DS04-27224-1E
FUJITSU SEMICONDUCTOR
DATA SHEET
ASSP For Power Management Applications
8
-ch DC/DC Converter IC with Synchronous
Rectifier
for Voltage Step-up and Step-down
MB3881
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DESCRIPTION
The MB3881 a step-up/step-down type of 8-channel, DC/DC converter IC. It uses pulse width modulation (PWM)
and synchronous rectification, designed for low voltage, high efficiency, and compactness. This IC is ideal for
down conversion and up/down conversion (employing a step-up/step-down Zeta system enabling free I/O setting).
The MB3881 can use channel 8 as its own power supply to provide a wide range of supply voltages, allowing
itself to operate at low voltage.
In addition, the MB3881 contains a triangular wave oscillator which can operate in synchronization with an external
device, allowing the switching timing to be controlled externally. This contributes to reduction in switching noise,
facilitating system configuration.
The MB3881 is designed to be compact using the LQFP-64P package whose body size is 7
×
7 mm.
The IC is the best for the power supply for advanced portable equipment such as a camera integrated VTR.
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FEATURES
· Supporting the step-up/step-down Zeta methods (CH1 to CH7)
· Supporting synchronous rectification (CH1, CH2)
· Low start-up voltage : 1.8 V (CH8)
· Power-supply voltage range : 4 V to 13 V (CH1 to CH7)
· Built-in high-precision reference voltage generator : 2.5 V
±
1%
· Oscillation frequency range : 100 kHz to 800 kHz
· Built-in triangular wave oscillator capable of external synchronization
· Error amplifier output for soft start (CH1 to CH4, CH7)
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PACKAGE
64-pin plastic LQFP
(FPT-64P-M16)
MB3881
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PIN DESCRIPTION
(Continued)
Pin No.
Symbol
I/O
Descriptions
CH1
47
FB1
O
Error amplifier output pin.
46
-
IN1
I
Error amplifier inverted input pin.
48
DTC1
I
Dead time control pin.
50
OUT1-1
O
Main side output pin.
51
OUT1-2
O
Synchronous rectifier side output pin.
CH2
44
FB2
O
Error amplifier output pin.
43
-
IN2
I
Error amplifier inverted input pin.
45
DTC2
I
Dead time control pin.
53
OUT2-1
O
Main side output pin.
54
OUT2-2
O
Synchronous rectifier side output pin.
CH3
41
FB3
O
Error amplifier output pin.
40
-
IN3
I
Error amplifier inverted input pin.
42
DTC3
I
Dead time control pin.
56
OUT3
O
Output pin.
CH4
38
FB4
O
Error amplifier output pin.
37
-
IN4
I
Error amplifier inverted input pin.
39
DTC4
I
Dead time control pin.
57
OUT4
O
Output pin.
CH5
20
FB5
O
Error amplifier output pin.
21
-
IN5
I
Error amplifier inverted input pin.
22
+
IN5
I
Error amplifier non-inverted input pin.
23
-
IN5 (C)
I
Short detection comparator input pin.
19
DTC5
I
Dead time control pin.
60
OUT5
O
Output pin.
CH5, CH6
18
OVP
I
Output maximum voltage setting pin.
CH6
14
FB6
O
Error amplifier output pin.
15
-
IN6
I
Error amplifier inverted input pin.
16
+
IN6
I
Error amplifier non-inverted input pin.
17
-
IN6 (C)
I
Short detection comparator input pin.
13
DTC6
I
Dead time control pin.
61
OUT6
O
Output pin.
CH7
10
FB7
O
Error amplifier output pin.
11
-
IN7
I
Error amplifier inverted input pin.
12
+
IN7
I
Error amplifier non-inverted input pin.
9
DTC7
I
Dead time control pin.
62
OUT7
O
Output pin.
MB3881
4
(Continued)
Pin No.
Symbol
I/O
Descriptions
CH8
4
FB8
O
Error amplifier output pin.
5
-
IN8
I
Error amplifier inverted input pin.
6
+
IN8
I
Error amplifier non-inverted input pin.
7
-
IN8 (C)
I
Short detection comparator inverted input pin.
8
+
IN8 (C)
I
Short detection comparator non-inverted input pin.
3
DTC8
I
Dead time control pin.
2
RB8
Output current setting pin.
64
OUT8
O
Output pin.
OSC
33
RT
Triangular wave frquency setting resistor connection pin.
34
CT
Triangular wave frquency setting capacitor connection pin
35
SYNC
I
External synchronous signal input pin.
Control
28
CTL-1
I
Power supply, CH 1, 3, 4, 8 control circuit.
"H" level : Power supply operating mode
"L"level : Standby mode
29
CTL-2
I
CH 2 control circuit.
·
CTL-1pin
=
"H" level
"H" level : CH2 operating mode
"L" level : CH2 OFF mode
30
CTL-3
I
CH5, 6 control circuit.
·
CTL-1pin
=
"H" level
"H" level : CH5, CH6 operating mode
"L" level : CH5, CH6 OFF mode
31
CTL-4
I
CH7 control circuit.
·
CTL-1pin
=
"H" level
"H" level : CH7 operating mode
"L" level : CH7 OFF mode
26
CSCP
Short protection circuit capacitor connection pin.
32
CS
CH1, 2, 3, 4, 7 soft start circuit capacitor connection pin.
Power
27
VCC
Reference voltage and control circuit power supply pin.
58
VCC (O) -1
CH1, 2, 3, 4 output circuit power supply pin.
59
VCC (O) -2
CH5, 6, 7, 8 output circuit power supply pin.
49
VSS (O) -1
CH1, 2, 3, 4 output circuit power supply pin.
63
VSS (O) -2
CH5, 6, 7 output circuit power supply pin.
52
VDD (O)
CH1, 2 synchronous rectifier side output circuit power supply pin.
24
VREF
O
Refernce voltage output pin.
36
VB
O
Triangular wave oscillator regulator output pin.
25
GND
Ground pin.
55
GND (O) -1
CH1, 2, 3, 4 output circuit ground pin.
1
GND (O) -2
CH5, 6, 7, 8 output circuit ground pin.
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