Fujitsu MB3875PFV Dc/dc converter ic for charging Datasheet

FUJITSU SEMICONDUCTOR
DATA SHEET
DS04-27703-4E
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.
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-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)
(Continued)
■ PACKAGE
24-pin plastic SSOP
(FPT-24P-M03)
MB3875/3877
(Continued)
• High precision reference voltage source: 4.2 V ± 0.8 %
• Support for frequency setting using an external resistor
(Frequency setting capacitor integrated) :100 kHz to 500 kHz
• On-chip current detector amplifier with wide in-phase input voltage range : 0 V to VCC
• On-chip standby current function: 0 µA (Typ)
• On-chip soft-start function
• Internal totem-pole output stage supporting P-channel MOS FETs devices
■ PIN ASSIGNMENT
(TOP VIEW)
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)
2
MB3875/3877
■ PIN DESCRIPTION
Pin No.
Symbol
I/O
Descriptions
1
–INC2
I
Current detection amplifier (Current Amp. 2) input pin.
2
IN3
I
DC/DC output voltage (charge voltage) input pin.
3
FB2
O
Error amplifier (Error Amp. 2) output pin.
4
OUTC2
O
Current detection amplifier (Current Amp. 2) output pin.
5
VREF
O
Reference voltage output pin.
6
–INE2
I
Error amplifier (Error Amp. 2) inverted input pin.
7
+INE2
I
Error amplifier (Error Amp. 2) non-inverted input pin.
8
+INE1
I
Error amplifier (Error Amp. 1) non-inverted input pin
9
FB1
O
Error amplifier (Error Amp. 1) output pin.
10
OUTC1
O
Current detection amplifier (Current Amp. 1) output pin.
11
–INE1
I
Error amplifier (Error Amp. 1) inverted input pin.
12
–INC1
I
Current detection amplifier (Current Amp. 1) input pin.
13
+INC1
I
Current detection amplifier (Current Amp. 1) input pin.
14
CTL
I
Power supply control pin.
Setting the CTL pin low places the IC in the standby mode.
15
FB3
O
Error amplifier (Error Amp. 3) output pin.
16
–INE3
I
Error amplifier (Error Amp. 3) inverted input pin.
17
RT
—
Triangular-wave oscillation frequency setting resistor connection pin.
18
VCC
—
Power supply pin for reference power supply and control circuit.
19
VH
O
Power supply pin for FET drive circuit (VH = Vcc − 5 V).
20
OUT
O
High-side FET gate drive pin.
21
VCC(O)
—
Output circuit power supply.
22
CS
—
Soft-start capacitor connection pin.
23
GND
—
Ground pin.
24
+INC2
I
Current detection amplifier (Current Amp. 2) input pin.
3
MB3875/3877
■ 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
CTL
<OSC>
<REF>
<CTL>
(45 pF)
RT
17
VREF
5
GND
23
∗ : MB3875 100 kΩ
MB3877 150 kΩ
4
VCC
18
14
MB3875/3877
■ ABSOLUTE MAXIMUM RAGINGS
Parameter
Symbol
Rating
Conditions
VCC,VCC(O)
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
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.
5
MB3875/3877
■ ELECTRICAL CHARACTERISTICS
(MB3875: Ta = +25°C, VCC = 16 V, VCC (O) = 16 V, VREF = 0 mA)
(MB3877: Ta = +25°C, VCC = 19 V, VCC (O) = 19 V, VREF = 0 mA)
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
18
VTHL
Under voltage
lockout protection
circuit block (UVLO)
Value
Output voltage
VTLH
Triangular waveform Soft-start
block
oscillator circuit
(SOFT)
block (OSC)
Conditions
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)
6
MB3875/3877
(MB3875: Ta = +25°C, VCC = 16 V, VCC (O) = 16 V, VREF = 0 mA)
(MB3877: Ta = +25°C, VCC = 19 V, VCC (O) = 19 V, VREF = 0 mA)
Parameter
Symbol Pin No
Input offset
voltage
Error amplifier block
(Error Amp.1, 2)
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)
7
MB3875/3877
(MB3875: Ta = +25°C, VCC = 16 V, VCC (O) = 16 V, VREF = 0 mA)
(MB3877: Ta = +25°C, VCC = 19 V, VCC (O) = 19 V, VREF = 0 mA)
Parameter
Symbol Pin No.
I+INCH
Input current
I–INCH
Current detection amplifier block
(Current Amp.1,2)
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)
8
MB3875/3877
(Continued)
(MB3875 : Ta = +25°C, VCC = 16 V, VCC (O) = 16 V, VREF = 0mA)
(MB3877 : Ta = +25°C, VCC = 19 V, VCC (O) = 19 V, VREF = 0mA)
PWM comparator
block
(PWM Comp.)
Parameter
Symbol Pin No.
Conditions
Output block
(OUT)
Typ
Max
Unit Remarks
VTL
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 )
(t = 1/fosc × Duty )
Output sink current
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)
Min
Threshold voltage
Output source
current
General
Value
CTL input voltage
Input current
(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
*: Standard design value.
9
MB3875/3877
■ 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)
10
MB3875/3877
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)
350
VCC = 16 V (MB3875)
VCC = 19 V (MB3877)
CTL = 5 V
RT = 47 kΩ
340
330
320
310
300
290
280
270
260
250
−40
−20
0
20
40
60
Ambient temperature Ta (°C)
80
100
350
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
Power supply voltage VCC (V)
Error amplifier threshold voltage vs.
ambient temperature
Error amplifier threshold voltage ∆VTH(%)
Triangular wave oscillator frequency fOSC(kHz)
Triangular wave oscillator frequency vs.
ambient temperature
Triangular wave oscillator 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
100
Ambient temperature Ta (°C)
11
MB3875/3877
(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
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
Ambient temperature Ta (°C)
12
80
100
24
(13)
0.1 V
∗
1
(12)
+
× 25
−
100 kΩ
4
(10)
Current Amp.2
(Current Amp.1)
∗ : MB3875 12.6 V
MB3877 16.8 V
OUT
MB3875/3877
■ 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.
13
MB3875/3877
(7) PWM comparator block (PWM Comp.)
The PWM comparator circuit is a voltage-pulse width converter for controlling the output duty of the error
amplifiers (Error Amp. 1 to Error Amp. 3) depending on their output voltage.
The 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.
14
MB3875/3877
■ METHOD OF SETTING THE CHARGING CURRENT
The charge current (output control current) value can be set with the voltage at the +INE2 terminal.
If a current exceeding the set value attempts to flow, the charge voltage drops according to the set current value.
Battery charge current setting voltage
+INE2 (V) = 25 × I1 (A) × RS (Ω)
■ METHOD OF SETTING THE SOFT-START TIME
Upon activation, the IC starts charging the capacitor (Cs) connected to the CS terminal (pin 22).
The 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)
15
MB3875/3877
■ 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
16
Constant voltage
control
Constant current control
AC adapter dynamicallycontrolled charging
MB3875/3877
■ 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
VH
D
Battery 1
17
MB3875/3877
■ APPLICATION EXAMPLE
R5
330 kΩ
R6
68 kΩ
FB1
150 kΩ
R7
R12
22 kΩ
R14
1.3 kΩ
Q2
<PWM
Comp.>
+
+
+
−
6
4
<Current Amp.2>
+INC2
+
A
24
× 25
−INC2
−
B
1
+INE2
FB2
110 Ω
R15
IN3
SW1
+
C5
0.1 µF
C1
22 µF
<OUT>
A
OUT
Drive
Q1
L1
20
B
RS
Bias voltage
block
+
<VH>
19
VH
+
+
−
−
D1
(VCC − 5 V)
3
2
∗1
16
C6
3900 pF
200 kΩ
R3
50 kΩ
<Error
Amp.3> VREF
15
VCC
(VCC UVLO) 215 kΩ
+
−
+
+
35 kΩ
−
0.91 V
(0.77 V)
VREF
(4.2 V)
FB3
VREF
ULVO
<SOFT>
VREF
1 µA
VCC
CS
22
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
18
BATT
∗4
0.033 Ω
C3
C2
100 µF 100 µF
VCC
<UVLO>
CS
2200 pF
−
27 µH
<Error
Amp.2> VREF
−
7
VIN
∗3
−INE3
VCC (O)
21
100 kΩ
OUTC2
30 kΩ
R13
R16
200 kΩ
+
9
−INE2
R8
C8
3900 pF
<Error
Amp.1> VREF
−
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
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
MB3875/3877
■ 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.
19
MB3875/3877
■ 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
Conversion efficiency η(%)
Conversion efficiency η(%)
100
Vin = 16 V
94
92
Vin = 19 V
90
88
86
84
82
80
10 m
100 m
1
94
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
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)
Note: KIKUSUI : KIKUSUI Electronics Corp.
BATT voltage VBATT(V)
18
18
BATT voltage VBATT(V)
Vin = 16 V
R4 = 0 Ω
92
BATT voltage vs. BATT charge current
20
(Product of KIKUSUI PLZ-150W)
96
BATT charge current IBATT(A)
0
BATT= Electronic load
98
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)
MB3875/3877
(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
1 µs
5V
5V
15
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
4
6
8
10
t (µs)
DC/DC converter switching waveforms
Vin = 19 V
FOSC = 288.8 kHz
Load: BATT = 2A
Vin = 19 V
Load: BATT = 20 Ω
− INE1 = 0 V
BATT (V)
20
1 µs
5V
5V
15
2
CTL (V)
20
10
5
OUT (V)
20
15
0
15
10
10
5
5
0
0
5V
0
40
20 ms
80
120
160
−5
200
t (ms)
0
2
4
6
8
10
t (µs)
21
MB3875/3877
• MB3877
Conversion efficiency vs. charge voltage
Conversion efficiency vs.charge current
BATT charge voltage=12.6V fOSC=288.78kHz
efficiency η(%)=(VBATT × IBATT)/(Vin × Iin) × 100
98
100
Conversion efficiency η(%)
Conversion efficiency η(%)
100
96
94
92
Vin = 19 V
90
88
86
84
82
80
10 m
100 m
1
10
BATT charge current IBATT(A)
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.
22
BATT= Electronic load
98
(Product 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
BATT charge voltage VBATT(V)
16
18
MB3875/3877
(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
1 µs
5V
BATT (V)
20
CTL (V)
20
10
OUT (V)
20
0
15
10
10
5
5
0
5V
0
40
0
20 ms
80
120
160
−5
200
t (ms)
0
2
4
6
8
10
t (µs)
23
MB3875/3877
■ NOTES ON USE
• Take account of common impedance when designing the earth line on a printed wiring board.
• Take measures against static electricity.
- For semiconductors, use antistatic or conductive containers.
- When storing or carrying a printed circuit board after chip mounting, put it in a conductive bag or container.
- The work table, tools and measuring instruments must be grounded.
- The worker must put on a grounding device containing 250 kΩ to 1 MΩ resistors in series.
• Do not apply a negative voltage
- Applying a negative voltage of −0.3 V or less to an LSI may generate a parasitic transistor, resulting in
malfunction.
■ ORDERING INFORMATION
Part number
MB3875PFV
MB3877PFV
24
Package
24-pin plastic SSOP
(FPT-24P-M03)
Remarks
MB3875/3877
■ PACKAGE DIMENSION
Note 1) *1 : Resin protrusion. (Each side : +0.15 (.006) MAX) .
Note 2) *2 : These dimensions do not include resin protrusion.
Note 3) Pins width and pins thickness include plating thickness.
Note 4) Pins width do not include tie bar cutting remainder.
24-pin plastic SSOP
(FPT-24P-M03)
0.17±0.03
(.007±.001)
*17.75±0.10(.305±.004)
24
13
*2 5.60±0.10
7.60±0.20
(.220±.004) (.299±.008)
INDEX
Details of "A" part
+0.20
1.25 –0.10
+.008
.049 –.004
(Mounting height)
0.25(.010)
1
"A"
12
0.65(.026)
0.24
.009
+0.08
–0.07
+.003
–.003
0.13(.005)
0~8˚
M
0.50±0.20
(.020±.008)
0.60±0.15
(.024±.006)
0.10±0.10
(.004±.004)
(Stand off)
0.10(.004)
C
2003 FUJITSU LIMITED F24018S-c-4-5
Dimensions in mm (inches) .
Note : The values in parentheses are reference values.
25
MB3875/3877
FUJITSU LIMITED
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, such as descriptions of function and application
circuit examples, in this document are presented solely for the
purpose of reference to show examples of operations and uses of
Fujitsu semiconductor device; Fujitsu does not warrant proper
operation of the device with respect to use based on such
information. When you develop equipment incorporating the
device based on such information, you must assume any
responsibility arising out of such use of the information. Fujitsu
assumes no liability for any damages whatsoever arising out of
the use of the information.
Any information in this document, including descriptions of
function and schematic diagrams, shall not be construed as license
of the use or exercise of any intellectual property right, such as
patent right or copyright, or any other right of Fujitsu or any third
party or does Fujitsu warrant non-infringement of any third-party’s
intellectual property right or other right by using such information.
Fujitsu assumes no liability for any infringement of the intellectual
property rights or other rights of third parties which would result
from the use of information contained herein.
The products described in this document are designed, developed
and manufactured as contemplated for general use, including
without limitation, ordinary industrial use, general office use,
personal use, and household use, but are not designed, developed
and manufactured as contemplated (1) for use accompanying fatal
risks or dangers that, unless extremely high safety is secured, could
have a serious effect to the public, and could lead directly to death,
personal injury, severe physical damage or other loss (i.e., nuclear
reaction control in nuclear facility, aircraft flight control, air traffic
control, mass transport control, medical life support system, missile
launch control in weapon system), or (2) for use requiring
extremely high reliability (i.e., submersible repeater and artificial
satellite).
Please note that Fujitsu 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.
F0308
 FUJITSU LIMITED Printed in Japan