MB3876PFV - Fujitsu Quantum Devices Limited

DS04-27704-3E

FUJITSU SEMICONDUCTOR

DATA SHEET

ASSP

F or Power Supply Applications (Lithium ion battery charger)

DC/DC Con verter IC for Parallel Charging

MB3874/MB3876

■

■■

■DESCRIPTION

The MB3874 and MB3876 are parallel charging DC/DC con v erter ICs suitable f or do wn-con version, which uses

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

These ICs can dynamically control the secondary battery’s charge current by detecting a voltage drop 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.

The IC also enable parallel charging, or charging two batteries at the same time, dramatically reducing the charging

time.

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 MB3874 support 3-cell battery and the MB3876 support 4-cell battery.

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

■

■■

■FEATURES

• Detecting a voltage drop in the AC adapter and dynamically controlling the charge current (Dynamically-con-

trolled charging)

• High efficiency : 93 %(In reverse-current preventive diode)

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

(Continued)

■

■■

■PACKAGE

24-pin plastic SSOP

(FPT-24P-M03)

MB3874/MB3876

(Continued)

• Output voltage precision

(Built-in output voltage setting resistor ): ± 0.8 % (Ta = + 25 °C)

• 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

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

• Built-in standby current function: 0 µA (Typ)

• Built-in soft-start function

• Capable of parallel charging (Charging the two battery packs at a time)

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

MB3874/MB3876

■

■■

■PIN ASSIGNMENT

(TOP VIEW)

(FPT-24P-M03)

−INC1 :

FB2 :

−INE2 :

+INE2 :

VREF :

CTL :

FB1 :

−INE1 :

+INE3 :

−INE3 :

FB3 :

−INC2 :

: +INC1

: GND

: CS

: VCC

: OUT

: VH

: OUTM

: RT

: −INE4

: FB4

: −INE5

: +INC2

MB3874/MB3876

■

■■

■PIN DESCRIPTION

Pin No. Symbol I/O Descriptions

1 –INC1 I Output voltage feedback input pin.

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

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

4+INE2 I

Error amplifier (Error Amp. 2) non-inverted input pin.

Input pin for charge current setting voltage

5 VREF O Reference voltage output pin.

6CTL I

Power supply control pin.

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

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

8–INE1 I

Error amplifier (Error Amp. 1) inverted input pin

Input pin for dynamically-controlled charging voltage setting

9+INE3 I

Error amplifier (Error Amp. 3) non-inverted input pin.

Input pin for charge current setting voltage

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

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

12 –INC2 I Output voltage feedback input pin.

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

14 –INE5 I Error amplifier (Error Amp. 5) inverted input pin.

15 FB4 O Error amplifier (Error Amp. 4, 5) output pin.

16 –INE4 I Error amplifier (Error Amp. 4) inverted input pin.

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

18 OUTM O Output pin for dynamically controlled charging identification signal

“H” level: Constant-voltage or constant-current charging mode

“L” level: Dynamically controlled charging mode

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

22 CS — Soft-start capacitor connection pin.

23 GND — Ground pin.

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

MB3874/MB3876

−−

× 25

−

17 5 23

<Current Amp.1> <Error

Amp.2> VREF

−

<Error Amp.1> VREF

<Current Amp.2> <Error

Amp.3> VREF

<Error

Amp.5> VREF

−

<Error

Amp.4> VREF

VREF

(4.2 V)

∗

50 kΩ

100 kΩ

42 kΩ

208 kΩ

1 µA

<SOFT>

2.5 V

1.5 V

<OUT>

<UVLO>

<OSC>

<VH>

<PWM

Comp.>

Drive

− 5 V)

UVLO)

CTL

215 kΩ

35 kΩ

0.91 V

(0.77 V)

VREF

ULVO

bias

−INC2

FB3

−INE3

FB2

VREF

+INE3

+INE2

−INE2

−INE1

FB1

−INC1

+INC2

GND

OUT

OUTM

−INE5

−INE4

FB4

+INC1

MB3874 100 kΩ

MB3876 150 kΩ

∗

(45 pF)

−

■

■■

■BLOCK DIAGRAM

Bias voltage

block

MB3874/MB3876

■

■■

■ABSOLUTE MAXIMUM RATINGS

*: 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

FUJITSU representatives beforehand.

Parameter Symbol Conditions Rating Unit

Min Max

Power supply voltage VCC ——28V

Output terminal current IOUT ——60mA

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

OUTM terminal output voltage VOUTM ——17V

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 —7—25V

Reference voltage output

current IREF —–1—0mA

VH pin output current IVH —0—30mA

Input voltage V-INC –INC1, –INC2 0 — 17 V

VINE –INE1 to –INE5, +INE2 0 — VCC – 1.8 V

V+INC +INC1, +INC2 0 — VCC V

CTL pin input voltage VCTL —0—25V

Output current IOUT OUT pin –45 — 45 mA

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

OUTM pin output voltage VOUTM ——315V

OUTM pin output current IOUTM ———1mA

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

MB3874/MB3876

■

■■

■ELECTRICAL CHARACTERISTICS (MB3874 : Ta = +25°C, VCC = 16 V, VREF = 0 mA)

(MB3876 : Ta = +25°C, VCC = 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

21 VCC = 6.3 6.6 6.9 V

VTHL VCC = 5.3 5.6 5.9 V

Hysteresis width VH21 — 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* — %

Reference voltage

block (Ref)

Under voltage

lockout protection

circuit block (UVLO)

Soft-start

block

(SOFT)

Triangular waveform

oscillator circuit

block (OSC)

MB3874/MB3876

(Continued)

(MB3874 : Ta = +25°C, VCC = 16 V, VREF = 0 mA)

(MB3876 : Ta = +25°C, VCC = 19 V, VREF = 0 mA)

*: Standard design value.

(Continued)

Parameter Symbol Pin No Conditions Value Unit Remarks

Min Typ Max

Threshold

voltage VTH 21

FB1 = 2 V,

–INE1 = 2.35 V 14.00 14.20 14.40 V MB3874

FB1 = 2 V,

–INE1 = 2.83 V 16.80 17.10 17.40 V MB3876

Input pin current IIN 8 –INE1= 0 V –100 –30 — nA

Voltage gain AV7 DC — 100* — dB

Frequency

bandwidth BW 7 AV = 0 dB — 2.0* — MHz

Output voltage VFBH 7—3.94.1—V

VFBL 7 — — 20 200 mV

Output source

current ISOURCE 7 FB1 = 2 V — –2.0 –0.6 mA

Output sink

current ISINK 7 FB1 = 2 V 150 300 — µA

Input offset

voltage VIO 3,4

9,10 FB2 = FB3 = 2 V — 1* — mV

Input pin

current IINE 4,9 +INE2 = +INE3 = 0 V –100 –30 — nA

Common mode

input voltage

range VCM 3,4

9,10 —0—VCC–1.8 V

Voltage gain AV2, 11 DC — 100* — dB

Frequency

bandwidth BW 2, 11 AV = 0 dB — 2.0* — MHz

Output voltage VFBH 2, 11 — 3.9 4.1 — V

VFBL 2, 11 — — 20 200 mV

Output source

current ISOURCE 2, 11 FB2 = FB3 = 2 V — –2.0 –0.6 mA

Output sink

current ISINK 2, 11 FB2 = FB3 = 2 V 150 300 — µA

Error amplifier block

(Error Amp.1)

Error amplifier block

(Error Amp.2, 3)

MB3874/MB3876

(Continued)

(MB3874 : Ta = +25°C, VCC = 16 V, VREF = 0 mA)

(MB3876 : Ta = +25°C, VCC = 19 V, VREF = 0 mA)

*: Standard design value.

(Continued)

Parameter Symbol Pin No Conditions Value Unit Remarks

Min Typ Max

Threshold

voltage VTH 1, 12

FB4 = 2 V,

Ta = +25 °C 12.500 12.600 12.700 V MB3874

16.666 16.800 16.934 V MB3876

FB1 = 2 V,

Ta = –30 °C to +85 °C12.474 12.600 12.726 V MB3874

16.632 16.800 16.968 V MB3876

Input current

IINEH 1, 12 –INC1 = –INC2 = 12.6 V — 84 150 µAMB3874

–INC1 = –INC2 = 16.8 V — 84 150 µAMB3876

IINEL 1, 12

VCC = 0 V,

–INC1 = –INC2 = 12.6 V —0 1µAMB3874

VCC = 0 V,

–INC1 = –INC2 = 16.8 V —0 1µAMB3876

Input resistor R11, 12 — 70 100 130 kΩMB3874

105 150 195 kΩMB3876

R214, 16 — 355065kΩ

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 FB4 = 2 V — –2.0 –0.6 mA

Output sink

current ISINK 15 FB4 = 2 V 150 300 — µA

Error amplifier block

(Current Amp.4, 5)

MB3874/MB3876

(Continued)

(MB3874 : Ta = +25°C, VCC = 16 V, VREF = 0 mA)

(MB3876 : Ta = +25°C, VCC = 19 V, VREF = 0 mA)

(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 —1020µAMB3874

+INC1= +INC2=16.9 V,

–INC1= –INC2=16.8 V —1020µAMB3876

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

–INC1= –INC2= 0 V –130 –65 — µA

Current detection

voltage

V-INE1 3, 10

+INC1= +INC2=12.7 V,

–INC1= –INC2=12.6 V 2.25 2.50 2.75 V MB3874

+INC1= +INC2=16.9 V,

–INC1= –INC2=16.8 V 2.25 2.50 2.75 V MB3876

V-INE2 3, 10

+INC1= +INC2=12.63V,

–INC1= –INC2=12.6 V 0.50 0.75 1.00 V MB3874

+INC1= +INC2=16.83 V,

–INC1= –INC2=16.8 V 0.50 0.75 1.00 V MB3876

V-INE3 3, 10 +INC1= +INC2= 0.1 V ,

–INC1= –INC2= 0 V 1.25 2.50 3.75 V

V-INE4 3, 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—VCC V

Voltage gain AV3, 10

+INC1= +INC2=12.7 V,

–INC1= –INC2=12.6 V 22.5 25 27.5 V/V MB3874

+INC1= +INC2=16.9 V,

–INC1= –INC2=16.8 V 22.5 25 27.5 V/V MB3876

Output voltage VOUTCH 3, 10 — 3.9 4.1 — V

VOUTCL 3, 10 — — 20 200 mV

PWM comparator

block

(PWM Comp.)

Threshold voltage

VTL 2, 7,

11, 15 Duty cycle = 0 % 1.4 1.5 — V

VTH 2, 7,

11, 15 Duty cycle = 100 % — 2.5 2.6 V

Threshold voltage VTLH 18 FB1 = 2.7 2.8 2.9 V

VTHL 18 FB1 = 2.4 2.5 2.6 V

Hysteresis width VH18 — 0.2 0.3 0.4 V

Output leak current ILEAK 18 OUTM = 5 V — 0 1 µA

Output voltage VOL 18 OUTM = 1 mA — 0.15 0.4 V

Current detection amplifier block

(Current Amp.1, 2)

Constant power

detection block

(MASK Comp.)

MB3874/MB3876

(Continued)

(MB3874 : Ta = +25°C, VCC = 16 V, VREF = 0 mA)

(MB3876 : Ta = +25°C, VCC = 19 V, VREF = 0 mA)

*: Standard design value

Parameter Symbol Pin No. Conditions Value Unit Remarks

Min Typ Max

Output source

current ISOURCE 20

OUT = 11 V,

Duty ≤ 5 %

(t = 1/fosc × Duty ) — –200* — mA MB3874

OUT = 14 V,

Duty ≤ 5 %

(t = 1/fosc × Duty ) — –200* — mA MB3876

Output sink current ISINK 20

OUT = 16 V,

Duty ≤ 5 %

(t = 1/fosc × Duty ) — 200* — mA MB3874

OUT = 19 V,

Duty ≤ 5 %

(t = 1/fosc × Duty ) — 200* — mA MB3876

Output ON resistor ROH 20 OUT = −45 mA — 8.0 16.0 Ω

ROL 20 OUT = 45 mA — 6.5 13.0 Ω

Rise time tr1 20 OUT = 3300 pF

(Equivalent to Si4435DY) —70*—ns

Fall time tf1 20 OUT = 3300 pF

(Equivalent to Si4435DY) —60*—ns

CTL input voltage VON 6Active mode 2.0 — 25.0 V

VOFF 6Standby mode 0—0.8V

Input current ICTLH 6CTL = 5 V — 100 200 µA

ICTLL 6CTL = 0 V —0 1µA

Output voltage VH 19 VCC = 7 V to 25 V,

VH = 0 to 30 mA VCC –

5.5 VCC –

5.0 VCC –

4.5 V

Standby current ICCS 21 CTL = 0 V —010µA

Power supply

current ICC 21 CTL = 5 V —6.09.0mA

MB3874

—6.59.5mA

MB3876

Output block

(OUT)

Control block

(CTL)

Bias

voltage

block (VH)

General

MB3874/MB3876

■

■■

■TYPICAL CHARACTERISTICS

(Continued)

00 5 10 15 20 25

Ta = +25 °C

VCC = 16 V (MB3874)

VCC = 19 V (MB3876)

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

Reference voltage VREF (V)

Reference voltage vs. VREF load current

Reference voltage vs. CTL pin voltage

Reference voltage VREF (V)

CTL pin voltage VCTL(V) CTL 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 (MB3874)

VCC = 19 V (MB3876)

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 (MB3874)

VCC = 19 V (MB3876)

CTL = 5 V

VREF = 0 mA

1.0

0.8

0.6

0.4

0.2

0.0 0 5 10 15 20 25

Ta = +25 °C

VCC = 16 V (MB3874)

VCC = 19 V (MB3876)

Reference voltage vs. ambient temperature

Reference voltage ∆VREF (%)

Ambient temperature Ta (°C)

VREF load current IREF (mA)

MB3874/MB3876

(Continued)

1 M

100 k

10 k

10 k 100 k 1 M

Ta = +25 °C

VCC = 16 V (MB3874)

VCC = 19 V (MB3876)

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 resistor 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 (MB3874)

VCC = 19 V (MB3876)

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

= 16 V (MB3874)

= 19 V (MB3876)

CTL = 5 V

Triangular wave oscillator frequency vs.

ambient temperature

Triangular wave oscillator frequency fOSC(kHz)

Error amplifier threshold voltage vs.

ambient temperature

Error amplifier threshold voltage ∆VTH(%)

Ambient temperature Ta (°C)

MB3874/MB3876

(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 (MB3874)

VCC = 19 V (MB3876)

− +−

(9) (11)

(10)

2.088 V

10 kΩ

2.4 kΩ

240 kΩ

10 kΩ

4.2 V

2OUT

IN 1 µF

Error Amp.2

(Error Amp.3)

Phase φ (deg)

−

24 3

(13)

(12) (10)

100 kΩOUT

× 25

0.1 V

∗ : MB3874 12.6 V

MB3876 16.8 V

Current Amp.1

(Current Amp.2)

VCC = 16 V (MB3874)

VCC = 19 V (MB3876)

100 1 k 10 k 100 k 1 M

−20

−40

180

−90

−180

Ta = +25 °C

φIN

∗

Phase φ (deg)

800

740

700

600

500

400

300

200

100

−40 −20 0 20 40 60 80 100

MB3874/MB3876

■

■■

■FUNCTIONAL DESCRIPTION

1. DC/DC Converter Unit

(1) Reference voltage block (Ref)

The ref erence v oltage generator uses the v oltage supplied from the Vcc terminal (pin 21) to generate a temper-

ature-compensated, stable voltage ( := 4.2 V) used as the ref erence supply v oltage 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 oscillator block (OSC)

The triangular wave oscillator generates a triangular wavefor m with a frequency setting resistor connected to

the internal frequency setting capacitor via the RT 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

as well as a signal to the dynamically controlled charging detection block (MASK Comp.).

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

ter minal (pin 7) to the −INE1 terminal (pin 8) of the error amplifier, enabling stable phase compensation to the

system.

(4) Error amplifier block (Error Amp.2, 3)

These error amplifiers (Error Amp .2, Error Amp.3) detect the output signals from the current detector amplifiers

(Current Amp .1, Current Amp .2), compare them with the +INE2 terminal (pin 4) and +INE3 terminal (pin 9), and

output PWM control signals to control the charge current.

In addition, these amplifiers allow an arbitrary loop gain to be set by connecting a feedback resistor and capacitor

from the FB2 terminal (pin 2) to −INE2 terminal (pin 3) and from the FB3 terminal (pin 11) to −INE3 terminal (pin

10) of the error amplifiers, enabling stable phase compensation to the system.

(5) Error amplifier block (Error Amp.4, 5)

This error amplifier (Error Amp.4, Error Amp.5) detects the output voltage from the switching rerulator and outputs

the PWM control signal. The error amplifier inv erted input pin is connected to the output voltage setting resistor

in the IC , eliminating the need for an external resistor for setting the output voltage. The MB3874 and MB3876

are set to output v oltage of 12.6 V (for a 3-cell battery) and 16.8 V (f or 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 FB4

ter minal (pin 15) to the −INE4 terminal (pin 16) to the −INE5 terminal (pin 14) of the error amplifier, enabling

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.1, 2)

The current detection amplifier (Current Amp.1, Current Amp.2) detects a voltage drop which occurs between

both ends of the output sense resistor (RS1) due to the flow of the charge current, using the +INC1 terminal

(pin 24) and

−INC1 ter minal (pin 1). Then it outputs the signal amplified by 25 times to the error amplifier (Error Amp.2) at

the ne xt stage.The amplifiers also detect a voltage drop which occurs at both ends of the output sense resistor

MB3874/MB3876

(RS2) using the +INC2 terminal (pin 13) and −INC2 terminal (pin 12) and output the signal amplified by 25 times

to the error amplifier (Error Amp. 3) at the next stage.

(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. 5) depending on their output voltage.

The PWM comparator circuit compares the triangular wave generated by the tr iangular wave oscillator 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 output “L” level sets the output amplitude to 5 V (typical) using the voltage generated by the bias voltage

block (VH).

This results in increasing conv ersion efficiency and suppressing the withstand voltage of the connected e xternal

transistor in a wide range of input voltages.

(9) Control block (CTL)

Setting the CTL terminal (pin 6) 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 v oltage circuit outputs Vcc − 5 V (typical) as the minimum potential of the output circuit. In the standb y

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 malfunctions in the control IC, resulting in breakdown

or degradation of the system. To prevent such malfunction, the low-Vcc malfunction preventive circuit detects

a supply voltage or inter nal reference voltage drop and fixes the OUT terminal (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) pre v ents surge currents when the IC is turned on. Using an

error amplifier for soft-start detection makes the soft-star t time constant, independent of the output load of the

DC/DC converter.

4. Additional Functions

Dynamically controlled charging detection block (MASK Comp.)

The dynamically controlled charging detection block (MASK Comp.) usually output the “H” level signal. The

OUTM signal becomes low (“L” leve l) when the output voltage of the error amplifier (Error Amp. 1) that detects

the input v oltage (Vcc) becomes low er than the crest v alue (2.5 V) of the triangular wa v eform generator (OSC).

The OUTM signal return high (“H” level) when the input voltage reaches 2.8 V or more.

MB3874/MB3876

■

■■

■METHOD OF SETTING THE CHARGING CURRENT

The charge current (output control current) value can be set with the voltage at the +INE2, +INE3 terminal.

If a current e xceeding the set value attempts to flow , the charge v oltage drops according to the set current value .

Battery 1 charge current setting voltage : +INE2

+INE2 (V) = 25 × I1 (A) × RS1 (Ω)

Battery 2 charge current setting voltage : +INE3

+INE3 (V) = 25 × I2 (A) × RS 2 (Ω)

■

■■

■METHOD OF SETTING THE SOFT-START TIME

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

The error amplifier causes soft-start operation to be performed with the output voltage in propor tion 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 WAVE OSCILLAT OR FREQUENCY SETTING

The trianguar wav e oscillator frequency can be set by the timing resistor (RT) connected the R T terminal (pin 17).

Triangular wave oscillator frequency fOSC

fOSC (kHz) := 14444 / RT (kΩ)

■

■■

■AC ADAPTER VOLTAGE DETECTION

When par tial potential point A of the AC adapter voltage (Vcc) becomes lower than the voltage at the –INE1

pin, the IC enters the constant-power mode to reduce the charge current in order to keep AC adapter power

constant.

AC adapter detected voltage setting Vth

Vth (V) = (208k + 42k) / 42k × − INE1 := 5.95 × − INE1

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

−

VCC 208 kΩ

−INE1

42 kΩ

MB3874/MB3876

■

■■

■OPERATION TIMING DIAGRAM

About the OUTM signal

The OUTM signal becomes low when the output voltage of the error amplifier (Error Amp. 1) that detects the

AC adapter voltage (Vcc) becomes lower than the crest value (2.5 V) of the triangular waveform generator (OSC).

If the sum of the current consumption by the system and that b y the charger e xceeds the current capacity of the

AC adapter, the IC detects a voltage drop in the AC adapter output and switches to the dynamically-controlled

charging mode from C.V.C.C (constant-voltage/constant-current charging control) mode.

In the dynamically-controlled charging mode, the OUTM pin outputs the L level signal to distinguish between

the case in which the charge current has become small as the system current consumption has increased and

the case in which it has become small as battery charging has been finished.

L: Dynamically-controlled charging

H: C.V.C.C (constant-voltage/constant-current charging control) or IC standby mode

2.8 V

2.5 V

1.5 V

Err Amp.2, 3

Err Amp.4, 5

Err Amp.1

FB2,3

FB4

FB1

OUT

OUTM

Constant voltage

control

AC adapter dynamically-

controlled charging Constant current control AC adapter dynamically-

controlled charging

Battery

Charger

MB3874

MB3876

Mode

Signal

System

Power

VIN

Adaptor Battery

Ichg

ISYS

MB3874/MB3876

■

■■

■ NOTE ON AN EXTERNAL REVERSE-CURRENT PREVENTIVE DIODE

If there is an imbalance in charge current (I1, I2) under constant-v oltage control, v oltage is controled at the side

with a lower battery voltage and thus the battery voltage at one side is higher than that at the other by the voltage

diff erence betw een the re verse-current pre v entive diodes (D1, D2) and between the sense resistors (Rs1, Rs2)

Pay attention to the voltage/current character istics of the reverse-current preventive diode (D1, D2) not to let it

exceed the overcharge stop voltage.

VCC

OUT

VIN

(16 V/19 V)

I1 RS1

BATT1

12.6 V/16.8 V

A B

I2 RS2

BATT2

12.6 V/16.8 V

C D

to 24 pin to 1 pin

Battery 1

to 12 pin

to 13 pin

Battery 2

MB3874/MB3876

■

■■

■APPLICATION EXAMPLE

−−

× 25

−

17 5 23

<Current Amp.1> <Error

Amp.2> VREF

−

<Error Amp.1> VREF

VCC

<Current Amp.2> <Error

Amp.3> VREF

<Error

Amp.5> VREF

−

<Error

Amp.4> VREF

VREF

(4.2 V)

∗

50 kΩ

3900 pF

200 kΩ

150 kΩ

R17

22 kΩ

R18

200 kΩ

330 kΩ

R15

5.6 kΩ

33 kΩ

R13

200 kΩ

2200 pF

50 kΩ

100 kΩ

42 kΩ

208 kΩ

1 µA

15 <SOFT>

2.5 V

(2.8 V)

1.5 V

<OUT>

<UVLO>

<OSC>

<VH>

<PWM

Comp.>

Drive

VCC

(VCC − 5 V)

(VCC UVLO)

VCC

CTL

215 kΩ

35 kΩ

47 kΩ

0.91 V

(0.77 V)

VREF

ULVO

bias

−INC2

FB3

−INE3

FB2

VREF

+INE3

+INE2

−INE2

−INE1

FB1

−INC1

+INC2

VIN SW2

GND

VCC

OUT

OUTM

−INE5

−INE4

FB4

+INC1

MB3874 100 kΩ

MB3876 150 kΩ

MB3874 22 kΩ

MB3876 15 kΩ

MB3874 16 V

MB3876 19 V

MB3874 12.6 V

MB3876 16.8 V

∗1 :

∗2 :

∗3 :

∗4 :

(45 pF)

−

0.1 µF

C12

3900 pF

6800 pF

150 kΩ

47 kΩ

R11

30 kΩ

R10

∗2

R16

22 kΩ

R19

200 kΩ

R14

5.6 kΩ

33 kΩ

R12

SW1

0.1 µF

C13

L1 I1 RS1 BATT1

∗4

A B

RS2

BATT2

∗4

C D

−

0.075Ω

22 µF

C14

0.1 µF

C10

0.1 µF

22 µF

100 µF

27 µH

100 µF

−−

−

Bias voltage

block

Pin 24 Pin 1

Battery 1

Pin 13 Pin 12

Battery 2

MB3874/MB3876

■

■■

■PARTS LIST

Note: VISHAY SILICONIX : VISHAY Intertechnology, Inc.

MOTOROLA : Motorola Japan Ltd.

ROHM : RHOM CO., LTD

SUMIDA : SUMIDA ELECTRIC CO., Ltd.

COMPONET ITEM SPECIFICATION VENDOR PARTS NO.

Q2, Q3 FET

FET Si4435DY

2N7002 VISHAY SILICONIX

VISHAY SILICONIX Si4435DY

2N7002

D2, D3 Diode

Diode MBRS130LT3

RB151L-40F MOTOROLA

ROHM MBRS130LT3

RB151L-40F

L1 Coil 27 µH 2.8 A, 80 mΩSUMIDA CDRH127-27µH

C1, C2

C3, C4

C5, C6

C10

C12, C13

C14

OS Condensor

Ceramics Condensor

22 µF

100 µF

3900 pF

6800 pF

3900 pF

0.1 µF

2200 µF

0.1 µF

25 V (10 %)

16 V (10 %)

25 V (10 %)

10 %

25 V

10 %

16 V

——

R1, R2

R3, R4

R10

R11, R12

R13

R14, R15

R16, R17

R18, R19

Resistor

0.075 Ω

200 kΩ

47 kΩ

330 kΩ

150 kΩ

47 kΩ

150 kΩ

22 kΩ

30 kΩ

5.6 kΩ

22 kΩ

200 kΩ

1.0 %

5 %

1.0 %

0.5 %

5 %

——

MB3874/MB3876

■

■■

■REFERENCE DATA

•MB3874

Note: KIKUSUI : KIKUSUI Electronics Corp.

Vin = 16 V

10 m 100 m 1 10

100

Vin = 16 V

R10 = 22 kΩ

100

800 2 4 6 810121416

Dead Battery MODE DCC MODE

DCC : Dynamically-Controlled Charging

0.0

00.40.2 0.80.6 1.21.0 1.61.4 2.01.8

Dead Battery MODE DCC MODE

DCC : Dynamically-Controlled Charging

0.0

00.40.2 0.80.6 1.21.0 1.61.4 2.01.8

Conversion efficiency vs. charge current

(Fixed voltage mode) Conversion efficiency vs. charge voltage

(Fixed current mode)

BATT1 charge current IBATT1 (A)

Conversion efficiency η(%)

Conversion effciency η(%)

BATT1 charge voltage VBATT1 (V)

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

BATT1 voltage VBATT1 (V)

BATT1 charge current IBATT1 (A)

Vin = 16V, BATT2= OPEN,

BATT1 : Electronic load,

(Product of KIKUSUI PLZ-150W)

Paralle charging, Vin = 16V,

BATT1 : Electronic load,

(Product of KIKUSUI PLZ-150W),

IBATTI=IBATT2

BATT1 charge voltage = 12.6V,

fOSC = 286.37kHz, BATT2 = OPEN

η(%)=(VBATT1 × IBATT1)/(Vin × Iin) × 100

BATT2= OPEN,

BATT1: Electronic load,

(Product of KIKUSUI PLZ-150W)

BATT1 charge current IBATT1 (A) BATT1 charge voltage VBATT1 (V)

Conversion efficiency η(%)

Conversion effciency η(%)

Vin = 16 V

10 m 100 m 1 10

100

Vin = 16 V

R10 = 22 kΩ

100

800 2 4 6 810121416

Conversion efficiency vs. charge current

(Fixed voltage mode) Conversion efficiency vs. charge voltage

(Fixed current mode)

Paralle charging, BATT1 charge voltage = 12.6V

fOSC = 286.37kHz

η(%)=((VBATT1 × IBATT1)+(VBATT2 × IBATT2))/(Vin × Iin) × 100

IBATTI = IBATT2

Paralle charging,

BATT1: Electronic load,

(Product of KIKUSUI PLZ-150W),

IBATTI = IBATT2

MB3874/MB3876

(Continued)

0 80 120 160 200

t (ms)

BATT1 (V)

CTL (V)

5 V

5 V 20 ms

046810

t (µs)

−5

OUT (V)

1 µs

5 V

Soft-start operating waveforms

Vin = 16 V

Load : BATT1 = 20 Ω

− INE1 = 0 V

BATT2 = OPEN

DC/DC converter switching waveforms

Vin = 16 V

FOSC = 286.7 kHz

Load : BATT1 = 1A

BATT2 = OPEN

MB3874/MB3876

•MB3876

Note: KIKUSUI : KIKUSUI Electronics Corp.

Vin = 19 V

10 m 100 m 1 10

100

Vin = 19 V

R10 = 15 kΩ

100

0 2 4 6 81012141618

Dead Battery MODE DCC MODE

DCC : Dynamically-Controlled Charging

0.0

00.40.2 0.80.6 1.21.0 1.61.4 2.01.8

Conversion efficiency vs.charge current

(Fixed voltage mode)

BATT1 charge current IBATT1 (A)

Conversion efficiency η(%)

BATT1 charge voltage =16.8V,

fOSC = 282.71kHz, BATT2 = OPEN,

η(%)=(VBATT1 × IBATT1)/(Vin × Iin) × 100

Conversion efficiency vs. charge voltage

(Fixed current mode)

Conversion efficiency η(%)

BATT1 charge voltage VBATT1 (V)

BATT voltage vs. BATT charge current

BATT1 voltage VBATT1 (V)

BATT1 charge current IBATT1 (A)

Vin = 19V,

BATT2 = open,

BATT1:Electronic load,

(Product of KIKUSUI

PLZ-150W)

BATT1 charge current IBATT1 (A)

BATT1 voltage VBATT1 (V)

Dead Battery MODE DCC MODE

DCC : Dynamically-Controlled Charging

0.0

00.40.2 0.80.6 1.21.0 1.61.4 2.01.8

BATT voltage vs. BATT charge current

BATT1 charge current IBATT1 (A)

Conversion efficiency η(%)

Vin = 19 V

10 m 100 m 1 10

100

Vin = 19 V

R10 = 15 kΩ

100

0 2 4 6 81012141618

Conversion efficiency vs.charge current

(Fixed voltage mode) Conversion efficiency vs. charge voltage

(Fixed current mode)

BATT2 = OPEN,

BATT1 : Electronic load,

(Prouct of KIKUSUI PLZ-150W)

BATT1 charge voltage VBATT1 (V)

Parallel charging, BATT1 Charge voltage =16.8 V,

fOSC = 282.71 kHz,

η(%)=((VBATT1 × IBATT1)+(VBATT2 × IBATT2))/(Vin × Iin) × 100,

IBATTI = IBATT2

Parallel charging,

BATT1 : Electronic load,

(Prouct of KIKUSUI PLZ-150W),

IBATTI = IBATT2

Parallel charging,

Vin = 19V,

BATT1: Electronic load,

(Product of KIKUSUI

PLZ-150W),

IBATTI = IBATT2

MB3874/MB3876

(Continued)

0 80 120 160 200

t (ms)

BATT1 (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 : BATT1 = 50 Ω

− INE1 = 0 V

BATT2 = OPEN

DC/DC converter switching waveforms

Vin = 19 V

FOSC = 282.6 kHz

Load : BATT1 = 1 A

BATT2 = OPEN

MB3874/MB3876

■

■■

■USAGE PRECAUTIONS

1. Never use settings exceeding maximum rated conditions.

Exceeding maximum rated conditions may cause permanent damage to the LSI.

Also, it is recommended that recommended operating conditions be observed in normal use.

Exceeding recommended operating conditions may adversely affect LSI reliability.

2. Use this device within recommended operating conditions.

Recommended operating conditions are v alues within which normal LSI operation is warranted. Standard elec-

trical characteristics are warranted within the range of recommended oper ating conditions and within the listed

conditions for each parameter.

3. Printed circuit board ground lines should be set up with consideration for common imped-

ance.

4. Take appropriate static electricity measures.

• Containers f or semiconductor materials should ha ve anti-static protection or be made of conductive material.

• After mounting, printed circuit boards should be stored and shipped in conductive bags or containers.

• Work platforms, tools, and instruments should be properly grounded.

• Working personnel should be grounded with resistance of 250 kΩ to 1 MΩ between body and ground.

5. Do not apply negative voltages.

The use of negative voltages below –0.3 V may create parasitic transistors on LSI lines, which can cause

abnormal operation

■

■■

■ORDERING INFORMATION

Part number Package Remarks

MB3874PFV

MB3876PFV 24-pin plastic SSOP

(FPT-24P-M03)

MB3874/MB3876

■

■■

■PACKAGE DIMENSION

24-pin plastic SSOP

(FPT-24P-M03) Note1 : Pins width and pins thickness include plating thickness.

Note2 : *This dimension does not include resin protrusion.

Dimensions in mm (inches)

2001 FUJITSU LIMITED F24018S-c-3-4

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)

MB3874/MB3876

FUJITSU LIMITED

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

Customers are advised to consult with FUJITSU sales

representatives before ordering.

The information and circuit diagrams in this document are

presented as examples of semiconductor device applications, and

are not intended to be incorporated in devices for actual use. Also,

FUJITSU is unable to assume responsibility for infringement of

any patent rights or other rights of third parties arising from the use

of this information or circuit diagrams.

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 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.

If any products described in this document represent goods or

technologies subject to certain restrictions on export under the

Foreign Exchange and Foreign Trade Law of Japan, the prior

authorization by Japanese government will be required for export

of those products from Japan.

F0209

 FUJITSU LIMITED Printed in Japan