MB3875PFV - Fujitsu Limited

DS04-27703-4Ea

FUJITSU MICROELECTRONICS

DATA SHEET

2003.8

ASSP

For Power Supply Applications (Lithium ion battery charger)

DC/DC Converter IC for Charging

MB3875/MB3877

■DESCRIPTION

The MB3875 and MB3877 are ch arging DC/DC converte r ICs suitable for down-conversion, which uses pulse

width modulation (PWM) for controlling the output voltage and current independently.

These ICs c an d yn ami ca ll y c ontr o l the sec on dary bat tery ’s char ge c ur rent by detec ti ng a voltage dro p in an AC

adapter in order to keep its power constant (dynamically-controlled charging).

The charging method enables quick charging, for example, with the AC adapter during operation of a notebook PC.

With an on-chip output voltage setting resistor which allows the output voltage to be set at high precision, these

ICs are best suited as internal battery chargers for notebook PCs.

The MB3875 and MB3877 support 3-cell and 4-cell batteries, respectively.

These products are covered by US Patent Number 6,147,477.

■FEATURES

• Detec ting a voltage drop in th e AC adapte r and d ynami call y co ntrol ling the char ge cur rent (Dynami call y-con-

trolled charging)

• High efficiency : 95 %

• Wide range of operating supply voltages: 7 V to 25 V

• Output voltage precision (Output voltage setting resistor integrated): 0 ± 0.8 % (Ta = + 25 °C) (Continued)

■PACKAGE

24-pin plastic SSOP

(FPT-24P-M03)

MB3875/3877

(Continued)

• High precision reference voltage source: 4.2 V ± 0.8 %

• Support for frequency setting using an external resistor

(Frequency setting capacitor integrated) :100 kHz to 500 kHz

• On-chip current detector amplifier with wide in-phase input voltage range : 0 V to VCC

• On-chip standby current function: 0 µA (Typ )

• On-chip soft-start function

• Internal totem-pole output stage supporting P-channel MOS FETs devices

■PIN ASSIGNMENT

(TOP VIEW)

(FPT-24P-M03)

−INC2 :

IN3 :

FB2 :

OUTC2 :

VREF :

−INE2 :

+INE2 :

+INE1 :

FB1 :

OUTC1 :

−INE1 :

−INC1 :

: +INC2

: GND

: CS

: VCC (O)

: OUT

: VH

: VCC

: RT

: −INE3

: FB3

: CTL

: +INC1

MB3875/3877

■PIN DESCRIPTION

Pin No. Symbol I/O Descriptions

1 –INC2 I Current detection amplifier (Current Amp. 2) input pin.

2 IN3 I DC/DC output voltage (charge voltage) input pin.

3 FB2 O Error amplifier (Error Amp. 2) output pin.

4 OUTC2 O Current detection amplifier (Current Amp. 2) output pin.

5 VREF O Reference voltage output pin.

6 –INE2 I Error amplifier (Error Amp. 2) inverted input pin.

7 +INE2 I Error amplifier (Error Amp. 2) non-inverted input pin.

8 +INE1 I Error amplifier (Error Amp. 1) non-inverted input pin

9 FB1 O Error amplifier (Error Amp. 1) output pin.

10 OUTC1 O Current detection amplifier (Current Amp. 1) output pin.

11 –INE1 I Error amplifier (Error Amp. 1) inverted input pin.

12 –INC1 I Current detection amplifier (Current Amp. 1) input pin.

13 +INC1 I Current detection amplifier (Current Amp. 1) input pin.

14 CTL I Power supply control pin.

Setting the CTL pin low places the IC in the standby mode.

15 FB3 O Error amplifier (Error Amp. 3) output pin.

16 –INE3 I Error amplifier (Error Amp. 3) inverted input pin.

17 RT — Triangular-wave oscillation frequency setting resistor connection pin.

18 VCC — Power supply pin for reference power supply and control circuit.

19 VH O Power supply pin for FET drive circuit (VH = Vcc − 5 V).

20 OUT O High-side FET gate drive pin.

21 VCC(O) — Output circuit power supply.

22 CS — Soft-start capacitor connection pin.

23 GND — Ground pin.

24 +INC2 I Current detection amplifier (Current Amp. 2) input pin.

MB3875/3877

■BLOC K DIAGRAM

−−

× 25

−

17 5 23

<Current Amp.1> <Error

Amp.1>

VREF

<Current Amp.2> <Error

Amp.2>VREF

<Error

Amp.3>VREF

VREF

(4.2 V)

∗

50 kΩ

1 µA

15 <SOFT>

2.5 V

1.5 V

<OUT>

<UVLO>

<OSC>

<VH>

<PWM

Comp.>

Drive

VCC

(VCC − 5 V)

(VCC UVLO)

VCC

VCC VCC

CTL

215 kΩ

35 kΩ

0.91 V

(0.77 V)

VREF

ULVO

bias

−INC2

IN3

FB2

OUTC2

VREF

−INE2

+INE2

+INE1

FB1

OUTC1

−INE1

−INC1

+INC2

GND

VCC (O)

OUT

−INE3

FB3

+INC1

MB3875 100 kΩ

MB3877 150 kΩ

∗ :

(45 pF)

Bias voltage

block

MB3875/3877

■ABSOLUTE MAXIMUM RAGINGS

*: The package is mounted on the dual-sided epoxy board (10 cm × 10 cm).

WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current,

temperature, etc.) in excess of absolute maximum ratings. Do not exceed these ratings.

■RECOMMENDED OPERATING CONDITIONS

WARNING: The recommended operating conditions are required in order to ensure the normal operation of the

semiconductor device. All of the device’s electrical characteristics are warranted when the device is

operated within these ranges.

Always use semiconductor devices within their recommended operating condition ranges. Operation

outside these ranges may adversely affect reliability and could result in device failure.

No warranty is made with respect to uses, operating conditions, or combinations not represented on

the data sheet. Users considering application outside the listed conditions are advised to contact their

representatives beforehand.

Parameter Symbol Conditions Rating Unit

Min Max

Power supply voltage VCC VCC,VCC(O) — 28 V

Output current IOUT ——60mA

Peak output current IOUT Duty ≤ 5% (t =1 / fOSC × Duty) — 500 mA

Power dissipation PDTa ≤ +25°C — 740* mW

Storage temperature Tstg — –55 +125 °C

Parameter Symbol Conditions Value Unit

Min Typ Max

Power supply voltage VCC VCC,VCC(O) 7 — 25 V

Reference voltage output

current IREF —–1—0mA

VH pin output current IVH —0—30mA

Input vo lta ge

VIN IN3 0 — 17 V

VINE –INE1,–INE2,+INE1,+INE2 0 — VCC – 1.8 V

VINC +INC1,+INC2,–INC1,–INC2, 0 — VCC V

CTL pin input voltage VCTL —0—25V

Output current IOUT —–45—45mA

Peak output current IOUT Duty ≤ 5% (t =1 / fOSC × Duty) –450 — 450 mA

Oscillator frequency fOSC — 100 290 500 kHz

Timing resistor RT— 33 47 130 kΩ

Soft-start capacitor CS— — 2200 100000 pF

VH pin capacitor CVH ——0.11.0µF

Reference voltage output

capacitor CREF ——0.11.0µF

Operating temperature Ta — –30 +25 +85 °C

MB3875/3877

■ELECTRICAL CHARACTERISTICS (MB3875: Ta = +25°C, VCC = 16 V, VCC (O) = 16 V, VREF = 0 mA)

(MB3877: Ta = +25°C, VCC = 19 V, VCC (O) = 19 V, VREF = 0 mA)

*: Standard design value. (Continued)

Parameter Symbol Pin No. Conditions Value Unit Remarks

Min Typ Max

Output voltage VREF 5Ta = +25°C 4.167 4.200 4.233 V

Ta = –30°C to +85°C 4.158 4.200 4.242 V

Input stability Line 5 VCC = 7 V to 25 V — 3 10 mV

Load stability Load 5 VREF = 0 mA to –1 mA — 1 10 mV

Short-circuit

output current IOS 5 VREF = 1 V –25 –15 –5 mA

Threshold

voltage

VTLH

VCC =VCC (O),

VCC = 6.3 6.6 6.9 V

VTHL VCC =VCC (O),

VCC = 5.3 5.6 5.9 V

Hysteresis width VH18 VCC =VCC (O) 0.7 1.0 1.3 V

Threshold

voltage

VTLH

5VREF = 2.6 2.8 3.0 V

VTHL VREF= 2.4 2.6 2.8 V

Hysteresis width VH5 — 0.05 0.20 0.35 V

Charge current ICS 22 — –1.3 –0.8 –0.5 µA

Oscillation

frequency fOSC 20 RT = 47 kΩ260 290 320 kHz

Frequency tem-

perature stability ∆f/fdT 20 Ta = –30°C to +85°C — 1* — %

Ref erence vo ltage

block (Ref)

Under voltag e

lockout protection

circuit block (UVLO)

Soft-start

block

(SOFT)

Triangular waveform

oscillator circuit

block (OSC)

MB3875/3877

(MB3875: Ta = +25°C, VCC = 16 V, VCC (O) = 16 V, VREF = 0 mA)

(MB3877: Ta = +25°C, VCC = 19 V, VCC (O) = 19 V, VREF = 0 mA)

*: Standard design value. (Continued)

Parameter Symbol Pin No Conditions Value Unit Remarks

Min Typ Max

Input offset

voltage VIO 6,7,8,11 FB1 = FB2 = 2 V — 1 5 mV

Input bias

current IB6,7,8,11 — –100 –30 — nA

Common

mode input

voltage range VCM 6,7,8,11 — 0 — VCC–1.8 V

Voltage gain AV3,9 DC — 100* — dB

Frequency

bandwidth BW3,9 AV = 0 dB — 2.0* — MHz

Output voltage VFBH 3,9 — 3.9 4.1 — V

VFBL 3,9 — — 20 200 mV

Output source

current ISOURCE 3,9 FB1 = FB2 = 2 V — –2.0 –0.6 mA

Output sink

current ISINK 3,9 FB1 = FB2 = 2 V 150 300 — µA

Threshold

voltage VTH 2

FB3 = 2 V,

Ta = +25 °C 12.500 12.600 12.700 V MB3875

16.666 16.800 16.934 V MB3877

FB3 = 2 V,

Ta = –30 °C to +85 °C12.474 12.600 12.726 V MB3875

16.632 16.800 16.968 V MB3877

Input cu rren t

IINE3H 2IN3 = 12.6 V — 84 150 µAMB3875

IN3 = 16.8 V — 84 150 µAMB3877

IINE3L 2VCC = 0 V, IN3 = 12.6 V — 0 1 µAMB3875

VCC = 0 V, IN3 = 16.8 V — 0 1 µAMB3877

Input resi st or R12—

70 100 130 kΩMB3875

105 150 195 kΩMB3877

R216 — 35 50 65 kΩ

Voltage gain AV15 DC — 100* — dB

Frequency

bandwidth BW 15 AV = 0 dB — 2.0* — MHz

Output voltage VFBH 15 — 3.9 4.1 — V

VFBL 15 — — 20 200 mV

Output source

current ISOURCE 15 FB3 = 2 V — –2.0 –0.6 mA

Output sink

current ISINK 15 FB3 = 2 V 150 300 — µA

Er ro r a mplif ier blo ck

(Error Amp.1, 2)

Error amplifier block

(Error Am p.3)

MB3875/3877

(MB3875: Ta = +25°C, VCC = 16 V, VCC (O) = 16 V, VREF = 0 mA)

(MB3877: Ta = +25°C, VCC = 19 V, VCC (O) = 19 V, VREF = 0 mA)

*: Standard design value. (Continued)

Parameter Symbol Pin No. Conditions Value Unit Remarks

Min Typ Max

Input current

I+INCH 13, 24

+INC1= +INC2=12.7 V

–INC1= –INC2=12.6 V —1020µAMB3875

+INC1= +INC2=16.9 V

–INC1= –INC2=16.8 V —1020µAMB3877

I–INCH 1, 12

+INC1= +INC2=12.7 V

–INC1= –INC2=12.6 V —0.10.2µAMB3875

+INC1= +INC2=16.9 V

–INC1= –INC2=16.8 V —0.10.2µAMB3877

I+INCL 13, 24 +INC1= +INC2= 0.1 V

–INC1= –INC2= 0 V –130 –65 — µA

I–INCL 1, 12 +INC1= +INC2= 0.1V

–INC1= –INC2= 0 V –140 –70 — µA

Current detection

voltage

VOUTC1 4, 10

+INC1= +INC2=12.7 V

–INC1= –INC2=12.6 V 2.25 2.5 2.75 V MB3875

+INC1= +INC2=16.9 V

–INC1= –INC2=16.8 V 2.25 2.5 2.75 V MB3877

VOUTC2 4, 10

+INC1= +INC2=12.63V

–INC1= –INC2=12.6 V 0.50 0.75 1.00 V MB3875

+INC1= +INC2=16.83V

–INC1= –INC2=16.8 V 0.50 0.75 1.00 V MB3877

VOUTC3 4, 10 +INC1= +INC2= 0.1 V

–INC1= –INC2= 0 V 1.25 2.50 3.75 V

VOUTC4 4, 10 +INC1= +INC2= 0.03 V

–INC1= –INC2= 0 V 0.125 0.750 1.375 V

Common mode

input voltage range VCM 1, 12,

13, 24 —0—V

CC V

Voltage gain AV4, 10

+INC1= +INC2=12.7 V

–INC1= –INC2=12.6 V 22.5 25 27.5 V/V MB3875

+INC1= +INC2=16.9 V

–INC1= –INC2=16.8 V 22.5 25 27.5 V/V MB3877

Frequency

bandwidth BW 4, 10 AV = 0 dB — 2.0* — MHz

Output voltage VOUTCH 4, 10 — 3.9 4.1 V

VOUTCL 4, 10 — — 20 200 mV

Output source

current ISOURCE 4, 10 OUTC1 = OUTC2 = 2 V — –2.0 –0.6 mA

Output sink

current ISINK 4, 10 OUTC1 = OUTC2 = 2 V 150 300 — µA

Current detection amplifier block

(Current Amp.1,2)

MB3875/3877

(Continued) (MB3875 : Ta = +25°C, VCC = 16 V, VCC (O) = 16 V, VREF = 0mA)

(MB3877 : Ta = +25°C, VCC = 19 V, VCC (O) = 19 V, VREF = 0mA)

*: Standard design value.

Parameter Symbol Pin No. Conditions Value Unit Remarks

Min Typ Max

Threshold voltage

VTL 3,9,15 Duty cycle = 0 % 1.4 1.5 — V

VTH 3,9,15 Duty cycle = 100 % — 2.5 2.6 V

Output source

current ISOURCE 20

OUT = 11 V

Duty ≤ 5 %

(t = 1/fosc × Duty ) — –200* — mA MB3875

OUT = 14 V

Duty ≤ 5 %

(t = 1/fosc × Duty ) — –200* — mA MB3877

Output sink current ISINK 20

OUT = 16 V

Duty ≤ 5 %

(t = 1/fosc × Duty ) — 200* — mA MB3875

OUT = 19 V

Duty ≤ 5 %

(t = 1/fosc × Duty ) — 200* — mA MB3877

Output ON resistor ROH 20 OUT = −45 mA — 8.0 16 Ω

ROL 20 OUT = 45 mA — 6.5 13 Ω

Rise time tr1 20 OUT = 3300 pF

(Equivalent to Si4435DY) — 70* — ns

Fall time tf2 20 OUT = 3300 pF

(Equivalent to Si4435DY) — 60* — ns

CTL input voltage VON 14 Active mode 2—25V

VOFF 14 Standby mode 0—0.8V

Input current ICTLH 14 CTL = 5 V — 100 200 µA

ICTLL 14 CTL = 0 V —01µA

Output voltage VH 19 VCC = VCC(O)

= 7 V to 25 V,

VH = 0 to 30 mA VCC–5.5 VCC–5.0 VCC–4.5 V

Standby current ICCS 18 VCC = VCC(O),

CTL = 0 V —010µA

Power supply current ICC 18 VCC = VCC(O),

CTL = 5 V —6.09.0mA

MB3875

—6.59.5mA

MB3877

PWM comp arator

block

(PWM Comp.)

Out put bloc k

(OUT)

General Bias

voltage

block (VH)

Control block

(CTL)

MB3875/3877

■TYPICAL CHARACTERISTICS

(Continued)

00 5 10 15 20 25

Ta = +25 °C

VCC = 16 V (MB3875)

VCC = 19 V (MB3877)

VREF = 0 mA

Power supply current ICC (mA)

Power supply voltage VCC (V)

Power supply current vs. power supply voltage

Power supply voltage VCC (V)

Reference voltage vs. power supply voltage

Referenc e voltag e VREF (V)

Reference voltage VREF (V)

Refe rence volt age vs. VREF load current

Reference voltage vs. CTL pin voltage

Reference voltage VREF (V)

CTL pin voltage VCTL(V) Control pin voltage VCTL (V)

CTL pin current vs. CTL pin voltage

CTL pin current ICTL (µA)

00 5 10 15 20 25

Ta = +25 °C

CTL = 5 V Ta = +25 °C

CTL = 5 V

VREF = 0 mA

00 5 10 15 20 25

00 5 10 15 20 25 30

Ta = +25 °C

VCC = 16 V (MB3875)

VCC = 19 V (MB3877)

CTL = 5 V

2.0

1.5

1.0

0.5

0.0

−0.5

−1.0

−1.5

−2.0

−40 −20 0 20 40 60 80 100

VCC = 16 V (MB3875)

VCC = 19 V (MB3877)

CTL = 5 V

VREF = 0 mA

00 5 10 15 20 25

Ta = +25 °C

VCC = 16 V (MB3875)

VCC = 19 V (MB3877)

Reference voltage vs. ambient temperature

Reference voltage ∆VREF (%)

Ambient temperature Ta (°C)

VREF load current IREF (mA)

MB3875/3877

(Continued)

1 M

100 k

10 k

10 k 100 k 1 M

Ta = +25 °C

= 16 V (MB3875)

= 19 V (MB3877)

CTL = 5 V

350

340

330

320

310

300

290

280

270

260

250 0 5 10 15 20 25

Ta = +25 °C

CTL = 5 V

RT = 47 kΩ

Triangular wave oscillator frequency vs.

timing resistor

Triangular wave oscillator frequency fOSC(Hz)

Timing resi stor RT (Ω)

Triangular wave oscillator frequency fOSC(kHz)

Triangular wave oscillator frequency vs.

power supply voltage

Power supply voltage VCC (V)

Ambient temperature Ta (°C)

350

340

330

320

310

300

290

280

270

260

250

−40 −20 0 20 40 60 80 100

VCC = 16 V (MB3875)

VCC = 19 V (MB3877)

CTL = 5 V

RT = 47 kΩ

5.0

4.0

3.0

2.0

1.0

0.0

−40 −20 0 20 40 60 80 100

−1.0

−2.0

−3.0

−4.0

−5.0

VCC = 16 V (MB3875)

VCC = 19 V (MB3877)

CTL = 5 V

Triangular wave oscillator frequency vs.

ambient temperature

Triangular wave oscillator frequency fOSC(kHz)

Error amplifier threshold voltage vs.

ambient temper at ure

Error amplifier threshold voltage ∆VTH(%)

Ambient temperature Ta (°C)

MB3875/3877

(Continued)

Power dissipation vs. ambient temperature

Power dissipation PD (mW)

Ambient temperature Ta (°C)

Error amplifier gain and phase vs. frequency

Gain AV (dB)

Frequency f (Hz)

Current detection amplifier gain and phase vs. frequency

Gain AV (dB)

Frequency f (Hz)

Ta = +25 °C

−20

−40

100 1 k 10 k 100 k 1 M 10 M

180

−90

−180

VCC = 16 V (MB3875)

VCC = 19 V (MB3877)

− + −

(7) (3)

(6)

2.088 V

10 kΩ

2.4 kΩ

240 kΩ

10 kΩ

4.2 V

9OUT

Phase φ (deg)

−

24 4

(13)

(12) (10)

100 kΩOUT

× 25

0.1 V

∗ : MB3875 12.6 V

MB3877 16.8 V

Current Amp.2

(Current Amp.1)

VCC = 16 V (MB3875)

VCC = 19 V (MB3877)

100 1 k 10 k 100 k 1 M

−20

−40

180

−90

−180

Ta = +25 °C

φ∗

Phase φ (deg)

800

740

700

600

500

400

300

200

100

−40 −20 0 20 40 60 80 100

MB3875/3877

■FUNCTIONAL DESCRIPTION

1. DC/DC Converter Unit

(1) Reference voltage block (Ref)

The reference v oltage generator uses the voltage supplied from the Vcc terminal (pin 18) to generate a temper-

ature-compensated, stable voltage ( := 4.2 V) used as the ref erence supply voltage for the IC’ s internal circuitry.

The reference voltage can be output, up to 1 mA, to an external device through the VREF terminal (pin 5).

(2) Triangular wave oscilla tor block(OSC)

The tr iangular wave oscillat or generates a tr iangular wavefor m with a freque ncy setting res istor connect ed to

the internal frequency setting capacitor via the R T terminal (pin 17).

The triangular wave is input to the PWM comparator on the IC.

(3) Error amplifier block (Error Amp. 1)

This error amplifier (Error Amp. 1) detects a voltage drop in the AC adapter and outputs a PWM control signal.

In addition, an arbitrary loop gain can be set by connecting a feedback resistor and capacitor from the FB1

terminal (pin 9) to the -INE1 terminal (pin 11) of the error amplifier, enabling stable phase compensation to the

system.

(4) Error amplifier block (Error Amp. 2)

This error amplifier (Error Amp. 2) detects the output signal from the current detector amplifier

(Current Amp. 2), compares it with the +INE2 terminal (pin 7), and outputs a PWM control signal to control the

char ge current.

In addition, an arbitrary loop gain can be set by connecting a feedback resistor and capacitor from the FB2

ter minal (pin 3) to the -INE2 ter minal ( pin 6) of the error amplifier, enabling stable phase comp ensation to the

system.

(5) Error amplifier block (Error Amp. 3)

This erro r am pl ifi er (Er ror A mp. 3) detects the ou tpu t voltage from th e DC/DC conver ter and outpu ts the PW M

cont rol s ignal. The error amp lifier inver ting input pin is connected to the outpu t voltage se tting resist or in the

IC, eliminatin g the need for an exter nal resis tor for setting the outpu t voltage. The MB3875 and MB3 877 are

set to output voltage of 12.6 V (for a 3-cell battery) and 16.8 V (for a 4-cell battery), respectively; these ICs are

suitable for use in equipment that uses a lithium-ion battery.

In addition, an arbitrary loop gain can be set by connecting a feedback resistor and capacitor from the FB3

terminal (pin 15) to the -INE3 terminal (pin 16) of the error amplifier , enab ling stable phase compensation to the

system.

Connecting a soft-start capacitor to the CS terminal (pin 22) prevents surge currents when the IC is turned on.

Using an error amplifier for soft-start detection makes the soft-start time constant, independent of the output load.

(6) Current detector amplifier block (Current Amp. 2)

The current detection amplifier (Current Amp. 2) detects a voltage drop which occurs between both ends of the

output sens e re sistor (RS) d ue to th e fl ow of th e c har ge cur re nt, using the +INC2 termi nal ( pi n 2 4) and −INC2

terminal (pin 1). Then it outputs the signal amplified by 25 times to the error amplifier (Error Amp. 2) at the next

stage.

MB3875/3877

(7) PWM comparator block (PWM Comp.)

The PWM comparator circuit is a voltage-pulse width converter for controlling the output duty of the error

amplifiers (Error Amp. 1 to Error Amp. 3) depending on their output voltage.

The PW M comparator ci rcuit compares the tria ngular wave generated by the tr iangular wave os cillator to the

error amplifier output voltage and turns on the external output transistor during the interval in which the triangular

wave voltage is lower than the error amplifier output voltage.

(8) Output block (OUT)

The output circuit uses a totem-pole configuration capable of driving an external P-channel MOS FET.

The outpu t “L” level sets the output ampl itude to 5 V (typic al) using the voltage generated by the bias voltage

blo ck ( VH ) .

This results in increasing conversion efficiency and suppressing the withstand voltage of the connected external

transistor in a wide range of input voltages.

(9) Control block (CTL)

Setting the CTL terminal (pin 14) low places the IC in the standby mode. (The supply current is 10 µA at maximum

in the standby mode.)

(10) Bias voltage block (VH)

The bias voltage circuit outputs Vcc − 5 V (typical) as the minimum potential of the output circuit. In the standby

mode, this circuit outputs the potential equal to Vcc.

2. Protection Functions

Low-Vcc malfunction preventive circuit (UVLO)

The transient state or a momentary decrease in supply voltage or internal reference voltage (VREF), which

occurs when the power supply is tur ned on, may cause malfun ctions in the control IC, resulting in bre akdown

or degradation of the sys tem. To prevent such m alf unction, th e low-Vcc mal functi on preventive circu it detects

a supply voltage or internal reference voltage drop and fixes the OUT ter minal (pin 20) to the “H” level. The

system restores voltage supply when the supply voltage or internal reference voltage reaches the threshold

voltage of the low-Vcc malfunction preventive circuit.

3. Soft-Start Function

Soft-start block (SOFT)

Connecting a capacitor to the CS terminal (pin 22) prev ents surge currents when the IC is turned on. Using an

error a mpl ifier for soft-start detecti on makes t he sof t -sta rt time const ant, ind epe nde nt o f the output loa d of the

DC/DC converter.

MB3875/3877

■METHOD OF SETTING THE CHARGING CURRENT

The charge current (output control current) value can be set with the voltage at the +INE2 terminal.

If a current exceeding the set value attempts to flow , the charge voltage drops according to the set current value.

Battery charge current setting voltage

+INE2 (V) = 25 × I1 (A) × RS (Ω)

■METHOD OF SETTING THE SOFT-START TIME

Upon activation, the IC starts charging the capacitor (Cs) connected to the CS terminal (pin 22).

The erro r amplifi er causes soft-sta rt operation to be performe d with t he output voltage in pro port ion to the CS

pin voltage regardless of the load current of the DC/DC converter.

Soft-start time ts (Time taken for the output voltage to reach 100 %)

ts (s) := 4.2 × CS (µF)

■METHOD OF SETTING THE TRIANGULAR W AVE OSCILLA T OR FREQUENCY SETTING

The trianguar wave oscillator frequency can be set by the timing resistor (RT) connected the RT terminal (pin 17).

Triangular wave oscillator frequency fOSC

fOSC (kHz ) := 14444 / RT (kΩ)

MB3875/3877

■AC ADAPTER VOLTAGE DETECTION

With an exter nal resist or connec ted to the + INE1 ter minal , the IC en ters the dy namical ly-control led chargi ng

mode to reduce the charge current to keep AC adapter power constant when the partial potential point A of the

AC adapter voltage (Vcc) becomes lower than the voltage at the -INE1 terminal.

AC adapter detected voltage setting Vth

Vth (V) = (R1 + R2) / R2 × − INE1

− INE1 setting voltage range : 1.176 V to 4.2 V (equivalent to 7 V to 25 V for Vcc)

■OPERATION TIMING DIAGRAM

−

VCC R1

+INE1

−INE1

2.5 V

1.5 V

Error Amp.2

Error Amp.3

Error Amp.1

FB2

FB3

FB1

OUT

Constant voltage

control

AC adapter dynamically-

controlled charging Constant current control AC adapter dynami cally-

contr oll ed cha rgi ng

MB3875/3877

■ NOTE ON AN EXTERNAL REVERSE-CURRENTPREVENTIVE DIODE

Inse r t a r everse-curr ent preventive diode (D) at on e of t he three lo catio ns mar ked * t o prevent reverse cur rent

from the battery.

Pay attention to the voltage/current characteristics of the reverse-current prev entive diode (D) not to let it exceed

the overcharge stop voltage.

VCC(O)

OUT

VIN

(16 V/19 V)

I1 RS

BATT

12.6 V/16.8 V

A B

∗

Battery 1

MB3875/3877

■APPLICATION EXAMPLE

−−

× 25

−

<Current Amp.1> <Error

Amp.1>VREF

<Current Amp.2> <Error

Amp.2>VREF

<Error

Amp.3>VREF

VREF

(4.2 V)

∗1

50 kΩ

1 µA

<SOFT>

2.5 V

1.5 V

<OUT>

<UVLO>

<PWM

Comp.>

Drive

− 5 V)

UVLO)

CTL

215 kΩ

35 kΩ

0.91 V

(0.77 V)

VREF

ULVO

bias

−INC2

IN3

FB2

VREF

−INE2

+INE1

FB1

OUTC1

−INE1

−INC1

+INC2

GND

(O)

OUT

−INE3

FB3

+INC1

MB3875

MB3877

Vin = 16 V

Vin = 19 V

MB3875

MB3877

MB3875

MB3877

100 kΩ

150 kΩ

0 Ω

82 kΩ

16 V/19 V

19 V

12.6 V

16.8 V

∗ 1 :

∗ 2 :

∗ 3 :

∗ 4 :

−

150 kΩ

100 kΩ

C10 3900 pF

3900 pF

R10

22 kΩ

∗ 2

330 kΩ

68 kΩ

R11

30 kΩ

OUTC2

B+INE2

R12

22 kΩ

R14

1.3 kΩ

R16

200 kΩ

VIN

∗ 3

SW1

30 kΩ

R13

110 Ω

R15

200 kΩ

3900 pF

2200 pF

150 kΩ

523

(45 pF)

47 kΩ

0.1 µF

0.1 µFC1

22 µF

100 µFC3

100 µF

27 µH

BATT

∗ 4

0.033 Ω

A B

<VH>

Bias voltage

block

Battery

MB3875/3877

■PARTS LIST

Note: VISHAY SILICONIX : VISHAY Intertechrology, Inc.

MOTOROLA : Motorola Japan Ltd.

SUMIDA : SUMIDA ELECTRIC CO., Ltd.

COMPONET ITEM SPECIFICATION VENDOR PARTS NO.

Q2 FET

FET Si4435DY

2N7002 VISHAY SILICONIX

VISHAY SILICONIX Si4435DY

2N7002

D1 Diode MBRS130LT3 MOTOROLA MBRS130LT3

L1 Coil 27µH 3.4A, 34mΩSUMIDA CDRH127-27uH

C10

OS Condensor

Ceramics Condensor

22µF

100µF

2200pF

0.1µF

3900pF

0.1pF

3900pF

0.1µF

3900pF

25V(10%)

16V(10%)

25V(10%)

16V(10%)

25V(10%)

10%

16V

10%

25V

10%

16V

10%

——

R10

R11

R12

R13

R14

R15

R16

Resistor

0.033Ω

47kΩ

200kΩ

0Ω

82kΩ

330kΩ

68kΩ

150kΩ

100kΩ

150kΩ

22kΩ

30kΩ

22kΩ

30kΩ

1.3kΩ

110Ω

200kΩ

1.0%

Jumpe r lin e

0.5%

1.0%

0.5%

——

MB3875/3877

■REFERENCE DATA

•MB3875

Note: KIKUSUI : KIKUSUI Electronics Corp.

Vin = 16 V

Vin = 19 V

10 m 100 m 1 10

100

Vin = 16 V

R4 = 0 Ω

Vin = 19 V

R4 = 82 kΩ

100

800 2 4 6 8 10121416

Dead Battery MODE DCC MODE

DCC : Dynamically-Controlled Charging

012345

Dead Battery MODE DCC MODE

DCC : Dynamically-Controlled Charging

012345

Conversion efficiency vs. charge current

(Fixed vo ltage mode) Conversion eff iciency vs. charge voltage

(Fixed current mode)

BATT charge current IBATT(A)

Conversion efficiency η(%)

BATT charge voltage=12.6V fOSC=288.78kHz

efficiency η(%)=(VBATT × IBATT)/(Vin × Iin) × 100

Conversion efficiency η(%)

BATT= Electronic load

(Product of KIKUSUI PLZ-150W)

BATT charge voltage VBATT(V)

BATT voltage vs. BATT charge current BATT voltage vs. BATT charge current

BATT voltage VBATT(V)

BATT charge current IBATT(A)

Vin=16v

BATT: Electronic load

(Product of KIKUSUI PLZ-150W)

Vin=19v

BATT: Electronic load

(Product of KIKUSUI PLZ-150W)

MB3875/3877

(Continued)

0 80 120 160 200

t (ms)

BATT (V)

CTL (V)

5 V

5 V 20 ms

046810

t (µs)

−5

OUT (V)

1 µs

5 V

0 80 120 160 200

t (ms)

BATT (V)

CTL (V)

5 V

5 V 20 ms

046810

t (µs)

−5

OUT (V)

1 µs

5 V

Soft-star t operating wavefo rms

Vin = 16 V

Load: BATT = 20 Ω

− INE1 = 0 V

DC/DC converter switching waveforms

Vin = 16 V

FOSC = 288.8 kHz

Load: BATT = 2A

Soft-start operating waveforms

Vin = 19 V

Load: BATT = 20 Ω

− INE1 = 0 V

DC/DC converter switching waveforms

Vin = 19 V

FOSC = 288.8 kHz

Load: BATT = 2A

MB3875/3877

•MB3877

Note: KIKUSUI : KIKUSUI Electronics Corp.

Vin = 19 V

100

10 m 100 m 1 10

100

80024681012141618

Vin = 19 V

R4 = 82 kΩ

Dead Battery MODE DCC MODE

DCC : Dynamically-Controlled Charging

12345

Conversion efficiency vs.charge current

BATT charge current IBATT(A)

Conver si on effici enc y η(%)

BATT charge voltage=12.6V fOSC=288.78kHz

efficiency η(%)=(VBATT × IBATT)/(Vin × Iin) × 100

Conversion efficiency vs. charge voltage

Conversion efficiency η(%)

BATT= Electronic load

(Product of KIKUSUI PLZ-150W)

BATT charge voltage VBATT(V)

BATT voltage vs. BATT charge current

BATT voltage VBATT(V)

BATT charge current IBATT(A)

Vin=19v

BATT: Electronic load

(Product of KIKUSUI PLZ-150W)

MB3875/3877

(Continued)

0 80 120 160 200

t (ms)

BATT (V)

CTL (V)

10 V

5 V 20 ms

046810

t (µs)

−5

OUT (V)

1 µs

5 V

Soft-start operating waveforms

Vin = 19 V

Load: BATT = 50 Ω

− INE1 = 0 V

DC/DC converter switching waveforms

Vin = 19 V

FOSC = 287.4 kHz

Load: BATT = 2 A

MB3875/3877

■NOTES ON USE

• Take account of common impedance when designing the earth line on a printed wiring board.

• Take measures against static electricity.

- For semiconductors, use antistatic or conductive containers.

- When storing or carrying a printed circuit board after chip mounting, put it in a conductive bag or container.

- The work table, tools and measuring instruments must be grounded.

- The worker must put on a grounding device containing 250 kΩ to 1 MΩ resistors in series.

• Do not apply a negative voltage

- Applying a negative voltage of −0.3 V or less to an LSI may generate a parasitic transistor, resulting in

malfunction.

■ORDERING INFORMATION

Part number Package Remarks

MB3875PFV

MB3877PFV 24-pin plastic SSOP

(FPT-24P-M03)

MB3875/3877

■PACKAGE DIMENSION

24-pin plastic SSOP

(FPT-24P-M03)

Note 1) *1 : Resin protrusion. (Each side : +0.15 (.006) MAX) .

Note 2) *2 : These dim ensio ns do not incl ude resi n pro tr usi on .

Note 3) Pins width and pins thickness include plating thickness.

Note 4) Pins width do not include tie bar cutting remainder.

Dimensions in mm (inches) .

Note : The values in parentheses are reference values.

2003 FUJITSU LIMITED F24018S-c-4-5

7.75±0.10(.305±.004)

5.60±0.10 7.60±0.20

(.220±.004) (.299±.008)

0.10(.004)

112

1324

0.65(.026) –0.07

+0.08

0.24

.009 +.003

–.003 M

0.13(.005)

INDEX

0.17±0.03

(.007±.001)

"A"

0.25(.010)

0.10±0.10

(.004±.004)

(Stand off)

Details of "A" part

(Mounting height)

1.25 +0.20

–0.10

–.004

+.008

.049

0~8˚

0.50±0.20

(.020±.008)

0.60±0.15

(.024±.006)

0.10(.004)

MB3875/3877

MEMO

MB3875/3877

MEMO

FUJITSU MICROELECTRONICS LIMITED

Shinjuku Dai-Ichi Seimei Bldg. 7-1, Nishishinjuku 2-chome, Shinjuku-ku,

Tokyo 163-0722, Japan Tel: +81-3-5322-3347 Fax: +81-3-5322-3387

http://jp.fujitsu.com/fml/en/

For further information please contact:

North and South America

FUJITSU MICROELECTRONICS AMERICA, INC.

1250 E. Arques Avenue, M/S 333

Sunnyvale, CA 94085-5401, U.S.A.

Tel: +1-408-737-5600 Fax: +1-408-737-5999

http://www.fma.fujitsu.com/

Europe

FUJITSU MICROELECTRONICS EUROPE GmbH

Pittlerstrasse 47, 63225 Langen,

Germany

Tel: +49-6103-690-0 Fax: +49-6103-690-122

http://emea.fujitsu.com/microelectronics/

Korea

FUJITSU MICROELECTRONICS KOREA LTD.

206 KOSMO TOWER, 1002 Daechi-Dong,

Kangnam-Gu,Seoul 135-280

Korea

Tel: +82-2-3484-7100 Fax: +82-2-3484-7111

http://www.fmk.fujitsu.com/

Asia Pacific

FUJITSU MICROELECTRONICS ASIA PTE LTD.

151 Lorong Chuan, #05-08 New Tech Park,

Singapore 556741

Tel: +65-6281-0770 Fax: +65-6281-0220

http://www.fujitsu.com/sg/services/micro/semiconductor/

FUJITSU MICROELECTRONICS SHANGHAI CO., LTD.

Rm.3102, Bund Center, No.222 Yan An Road(E),

Shanghai 200002, China

Tel: +86-21-6335-1560 Fax: +86-21-6335-1605

http://cn.fujitsu.com/fmc/

FUJITSU MICROELECTRONICS PACIFIC ASIA LTD.

10/F., World Commerce Centre, 11 Canton Road

Tsimshatsui, Kowloon

Hong Kong

Tel: +852-2377-0226 Fax: +852-2376-3269

http://cn.fujitsu.com/fmc/tw

The contents of this document are subject to change without notice.

Customers are advised to consult with sales representatives before ordering.

The information, such as descriptions of function and application circuit examples, in this document are presented solely for the purpose

of reference to show examples of operations and uses of FUJITSU MICROELECTRONICS device; FUJITSU MICROELECTRONICS

does not warrant proper operation of the device with respect to use based on such information. When you develop equipment incorporat-

ing the device based on such information, you must assume any responsibility arising out of such use of the information.

FUJITSU MICROELECTRONICS assumes no liability for any damages whatsoever arising out of the use of the information.

Any information in this document, including descriptions of function and schematic diagrams, shall not be construed as license of the use

or exercise of any intellectual property right, such as patent right or copyright, or any other right of FUJITSU MICROELECTRONICS

or any third party or does FUJITSU MICROELECTRONICS warrant non-infringement of any third-party's intellectual property right or

other right by using such information. FUJITSU MICROELECTRONICS assumes no liability for any infringement of the intellectual

property rights or other rights of third parties which would result from the use of information contained herein.

The products described in this document are designed, developed and manufactured as contemplated for general use, including without

limitation, ordinary industrial use, general office use, personal use, and household use, but are not designed, developed and manufactured

as contemplated (1) for use accompanying fatal risks or dangers that, unless extremely high safety is secured, could have a serious effect

to the public, and could lead directly to death, personal injury, severe physical damage or other loss (i.e., nuclear reaction control in

nuclear facility, aircraft flight control, air traffic control, mass transport control, medical life support system, missile launch control in

weapon system), or (2) for use requiring extremely high reliability (i.e., submersible repeater and artificial satellite).

Please note that FUJITSU MICROELECTRONICS will not be liable against you and/or any third party for any claims or damages arising

in connection with above-mentioned uses of the products.

Any semiconductor devices have an inherent chance of failure. You must protect against injury, damage or loss from such failures by

incorporating safety design measures into your facility and equipment such as redundancy, fire protection, and prevention of over-current

levels and other abnormal operating conditions.

Exportation/release of any products described in this document may require necessary procedures in accordance with the regulations of

the Foreign Exchange and Foreign Trade Control Law of Japan and/or US export control laws.

The company names and brand names herein are the trademarks or registered trademarks of their respective owners.

Edited Strategic Business Development Dept.