DS04-27704-2E
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.
■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
• Output voltage precision
(Built-in output voltage setting resistor ) : ± 0.8 % (Ta = + 25 °C)
• High precision reference voltage source : 4.2 V ± 0.8 %
(Continued)
■PACKAGE
24-pin plastic SSOP
(FPT-24P-M03)
MB3874/MB3876
2
(Continued)
• 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 standb y 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
3
■PIN ASSIGNMENT
(TOP VIEW)
(FPT-24P-M03)
1
2
3
4
5
6
7
8
9
10
11
12
−INC1 :
FB2 :
−INE2 :
+INE2 :
VREF :
CTL :
FB1 :
−INE1 :
+INE3 :
−INE3 :
FB3 :
−INC2 :
24
23
22
21
20
19
18
17
16
15
14
13
: +INC1
: GND
: CS
: VCC
: OUT
: VH
: OUTM
: RT
: −INE4
: FB4
: −INE5
: +INC2
MB3874/MB3876
4
■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
5
+
−−
+
24
1
4
+
−−
+
10
13
12
9
× 25
× 25
+
+
+
+
−
11
20
21
19
−
+
+
+
−
14
22
17 5 23
6
18
<Current Amp.1> <Error
Amp.2> VREF
−
+
<Error Amp.1> VREF
V
CC
<Current Amp.2> <Error
Amp.3> VREF
<Error
Amp.5> VREF
−
+
+
<Error
Amp.4> VREF
VREF
VREF
(4.2 V)
R1
∗
R1
∗
R2
50 kΩ
R2
50 kΩ
100 kΩ
100 kΩ
42 kΩ
208 kΩ
1 µA
15
<SOFT>
2.5 V
2.5 V
1.5 V
<OUT>
<UVLO>
<OSC>
<VH>
<Ref> <CTL>
<PWM
Comp.>
<MASK Comp.>
Drive
V
CC
(V
CC
− 5 V)
(V
CC
UVLO)
V
CC
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
CS
V
CC
V
CC
OUT
OUTM
VH
RT
−INE5
−INE4
FB4
+INC1
MB3874 100 kΩ
MB3876 150 kΩ
∗
:
(45 pF)
+
−
16
2
3
7
8
■BLOCK DIAGRAM
Bias voltage
block
MB3874/MB3876
6
■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
7
■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
8
(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
9
(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
10
(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
11
(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
12
■TYPICAL CHARACTERISTICS
(Continued)
10
8
6
4
2
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 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)
10
8
6
4
2
00 5 10 15 20 25
Ta = +25 °C
CTL = 5 V Ta = +25 °C
CTL = 5 V
VREF = 0 mA
10
8
6
4
2
00 5 10 15 20 25
10
8
6
4
2
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
13
(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
V
CC
= 16 V (MB3874)
V
CC
= 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
14
(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
φ
AV
40
20
0
−20
−40
100 1 k 10 k 100 k 1 M 10 M
180
90
0
−90
−180
VCC = 16 V (MB3874)
VCC = 19 V (MB3876)
− +−
+
4
(9) (11)
(10)
2.088 V
3
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)
+
−
1
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)
40
20
0
100 1 k 10 k 100 k 1 M
−20
−40
180
90
0
−90
−180
Ta = +25 °C
AV
φIN
∗
Phase φ (deg)
800
740
700
600
500
400
300
200
100
0
−40 −20 0 20 40 60 80 100
MB3874/MB3876
15
■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 ter minal (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
16
(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 start 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
17
■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 proportion 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)
−
+
8
VCC 208 kΩ
−INE1
A
<Error Amp.1>
42 kΩ
MB3874/MB3876
18
■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
AC
Adaptor Battery
Ichg
ISYS
MB3874/MB3876
19
■ 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)
VH
I1 RS1
BATT1
12.6 V/16.8 V
20
21
19
A B
D1
I2 RS2
BATT2
12.6 V/16.8 V
C D
D2
to 24 pin to 1 pin
Battery 1
to 12 pin
to 13 pin
Battery 2
MB3874/MB3876
20
■APPLICATION EXAMPLE
+
−−
+
24
1
4
+
−−
+
10
13
12
C
D
9
× 25
× 25
+
+
+
+
−
11
20
21
19
−
+
+
+
−
14
22
17 5 23
6
18
<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
VREF
(4.2 V)
∗
1
∗
3
∗
1
50 kΩ
C5
3900 pF
C6
3900 pF
3900 pF
R3
200 kΩ
R7
150 kΩ
R17
22 kΩ
R18
200 kΩ
R6
330 kΩ
R15
5.6 kΩ
33 kΩ
R13
R4
200 kΩ
CS
2200 pF
50 kΩ
100 kΩ
100 kΩ
42 kΩ
208 kΩ
1 µA
15 <SOFT>
2.5 V
2.5 V
(2.8 V)
1.5 V
<OUT>
<UVLO>
<OSC>
<VH>
<Ref> <CTL>
<PWM
Comp.>
<MASK 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
CS
VCC
VCC
OUT
OUTM
VH
RT
RT
−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)
+
−
16
2
3
7
8
C7
0.1 µF
C12
A
B
3900 pF
6800 pF
R9
150 kΩ
R8
47 kΩ
R11
30 kΩ
R10
∗2
R16
22 kΩ
R19
200 kΩ
R14
5.6 kΩ
33 kΩ
R12
SW1
C9
C8
0.1 µF
C13
Q2
Q3
L1 I1 RS1 BATT1
∗4
A B
D2
I2
D3
RS2
BATT2
∗4
C D
D1
+
−
0.075Ω
0.075Ω
C1
22 µF
C14
0.1 µF
C10
0.1 µF
C2
22 µF
C4
100 µF
27 µH
C3
100 µF
Q1
++
−−
+
−
Bias voltage
block
Pin 24 Pin 1
Battery 1
Pin 13 Pin 12
Battery 2
MB3874/MB3876
21
■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.
Q1
Q2, Q3 FET
FET Si4435DY
2N7002 VISHAY SILICONIX
VISHAY SILICONIX Si4435DY
2N7002
D1
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
C7
C8
C9
C10
CS
C12, C13
C14
OS Condensor
OS Condensor
Ceramics Condensor
Ceramics Condensor
Ceramics Condensor
Ceramics Condensor
Ceramics Condensor
Ceramics Condensor
Ceramics Condensor
Ceramics Condensor
22 µF
100 µF
3900 pF
3900 pF
6800 pF
3900 pF
0.1 µF
2200 µF
0.1 µF
0.1 µF
25 V (10 %)
16 V (10 %)
25 V (10 %)
10 %
10 %
10 %
10 %
25 V
10 %
16 V
16 V
——
R1, R2
R3, R4
RT
R6
R7
R8
R9
R10
R11, R12
R13
R14, R15
R16, R17
R18, R19
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
0.075 Ω
200 kΩ
47 kΩ
330 kΩ
150 kΩ
47 kΩ
150 kΩ
22 kΩ
30 kΩ
30 kΩ
5.6 kΩ
22 kΩ
200 kΩ
1.0 %
1.0 %
1.0 %
5 %
1.0 %
1.0 %
1.0 %
0.5 %
0.5 %
0.5 %
0.5 %
0.5 %
5 %
——
MB3874/MB3876
22
■REFERENCE DATA
•MB3874
Note: KIKUSUI : KIKUSUI Electronics Corp.
Vin = 16 V
10 m 100 m 1 10
100
98
96
94
92
90
88
86
84
82
80
Vin = 16 V
R10 = 22 kΩ
100
98
96
94
92
90
88
86
84
82
800 2 4 6 810121416
Dead Battery MODE DCC MODE
DCC : Dynamically-Controlled Charging
0.0
18
16
14
12
10
8
6
4
2
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
18
16
14
12
10
8
6
4
2
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 voltage VBATT1 (V)
BATT1 charge current IBATT1 (A)
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
98
96
94
92
90
88
86
84
82
80
Vin = 16 V
R10 = 22 kΩ
100
98
96
94
92
90
88
86
84
82
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
23
(Continued)
20
15
10
5
0
20
15
10
5
0
0 80 120 160 200
t (ms)
40
BATT1 (V)
CTL (V)
5 V
5 V 20 ms
20
15
046810
t (µs)
2
10
5
0
−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
24
•MB3876
Note: KIKUSUI : KIKUSUI Electronics Corp.
Vin = 19 V
10 m 100 m 1 10
100
98
96
94
92
90
88
86
84
82
80
Vin = 19 V
R10 = 15 kΩ
100
98
96
94
92
90
88
86
84
82
80
0 2 4 6 81012141618
Dead Battery MODE DCC MODE
DCC : Dynamically-Controlled Charging
0.0
18
20
16
14
12
10
8
6
4
2
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
18
20
16
14
12
10
8
6
4
2
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(%)
Conversion efficiency η(%)
Vin = 19 V
10 m 100 m 1 10
100
98
96
94
92
90
88
86
84
82
80
Vin = 19 V
R10 = 15 kΩ
100
98
96
94
92
90
88
86
84
82
80
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
25
(Continued)
20
10
0
0 80 120 160 200
t (ms)
40
BATT1 (V)
20
15
10
5
0
CTL (V)
10 V
5 V 20 ms
20
15
046810
t (µs)
2
10
5
0
−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
26
■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
27
■PACKAGE DIMENSION
24-pin plastic SSOP
(FPT-24P-M03) * : These dimensions do not include resin protrusion.
Dimensions in: mm (inches)
C
1994 FUJITSU LIMITED F24018S-2C-2
0.50±0.20
(.020±.008)
0.10±0.10(.004±.004)
(STAND OFF)
0 10°
Details of "A" part
7.75±0.10(.305±.004)
0.65±0.12(.0256±.0047)
7.15(.281)REF
6.60(.260)5.60±0.10 NOM
7.60±0.20
(.220±.004) (.299±.008)
"A"
.006 –.001
+.002
–0.02
+0.05
0.15
.049 –.004
+.008
–0.10
+
0
.
20
1.25
.009 –.002
+.004
–0.05
+0.10
0.22
0.10(.004)
INDEX
*
*
(Mounting height)
C
1994 FUJITSU LIMITED F24018S-2C-2
0.50±0.20
(.020±.008)
0.10±0.10(.004±.004)
(STAND OFF)
0 10°
Details of "A" part
7.75±0.10(.305±.004)
0.65±0.12(.0256±.0047)
7.15(.281)REF
6.60(.260)5.60±0.10 NOM
7.60±0.20
(.220±.004) (.299±.008)
"A"
.006 –.001
+.002
–0.02
+0.05
0.15
.049 –.004
+.008
–0.10
+0.20
1.25
.009 –.002
+.004
–0.05
+0.10
0.22
0.10(.004)
INDEX
*
*
(Mounting height)
MB3874/MB3876
FUJITSU LIMITED
For further information please contact:
Japan
FUJITSU LIMITED
Corporate Global Business Support Division
Electronic Devices
KAWASAKI PLANT, 4-1-1, Kamikodanaka
Nakahara-ku, Kawasaki-shi
Kanagawa 211-8588, Japan
Tel: 81(44) 754-3763
Fax: 81(44) 754-3329
http://www.fujitsu.co.jp/
Nor th and South America
FUJITSU MICROELECTRONICS, INC.
Semiconductor Division
3545 North First Street
San Jose, CA 95134-1804, USA
Tel: (408) 922-9000
Fax: (408) 922-9179
Customer Response Center
Mon. - Fri.: 7 am - 5 pm (PST)
Tel: (800) 866-8608
Fax: (408) 922-9179
http://www.fujitsumicro.com/
Europe
FUJITSU MICROELECTRONICS EUR OPE GmbH
Am Siebenstein 6-10
D-63303 Dreieich-Buchschlag
Germany
Tel: (06103) 690-0
Fax: (06103) 690-122
http://www.fujitsu-fme.com/
Asia Pacific
FUJITSU MICROELECTR ONICS ASIA PTE LTD
#05-08, 151 Lorong Chuan
New Tech Park
Singapore 556741
Tel: (65) 281-0770
Fax: (65) 281-0220
http://www.fmap.com.sg/
F0001
FUJITSU LIMITED Printed in Japan
All Rights Reserved.
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.
FUJITSU semiconductor devices are intended for use in
standard applications (computers, office automation and other
office equipment, industrial, communications, and
measurement equipment, personal or household devices, etc.).
CAUTION:
Customers considering the use of our products in special
applications where failure or abnormal operation may directly
affect human lives or cause physical injury or property damage,
or where extremely high levels of reliability are demanded
(such as aerospace systems, atomic energy controls, sea floor
repeaters, vehicle operating controls, medical devices for life
support, etc.) are requested to consult with FUJITSU sales
representatives before such use. The company will not be
responsible for damages arising from such use without prior
approval.
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.
