILED and ISET pin connecting resistor RISET are as bellow.
However, current setting range is from 40mA to 150mA.
And the setting of ISET resistor is bellow at using 150mA to 250mA.
ILED(mA) 150 160 170 180 190 200 210 220 230 240 250
RSET(kohm) 20.00 18.80 17.72 16.76 15.90 15.12 14.42 13.78 13.19 12.66 12.16
For a setting example, please refer to ‘3.1 application explanation / LED current setting’.
When the RISET is shorted and the ISET pin is grand shorted, the LED current is OFF and the FAIL=OPEN(abnormal
signal) to prevent flowing a large current to LED pin when it becomes less than VISET×0.90V(typ).
When the ISET pin back to normal state the LED current return to former system, too and the FAIL=GND(normal signal).
It prepare automatically to suitable LED feedback voltage that can output LED curr ent set b y ISET pin.
In short LED feedback voltage is dropped when the LED current is small and the IC heating is held automatically.
In case of a large current is needed, raise the LED pin feedback voltage. And it adjust automatically to LED pin voltage that
can be flow large LED current.
The calculation is as below.
The LED feedback voltage (VLED) is clamped to 0.4V(typ.) when the LED current (ILED) is less than 115.6mA.
○PWM1-6 （HTSSOP-B28:9,10,11,12,13,14PIN / HSOP-M28：2,3,4,5,6,7PIN）
The ON/OFF pin for LED driver. Light can be modulated by changing the duty cycle through the direct input of a PWM
light modulation signal in each PWM pin.
The high and low voltage levels of PWM_x pins are as listed in the table below.
State
PWMxvoltage
LED ON state PWMx=1.5V~15.0V
LED OFF state PWMx=‐0.3V～0.8V
The sequence of STB/PWM for start-up, please input PWM signal before STB or the same timing STB=PWM=ON.
○GND （HTSSOP-B28:15PIN / HSOP-M28：8PIN）
IC internal analog GND pin.
○FAIL （HTSSOP-B28:16PIN / HSOP-M28：9PIN）
FAIL signal output pin （OPEN DRAIN）.Internal NMOS will become OPEN while abnormal is detected.
○OVP （HTSSOP-B28:17PIN / HSOP-M28：10PIN）
The OVP pin is an input pin for overvoltage protection and short circuit protection of DC/DC output voltage. If over voltage
is detected, the OVP pin will stop the DC/DC converter conducting step-up operation. If Vout was increased by abnormality,
timer is set while OVP＞2.9V(typ.).when it comes to OVP＞3.0V, timer will ON at the same time and to stop DCDC.
Although Counter will be stopped when OVP＜2.9V during counting time, in the state of OVP>2.9V, when internal counter
completed 218count （262152 count）, the system will be latched.
When the short circuit protection (SCP) function is activated, the DC/DC converter will stop operation, and then the timer
will start counting, after 216 count（65536 count）, DCDC and LED driver will stop and latch.
The OVP pin is of the high impedance type and involves no pull-down resistor, resulting in unstable potential in the
open-circuit state. To avoid this problem, be sure to make input voltage setting with the use of a resistive divider or
otherwise. OVP pin will be feedback pin when PWM=L. Also, this pin will hold OVP voltage at that time when switch PWM
= H to L.
For setting example, refer to information in“3.4 Selection of External Components-OVP/SCP s etting procedure
OVP Voltage keep internal IC with PWM=Low timing, and VOUT voltage can hold by using copied OVP voltage while
PWM=Low.（The OVP keep voltage range is 0~3V, 30steps）.For setting example, refer to information in “3.2 Selection of
External Components”, “Explanation of VOUT（OVP） voltage holding function when PWM=Low”
State FAILoutput
Normal GND
Abnormal（After Timer Latch） OPEN Level
　　][
][
3000 Ω= k
mAI
R
LED
ISET
　　][][462.3 VAIVLED LED
×=
　　][)][(2653 9753.0 Ω×= −kmAIR LEDISET
10/35 TSZ02201-0F10C1002000-1-2
© 2013 ROHM Co., Ltd. All rights reserved. 19.Oct .2 013 Rev.003
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
○LED1-6 （HTSSOP-B28:18,19,20,22,23,24PIN / HSOP-M28：11,12,13,15,16,17PIN）
LED constant current output pins. Current value setting can be made by connecting a resistor to the ISET pin.
For the current value setting procedure, refer to the description of “ISET pin”.
If any of the LED pins is put in an abnormality state (short circuit mode, open circuit mode, ground short mode), the
relevant protection function will be activated.
・LED pin short circuit protection function ( LSP)
When any LED is in short state (more than LED=9.0V(typ)) the LED SHORT is detected.
After abnormal detection, the timer count starts. The LED that is abnormal detection after 216 count is stopped and other
LED driver operates normally.
・LED pin open circu it prot e cti on function (LOP)
If any of the LED pins becomes open-circuited (0.2V (Typ.) or less), LED_OPEN will be detected. When this error is
detected, the timer will start counting, When it completes counting the preset period of time, only LED driver that detected
the error will stop operation and other LED driver will conduct normal operation.
・LED GND_SHORT protection function
When any LED pin is GND shorted the LED pin becomes less than 0.20V and the pin is latched because of LED_OPEN
detection. After that, the LED pin is pull upped by inner supply but it continues less than 0.2V state in grand sho rte d. After
detecting timer of open state, if the grand shorted (open) state continues 27 counts all systems are latched.
To prevent the miss detection there is 4 count interval of mask before starting the timer count.
If PWM=H time is
P WM=H time < 4count・・・Not detect protecti on beca us e it is in int er v al time
PWM=H time > 4count・・・Detect protection because it is out of interval time
Please verify enough to operate narrow PWM.
○LED_GND （HTSSOP-B28:21PIN / HSOP-M28：14PIN）
The LED_GND pin is a power ground pin used for the LED driver block.
○UVLO （HTSSOP-B28:25PIN / HSOP-M28：18PIN）
This pin is used to for step-up DC/DC converter. When UVLO pin voltage reaches 3.0V (Typ.) or more, IC will initiate
step-up operation. If it reaches 2.7V (Typ.) or less, the IC will stop the step-up operation.
The UVLO pin is of the high impedance type and involves no pull-down resistor, resulting in unstable potential in the
open-circuited state. To avoid this problem, be sure to make input voltage setting with the use of a resistive divider or
otherwise.
For calculation examples, refer to information in ’3.1 application explanation/UVLO setting p roced ur e’
○LSP （HTSSOP-B28:26PIN / HSOP-M28：19PIN）
The setting pin for detection voltage of LED short circuit protection. The LED short circuit detection voltage is set to 9V
(Typ.) with the LSP pin being in the open-circuited state. However, making a change to the LSP pin input voltage will allow
the threshold for LED short circuit protection to be changed.
The relation between the LSP pin voltage and the LED short circuit protection detection voltage is given by the following
equation.
Here LEDSHORT：LED detection voltage
VLSP：LSP setting voltage
LSP pin input voltage setting should be made in the range of 0.3V to 2.5V.
For setting example, refer to information in’3.1 appli cati on ex planation/LSP setting procedure’
][
10 V
VLED
VLSP SHORT
SHORT 　=
LEDx
CLK
FAIL
1 2 3 4 1 2 216
9V
Interval of mas k
Ti m er count
Figure 14. Timing chart of timer count
11/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
○STB (HTSSOP-B28:27PIN / HSOP-M28：20PIN）
The pin is used to ON/OFF the IC and allowed for use to reset the IC from shutdown.
The IC state is switched between ON and OFF state according to voltages input in the STB pin. Avoid using the STB pin
between two states (0.8 to 2.0V).
Input sequence of ST B/PWM for startup, please input PWM before STB or at the same timing.
While in shutdown mode, the timer keeps counting until the IC is completely shut down. For details of shutdown operation,
refer to information in’3.1 application explanation/ the setting of REG58 capacity and shutdown procedure'
○VCC （HTSSOP-B28:28PIN / HSOP-M28：21PIN）
IC power supply pin. Input range is 9~35V.
VCC pin voltage reaches 7.5V (Typ.) or more, the IC will initiate operation. If it reaches 7.2V (Typ.) or less, IC will be shut
down.
○REG58 （HTSSOP-B28:1PIN / HSOP-M28：22PIN）
The REG pin is used in the DC/DC converter driver block to output 5.8V voltage. The maximum operating current is
15mA.Using the REG pin at a current higher than 15mA can affect the N pin output pulse, causing the IC to malfunction
and leading to heat generation of the IC itself. To avoid this problem, it is recommended to make load setting to the
minimum level.
In addition, The REG58 pin is also allowed for use as discharge timer for DC/DC output capacitance.
For details, refer to information in ’3.1 application explanation/ the setting of REG58 capacity and shutdown procedure'
○CS （HTSSOP-B28:2PIN / HSOP-M28：23PIN）
The CS pin has the following two functions.
１．DC/DC current mode current feed Back function
Current flowing through the inductor is converted into voltage by the current sensing resistor RCS which connected to CS
pin and this voltage is compared with voltage set with the error amplifier to control the DC/DC output voltage.
2．Inductor current limit function (OCP pin)
The CS pin also incorporates the overcurrent protection (OCP) function. If the CS pin voltage reaches 0.4V (Typ.) or more,
switching operation will be forcedly stopped.
For detailed explanation, Please refer to information in “3.2 Selection of DC/DC Components-OCP setting procedure /
DC/DC component current tolerance selection procedure”.
○N （HTSSOP-B28:3PIN / HSOP-M28：24PIN）
The N pin is used to output power to the external NMOS gate driver for the DC/DC converter in the amplitude range of
approximately 0 to 5.8V.Frequency setting can be adjusted by a resistor connected to the RT pin. For details of frequency
setting, refer to the description of the RT pin.
○DCDC_GND （HTSSOP-B28:4PIN / HSOP-M28：25PIN）
The DCDC_GND pin is a power ground pin for the driver block of the output pin N.
○RT （HTSSOP-B28:5PIN / HSOP-M28：26PIN）
The RT pin is used to connect a DC/DC frequency setting resistor. DC/DC drive frequency is determined by connecting the
RT resistor.
・Relationship between Drive frequency and RT resistance (Ideal)
However, drive frequency setting is limited in the range of 100 kHz to 500kHz.
For calculation, refer to information in ’3.1 applicati on explanation/ DC/DC converter drive frequency setting’
When it reaches under VRT×0.90V(typ), DCDC operation will be stopped in order to prevent from high speed oscillation
when the RT resistance is shorted to GND. And when RT pin returns to normal state, DCDC also returns to operation.
○FB （HTSSOP-B28:6PIN / HSOP-M28：27PIN）
The FB pin is an output of DC/DC current mode error amplifier. FB pin detects the voltages of LED pins (1 to 6) and
controls inductor current so that the pin voltage of the LED located in the row with the highest Vf will come to 0.45V(130mA,
typ.). Therefore, the pin voltages of other LEDs will become higher by Vf variation.
FB Voltage keep internal IC with PW M=Low timing, and it can hold by using copied FB voltage while PW M=Low.（The FB
keep voltag e ra nge is 0~4V, 40steps）
For setting example, refer to information in ’3.1 application explanation/ the necessity for holding output voltage and FB
voltage while PWM=Low’
○SS （HTSSOP-B28:7PIN / HSOP-M28：28PIN）
Soft start time and duty for soft start setting pin. The SS pin normally sources 2.0uA (Typ.) of current.
The IC has a built-in soft start start-up circuit independent of PWM light mo dula t io n, and thereby raises FB voltage as SS
pin voltage rises independent of the duty cycle range of PWM light modulation. When the SS pin voltage reaches 3.7V
(Typ.), soft start operation will be completed to unmask the LED protection function.
For setting example, refer to information in ’3.1 applicati on ex plan atio n/ start-up and SS capacity setting explanation’
　][
][
15000 Ω= k
kHzf
R
SW
RT
12/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
SS
REG58
Css[F]
Iss[A] 4.7V＜Vss
⇒FB Output Current
=Source Only
V
V
VREG58[V]
Vss
3. Application of BD9470AEFV・BD9470AFM
3.1 BD9470AEFV・BD9470AFM examination for application
●Start-up and SS capacity setting explanation
This section described the start-up sequence of this IC.
○Description of start-up sequence
①STB=PWM=ON
②System is ON.SS starts to charge.
At this time, a circuit in which SS voltage for slow start is equal to FB voltage regardless of whether the PWM pin is set to
Low or High level.
③Since the FB pin and SS pin reach the lower limit of the internal sawtooth wave, the DC/DC converter operates and
VOUT voltage rising.
Until it reachs a certain voltage even PWM=Low by vlotage maintenance function.
（For detailed OVP maintanence function, please refer to”VOUT(OVP) maintanence function section”.）
⑤Vout voltage continues rising to reach a voltage at which LED current starts flowing.
⑥When the LED current reaches the set amount of current, isolate the FB circuit from the SS circuit. With this, the start-up
operation is completed.（Fast start-up is also diasabled by VOUT maintanence function）
⑦After that, conduct normal operation following the feedback operation sequence with the LED pins.
If the SS pin voltage reaches 3.7V or more, the LED protection function will be activated to forcedly end the SS and
FBequalizing circuit.
○ SS capacity set ting method
Boot system as above described, because of start-up in the state of FB=SS, the start-up time can be imaged of the time to
reach the point from the feedback voltage FB from STB = ON.If you SS> 4.9V, FB output current mode will become Source
mode operation.
If the feedback voltage of FB is the same as VSS and the time can be calculated as below.
][
][2 ][][ Sec
AVVFBFC
Tss
ss
µ
×
=
Figure 15. Timing chart of start-up
Figure 16. SS setting procedure in FB Source mode
STB
SS
SLOPE
PWM
N
VOUT
ILED
LED_OK
①
⑦
⑥
③
②
⑤
FB
OSC
④
LED_OK
SS=FB
Circuit
SS
FB
5V
0.3～
0.519V
LED_DRIVER
OSC
DRIVER
COMP N
LED
VOUT
ILED
PWM
PWM=L:STOP
2uA
SS
SLOPE
D
Q
PWM
Css
OVP
KEEP
OVP
STOP/ACT
LED_OK
Time
Vss, VFB[V]
SS=FB
Finished Start Up
VSS>4.9V FB=Source Mode
4.9V
13/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
SS
REG58
R1[ohm]R2[ohm]
Css[F]
Iss[A]
V
Vss
V
VREG58[V]
3.9V＜Vss＜4.4V
⇒FB Output Current
=Sink & Source mode
However, if SS is set too short, inductor rush current will occur during start-up.In addition, if SS time is set too long, will
result in the brighter in stages.SS capacity will veries with various factors, such as voltagestep-up ratio, DCDC driver
frequency, LED current and output output condencer, so it is recommended to test and confirm on the actual system.
（SS capacity is often set at about 0.047uF～0.47uF approximately as a reference value）
○Setting example
SS time when the start-up is complete and Css = 0.1uF, Iss = 2uA, Vss = 3.7V will be calculated as follows.
In addition, when FB output is operated in Sink/Source mode（refer to “FB pin output curre nt setting for detailed
explanation.）, SS voltage can be set to be in the range of 3.9V～4.4V at the SS pin voltage resistor divider.Soft-start time
will be set in that case is as follows.
○Setting example
When R1=200kohm, R2=470kohm, Css=1.0uF, VREG58=5.8V, Iss=2uA, Vss=3.7V, SS time is set as below
]Sec[185.0
]A[E2 ]V[7.3]F[E1.0
T
6
6
ss
=
×
=
−
−
][
][
ln Sec
BVVssA
A
Tss
×
−−= 1
1
][][
][ ][ ][][][ ][][
FCssAIss
ohmRVVREG
B
ohmRohmRFCss ohmRohmR
A
÷
+=
××
+
=
158
21 21
]Sec[266.0
31 7.312.7
1ln
12.71
Tss =
×
−−=
Figure 17. SS setting procedure in FB sink/ source mode
Time
Vss, VFB[V]
SS=FB
Finished Start Up
3.9V<VSS<4.4V
FB=Sin/Source Mode
4.9V
4.4V
3.9V
14/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
●The setting of REG58 capacity and shutdown procedure
VOUT discharge function is built-in this IC when IC is shutdowned, the below decribes the operation sequence.
○Explanation of shutdown sequence
①Set STB pin to “OFF” will stops DC/DC converter and REG58, but LED driver will remain operation.
（Reset signal is output 1uS extent to reset the latch on the IC at this time.Therefore, undershooting will be generated on
LED current, but 1uS is very short will not affect The brightness.）
②Discharge the REG58 pin voltage from 5.8V to 2.4V with −5uA current.
③The VOUT voltage will be fully discharged with ILED current and the ILED current will no longer flow.
④When REG58pin voltage will reach 2.4V (Typ.) or less to shut down all systems
○REG58 capacitance setting procedure
The shutdown time “TOFF” can be calaulated by the following equation.
The longest VOUT discharge time will be obtained when the PWM duty cycle is set to the minimum VOUT.
Make REG capacitance setting with an adequate margin so that systems will be shut off after VOUT voltage is fully
discharged.
][
][ ][.][ Sec
uA VFC
T
REG
OFF
　
543×
=
Figure 18.Timing chart of shutdown
2.4V
STB
VOUT
N
REG50
PWM
ILED
②
①
④
③
LED_DRIVER
DRIVER
N
LED
VOUT
ILED
PWM
PWM=L:STOP
CS
REG58
5uA
STB
ON->OFF
REG58
2.4V/2.5V ALL SHUTDOWN
C
REG
1uS Pulse
ALL SHUTDOWN
15/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
VCC
VIN
RVCC ΔV
I_IN
REG58
+
-
RREG
IREG
DCDC
DRIVER
NI_N
IC
BLOCK
ICC
IDCDC
● VCC series resistance setting procedure
By inserting a series resistor to VCC will has the following affection.
①Reduce the voltage VCC, and it is possible to suppress the heat generation of IC.
（ICC×VIN is power consumption of IC）
②Possible to Raise the surge ability to VCC.
However, if resistance is set too large, it is needed to consider that will
result in VCC become VCC<9V（Minimum operation voltage）.So the
appropriate series resistance setting is needed.
The current influx of IC I_IN as shown on the right is
・Circuit current of IC…ICC
・Current to load is connected toREG58…IREG
・Current which used to drive DCDC FET…IDCDC
There are 3 paths within IC and the ΔV of RVCC can be decided.
VCC voltage generated by the relation as above described at that time
can be represented as below.
The Criterion of 9V is the minimum operating limit of the IC.
When a series resistance is considered, please set with a sufficient
margin.
○Setting example
Above equation can be transformed as below.
In typical operation, VIN=24V, ICC=5.5mA, RREG=10kΩ, IDCDC=2mA can be assumed and the VCC voltage is
However, the result is in typical operation and the variability and margin is not considered.
If the variability of VIN=24V×(-20%）,ICC=8.5ｍA,RREG=10k×(-5%）,REG58=5.8V×(+5%),IDCDC=2mA×(+100%),VCC
operation limit voltage9V×(+20%) are assumed:
According to above result, set RVCC = 640Ω or less is adequate on actual application.
When a series resistance is considered, please set with a sufficient margin.
( )
][9][][][][][][][ VVRVCCAIREGAIDCDCAICCVVINVVCC >Ω×++−= 　
][][][ ][9][
][ AIREGAIDCDCAICC VVVIN
RVCC ++
−
<Ω
][86.1
][10000][8.5][002.0][0055.0 ][9][24
][ Ω=
Ω++
−
<Ω k
VAA VV
RVCC
][640
)95.0][10000(][015.18.5][2002.0][0085.0 ][2.19][8.024
][ Ω=
×Ω×+×+
×−×
<Ω VAA VV
RVCC
Figure 19. ICC paths diagram
16/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
-
+
GMAMP
L
H
FB
LED1
PWM signal
L
H
Holding FB Vol.
BLOCK
FB IN FB COPY
-
LED2
-
L
H
L
H
100pF～2200pF
●The necessity for holding output voltage and FB voltage while PWM=Low
In conventional control method, DCDC will be stopped and FB voltage become high impendence while PWM=Low.
However, if PWM=0% is continued to inputted to system, output voltage and FB voltage is reduced because of discharge
phenomenon.eventually output voltage is equal to VIN, and FB voltage drop to 0V.There are several problems such as the
following listed if PWM dimming signal is tried to light-up a system.
①Slow start cannot be controlled resulting in the FB voltage overshoot and rush current flow to Inductor.
②Flash phenomenon occur due to start-up control does not work.
③Because there is a need to re-boost, take a long time to light up.
In this IC, the problems as above mentioned is resolved by coping output voltage and FB voltage to IC internally at a time
of PWM from High to Low.
The below describes FB and VOUT voltage holding function in detail.
○Explanation of FB voltage holding function while PWM=Low
FB holding function means FB voltage will be copy to IC internally at a time of PWM from High to Low, FB voltage will be
maintained even in the period of PWM=Low.
Because FB voltage resolution is split by 40 from 4 V, so the voltage can be copied to IC internally in 0.1V Step.
In addition, FB pin voltage will be influenced by DCDC operation, the copied have ±0.1V difference problem. But because
FB voltage is returned as feedback voltage immediately and will not cause an operational problem while PWM=H, it is
recommende d to add about 100pF～2200pF to FB pin for noise reduction.
Figure 20. Block diagr am of KEEP_FB
17/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
①PWM=High, normal feedback operation by LED pin
②FB voltage is copied to IC at a time of PWM from High to Low. FB voltage will be copied by less than 1Bit.
For Example：when FB=2.16V, FB COPY voltage is 2.1V.
③GMAMP is works as Buffer with while PWM=Low, FB voltage is discharged to FB COPY voltage.
④FB COPY=FB voltage.
⑤FB COPY=FB voltage and maintain.
If PWM=0% and because follow the state⑤ continuously, FB voltage will not dropped by natural discharge.
※Notice
FB voltage holding function is performed at 0.1V STEP. If PWM signal is in low duty, FB voltage is not able to rise
sufficiently when FB series resistance is small causing to RFB×IFB(typ.100uA)＜0.1V(typ.), The output voltage may not be
boosted up to the set voltage.
Therefore, it is recommende d to set RF B> 2kohm so that ΔV = RFB × IFB> 0.2V.
Figure 21. Timing chart of KEEP_FB
Figure 22. Voltage to FB resistor
PWM
FB COPY
FB
①
②④
③⑤
FB
IFB(100uA typ)
RFB
CFB
⊿V=RFB×IFB>0.2V
18/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
VIN
CS
DCDC_GND
N
LED1-6
VCC
OVP
VOUT
OVP_IN
OVP COPY
-
+
OVP
COMP
PWM signal
-
ICOMP
+
SLOPE
SS
+
FB
CONTROL
LOGIC DRIVER
+
Holding OVP
Vol. BLOCK
H : DCDC ON
L : DCDC OFF
LED_OK
●Explanation of VOUT（OVP） voltage holding function when PWM=Low
OVP holding function means VOUT(OVP) voltage will be copy to IC internally at a time of PWM from High to Low, voltage
will be maintained even in the period of PWM=Low.
In addition to measures of the above problems, by applying this function, the high-speed start-up can be achieved without
depending on the PWM.
Because VOUT voltage resolution is the same as FB holding function which is split by 40 from 4V,so the voltage can be
copied to IC internally in 0.1V Step.
The description of OVP holding function is divided into narrow PWM operation and start-up operation.
○Explanation of OVP holding function at start-up
In order to launch high speed start-up without depending on the PWM DUTY, OVP holding function will behave like the
following descriptions.
①PWM=High, normal boost operation.
②OVP voltage is copied into IC when PWM is from High to Low.OVP voltage will be copied upper 1BIT at this time. For
example: if OVP=2.43V, the copied voltage is 2.5V in IC.
③The copied OVP voltage will be compared with OVP pin voltage internally, if OVP_COPY>OVP, DCDC is operated.In
other words, it is possible to achieve fast start-up by letting the voltage on the 1BIT boosted up in the interval of PWM =
Low.
④When OVP_COPY<OVP pin voltage, DCDC is stopped.
⑤Even if in the period of PWM=Low and VOUT is discharged, output voltage will be hold by performing DCDC operation
in order to let OVP_COPY＜OVP pin voltage.
Figure 23. Block diagr am of KEEP_OVP
Figure 24. Timing chart 1 of KEEP_OVP
PWM
OVP COPY
OVP
N
①
②
③
④
⑤
19/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
○Explanation of OVP holding function in narrow PWM duty
DCDC operates only in the duration of PWM=High while narrow PWM is inputted, output voltage drops when PWM=0%.
But, DCDC is operated by coping voltage even if PWM=Low duration in this IC and output voltage will not drops.
①PWM=High, normal operation.
②OVP voltage is copied into IC when PWM is from High to Low.OVP voltage will be copied under 1BIT at this time. For
example: if OVP=2.43V, the copied voltage is 2.4V in IC.
③VOUT is discharged by OVP resistance.
④When copied OVP_COPY＞OVP pin voltage, DCDC is operated, when OVP_COPY＜OVP voltage, DCDC is stops.
When operates in PWM=0%, the point④ will be repeated and repeated, so the output voltage will not drops naturally.
○Condition of copy OVP voltage
The copied OVP pin voltage as above explanation, it has upper and lower 1BIT difference according to below condition.
Conditions of copy upper 1BIT
：From startup to completion of step-up
：OVP detection state
Conditions of copy lower 1BIT
：Normal oper ation state ( OVP undetected state)
※The reason about why copy the voltage of upper 1BIT when OVP is det ected
When OVP is detected by OVP=3V and stops DCDC operation. After that while PW M=Low and if copy lower 1BIT voltage will results in
OVP=2.9V and release OVP detection function, therefore it is designed to copy upper 1BIT when OV P is detected.
Figure 25. Timing chart 2 of KEEP_OVP
PWM
OVP COPY
OVP
N
①②
④
③
20/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
PWM5
PWM6
PWM4
PWM2
PWM3
PWM1
PGND
RCS
CS
N
OVP
LED1
LED2
LED3
LED4
LED5
LED6
FB
CFB
RFB
●FB current Source mode・Sink/Source mode
The output of GMAMP is constant current control in normal operation ans output anout±100uA(typ.) in this IC.
But, when PWM scanning operation and local dimming is performed, total LED current and output voltage will different by
each timming and FB feedback voltage.The below describes the this operation.
As above shown,short PWM1,2,3 ans PWM4,5,6, assumed that scanning operation is performed.
At this time, the sequence is described as below.
①When PWM4,5,6=High→Low, FB voltage, VOUT（OVP）voltage is copied
②Copied voltage is hold.
③When PWM1,2,3=High again, normal DCDC operation
④When PWM4,5,6=High again, LED current increase.
⑤Because LED current increase resulting in FB voltage change.it take a long transition time because FB source current is
100uA at this time, therefore FB voltage is not insufficient and output voltage and LED current will drop.
⑥FB voltage reaches the feedback voltage and LED current and output voltage will operate normally.
In other words, ILED current drops at the point ⑤, This may be due to the transition time of the behavior that FB current
sink first and then charge again.
Figure 26. Timing chart of FB sink/source mode
PWM
1,2,3
PWM
4,5,6
FB
ILED
①
④
③
⑤
②
⑥
VOUT
21/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
Therefore, in order to solve this problem in this IC, equipped with a mode of “FB current only source 0uA～+100uA”as a
countermeasure to reduce the LED current drop problem.
“FB Source mode”is described as below.
①when PWM4,5,6=High→Low, FB voltage, VOUT（OVP）voltage is copied
②copied voltage is hold.
③when PWM1,2,3=High again, normal DCDC operation.but, FB voltage is larger than feedback voltage, and VOUT setting
voltage also higher.
③when PWM4,5,6=High, LED current increases.
④although LED current is increased but the FB voltage has reached the feedback voltage and will not change at this
time.Therefore, there is no transition and VOUT, LED current will not drop.
⑥LED current and output voltage is operate normally
⑦When PWM1,2,3=Low, LED current reduces.But, FB is only has source ability , FB voltage is maintained continuely
（But, despite the decreasing of LED current, output voltage is increases because FB voltage is not changed.）
According to above operation, the LED undershoot problem cab be prevented by FB source mode.
However, the above description is a simplified explanation for behavior, because the actual behavior of a waveform is
different from the above, please check on the actual system.
When FB source mode is used, care must be taken to the fo llowing contents .
Because it can be held at a higher voltage than normal FB voltage, output voltage may be higher. Therefore, please note
that the heat might be higher than PWM = 100% while scanning operation is performed.
Figure 27. Timing chart of FB source mode
PWM
1,2,3
PWM
4,5,6
FB
ILED
①
④
③
⑤
②
⑥
VOUT
⑦
22/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
●LED Current setting
Setting of LED output current “ILED” can be made by connecting a resistor RISET to the ISET pin.
RISET and ILED current setting equation
However, LED current setting should be made in the range of 40mA to 150mA.
And the setting of ISET resistor is bellow at using 150mA to 250mA.
ILED(mA)
150
160
170
180
190
200
210
220
230
240
250
RSET(kohm)
20.00
18.80
17.72
16.76
15.90
15.12
14.42
13.78
13.19
12.66
12.16
○Setting Example
To set ILED current to 100mA, RISET resistance is given by the following equation
●DC/DC converter d rive frequency settin g
DC/DC converter drive frequency is determined by making RT resistance setting.
○Drive frequency vs. RT resistance (ideal) equation
○Setting example
To set DC/DC drive frequency “fsw” to 200 kHz, RRT is given by the following equation
And , the drive frequency setting range is 100kHz～500kHz.
　　][
][
3000 Ω= k
mAI
R
LED
ISET
　　][30
][100
3000
][
3000 Ω=== k
mAmAI
R
LED
ISET
　][
][
15000 Ω= k
kHzf
R
SW
RT
　　][75
][200
15000
][
15000 Ω=== k
kHzkHzf
R
sw
RT
This equation has become an ideal equation without any correction item included.
For accurate frequency settings, thorough verification should be performed on
practical sets.
Here fsw = DC/DC converter oscillation frequency
[kHz]
　　][)][(2653 9753.0 Ω×= −kmAIR LEDISET
23/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
●UVLO setting procedure
UVLO pin for step-up DC/DC power supply. If the UVLO pin voltage reaches 3.0V (Typ.) or more, the IC will start step-up
operation. If it reaches 2.7V (Typ.) or less, the IC will stop the step-up operation.
UVLO pin is the high impedance type and no pull-down resistor inside, resulting in unstable potential in the open-circuit
state. To avoid this problem, be sure to set input voltage with the use of a resistive divider.
While the VIN voltage to be detected is set by the use of resistive dividers R1 and R2 as described below, resistance
setting will be made by the following equation.
○UVLO setting procedure
Assume that VIN is reduced and detected,
UVLO is “VINDET”, R1 and R2 setting will be made by the following equation:
○UVLO release voltage setting equation
When R1 and R2 setting is determined by the equation shown above,
UVLO release voltage will be given by the following equation.
○Setting example
Assuming that the normal VIN operating voltage is 24V, UVLO detection voltage is 18V, and R2 resistance is 30kΩ, R1
resistance setting is made by the following equation
And, when UVLO release voltage VINCAN setting is made with R1 and R2, it will be given by the following equation
To select DC/DC components, give consideration to IC variations as well as individual component variations, and then
conduct thor ough verifi cat ion o n actual sy ste ms .
　][
]
[7.2 ])[7.2][(
][21 Ω
−
×Ω= k
VVVVIN
kRR
DET
　][
][2 ])[2][1(
0.3 V
kR kRkR
VVIN
CAN
Ω
Ω+Ω
×=
UVLO
CUVLO
VIN
R2
R1
2.7V/3.0V
+
-
ON/OFF
][170
][7.2 ])[7.2][18(
][30
][7.2 ])[7.2][(
][21 Ω=
−
×Ω=
−
×Ω= k
VVV
k
VVVVIN
kRR
DET
][20][
][30 ][170][30
][0.3
][2 ])[2][1(
][0.3 VV
kkk
V
kR kRkR
VVIN
CAN
=
Ω
Ω+Ω
×=
Ω
Ω+Ω
×= 　
Figure 28. Block diagr am of UVLO
24/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
●OVP/SCP setting method
The OVP pin is an input pin for overvoltage protection and short circuit protection of DC/DC output voltage.
The OVP pin is a high impedance type and no pull-down resistor inside, resulting in unstable potential in the open circuit
state. To avoid this problem, be sure to make input voltage setting with the use of a resistive divider.
Conditions for each OVP protections are as listed in the table below.
Protection name Protection
pin Detection
Condition Release
Condition Timer
Operation Protection type FAIL pin
OVP Timer SET /
OVP Cancel
OVP OVP>2.9V OVP<2.9V Yes All latch GND
OVP Detect /
DCDC STOP
OVP OVP>3.0V OVP<3.0V No
Only DCDC converter
stops during detection
OPEN
SCP
OVP
OVP<0.1V
OVP>0.1V
Yes
All latch
GND
The following describes the setting procedures of that VOUT pin voltage to be detected is set by the use of resistive
dividers R1 and R2 as shown in the circuit diagram below.
○OVP detection setting method
Assuming that a voltage causing VOUT to abnormally rise
and detecting OVP is “VOVPDET”,
R1 and R2 setting will be made by the following equation.
○Timer set・OVP release setting equation
When R1 and R2 setting is determined by the equation
shown above, OVP release voltage VOVPCAN will be
given by the following equation:
○SCP dete cti on equation
When R1 and R2 setting is determined by the equation
shown above, SCP setting voltage VSCPDET will be given
by the following equation.
○Setting example
Assuming that normal VOUT voltage is 40V, OVP detection voltage VOVPDET is 48V, and R2 resistance is 10kΩ, R1
resistance is calculated by the following equation
When OVP release voltage VOVPCAN setting is made with the said R1 and R2, it will be given by the following equation
SCP detection voltage is given by the following equation
Give consideration to IC variati ons as well as individual component variati ons, and then evaluat e on actual systems.
　][
][0.3 ])[0.3][(
][21 Ω
−
×Ω= k
VVVVOVP
kRR DET
][150
][3 ])[3][48(
][10
][0.3 ])[0.3][(
][21 Ω=
−
×Ω=
−
×Ω= k
VVV
k
VVVVOVP
kRR
DET
][4.46][
][10 ][150][10
][9.2
][2 ])[2][1(
][9.2 VV
kkk
V
kR kRkR
VVOVPCAN =
Ω
Ω+Ω
×=
Ω
Ω+Ω
×= 　
][6.1][
][10 ][150][10
][1.0
][2 ])[2][1(
][1.0 VV
kkk
V
kR kRkR
VVSCPDET =
Ω
Ω+Ω
×=
Ω
Ω+Ω
×= 　
Figure 29. OVP block diagram
DQ
+
-
+
-
+
-
OVP
DCDC_STOP_COMP
OVP_TIMER_COMP
SCP_TIMER_COMP
VOUT
DRIVER
N
CP
Timer
65536
CP
Timer
65536×8
3.0V
2.9V
H:STOP
L:ACT
0.1V
R1
R2
　][
][2 ])[2][1(
9.2 V
kR kRkR
VVOVP
CAN
Ω
Ω+Ω
×=
　][
][2 ])[2][1(
1.0 V
kR kRkR
VVSCP
DET
Ω
Ω+Ω
×=
25/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
+
-
LSP
CLSP
REG58=5.8V
R1
R2
R3=
3100kΩ
R4
900kΩ
REF=4V
LEDx
900kΩ
100kΩ
●LSP setting procedure
LED SHORT threshold voltage can be adjusted by setting LSP pin voltage.
LED SHORT detection voltage is set to 9V when LSP pin=OPEN state.
Please set input voltage of LSP pin from 0.3V~2.5V range.
The relation between LSP pins and LED SHORT protection voltage as below.
Also, LSP pin divides 4V within the IC using resistive dividers (see the circuit diagram shown below)
Therefore, connecting an external resistor to the LSP pin will produce resistance combined with the internal IC resistance.
Consequently, LSP pin voltage setting using external resistive dividers, it is recommended to connect them having
resistance little affected by the internal resistance.(Smaller resistance have less influence on internal resistance, but will
result in larger power consumption.)
○LSP detection voltage setting
If the setting of LSP detection voltage VLSP is made by dividing the REG58V voltage by the use of resistive dividers
R1and R2, VLSP will be given by the following equation.
However, this equation includes no internal IC resistance. If internal resistance is taken into account, detection voltage
VLSP will be given by the following equation.
Make setting of R1 and R2 resistance so that a difference between resistance values found by Equations (1) and (2) will
come to approximately 2% or less as a guide.
○Setting example
Assuming that LSP is approximated by Equation (1) in order to set LSP detection voltage to 5V, R1 comes to 53kΩ andR2
comes to 5kΩ.LSP detection voltage taking into account internal IC resistance by Equation (2), it will be given as
The difference is given as:
As a result, this setting will be little affected by internal impedance.
)1(][10
][2][1( ][2
][58 　V
kRkR kR
VREGVLSP ×
Ω+Ω
Ω
×=
( )
( ) ( )
)2(][10
][3][1][4][242][3][1( ][1][3][58][4][2 　V
kRkRkRkRRRkRkR kRVREFRVREGkRkR
VLSP ×
Ω+Ω×Ω×Ω++×Ω×Ω
Ω×+××Ω×Ω
=
( )
( ) ( )
][033.510
][3100][53][900][5][900][5][3100][53( ][53][4][3100][8.5][900][5 VV
kkkkkkkk kVkVkk
VLSP =×
Ω+Ω×Ω×Ω+Ω+Ω×Ω×Ω
Ω×+Ω××Ω×Ω
=
( )
%66.0100][5/][5][033.5 =×− VVV
][
10 V
VLED
VLSP
SHORT
SHORT
　=
Figure 30. LSP Block diagram
26/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
1
2
CP COUNT UP
START
LED1_Voltage 0.8V
12V
Oscllator
(internal IC)
CP COUNTER 0V
LED1 SHORT Pro.
detect
I_LED1
Current
FAIL (OPEN)
LOW
3
65535
65536
65534
CP COUNT UP
END
LED1
LATCH UP
FAIL
DET
●Timer latch function
This IC has a built-in timer latch counter to make setting of timer latch time by counting a clock frequency set with the RT
pin.
○Timer latch time
The timer latch counter begins counting from the timing when any abnormal state is detected. The timer will be latched
after a lapse of a period of time given by the following equation.
If the abnormal state continues even when PWM is set to Low level, the counter will not reset counting.
Here LATCHTIME= A period of time, which the timer is latched
RRT=RT pin connecting resistance
Protection time which described above is applied for LED pin OPEN protection, LED pin SHORT protection, SCP
protection.
The protection of FB overshoot and OVP protection as below:
Clock oscillation of timer latch uses DCDC clock. So timer latch time depend on unevenness of DCDC oscillation. In
150kHz, timer latch time is ±5% unevenness.
○Setting Example
In LED_OPEN protection, LED_SHORT protection, SCP protection,
When RT resistance=100kohm, the timer latch time is
And, FB overshoot protection, OVP protection is
　][
105.1 ][
65536
105.1
2
710
16
S
kRR
LATCH
RTRT
TIME
×
Ω
×=
×
×=
　][437.0
105.1
][100
65536
105.1
][
65536
77
S
k
kR
LATCH
RT
TIME
=
×
Ω
×=
×
Ω
×=
　][
.][
.S
kRR
LATCH
RTRT
TIME 710
18
1051
262144
1051
2×
Ω
×=
×
×=
　][.
.][
.][ S
k
kR
LATCH
RT
TIME
751
1051
100
262144
1051
524288
77
=
×
Ω
×=
×
Ω
×=
Figure 31. Timing chart of LSP time la tch
27/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
3.2 Selection o f DCDC components
●OCP setting procedure/DCDC component current tolerance selection procedure
The OCP detection function that is one of the functions of the CS pin will stop the DC/DC converter operating if the CS pin
voltage becomes greater than 0.4V. Consequently, it is needed to calculate a peak current flowing through the coilL and
then review the resistance of RCS. Furthermore, a current tolerance for DC/DC components should be larger than that for
peak current flowing through the coil L.
The following section describes the peak coil current calculation procedure, CS pin connection resistor RCS selection
procedure, and DC/DC component current tolerance selection procedure
○Calculation of coil current Ipeak
Ripple voltage generated at the CS pin is determined by conditions for DC/DC application components. Assuming the
conditions:
output voltage=VOUT [V]
LED total current=IOUT [A]
DCDC input voltage=VIN [V]
DCDC efficiency=η [%]
mean input current IIN required for the whole system is given by the following
equation
Further, according to drive operation with the DC/DC converter switching
frequency fsw [Hz], inductor ripple current ΔIL [A] generated at the inductor L
is given by the following equation.
As a result, the peak current Ipeak of IL is given by the following equation.
○CS pin connect ion res ist or R C S selecti on proce dure
The current Ipeak flows into RCS to generate voltage.(See timing chart
shown to the right.)
The voltage VCSpeak is given by the following equation.
If this VCSpeak voltage reaches 0.4V, DC/DC output will stop.
Consequently, to select RCS resistance, the following condition should be
met.
○DCDC compo nent curr ent to lerance selection procedur e
Iocp current needed for OCP detection voltage CS to reach 0.4V is given
by the following equation
The relation among Ipeak current (Equation (1)), Iocp current (Equation (2)),
DC/DC application components including FETs, inductors, and diodes should be selected so that the Equation shown
above will be met.
Furthermore, it is recommended to normally use DC/DC application components in continuous mode. Assuming that the
lower limit value of coil ripple current is Imin, the following equation should be met
A failure to meet this condition is referred to as discontinuous mode.
　][
[%]][ ][][ A
VV AIVV
I
IN
OUTOUT
IN
η
×
×
=
][
][][][ ][])[][( A
HzfVVHL VVVVVV
IL
SWOUT
ININOUT
××
×−
=Δ
)1(][
2][
][ A
AIL
AIIpeak
IN
∆
+=
][VIpeakRcsVCSpeak ×=
<< ocppeak II
Max. current tolerance for component
][4.0][][ VAIpeakRcs <×Ω
VIN
VOUT
N
CS
DCDC_GND
Rcs
IL
L
IOUT(total)
fsw
IIN
（A)
(t)
0.5V
(t)
（V)
(V)
VCS[V] IL[A]
ΔIL
(t)
N[V]
Ipeak
Imin
VCSpeak
)2(][
][ ][4.0 A
RcsV
Iocp Ω
=
　0][
2][
][Im >
∆
−= A
AIL
AIin IN
Figure32.
DCDCapplication diagram and coil current
28/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
○Setting example
Output voltage=VOUT [V]=40V
LED total current=IOUT [A]=120mA×6ch=0.72A
DCDC input voltage=VIN [V]=24V
DCDC efficiency=η[%]=90%
mean input current IIN required for the whole system is given by the following equation
DCDC switching frequency=fsw[Hz]=200kHz
Inductor L[H]=47μH
The Inductor ripple currentΔIL[A] is:
As a result, the IL peak current Ipeak is:
When RCS resistance is set to 0.15ohm, the VCS peak voltage will be given by the following equation
Consequently, the result meets the condition.
Furthermore, IOCP current at which OCP is detected is given by the following equation
If the current tolerance for components to be used (e.g. FETs, inductors, diodes) is smaller than 2.5A,
As a result, since the condition above is met, the selection of components is accepted.
And, the lower limit of IL ripple current Imin is:
The system will not be put into discontinuous mode.
To select DC/DC components, please consider IC variations as well as individual component variations, andthen conduct
thorough verification on practical systems.
][33.1
[%]90][24 ][72.0][40
[%]][
][][
][ A
VAV
VV
AIVV
AI
IN
OUTOUT
IN =
×
×
=
×
×
=　
η
][02.1
][10200][40][1047 ][24])[24][40(
][][][ ][])[][(
36
A
HzVH VVV
HzfVVHL VVVVVV
IL
SWOUT
ININOUT
=
××××
×−
=
××
×−
=
−
　Δ
][84.1
2][02.1
][33.1][
2][
][ A
A
AA
AIL
AIIpeak
IN
=+=
∆
+= 　
　0][82.0
2][02.1
][33.1][
2][
][Im >=−=
∆
−= A
A
AA
AIL
AIin
IN
VVAIpeakRcsVCS
peak
5.0][276.0][84.1][15.0 <=×Ω=×=
][67.2
][15.0 ][4.0 A
V
I
ocp
=
Ω
=
… Result of peak current
calculation
… Result of review of
RCS resistance
<<
OCPpeak
II
Max. Current tolerance for component
… Result of review of current
tolerance for DC/DC components
][0.3][67.2][84.1 AAA <<=
29/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
ΔIL
●Selection of Inductor
The value of inductor has significant influence on the input ripple current. As shown by Equation (1), the larger the inductor
and the higher the switching frequency, the inductor ripple current ∆IL becomes increasingly
lower.
(1)][
)( 　　　　　・・・・・　　Δ A
fVL
VVV
IL
SWOUT
ININOUT
××
×−
=
Efficiency as shown by Equation (2), peak input current is given as Equation (3).
Here,
L：Reactance value [H] VOUT：DC/DC output voltage[V]
VIN：input voltage[V] IOUT：output current(LED total current)[A]
IIN：input current[A] FSW：oscillation frequency[Hz]
If a current in excess of the rated current of the inductor applies to the
coil, the inductor will cause magnetic saturation, resulting in lower
efficiency.
Select an inductor with an adequate margin so that peak current will
not exceed the rated current of the inductor.
To reduce power dissipation from and increase efficiency of induct
or, select an inductor with low resistance component (DCR or AC
R).
●Selection of switching MOSFET transistors
There will be no problem for switching MOSFET transistors having absolute maximum rating higher than rated current of
the inductor L and VF higher than “COUT breakdown voltage + Rectifier diode”. However, to achieve high-speed switching,
select transist or s with sm all ga te cap a city (injec ted cha rge a moun t ).
・Rated current larger than current prote cti on setti ng curr e n t is recomm end ed
・Selecting transistors with low On resistance can obtain high efficiency.
●Selection of rectifier diodes
Select current capability higher than the rated current of the inductor L and inverse breakdown voltage higher that COUT
break-down voltage, particularly having low forward voltage VF.
VOUT
VIN
COUT
RCS
L
IL
(2)　　　　　　　・・・・・
ININ
OUTOUT IV IV
×
×
=
η
(3)
22 　・・・・・　　
Δ
　　　　
ΔIL
VIV
IL
IIL
IN
OUTOUT
INMAX
+
×
×
=+=
η
Figure33.
DCDC application cir cuit and coil current
30/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
3.3 Timing Chart
7.5V
STB
2.0V 0.8V
VCC
REG58
FAIL
2.6V 2.4V
( normal state )
ISET
RT
SS 3.7V
FB
VOUT
PWMｘ
ILEDｘ
SS=FB or LED
feed-back
LED_OPEN
LED_SHORT
OVP
SCP
LED
feed-back
LED_GND_SHORT
ISET_GND_SHORT
UVLO
REG58_UVLO
VCC_UVLO
1.5V 0.8V
1.5V
Disaable
Disaable
Disaable
Disaable
Disaable
Disaable
Disaable
Disaable
Disaable
Disaable
Enable
Enable
Enable
Enable
Enable
RT_GND_SHORT
GND
Figure 34. Timing Chart
31/35 TSZ02201-0F10C1002000-1-2
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TSZ22111・15・001
BD9470AFM・BD9470AEFV
3.4 List of Protection Functions
●List of protection detecting condition
Protection
names
Detection Detection condition Release
condition Timer Protection
type
pin
Detection pin
condition
PWM SS
LED OPEN LEDｘ LEDx < 0.20V H SS>3.7V LEDx > 0.20V 2 16 count
Latch
(Only detected
ｃｈ
)
LEDSHORT LEDｘ
LEDx > 9V
H SS>3.7V
LEDx < 9V
2 16 count
Latch
(Only
detected
ｃｈ
)
(LSP=OPEN) (LSP=OPEN)
LED GND
SHORT
LEDｘ LEDx < 0.20V H SS>3.7V LEDx > 0.20V
2 16 + 27
count
Latch
ISET GND
SHORT
ISET Under ISET×90%
Canceled
ISET=GND State
Immediately
detect
Auto-restart
RT GND
SHORT
RT Under RT×90% - -
Canceled
RT=GND State
Immediately
detect
Auto-restart
UVLO UVLO UVLO<2.7V - - UVLO>3V
Immediately
detect
Auto-restart
REG58 UVLO REG58 REG58<2.4V - - REG58>2.6V
Immediately
detect
Auto-restart
VCC UVLO VCC VCC<7.2V - - VCC>7.5V
Immediately
detect
Auto-restart
OVP OVP OVP>3.0V - - OVP<2.9V 2 18 count Latch
SCP OVP OVP<0.1V - - OVP>0.1V 2 16 count Latch
OCP CS OCP>0.4V - - -
Immediately
detect
Pulse-by-Pulse
* To clear the latch type, STB should be set to “L” once, and then to “H”
* The count of Timer means ” 1count = 1 duty of switching frequency.
●List of protection detecting operation
Protection Functions Operation when the hysteresis type protection is detected
DC/DC LED Driver Soft start FAIL pin
LED OPEN Continues operation
Only detected LED stops
operating after CP counting
Not discharged
Open after CP
counting
LEDSHORT Continues operatio n
Only detected LED stops
operating after CP counting
Not discharged
Open after CP
counting
LED GNDSHORT
Stops operatin g after
CP counting
Stops operating after CP counting Discharge
Open after CP
counting
ISET GND SHORT
Instantaneously stops
operating
Instantaneously stops operating Not discharged
OPEN
immediately
RT GND SHORT
Instantaneously stops
operating
Normal Operation Not discharged LOW
STB
Instantaneously stops
operating
Stops (and REG58<2.4V) Discharge
OPEN
immediately
UVLO
Instantaneously stops
operating
Instantaneously stops operating Discharge
OPEN
immediately
REG58 UVLO
Instantaneously stops
operating
Instantaneously stops operating Discharge
OPEN
immediately
VCC UVLO
Instantaneously stops
operating
Instantaneously stops operating Discharge
OPEN
immediately
OVP
Stops operating after
CP counting
Stops operatin g after CP counting Discharge
Open after CP
counting
SCP
Stops operating after
CP counting
Stops operating after CP counting Discharge
Open after CP
counting
OCP limits duty cycle C ontin ues oper at io n Not discharged LOW
32/35 TSZ02201-0F10C1002000-1-2
© 2013 ROHM Co., Ltd. All rights reserved. 19.Oct .2 013 Rev.003
www.rohm.com
TSZ22111・15・001
BD9470AFM・BD9470AEFV
4. Caution on use
1.) We pay utmost attention to the quality control of this product. However, if it exceeds the absolute maximum ratin
gs including applied voltage and operating temperature range, it may lead to its deterioration or breakdown. Furth
er, this makes it impossible to assume a breakdown state such as short or open circuit mode. If any special mod
e to exceed the absolute maximum ratings is assumed, consider adding physical safety measures such as fuses.
2.) Making a reverse connection of the power supply connector can cause the IC to break down. To protect the IC f
orm breakdown due to reverse connection, take preventive measures such as inserting a diode between the exter
nal power supply and the power supply pin of the IC.
3.) Since current regenerated by back electromotive force flows back, take preventive measures such as inserting a c
apacitor between the power supply and the ground as a path of the regenerative current and fully ensure that ca
pacitance presents no problems with characteristics such as lack of capacitance of electrolytic capacitors causes a
t low temperatures, and then determine the power supply line. Provide thermal design having an adequate margin
in consideration of power dissipation (Pd) in the practical operating conditions.
4.) The potential of the GND pin should be maintained at the minimum level in any operating state.
5.) Provide thermal design having an adequate margin in consideration of power dissipation (Pd) in the practical oper
ating conditions.
To mount the IC on a printed circuit board, pay utmost attention to the direction and displacement of the IC. Furthermore,
the IC may get damaged if it is mounted in an erroneous manner or if a short circuit is established due to foreign matters
entered between output pins or between output pin and power supply GND pin.
6.) Note that using this IC in strong magnetic field may cause it to malfunction.
7.) Please set the output Tr not to over absolute Maximum Ratings and ASO. CMOS IC and plural power supply IC
have a possible to flow lush current momentarily. Please note VCC capacitor, VCC and GND layout.
8.) This IC has a built-in thermal-protection circuit (TSD circuit).
The thermal-protection circuit (TSD circuit) is a circuit absolutely intended to protect the IC from thermal runaway,
not intended to protect or guarantee the IC. Consequently, do not use the IC based on the activation of this TS
D circuit for subsequent continuous use and operation of the IC.
9.) When testing the IC on a set board with a capacitor connected to the pin, the IC can be subjected to stress. In
this case, be sure to discharge the capacitor for each process. In addition, to connect the IC to a jig up to the t
esting process, be sure to turn OFF the power supply prior to connection, and disconnect the jig only after turnin
g OFF the power supply.
10.) This monolithic IC contains P + Isolation and P substrate layers between adjacent elements in order to keep them
isolated.
P-N junctions are formed at the intersections of these P layers and the N layers of other elements, thus making up
different types of parasitic elements.
For example, if a resistor and a transistor is connected with pins respectively as shown in Fig.
When GND>(Pin A) for the resistor, or when GND>(Pin B) for the transistor (NPN), P-N junctions operate as a a
parasitic diode.
When GND>(Pin B) for the transistor (NPN), the parasitic NPN transistor operates by the N layer of other element
adjacent to the parasitic diode aforementioned.
Due to the structure of the IC, parasitic elements are inevitably formed depending on the relationships of potential. The
operation of parasitic diodes can result in interferences in circuit operation, leading to malfunctions and eventually
breakdown of the IC. Consequently, pay utmost attention not to use the IC for any applications by which the parasitic
elements are operated, such as applying a voltage lower than that of GND (P substrate) to the input pin.
Status of this document
The Japanese version of this document is formal specification. A customer ma y us e this translation version only for a
reference to hel p reading the formal version.
If there are any differences in translation version of this document formal version takes priority
Figure 35. Ex ampl e of Simple Structure of
Monolithic IC
ＧＮＤ
B
C
E
Adjacent other elements
Parasitic
(Pin B)
GND
Parasitic element
(Pin A)
Parasitic element
Resistor
P substrate
N
GND
P
N
P
(Pin A)
P
N
Transistor (NPN)
B
Parasitic element
GND
E
C
GND
P
P
N
N
N
P
N
P substrate
(Pin B)
33/35 TSZ02201-0F10C1002000-1-2
© 2013 ROHM Co., Ltd. All rights reserved. 19.Oct .2 013 Rev.003
www.rohm.com
TSZ22111・15・001
BD9470AFM・BD9470AEFV
●Ordering Information
B D 9 4 7 0 A F M E 2
Part Number
Package
FM: HSOP-M
Packaging a nd for mi ng spe cif i cati on
E2: Embossed tape and reel
B D 9 4 7 0 A E F V E 2
Part Number
Package
EFV: HTSSOP-B
Packaging and forming specification
E2: Embossed tape and reel
●Physical Dimension Tape and Reel Informat ion
34/35 TSZ02201-0F10C1002000-1-2
© 2013 ROHM Co., Ltd. All rights reserved. 19.Oct .2 013 Rev.003
www.rohm.com
TSZ22111・15・001
BD9470AFM・BD9470AEFV
6. Revision history
Date
Revision
Changes
26.Oct.2012 001 New Release
09.Jan.2013 002 P6 / Verified min imum ISET resistor
002 P10 / Verified ISET terminal instruction
002 P23 / Verified LED Current setting
19.Oct.2013 003 P2 / Change Pin Configuration
003 P1 / Delete PbFree, RoHS
003 ADD NOTICE
35/35 TSZ02201-0F10C1002000-1-2
© 2013 ROHM Co., Ltd. All rights reserved. 19.Oct .2 013 Rev.003
www.rohm.com
TSZ22111・15・001
Datasheet
Datasheet
Notice - GE Rev.002
© 2014 ROHM Co., Ltd. All rights reserved.
Notice
Precaution on using ROHM Products
1. Our Products are designed and manufactured for application in ordinary electronic equipments (such as AV equipment,
OA equipment, telecommunication equipment, home electronic appliances, amusement equipment, etc.). If you
intend to use our Products in devices requiring extremely high reliability (such as medical equipment (Note 1), transport
equipment, traffic equipment, aircraft/spacecraft, nuclear power controllers, fuel controllers, car equipment including car
accessories, safety devices, etc.) and whose malfunction or failure may cause loss of human life, bodily injury or
serious damage to property (“Specific Applications”), please consult with the ROHM sales representative in advance.
Unless otherwise agreed in writing by ROHM in advance, ROHM shall not be in any way responsible or liable for any
damages, expenses or losses incurred by you or third parties arising from the use of any ROHM’s Products for Specific
Applications.
(Note1) Medical Equipment Classification of the Specific Applications
JAPAN USA EU CHINA
CLASSⅢ CLASSⅢ CLASSⅡb CLASSⅢ
CLASSⅣ CLASSⅢ
2. ROHM designs and manufactures its Products subject to strict quality control system. However, semiconductor
products can fail or malfunction at a certain rate. Please be sure to implement, at your own responsibilities, adequate
safety measures including but not limited to fail-safe design against the physical injury, damage to any property, which
a failure or malfunction of our Products may cause. The following are examples of safety measures:
[a] Installation of protection circuits or other protective devices to improve system safety
[b] Installation of redundant circuits to reduce the impact of single or multiple circuit failure
3. Our Products are designed and manufactured for use under standard conditions and not under any special or
extraordinary environments or conditions, as exemplified below. Accordingly, ROHM shall not be in any way
responsible or liable for any damages, expenses or losses arising from the use of any ROHM’s Products under any
special or extraordinary environments or conditions. If you intend to use our Products under any special or
extraordinary environments or conditions (as exemplified below), your independent verification and confirmation of
product performance, reliability, etc, prior to use, must be necessary:
[a] Use of our Products in any types of liquid, including water, oils, chemicals, and organic solvents
[b] Use of our Products outdoors or in places where the Products are exposed to direct sunlight or dust
[c] Use of our Products in places where the Products are exposed to sea wind or corrosive gases, including Cl2,
H2S, NH3, SO2, and NO2
[d] Use of our Products in places where the Products are exposed to static electricity or electromagnetic waves
[e] Use of our Products in proximity to heat-producing components, plastic cords, or other flammable items
[f] Sealing or coating our Products with resin or other coating materials
[g] Use of our Products without cleaning residue of flux (even if you use no-clean type fluxes, cleaning residue of
flux is recommended); or Washing our Products by using water or water-soluble cleaning agents for cleaning
residue after soldering
[h] Use of the Products in places subject to dew condensation
4. The Products are not subject to radiation-proof design.
5. Please verify and confirm characteristics of the final or mounted products in using the Products.
6. In particular, if a transient load (a large amount of load applied in a short period of time, such as pulse. is applied,
confirmation of performance characteristics after on-board mounting is strongly recommended. Avoid applying power
exceeding normal rated power; exceeding the power rating under steady-state loading condition may negatively affect
product performance and reliability.
7. De-rate Power Dissipation (Pd) depending on Ambient temperature (Ta). When used in sealed area, confirm the actual
ambient temperature.
8. Confirm that operation temperature is within the specified range described in the product specification.
9. ROHM shall not be in any way responsible or liable for failure induced under deviant condition from what is defined in
this document.
Precaution for Mounting / Circuit board design
1. When a highly active halogenous (chlorine, bromine, etc.) flux is used, the residue of flux may negatively affect product
performance and reliability.
2. In principle, the reflow soldering method must be used; if flow soldering method is preferred, please consult with the
ROHM representative in advance.
For details, please refer to ROHM Mounting specification
Datasheet
Datasheet
Notice - GE Rev.002
© 2014 ROHM Co., Ltd. All rights reserved.
Precautions Regarding Application Examples and External Circuits
1. If change is made to the constant of an external circuit, please allow a sufficient margin considering variations of the
characteristics of the Products and external components, including transient characteristics, as well as static
characteristics.
2. You agree that application notes, reference designs, and associated data and information contained in this document
are presented only as guidance for Products use. Therefore, in case you use such information, you are solely
responsible for it and you must exercise your own independent verification and judgment in the use of such information
contained in this document. ROHM shall not be in any way responsible or liable for any damages, expenses or losses
incurred by you or third parties arising from the use of such information.
Precaution for Electrostatic
This Product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. Please take proper
caution in your manufacturing process and storage so that voltage exceeding the Products maximum rating will not be
applied to Products. Please take special care under dry condition (e.g. Grounding of human body / equipment / solder iron,
isolation from charged objects, setting of Ionizer, friction prevention and temperature / humidity control).
Precaution for Storage / Transportation
1. Product performance and soldered connections may deteriorate if the Products are stored in the places where:
[a] the Products are exposed to sea winds or corrosive gases, including Cl2, H2S, NH3, SO2, and NO2
[b] the temperature or humidity exceeds those recommended by ROHM
[c] the Products are exposed to direct sunshine or condensation
[d] the Products are exposed to high Electrostatic
2. Even under ROHM recommended storage condition, solderability of products out of recommended storage time period
may be degraded. It is strongly recommended to confirm solderability before using Products of which storage time is
exceeding the recommended storage time period.
3. Store / transport cartons in the correct direction, which is indicated on a carton with a symbol. Otherwise bent leads
may occur due to excessive stress applied when dropping of a carton.
4. Use Products within the specified time after opening a humidity barrier bag. Baking is required before using Products of
which storage time is exceeding the recommended storage time period.
Precaution for Product Label
QR code printed on ROHM Products label is for ROHM’s internal use only.
Precaution for Disposition
When disposing Products please dispose them properly using an authorized industry waste company.
Precaution for Foreign Exchange and Foreign Trade act
Since our Products might fall under controlled goods prescribed by the applicable foreign exchange and foreign trade act,
please consult with ROHM representative in case of export.
Precaution Regarding Intellectual Property Rights
1. All information and data including but not limited to application example contained in this document is for reference
only. ROHM does not warrant that foregoing information or data will not infringe any intellectual property rights or any
other rights of any third party regarding such information or data. ROHM shall not be in any way responsible or liable
for infringement of any intellectual property rights or other damages arising from use of such information or data.:
2. No license, expressly or implied, is granted hereby under any intellectual property rights or other rights of ROHM or any
third parties with respect to the information contained in this document.
Other Precaution
1. This document may not be reprinted or reproduced, in whole or in part, without prior written consent of ROHM.
2. The Products may not be disassembled, converted, modified, reproduced or otherwise changed without prior written
consent of ROHM.
3. In no event shall you use in any way whatsoever the Products and the related technical information contained in the
Products or this document for any military purposes, including but not limited to, the development of mass-destruction
weapons.
4. The proper names of companies or products described in this document are trademarks or registered trademarks of
ROHM, its affiliated companies or third parties.
DatasheetDatasheet
Notice – WE Rev.001
© 2014 ROHM Co., Ltd. All rights reserved.
General Precaution
1. Before you use our Pro ducts, you are requested to care fully read this document and fully understand its contents.
ROHM shall n ot be in an y way responsible or liabl e for fa ilure, malfunction or acci dent arising from the use of a ny
ROHM’s Products against warning, caution or note contained in this document.
2. All information contained in this docume nt is current as of the issuing date and subj ect to change without any prior
notice. Before purchasing or using ROHM’s Products, please confirm the la test information with a ROHM sale s
representative.
3. The information contained in this doc ument is provi ded on an “as is” basis and ROHM does not warrant that all
information contained in this document is accurate an d/or error-free. ROHM shall not be in an y way responsible or
liable for an y damages, expenses or losses incurred b y you or third parties resulting from inaccur acy or errors of or
concerning such information.
Datasheet
Part Number bd9470aefv
Package HTSSOP-B28
Unit Quantity 2500
Minimum Package Quantity 2500
Packing Type Taping
Constitution Materials List inquiry
RoHS Yes
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