FUJITSU SEMICONDUCTOR
DATA SHEET
DS04-27708-2E
ASSP
for Power Supply Application (for secondary battery)
DC/DC Converter IC for Parallel Charging
of 3/4 cell Li-ion & NiMH Batteries
MB3879
s
DESCRIPTION
The MB3879 is a DC/DC converter IC for parallel charging of 3/4 cell Li-ion & NiMH batteries, which uses the
pulse-width modulation (PWM) for controlling output voltages and output currents independently.
This IC can dynamically control secondary batterie’s charge current, which detects voltage dropping in an AC
adapter in order to keep its power constant (Dynamically controlled charging). This operation allows quick charging
by variable charging current in accordance with operating status of a notebook PC.
Moreover, the total current of the system current and control IC input current are detected, and control of the
secondary battery is enabled.
An efficient charge becomes possible because of the charge current comes in changeability according to the
operation state of notebook PC by this operation.
The IC also allows parallel charging that charges two batteries simultaneously, reducing charging time dramatically.
The IC, using a built-in output voltage setting resistor, allows high-precision setting of output voltages. With its
output-voltage switching function that is ready for both graphite-type and coke-type Li-ion batteries as well as
NiMH battery, the IC is best suited to a built-in charger of a notebook PC.
This product is covered by US Patent Number 6,147,477.
s
FEATURES
• Detecting a voltage dropping in the AC adapter, and dynamically controlling the charge current (Dynamically-
controlled charging)
• Detecting total current of system current and control-IC input current (Differential-charging)
(Continued)
48-pin plastic LQFP
s
PACKAGE
(FPT-48P-M05)
MB3879
(Continued)
• Selection of output voltages by 4-bit decoder:
12.3V (3 cells: 4.1V), 12.6V (3 cells: 4.2V), 16.4V (4 cells: 4.1V), 16.8V (4 cells: 4.2V)
• High efficiency: 94% (using reverse current preventive diode)
• Wide range of power supply voltage: 8 V to 25 V
• Setting precision of output voltage (built-in output voltage setting resistor):
±
0.8% (Ta
= +25 °C)
• Setting precision of charge current:
±5%
• Setting of frequency for only external capacitor, using built-in frequency setting resistor.
• Oscillation frequency range: 100 kHz to 500 kHz
• Built-in current detect amplifier with wide range of in-phase input voltages: 0 V to Vcc
• Stand-by current: 0
µA
• Built-in load-independent soft-start circuit
• Built-in charge mode detection function
• Built-in totem-pole outputs supporting Pch MOS FET
2
MB3879
s
PIN ASSIGNMENT
(TOP VIEW)
OUTC1
+INC1
+INE1
+INE2
-INC1
-INE1
-INE2
GND
38
DTC
FB1
FB2
48
47
46
45
44
43
42
41
40
39
37
CT
VCC
D0
D1
D2
D3
VSS
CTL
VDD
VB
OUT-EV
OUT-EC
OUT-EA2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
36
35
34
33
32
31
30
29
28
27
26
25
IN2
+INC3
FB4
OUTC3
-INE4
+INE4
FB5
-INE5
TEST
GNDO
VH
VCCO
OUT-EA1
IN1
+INC2
FB3
OUTC2
-INE3
+INE3
FB6
-INE6
CS2
CS1
(FPT-48P- 05)
OUT
3
MB3879
s
PIN DESCRIPTION
Pin No.
1
2
3
4
5
6
7
8
9
Symbol
VCC
D0
D1
D2
D3
VSS
CTL
VDD
VB
I/O
I
I
I
I
I
O
Power supply terminal
VDD logic input terminal
VDD logic input terminal
VDD logic input terminal
VDD logic input terminal
VDD logic ground terminal
Power supply control terminal. Setting “L” level on CTL terminal
places the IC in standby mode.
VDD logic power supply terminal
Reference voltage output terminal
Constant-voltage charging distinction signal output terminal
H level: Dynamically-controlled charging, Differential charging, or
Constant-voltage charging mode
L level: BATT1 or BATT2 Constant-voltage charging mode
Constant-current charge distinction signal output terminal
H level: Dynamically-controlled charging, Differential charging, or
Constant-voltage charging mode
L level: BATT1 or BATT2 Constant-current charging mode
Differential-charging distinction signal output terminal
H level: Dynamically-controlled-charging, Constant-voltaging, or
Constant-current charging mode
L level: Differential-charging mode
Dynamically-controlled charging distinction signal output terminal
H level: Dynamically-controlled charging, Constant-voltage charging,
or Constant-current charging mode
L level: Dynamically-controlled charging mode
<BATT1> Current detection amplifier (Current Amp2) input terminal
Output voltage feedback input terminal
<BATT1> Current detection amplifier (Current Amp2) input terminal
<BATT1> Error amplifier (Error Amp3) output terminal
<BATT1> Current detection amplifier (Current Amp2) output terminal
<BATT1> Error amplifier (Error Amp3) inverted input terminal
<BATT1> Error amplifier (Error Amp3) non-inverted input terminal
<BATT1> Error amplifier (Error Amp6) output terminal
<BATT1> Error amplifier (Error Amp6) inverted input terminal
Soft-start capacitor connection terminal
Soft-start capacitor connection terminal
External FET gate driving terminal
Driver block power supply terminal
Descriptions
10
OUT-EV
O
11
OUT-EC
O
12
OUT-EA2
O
13
OUT-EA1
O
14
15
16
17
18
19
20
21
22
23
24
25
IN1
+INC2
FB3
OUTC2
−INE3
+INE3
FB6
−INE6
CS2
CS1
OUT
VCCO
I
I
O
O
I
I
O
I
O
(Continued)
4
MB3879
(Continued)
Pin No.
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
Symbol
VH
GND0
TEST
−INE5
FB5
+INE4
−INE4
OUTC3
FB4
+INC3
IN2
CT
GND
DTC
+INE2
−INE2
FB2
+INE1
−INE1
OUTC1
FB1
−INC1
+INC1
I/O
O
O
I
O
I
I
O
O
I
I
I
I
I
O
I
I
O
O
I
I
Ground terminal
Descriptions
FET driver circuit power supply terminal (VH
=
VCC−6V)
Internal reference voltage for setting charge voltage
<BATT2> Error amplifier (Error Amp5) inverted input terminal
<BATT2> Error amplifier (Error Amp5) output terminal
<BATT2> Error amplifier (Error Amp4) non-inverted input terminal
<BATT2> Error amplifier (Error Amp4) inverted input terminal
<BATT2> Current detection amplifier (Current Amp3) output terminal
<BATT2> Error amplifier (Error Amp4) output terminal
<BATT2> Current detection amplifier (Current Amp3) input terminal
<BATT2> Current detection amplifier (Current Amp3) input terminal
Output voltage feedback input terminal
Triangular wave oscillation frequency setting capacitor connection
terminal
Ground terminal
External duty control input terminal
Error amplifier (Error Amp2) non-inverted input terminal
Error amplifier (Error Amp2) inverted input terminal
Error amplifier (Error Amp2) output terminal
Error amplifier (Error Amp1) non-inverted input terminal
Error amplifier (Error Amp1) inverted input terminal
Current detection amplifier (Current Amp2) output terminal
Error amplifier (Error Amp1) output terminal
Current detection amplifier (Current Amp1) input terminal
Current detection amplifier (Current Amp1) input terminal
5
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