General Description
The MAX15005A evaluation kit (EV kit) is a fully assem-
bled and tested PCB that contains an 11W flyback DC-
DC converter for vacuum-fluorescent displays (VFDs) in
automotive applications. The circuit uses a MAX15005A
high-performance, current-mode pulse-width modulation
(PWM) controller in a 16-pin TSSOP package. The EV kit
circuit is configured for output voltages of 3V, 60V, and
110V, and provides up to 650mA, 12mA, and 55mA of
current from the respective output. Additionally, a 5V low-
dropout (LDO) voltage regulator output is provided that
can source up to 15mA. Power for the EV kit circuit is pro-
vided from a 6.5V to 16V DC source. The MAX15005A EV
kit input circuit can sustain a 40V transient.
High efficiency of up to 71% is achieved using a single-
transistor flyback DC-DC converter topology. Low cost
is achieved through the use of direct secondary-side
regulation that does not require optical couplers. Input
undervoltage lockout (UVLO), output overvoltage pro-
tection (OVP), and soft-start provide for a robust 11W
power supply.
Operation at 100kHz minimizes the size of the trans-
former and passive components.
Warning: The MAX15005A EV kit is designed to operate
with high voltages. Dangerous voltages are present on
this EV kit and on equipment connected to it. Users who
power up this EV kit, or power the sources connected to
it, must be careful to follow safety procedures appropriate
to working with high-voltage electrical equipment.
Under severe fault or failure conditions, this EV kit may
dissipate large amounts of power, which could result in
the mechanical ejection of a component or of compo-
nent debris at high velocity. Operate this kit with care to
avoid possible personal injury.
Features
♦6.5V to 16V DC Input Range
♦Outputs
3V Provides Up to 650mA (VFD Filament)
60V Provides Up to 12mA (VFD Grid)
110V Provides Up to 55mA (VFD Anode)
♦Output Voltage Accuracy
110V (Anode) = ±3% (Regulated Output)
60V (Grid) = ±5% (Proportional Loading)
3V (Filament) = ±10% (Proportional Loading)
♦71% Efficiency at 16V Input and Full Load
♦5V LDO Output Provides Up to 15mA
♦Hiccup Current-Limit and Overtemperature
Shutdown
♦100kHz Switching Frequency
♦Capacitor Adjustable Soft-Start
♦High-Accuracy Undervoltage Lockout (UVLO)
♦Output Overvoltage Protection (OVP)
♦Capable of Synchronizing to an External Clock
♦Low-Cost, Robust Flyback Design
♦Fully Assembled and Tested
Evaluates: MAX15005A
MAX15005A Evaluation Kit
________________________________________________________________
Maxim Integrated Products
1
19-0964; Rev 0; 8/07
Component List
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Ordering Information
PART TYPE
MAX15005AEVKIT+ EV Kit
+
Denotes lead-free and RoHS-compliant.
DESIGNATION QTY DESCRIPTION
C1 1
330µF, 50V electrolytic capacitor
(12.5mm x 13.5mm)
Panasonic EEVFK1H331Q
C2 1
0.1µF ±10%, 50V X7R ceramic
capacitor (0603)
Murata GRM188R71H104K
C3, C10 2
1µF ±10%, 16V X7R ceramic
capacitors (0805)
Murata GRM21BR71C105K
DESIGNATION QTY DESCRIPTION
C4 1
100pF ±2%, 50V C0G ceramic
capacitor (0603)
Murata GRM1885C1H101G
C5 1
1000pF ±5%, 50V C0G ceramic
capacitor (0603)
Murata GRM1885C1H102J
C6 1
4700pF ±10%, 50V X7R ceramic
capacitor (0603)
Murata GMR188R71H472K
Evaluates: MAX15005A
MAX15005A Evaluation Kit
2 _______________________________________________________________________________________
Component List (continued)
DESIGNATION QTY DESCRIPTION
C7 1
47pF ±5%, 50V C0G ceramic
capacitor (0603)
Murata GRM1885C1H470J
C8 1
0.68µF ±10%, 16V X7R ceramic
capacitor (0805)
Murata GRM219R71C684K
C9 1
560pF ±5%, 50V C0G ceramic
capacitor (0603)
Murata GRM1885C1H561J
C11 1
2200pF ±10%, 100V X7R ceramic
capacitor (0603)
Murata GRM188R72A222K
C12, C14 2
100pF ±10%, 63V C0G ceramic
capacitors (1206)
TKD C3216C0G2J101K
C13 1
10µF, 200V electrolytic capacitor
(10mm x 10.5mm)
SANYO 200CE10FS
C15 1
22µF, 80V electrolytic capacitor
(8mm x 10.2mm)
Panasonic EEEFK1K220P
C16 1
330µF, 6.3V electrolytic capacitor
(8mm x 10.5mm)
SANYO 6CE330EX
C17 1
2.2µF ±20%, 10V X5R ceramic
capacitor (0603)
AVX 0603ZD225MAT
C18 1
4700pF ±10%, 100V X7R ceramic
capacitor (0805)
Murata GRM219R72A472K
D1 1 100V, 1A super-fast diode (SMA)
Diodes Inc. ES1B-13-F
D2 1 600V, 1A super-fast diode (SMB)
Diodes Inc. MURS160-F
D3 1 400V, 1A super-fast diode (SMA)
Diodes Inc. MURS140-13-F
DESIGNATION QTY DESCRIPTION
D4 1 40V, 3A Schottky diode (SMA)
Diodes Inc. B340A-13-F
D5 1
8.2V, 350mW ±5% Zener diode
(SOT23)
Central Semiconductor CMPZ5237B
JU1, JU2 2 2-pin headers
JU3 1 3-pin header
N1 1 80V , 1.4A n-channel M OS FE T ( 8- p i n S O)
Vishay Si4896DY-T1-E3
R1 1 11.5kΩ ±1% resistor (0603)
R2 1 560Ω ±5% resistor (1210)
R3 1 51Ω ±5% resistor (0805)
R4 1 402kΩ ±1% resistor (0603)
R5 1 1kΩ ±5% resistor (0603)
R6 1 0.070Ω ±1% power resistor (2010)
IRC LRC-LR2010LF-01-R070-F
R7 1 510Ω ±5% resistor (1206)
R8 1 100kΩ ±5% resistor (1206)
R9 1 220Ω ±5% resistor (1206)
R10 1 36kΩ ±5% resistor (1206)
R11 1 1.33MΩ ±1% resistor (0603)
R12 1 12.1kΩ ±1% resistor (0603)
R13 1 118kΩ ±1% resistor (0603)
R14 1 1.33kΩ ±1% resistor (0603)
R15 1 100Ω ±5% resistor (0805)
R16 1 10Ω ±5% resistor (1210)
R17 1 187kΩ ±1% resistor (0603)
R18 1 47.5kΩ ±1% resistor (0603)
R19 1 10kΩ ±5% resistor (0805)
R20 1 232kΩ ±1% resistor (0603)
T1 1
15µH, 10W, 1:3.438:2.813:0.188 turn,
100kH z tr ansfor m er ( 10- p i n g ul l w i ng )
Coiltronics CTX03-17677-R
U1 1 M AX 15005AAU E + ( 16- p i n TS S O P - E P )
— 2 Shunts (JU1, JU2, JU3)
— 1 PCB: MAX15005A Evaluation Kit+
Evaluates: MAX15005A
MAX15005A Evaluation Kit
_______________________________________________________________________________________ 3
Quick Start
Required Equipment
Before beginning, the following equipment is needed:
• One 6.5V to 16V power supply capable of providing
up to 3A
• Three voltmeters
Procedure (Outputs)
The MAX15005A EV kit is fully assembled and tested.
Follow the steps below to verify board operation.
Caution: Do not turn on the power supply until all
connections are completed.
1) Connect a voltmeter to the FILAMENT+ and FILA-
MENT- pads.
2) Connect the second voltmeter to the V_GRID and
PGND pads.
3) Connect the third voltmeter to the V_ANODE and
PGND pads.
4) Verify that a shunt is installed across the pins of
jumpers JU1 (ON/OFF) and JU2 (SYNC).
5) Verify that a shunt is installed across pins 2-3 of
jumper JU3 (OVP).
6) Connect the power supply’s positive terminal to the
VIN pad. Connect the power supply’s ground to the
PGND pad.
7) Turn on the power supply above 7V and verify the
following voltmeters readings:
• FILAMENT = 3V
• V_GRID = 60V
• V_ANODE = 110V
The maximum current for each output should be limited
to less than 650mA, 12mA, and 55mA for each respec-
tive output detailed above in step 7.
Detailed Description
The MAX15005A EV kit is an 11W flyback DC-DC con-
verter that provides output voltages of 3V at up to
650mA, 60V at up to 12mA, and 110V at up to 55mA.
The MAX15005A flyback power supply is designed to
provide power to automotive VFDs. The circuit can be
powered from a 6.5V to 16V DC source, which provides
3A to the EV kit.
The flyback DC-DC converter achieves up to 71%
efficiency and the single-transistor topology provides
for a lower-cost design. The MAX15005A EV kit provides
cycle-by-cycle primary-side current-limit protection.
Current-sense resistor R6 senses the current through the
transformer’s (T1) primary winding, switching transistor
(N1), and turns off the transistor when the trip level of 0.3V
is reached. The MAX15005A EV kit features a resistor/
capacitor/diode (RCD) snubber network (R2, C11, and
D1) to minimize leakage energy ringing and clamp the
voltage at the drain of MOSFET N1 during switching.
Secondary-side regulation through feedback resistors
R13 and R14 provide ±3% regulation for the 110V
output (V_Anode). Resistors R8, R10, and R15 preload
the respective output and assist with overall regulation
at minimum loading. UVLO provides controlled turn-on
and shutdown during brownouts, power-up, or
power-down. The UVLO setting can be changed by
replacing resistor R18.
The MAX15005A analog soft-start allows the output volt-
age to slowly ramp up in a controlled manner within
56ms and is set by capacitor C8. The OVP is provided
by independently sensing the 110V output (V_Anode)
through resistors R11 and R12.
SUPPLIER PHONE WEBSITE
AVX Corp. 843-946-0238 www.avxcorp.com
Central Semiconductor 631-435-1110 www.centralsemi.com
Cooper Electronic Tech./Coiltronics 561-752-5000 www.cooperet.com
Diodes Inc. 805-446-4800 www.diodes.com
IRC 361-992-7900 www.irctt.com
Murata Mfg. Co., Ltd. 770-436-1300 www.murata.com
Panasonic Corp. 714-373-7366 www.panasonic.com
SANYO Corp. 619-661-6322 www.sanyodevice.com
Vishay 402-563-6866 www.vishay.com
Component Suppliers
Note: Indicate that you are using the MAX15005A when contacting these component suppliers.
Evaluates: MAX15005A
The MAX15005A controller switches at a fixed 100kHz
frequency and is set by resistor/capacitor network R1
and C5. The switching duty cycle is varied to control
energy transfer to the outputs. The maximum duty cycle
is 50% for the EV kit’s discontinuous current-mode fly-
back design.
Shutdown Mode (Jumper- or Remote-
Control Method)
The MAX15005A EV kit features a jumper (JU1) that
can be used to shut down the flyback DC-DC convert-
er. An alternate shutdown method (remote control) can
be done with a user-supplied relay contact connected
to pin 2 of jumper JU1 of the EV kit. Table 1 shows
jumper options.
SYNC Mode
The MAX15005A can be synchronized to an external
TTL/CMOS square-wave clock source. The 2-pin
jumper (JU2) selects the SYNC mode of operation or
100kHz internal frequency for the MAX15005A. Table 2
shows jumper options.
The TTL/CMOS square-wave clock source (from
105kHz to 130kHz) must provide the following signal
qualities:
• Output voltage:
Logic-low = 0 to 0.8V
Logic-high = 2V to 5.5V
• Output frequency = 105kHz to 130kHz
• Minimum positive-pulse width = 50ns
• Connect the external square-wave clock to the
SYNC and PGND pads. Refer to the MAX15005A
data sheet for more information on the SYNC pin.
Evaluating Other Current Limits, Input
UVLO, and Output OVP Shutdown
Current Limiting
The EV kit features current limiting for the transformer’s
primary current. The MAX15005A IC turns off switching
MOSFET N1 when the voltage at the MAX15005A CS
pin reaches 0.3V. Current-sense resistor R6 (0.07Ω)
limits the transformer peak primary current to 4.2A
(0.3V / 0.07Ω= 4.2A). To evaluate a lower current limit,
current-sense resistor R6 must be replaced with a
different surface-mount resistor (2010 size), as deter-
mined by the following equation:
R6 = (0.300V/IPRIMARY)
where IPRIMARY is the transformer’s maximum peak pri-
mary current.
Input UVLO (ON/OFF)
The MAX15005A EV kit features a brownout and input-
supply startup UVLO circuit that prevents operation
below the programmed input-supply-start voltage.
Resistors R17 and R18 set the input UVLO threshold of
the EV kit. To change the input UVLO voltage, replace
resistor R17 (or R18) with another surface-mount resis-
tor (0603 size). Using the desired startup voltage, resis-
tor R17 is then found by the following equation:
where VINSTARTUP is the desired startup voltage that
the EV kit starts at, and resistor R18 is typically in the
50kΩrange (47.5kΩdefault). Refer to the
Startup
Operation/UVLO/ON/OFF
section of the MAX15005A
data sheet for additional information on the ON/OFF pin
of the MAX15005A IC.
R17 VIN
1.230V 1xR18
STARTUP
=
()
−
⎛
⎝
⎜
⎞
⎠
⎟
MAX15005A Evaluation Kit
4 _______________________________________________________________________________________
Table 1. Jumper JU1 Shutdown Mode
SHUNT
POSITION ON/OFF PIN MAX15005A EV KIT
OUTPUT
Installed
UVLO resistors R17
and R18 determine
startup voltage
MAX15005A enabled
Not installed Pulled low to PGND
through resistor R18 Shutdown mode
Not installed
Relay contacts
connected between
JU1 pin 2
Remote mode
Table 2. Jumper JU2 SYNC Mode
Functions
SHUNT
POSITION SYNC PIN MAX15005A
OPERATING MODE
Installed Connected to SGND
Internal clock mode
(100kHz set by R1
and C5)
Not installed
Connected to an
external TTL/CMOS
square-wave clock
source at the SYNC
and SGND pads
Synchronization mode
(synchronized to an
external clock
frequency)
Output OVP Shutdown
The MAX15005A EV kit features an OVP circuit that pre-
vents operation above the programmed V_ANODE out-
put supply voltage (136V default). Jumper JU3 config-
ures the circuit for output OVP protection when the
shunt is placed across pins 2-3. Resistors R11 and R12
set the OVI threshold of the OVP circuit for the
MAX15005A IC. To evaluate other OVP voltages,
replace resistor R11 with another surface-mount resis-
tor (0603 size). Using the desired OVP voltage, resistor
R11 is then found by the following equation:
where OVP is the desired voltage that the circuit shut-
down is at and resistor R12 is typically in the 10kW
range (12.1kΩdefault). See Table 3 for configuring
jumper JU3 for output OVP protection.
Input OVP Shutdown (Load Dump Protection)
The MAX15005A EV kit OVP circuit can be reconfigured
to provide load dump protection for VIN when it rises
above the programmed VIN supply voltage (24.7V
default). Jumper JU3 configures the circuit for input
OVP protection when the shunt is placed across pins 1-
2. Resistors R12 and R20 set the OVI threshold of the
OVP circuit for the MAX15005A IC. To evaluate other
OVP voltages, replace resistor R20 with another sur-
face-mount resistor (0603 size). Using the desired OVP
voltage, resistor R20 is then found by the following
equation:
where OVP is the desired voltage that the circuit shut-
down is at and resistor R12 is typically in the 10kΩ
range (12.1kΩdefault). See Table 3 for configuring
jumper JU3 for input OVP protection.
R20 OVP
1.228V 1xR12=
()
−
⎛
⎝
⎜
⎜
⎞
⎠
⎟
⎟
R11 OVP
1.228V 1xR12=
()
−
⎛
⎝
⎜
⎜
⎞
⎠
⎟
⎟
Evaluates: MAX15005A
MAX15005A Evaluation Kit
_______________________________________________________________________________________ 5
Table 3. Jumper JU3 OVP Shutdown
SHUNT
POSITION OVI PIN OVP OPERATION
1-2 Sense VIN input Inp ut over vol tag e
p r otecti on ( l oad d um p )
2-3*) Sense V_ANODE
output
Output overvoltage
protection
Not installed No sensing OVP disabled
*
Default position.
Evaluates: MAX15005A
MAX15005A Evaluation Kit
6 _______________________________________________________________________________________
MAX15005A
U1
T1
EP
VIN
V_ANODE
PGND
V_GRID
PGND
PGND
REG5
SGND
IN
1
1
4
65
21
87
3
N1
6
7
9
8
10
4
JU1
ON/OFF
2
1
2C2
0.1μF
50V
R17
187kΩ
1%
R18
47.5kΩ
1%
R20
232kΩ
1%
C1
330μF
50V
C13
10μF
200V
C8
0.68μF
C7
47pF
C6
4700pF
SLOPE
4
C4
100pF C9
560pF
R2
560Ω
R15
100Ω
D1
C5
1000pF
VIN
JU2
1
2
JU3
1
2
3
OVI
3
N.C.
5
RTCT
6
R11
1.33MΩ
1%
R1
11.5kΩ
1%
R12
12.1kΩ
1%
R19
10kΩ
SGND
7
SYNC
SYNC
8
V_ANODE
V_ANODE
REG5
R5
1kΩ
R7
510Ω
R8
100kΩ
C12
100pF
D2
17
10
FB
14
PGND
11
COMP
12
CS
R3
51Ω
15
OUT
C10
1μF
16V
13
REG5
9
SS
C3
1μF
16V
16
VCC
R13
118kΩ
1%
R4
402kΩ
1%
R6
0.070Ω
1%
C18
4700pF
100V
R16
10Ω
C11
2200pF
100V
R14
1.33kΩ
1%
V_ANODE
REG5
D3
D4
C14
100pF
R9
220Ω
R10
36kΩ
C15
22μF
80V
FILAMENT+
FILAMENT-
C16
330μF
6.3V
D5
C17
2.2μF
10V
Figure 1. MAX15005A EV Kit Schematic
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________
7
© 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
Evaluates: MAX15005A
MAX15005A Evaluation Kit
janet freed
Figure 2. MAX15005A EV Kit Component Placement Guide—
Component Side
Figure 3. MAX15005A EV Kit PCB Layout—Component Side
Figure 4. MAX15005A EV Kit PCB Layout—Solder Side
