FUJITSU MB3875

FUJITSU SEMICONDUCTOR
DATA SHEET
DS04-27703-2E
ASSP For Power Supply Applications (Lithium ion battery charger)
DC/DC Converter IC for Charging
MB3875/MB3877
■ DESCRIPTION
The MB3875 and MB3877 are charging DC/DC converter ICs suitable for down-conversion, 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.
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.
■ FEATURES
• Detecting a voltage drop in the AC adapter and dynamically controlling the charge current (Dynamically-controlled 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)
• High precision reference voltage source
: 4.2 V ± 0.8 %
(Continued)
■ PACKAGE
24-pin plastic SSOP
(FPT-24P-M03)
MB3875/MB3877
(Continued)
• 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
2
MB3875/MB3877
■ PIN ASSIGNMENT
(TOP VIEW)
24 : +INC2
−INC2 : 1
IN3 : 2
23 : GND
FB2 : 3
22 : CS
21 : VCC (O)
OUTC2 : 4
VREF : 5
20 : OUT
−INE2 : 6
19 : VH
+INE2 : 7
18 : VCC
+INE1 : 8
17 : RT
16 : −INE3
FB1 : 9
OUTC1 : 10
15 : FB3
−INE1 : 11
14 : CTL
−INC1 : 12
13 : +INC1
(FPT-24P-M03)
3
MB3875/MB3877
■ PIN DESCRIPTION
4
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/MB3877
■ BLOCK DIAGRAM
−INE1
11
OUTC1
10
<Current Amp.1>
+
× 25
−INC1
−
12
+INC1
+INE1
FB1
−INE2
OUTC2
+INC2
−INC2
+INE2
FB2
IN3
13
<Error
Amp.1> VREF
−
+
8
<PWM
Comp.>
+
+
+
−
9
6
4
24
1
<Current Amp.2>
+
× 25
−
<Error
Amp.2> VREF
−
<OUT>
OUT
Drive
20
VCC
Bias voltage
block
+
7
19
VH
(VCC − 5 V)
<VH>
3
2
<UVLO>
−INE3
VCC (O)
21
R1
16
∗
R2
50 kΩ
<Error
Amp.3> VREF
(VCC UVLO) 215 kΩ
+
−
+
+
15
35 kΩ
−
0.91 V
(0.77 V)
VREF
(4.2 V)
FB3
VCC
VREF
ULVO
<SOFT>
VREF
1 µA
VCC
CS
22
bias
2.5 V
1.5 V
VCC
18
CTL
<OSC>
<REF>
<CTL>
14
(45 pF)
RT
17
VREF
5
GND
23
∗ : MB3875 100 kΩ
MB3877 150 kΩ
5
MB3875/MB3877
■ ABSOLUTE MAXIMUM RAGINGS
Parameter
Symbol
Rating
Conditions
Unit
Min.
Max.
—
28
V
Power supply voltage
VCC
Output current
IOUT
—
—
60
mA
Peak output current
IOUT
Duty ≤ 5% (t =1 / fOSC × Duty)
—
500
mA
Power dissipation
PD
Ta ≤ +25°C
—
740*
mW
–55
+125
°C
Storage temperature
VCC,VCC(O)
Tstg
—
*: 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
Parameter
Symbol
Conditions
Value
Unit
Min.
Typ.
Max.
7
—
25
V
Power supply voltage
VCC
Reference voltage output
current
IREF
—
–1
—
0
mA
VH pin output current
IVH
—
0
—
30
mA
VCC,VCC(O)
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
—
25
V
Output current
IOUT
—
–45
—
45
mA
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
—
—
0.1
1.0
µF
Reference voltage output
capacitor
CREF
—
—
0.1
1.0
µF
Operating temperature
Ta
—
–30
+25
+85
°C
Input voltage
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.
6
MB3875/MB3877
■ 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)
Reference voltage
block (Ref)
Parameter
Symbol Pin No.
Unit Remarks
Min.
Typ.
Max.
Ta = +25°C
4.167
4.200
4.233
V
Ta = –30°C to +85°C
4.158
4.200
4.242
V
VREF
5
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
VCC =VCC (O),
VCC =
6.3
6.6
6.9
V
VCC =VCC (O),
VCC =
5.3
5.6
5.9
V
VCC =VCC (O)
0.7
1.0
1.3
V
VREF =
2.6
2.8
3.0
V
VREF=
2.4
2.6
2.8
V
Threshold
voltage
Under voltage
lockout protection
circuit block (UVLO)
Value
Output voltage
VTLH
Triangular waveform Soft-start
oscillator circuit
block
block (OSC)
(SOFT)
Conditions
18
VTHL
Hysteresis width
VH
18
VTLH
Threshold
voltage
5
VTHL
Hysteresis width
VH
5
—
0.05
0.20
0.35
V
Charge current
ICS
22
—
–1.3
–0.8
–0.5
µA
Oscillation
frequency
fOSC
20
RT = 47 kΩ
260
290
320
kHz
Frequency temperature stability
∆f/fdT
20
Ta = –30°C to +85°C
—
1*
—
%
*: Standard design value.
(Continued)
7
MB3875/MB3877
(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)
Parameter
Symbol Pin No
Error amplifier block
(Error Amp.1, 2)
Input offset
voltage
Input bias
current
VIO
6,7,8,11 FB1 = FB2 = 2 V
Value
Unit Remarks
Min.
Typ.
Max.
—
1
5
mV
IB
6,7,8,11
—
–100
–30
—
nA
Common
mode input
voltage range
VCM
6,7,8,11
—
0
—
VCC–1.8
V
Voltage gain
AV
3,9
DC
—
100*
—
dB
Frequency
bandwidth
BW
3,9
AV = 0 dB
—
2.0*
—
MHz
VFBH
3,9
—
3.9
4.1
—
V
VFBL
3,9
—
—
20
200
mV
ISOURCE
3,9
FB1 = FB2 = 2 V
—
–2.0
–0.6
mA
ISINK
3,9
FB1 = FB2 = 2 V
150
300
—
µA
Output voltage
Output source
current
Output sink
current
Threshold
voltage
FB3 = 2 V,
Ta = +25 °C
VTH
2
FB3 = 2 V,
Ta = –30 °C to +85 °C
V
MB3877
12.474 12.600 12.726
V
MB3875
16.632 16.800 16.968
V
MB3877
µA
MB3875
IN3 = 16.8 V
—
84
150
µA
MB3877
VCC = 0 V, IN3 = 12.6 V
—
0
1
µA
MB3875
VCC = 0 V, IN3 = 16.8 V
—
0
1
µA
MB3877
70
100
130
kΩ
MB3875
105
150
195
kΩ
MB3877
35
50
65
kΩ
DC
—
100*
—
dB
AV = 0 dB
—
2.0*
—
MHz
—
3.9
4.1
—
V
—
—
20
200
mV
FB3 = 2 V
—
–2.0
–0.6
mA
FB3 = 2 V
150
300
—
µA
R1
2
—
R2
16
—
Voltage gain
AV
15
Frequency
bandwidth
BW
15
VFBH
15
VFBL
15
ISOURCE
15
ISINK
15
Output sink
current
16.666 16.800 16.934
150
2
Output source
current
MB3875
84
IINE3L
Output voltage
V
—
2
Input resistor
12.500 12.600 12.700
IN3 = 12.6 V
IINE3H
Input current
Error amplifier block
(Error Amp.3)
Conditions
*: Standard design value.
(Continued)
8
MB3875/MB3877
(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)
Parameter
Symbol Pin No.
I+INCH
Current detection amplifier block
(Current Amp.1,2)
Input current
I–INCH
Common mode
input voltage range
Voltage gain
Frequency
bandwidth
Output voltage
Output source
current
Output sink
current
1, 12
Value
Unit Remarks
Min.
Typ.
Max.
+INC1= +INC2=12.7 V
–INC1= –INC2=12.6 V
—
10
20
µA MB3875
+INC1= +INC2=16.9 V
–INC1= –INC2=16.8 V
—
10
20
µA MB3877
+INC1= +INC2=12.7 V
–INC1= –INC2=12.6 V
—
0.1
0.2
µA MB3875
+INC1= +INC2=16.9 V
–INC1= –INC2=16.8 V
—
0.1
0.2
µA MB3877
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
+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
+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
VOUTC1
Current detection
voltage
13, 24
Conditions
VOUTC2
4, 10
4, 10
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
VCM
1, 12,
13, 24
—
0
—
VCC
V
+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
—
2.0*
—
AV
4, 10
BW
4, 10
AV = 0 dB
VOUTCH
4, 10
—
3.9
4.1
VOUTCL
4, 10
—
—
20
200
mV
ISOURCE
4, 10
OUTC1 = OUTC2 = 2 V
—
–2.0
–0.6
mA
ISINK
4, 10
OUTC1 = OUTC2 = 2 V
150
300
—
µA
MHz
V
*: Standard design value.
(Continued)
9
MB3875/MB3877
(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)
PWM comparator
block
(PWM Comp.)
Parameter
Symbol Pin No.
Conditions
Output block
(OUT)
Output sink current
Max.
Unit Remarks
3,9,15 Duty cycle = 0 %
1.4
1.5
—
V
VTH
3,9,15 Duty cycle = 100 %
—
2.5
2.6
V
OUT = 11 V
Duty ≤ 5 %
—
–200*
—
mA MB3875
OUT = 14 V
Duty ≤ 5 %
—
–200*
—
mA MB3877
OUT = 16 V
Duty ≤ 5 %
—
200*
—
mA MB3875
OUT = 19 V
Duty ≤ 5 %
—
200*
—
mA MB3877
ISOURCE
20
(t = 1/fosc × Duty )
ISINK
20
(t = 1/fosc × Duty )
(t = 1/fosc × Duty )
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
—
70*
—
ns
Fall time
tf2
20
—
60*
—
ns
VON
14
Active mode
2
—
25
V
VOFF
14
Standby mode
0
—
0.8
V
ICTLH
14
CTL = 5 V
—
100
200
µA
ICTLL
14
CTL = 0 V
—
0
1
µA
Output voltage
VH
19
VCC = VCC(O)
= 7 V to 25 V,
VH = 0 to 30 mA
Standby current
ICCS
18
VCC = VCC(O),
CTL = 0 V
Power supply current
ICC
18
VCC = VCC(O),
CTL = 5 V
Output ON resistor
Bias
Control block
voltage
(CTL)
block (VH)
Typ.
VTL
(t = 1/fosc × Duty )
General
Min.
Threshold voltage
Output source
current
CTL input voltage
Input current
*: Standard design value.
10
Value
(Equivalent to Si4435DY)
OUT = 3300 pF
(Equivalent to Si4435DY)
VCC–5.5 VCC–5.0 VCC–4.5
V
—
0
10
µA
—
6.0
9.0
mA MB3875
—
6.5
9.5
mA MB3877
MB3875/MB3877
■ TYPICAL CHARACTERISTICS
10
Reference voltage vs. power supply voltage
10
Ta = +25 °C
CTL = 5 V
Reference voltage VREF (V)
Power supply current ICC (mA)
Power supply current vs. power supply voltage
8
6
4
2
0
0
5
10
15
20
Ta = +25 °C
CTL = 5 V
VREF = 0 mA
8
6
4
2
0
25
0
Reference voltage ∆VREF (%)
Reference voltage VREF (V)
Ta = +25 °C
VCC = 16 V (MB3875)
VCC = 19 V (MB3877)
CTL = 5 V
6
4
2
0
0
5
10
15
20
25
2.0
1.0
0.0
−0.5
−1.0
−1.5
−2.0
−40
30
−20
0
20
40
60
80
100
Ambient temperature Ta (°C)
CTL pin current vs. CTL pin voltage
10
Ta = +25 °C
VCC = 16 V (MB3875)
VCC = 19 V (MB3877)
VREF = 0 mA
CTL pin current ICTL (µA)
Reference voltage VREF (V)
25
0.5
Reference voltage vs. CTL pin voltage
8
20
VCC = 16 V (MB3875)
VCC = 19 V (MB3877)
CTL = 5 V
VREF = 0 mA
1.5
VREF load current IREF (mA)
10
15
Reference voltage vs. ambient temperature
Reference voltage vs. VREF load current
8
10
Power supply voltage VCC (V)
Power supply voltage VCC (V)
10
5
6
4
2
Ta = +25 °C
VCC = 16 V (MB3875)
VCC = 19 V (MB3877)
8
6
4
2
0
0
0
5
10
15
CTL pin voltage VCTL(V)
20
25
0
5
10
15
20
25
Control pin voltage VCTL (V)
(Continued)
11
MB3875/MB3877
Triangular wave oscillator frequency vs.
timing resistor
1M
Ta = +25 °C
VCC = 16 V (MB3875)
VCC = 19 V (MB3877)
CTL = 5 V
100 k
10 k
10 k
100 k
1M
Timing resistor RT (Ω)
Triangular wave oscillator frequency fOSC(kHz)
Triangular wave oscillator frequency fOSC(Hz)
(Continued)
330
320
310
300
290
280
270
260
250
−40
−20
0
20
40
60
Ambient temperature Ta (°C)
Ta = +25 °C
CTL = 5 V
RT = 47 kΩ
340
330
320
310
300
290
280
270
260
250
0
5
10
15
20
25
80
100
Error amplifier threshold voltage vs.
ambient temperature
Error amplifier threshold voltage ∆VTH(%)
Triangular wave oscillator frequency fOSC(kHz)
12
VCC = 16 V (MB3875)
VCC = 19 V (MB3877)
CTL = 5 V
RT = 47 kΩ
340
350
Power supply voltage VCC (V)
Triangular wave oscillator frequency vs.
ambient temperature
350
Triangular waveoscillator frequency vs.
power supply voltage
5.0
VCC = 16 V (MB3875)
VCC = 19 V (MB3877)
CTL = 5 V
4.0
3.0
2.0
1.0
0.0
−1.0
−2.0
−3.0
−4.0
−5.0
−40
−20
0
20
40
60
80
Ambient temperature Ta (°C)
100
MB3875/MB3877
(Continued)
Error amplifier gain and phase vs. frequency
Ta = +25 °C
AV
4.2 V
φ
20
VCC = 16 V (MB3875)
VCC = 19 V (MB3877)
180
90
Phase φ (deg)
Gain AV (dB)
40
0
0
−20
−90
−40
−180
100
1k
10 k
100 k
1M
240 kΩ
IN
− +
10 kΩ
2.4 kΩ
10 kΩ
−
11
(6)
8 +
(7)
2.088 V
OUT
9
(3)
10 M
Frequency f (Hz)
Current detection amplifier gain and phase vs. frequency
Ta = +25 °C
40
VCC = 16 V (MB3875)
VCC = 19 V (MB3877)
180
20
90
0
0
φ
−20
−90
−40
−180
100
1k
10 k
100 k
Phase φ (deg)
Gain AV (dB)
AV
24
(13)
0.1 V
∗
1
(12)
+
× 25
−
100 kΩ
4
(10)
OUT
Current Amp.2
(Current Amp.1)
∗ : MB3875 12.6 V
MB3877 16.8 V
1M
Frequency f (Hz)
Power dissipation PD (mW)
Power dissipation vs. ambient temperature
800
740
700
600
500
400
300
200
100
0
−40
−20
0
20
40
60
80
100
Ambient temperature Ta (°C)
13
MB3875/MB3877
■ FUNCTIONAL DESCRIPTION
1. DC/DC Converter Unit
(1) Reference voltage block (Ref)
The reference voltage generator uses the voltage supplied from the Vcc terminal (pin 18) to generate a temperature-compensated, stable voltage ( =: 4.2 V) used as the reference 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 oscillator block(OSC)
The triangular wave oscillator generates a triangular waveform 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.
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
charge current.
In addition, an arbitrary loop gain can be set by connecting a feedback resistor and capacitor from the FB2
terminal (pin 3) to the -INE2 terminal (pin 6) of the error amplifier, enabling stable phase compensation to the
system.
(5)
Error amplifier block (Error Amp. 3)
This error amplifier (Error Amp. 3) detects the output voltage from the DC/DC converter and outputs the PWM
control signal. The error amplifier inverting 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 MB3875 and MB3877 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, 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. 2)
The current detection amplifier (Current Amp. 2) detects a voltage drop which occurs between both ends of the
output sense resistor (RS) due to the flow of the charge current, using the +INC2 terminal (pin 24) 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.
14
MB3875/MB3877
(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 PWM comparator circuit compares the triangular wave generated by the triangular 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 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 turned 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 internal 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) 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 of the
DC/DC converter.
15
MB3875/MB3877
■ 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 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 OSCILLATOR 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)
16
MB3875/MB3877
■ AC ADAPTER VOLTAGE DETECTION
With an external resistor connected to the +INE1 terminal, the IC enters the dynamically-controlled charging
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)
<Error Amp.1>
−INE1
A
VCC
R1
+INE1
11
−
8
+
R2
■ OPERATION TIMING DIAGRAM
2.5 V
Error Amp.2 FB2
Error Amp.3 FB3
Error Amp.1 FB1
1.5 V
OUT
AC adapter dynamicallycontrolled charging
Constant voltage
control
Constant current control
AC adapter dynamicallycontrolled charging
17
MB3875/MB3877
■ NOTE ON AN EXTERNAL REVERSE-CURRENTPREVENTIVE DIODE
Insert a reverse-current preventive diode (D) at one of the three locations marked * to prevent reverse current
from the battery.
Pay attention to the voltage/current characteristics of the reverse-current preventive diode (D) not to let it exceed
the overcharge stop voltage.
21
VCC(O)
VIN
(16 V/19 V)
D
∗
A
B
OUT
20
D
∗
I1
BATT
RS 12.6 V/16.8 V
∗
19
18
VH
D
Battery 1
MB3875/MB3877
■ APPLICATION EXAMPLE
R5
330 kΩ
R6
68 kΩ
FB1
+
<PWM
Comp.>
+
+
+
−
6
100 kΩ
OUTC2
4
+INC2
24
150 kΩ A
R7
−INC2
B
1
R12
22 kΩ
+INE2
R14
7
1.3 kΩ
30 kΩ
R16
R13
FB2
200 kΩ
3
110 Ω
Q2
R15
IN3
2
SW1
<Current Amp.2>
+
× 25
−
−INE3
∗1
C6
3900 pF
200 kΩ
R3
50 kΩ
15
A
OUT
Drive
22
CS
2200 pF
Q1
L1
20
B
RS
BATT
∗4
0.033 Ω
C3
C2
100 µF 100 µF
<Error
Amp.2> VREF
−
VCC
Bias voltage
block
+
19
<Error
Amp.3> VREF
VH
+
+
−
−
D1
(VCC − 5 V)
VCC
(VCC UVLO) 215 kΩ
+
−
+
+
35 kΩ
−
0.91 V
(0.77 V)
VREF
ULVO
<SOFT>
VREF
1 µA
VCC
CS
C1
22 µF
27 µH
VREF
(4.2 V)
FB3
−
<OUT>
<VH>
16
+
C5
0.1 µF
<UVLO>
VIN
∗3
VCC (O)
21
9
−INE2
R8
C8
3900 pF
<Error
Amp.1> VREF
−
Battery
R4
∗2
−INE1
11
R10
22 kΩ
OUTC1
C10 3900 pF 10
<Current Amp.1>
+INC1
+
13
× 25
−INC1
R11
−
12
30 kΩ 150 kΩ
R9
8
+INE1
bias
2.5 V
1.5 V
VCC
18
CTL
<OSC>
<REF>
<CTL>
C7
0.1 µF
14
(45 pF)
RT
RT
17
VREF
47 kΩ
5
GND
C9
0.1 µF
23
∗ 1 : MB3875
MB3877
∗ 2 : Vin = 16 V
Vin = 19 V
∗ 3 : MB3875
MB3877
∗ 4 : MB3875
MB3877
100 kΩ
150 kΩ
0Ω
82 kΩ
16 V/19 V
19 V
12.6 V
16.8 V
19
MB3875/MB3877
■ PARTS LIST
COMPONET
ITEM
SPECIFICATION
VENDOR
PARTS NO.
QI
Q2
FET
FET
Si4435DY
2N7002
VISHAY SILICONIX
VISHAY SILICONIX
Si4435DY
2N7002
D1
Diode
MBRS130LT3
MOTOROLA
MBRS130LT3
L1
Coil
27µH
3.4A, 34mΩ
SUMIDA
CDRH127-27uH
C1
C2
OS Condensor
OS Condensor
22µF
100µF
C3
OS Condensor
100µF
CS
C5
C6
C7
C8
C9
C10
Ceramics Condensor
Ceramics Condensor
Ceramics Condensor
Ceramics Condensor
Ceramics Condensor
Ceramics Condensor
Ceramics Condensor
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%
—
—
RS
RT
R3
R4
Resistor
Resistor
Resistor
Resistor
R5
R6
R7
R8
R9
R10
R11
R12
R13
R14
R15
R16
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
0.033Ω
47kΩ
200kΩ
0Ω
82kΩ
330kΩ
68kΩ
150kΩ
100kΩ
150kΩ
22kΩ
30kΩ
22kΩ
30kΩ
1.3kΩ
110Ω
200kΩ
1.0%
1.0%
1.0%
Jumper line
0.5%
0.5%
0.5%
1.0%
1.0%
1.0%
0.5%
0.5%
0.5%
0.5%
0.5%
0.5%
5%
—
—
Note: VISHAY SILICONIX : VISHAY Intertechrology, Inc.
MOTOROLA : Motorola Japan Ltd.
SUMIDA : SUMIDA ELECTRIC CO., Ltd.
20
MB3875/MB3877
■ REFERENCE DATA
• MB3875
Conversion efficiency vs. charge voltage
(Fixed current mode)
Conversion efficiency vs. charge current
(Fixed voltage mode)
100
BATT charge voltage=12.6V fOSC=288.78kHz
efficiency η(%)=(VBATT × IBATT)/(Vin × Iin) × 100
98
96
Vin = 16 V
94
92
Vin = 19 V
90
88
86
84
82
80
10 m
100 m
1
94
Vin = 16 V
R4 = 0 Ω
92
90
Vin = 19 V
R4 = 82 kΩ
88
86
84
82
80
0
2
4
6
8
10
12
14
16
10
BATT charge voltage VBATT(V)
BATT voltage vs. BATT charge current
BATT voltage vs. BATT charge current
16
Vin=16v
BATT: Electronic load
14
(Product of KIKUSUI PLZ-150W)
12
10
Dead Battery MODE
DCC MODE
8
6
4
2
0
1
DCC : Dynamically-Controlled Charging
2
3
4
5
BATT charge current IBATT(A)
BATT voltage VBATT(V)
18
18
BATT voltage VBATT(V)
(Product of KIKUSUI PLZ-150W)
96
BATT charge current IBATT(A)
0
BATT= Electronic load
98
Conversion effciency η(%)
Conversion efficiency η(%)
100
16
Vin=19v
BATT:Electronic load
14
(Product of KIKUSUI PLZ-150W)
12
10
Dead Battery MODE
DCC MODE
8
6
4
2
0
0
1
DCC : Dynamically-Controlled Charging
2
3
4
5
BATT charge current IBATT(A)
Note: KIKUSUI : KIKUSUI Electronics Corp.
21
MB3875/MB3877
(Continued)
Soft start operating waveforms
DC/DC converter switching waveforms
Vin = 16 V
Load : BATT = 20 Ω
− INE1 = 0 V
Vin = 16 V
FOSC = 288.8 kHz
Load : BATT = 2A
BATT (V)
20
CTL (V)
20
10
5
OUT (V)
20
15
0
15
10
10
5
5
0
0
5V
0
20 ms
40
80
120
160
−5
200
t (ms)
Soft start operating waveforms
0
CTL (V)
20
10
15
0
4
6
8
10
t (µs)
Vin = 19 V
FOSC = 288.8 kHz
Load : BATT = 2A
BATT (V)
20
1 µs
5V
5V
15
2
DC/DC converter switching waveforms
Vin = 19 V
Load : BATT = 20 Ω
− INE1 = 0 V
OUT (V)
20
5
15
10
10
5
5
0
0
5V
0
22
1 µs
5V
5V
15
40
20 ms
80
120
160
−5
200
t (ms)
0
2
4
6
8
10
t (µs)
MB3875/MB3877
• MB3877
Conversion efficiency vs. charge voltage
Conversion efficiency vs.charge current
100
BATT charge voltage=12.6V fOSC=288.78kHz
efficiency η(%)=(VBATT × IBATT)/(Vin × Iin) × 100
98
Conversion efficiency η(%)
Conversion efficiency η(%)
100
96
94
92
Vin = 19 V
90
88
86
84
82
80
10 m
100 m
1
BATT charge current IBATT(A)
BATT= Electronic load
98
(Prouct of KIKUSUI PLZ-150W)
96
94
92
90
Vin = 19 V
R4 = 82 kΩ
88
86
84
82
80
0
2
4
6
8
10
12
14
16
18
10
BATT charge voltage VBATT(V)
BATT voltage vs. BATT charge current
20
Vin=19v
BATT:Electronic load
BATT voltage VBATT(V)
18
16
(Product of KIKUSUI PLZ-150W)
14
12
Dead Battery MODE
10
DCC MODE
8
6
4
2
0
0
1
DCC : Dynamically-Controlled Charging
2
3
4
5
BATT charge current IBATT(A)
Note: KIKUSUI : KIKUSUI Electronics Corp.
23
MB3875/MB3877
(Continued)
Soft start operating waveforms
DC/DC converter switching waveforms
Vin = 19 V
FOSC = 287.4 kHz
Load : BATT = 2 A
Vin = 19 V
Load : BATT = 50 Ω
− INE1 = 0 V
10 V
15
OUT (V)
20
0
15
10
10
5
5
0
5V
0
24
1 µs
5V
BATT (V)
20
CTL (V)
20
10
40
0
20 ms
80
120
160
−5
200
t (ms)
0
2
4
6
8
10
t (µs)
MB3875/MB3877
■ 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 values within which normal LSI operation is warranted. Standard electrical characteristics are warranted within the range of recommended operating conditions and within the listed
conditions for each parameter.
3. Printed circuit board ground lines should be set up with consideration for common impedance.
4. Take appropriate static electricity measures.
•
•
•
•
Containers for semiconductor materials should have 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.
■ ORDERING INFORMATION
Part number
MB3875PFV
MB3877PFV
Package
Remarks
24-pin plastic SSOP
(FPT-24P-M03)
25
MB3875/MB3877
■ PACKAGE DIMENSION
24-pin plastic SSOP
(FPT-24P-M03)
∗:These dimensions do not include resin protrusion.
+0.20
* 7.75±0.10(.305±.004)
* 7.75±0.10(.305±.004)
1.25 +0.20
–0.10
1.25 –0.10
+.008
–.004
.049 +.008
.049 –.004
(Mounting height)
(Mounting height)
0.10(.004)
0.10(.004)
INDEX
INDEX
0.65±0.12(.0256±.0047)
0.65±0.12(.0256±.0047)
7.15(.281)REF
7.15(.281)REF
CC
**5.60±0.10
5.60±0.10
(.220±.004)
(.220±.004)
+0.10
+0.10
0.22
0.22–0.05
–0.05
+.004
+.004
.009
–.002
.009 –.002
7.60±0.20
7.60±0.20
(.299±.008)
(.299±.008)
"A"
"A"
6.60(.260)
6.60(.260)
NOM
NOM
+0.05
+0.05
0.15 –0.02
–0.02
+.002
.006 +.002
–.001
–.001
Details of
of "A"
"A" part
part
Details
0.10±0.10(.004±.004)
0.10±0.10(.004±.004)
(STANDOFF)
OFF)
(STAND
10°
00 10°
0.50±0.20
0.50±0.20
(.020±.008)
(.020±.008)
1994FUJITSU
FUJITSULIMITED
LIMITEDF24018S-2C-2
F24018S-2C-2
1994
Dimensions in mm (inches)
26
MB3875/MB3877
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/
North 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 EUROPE 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 MICROELECTRONICS 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.