FUJITSU MICROELECTRONICS
DATA SHEET
DS04-27710-2Ea
ASSP For Power Supply Applications (Secondary battery)
DC/DC Converter IC for
Charging Li-ion Battery
MB3888
■
DESCRIPTION
The MB3888 is a DC/DC converter IC suitable for down-conversion, using pulse-width (PWM) charging and
enabling output voltage to be set to any desired level from one cell to four cells.
The MB3888 provides a broad power supply voltage range and low standby current as well as high efficiency,
making it ideal for use as a built-in charging device in products such as notebook PC.
This product is covered by US Patent Number 6,147,477.
■
FEATURES
•
•
•
•
•
Output voltage setting using external resistor : 1 cell to 4 cells
High efficiency
: 96% (VIN
=
19 V, Vo
=
16.8 V)
Wide range of operating supply voltages
: 8 V to 25 V
Output voltage setting accuracy
: 5 V
±
0.74% (Ta
= −10 °C
to 85
°C)
Charging current accuracy
:
±5%
(Continued)
■
PACKAGE
20-pin plastic SSOP
(FPT-20P-M03)
Copyright©2002-2008 FUJITSU MICROELECTRONICS LIMITED All rights reserved
2002.9
MB3888
(Continued)
• Built-in frequency setting capacitor enables frequency setting using external resistor only
• Oscillation frequency range
: 100 kHz to 500 kHz
• Built-in current detection amplifier with wide in-phase input voltage range : 0 V to V
CC
• In standby mode, leave output voltage setting resistor open to prevent inefficient current loss
• Built-in standby current function
: 0
µA
(standard)
• Built-in soft-start function independent of loads
• Built-in totem-pole output stage supporting P-channel MOS FETs devices
2
MB3888
■
PIN DESCRIPTION
Pin No.
1
2
Symbol
GND
RT
I/O
Ground terminal.
Triangular-wave oscillation frequency setting resistor connection
terminal.
Power supply control terminal.
Setting the CTL terminal at “L” level places the IC in the standby
mode.
Reference voltage output terminal.
PWM comparator block (PWM) input terminal.
Compares the lowest voltage among terminals FB1, FB2, and DTC,
with triangular wave and controls output.
Error amplifier (Error Amp2) output terminal.
Error amplifier (Error Amp2) inverted input terminal.
Error amplifier (Error Amp2) non-inverted input terminal.
With IC in standby mode, this terminal is set to “Hi-Z” to prevent loss
of current through output voltage setting resistance. Set CTL terminal
to “H” level and OUTD terminal to “L” level.
Current detection amplifier (Current Amp) input terminal.
Current detection amplifier (Current Amp) input terminal.
Current detection amplifier (Current Amp) output terminal.
Error amplifier (Error Amp1) non-inverted input terminal.
Error amplifier (Error Amp1) inverted input terminal.
Error amplifier (Error Amp1) output terminal.
Power supply terminal for reference power supply and control circuit.
Power supply terminal for FET drive circuit (VH
=
V
CC
−
6 V) .
External FET gate drive terminal.
Output circuit power supply terminal.
Soft-start capacitor connection terminal.
Descriptions
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
CTL
VREF
DTC
FB2
−INE2
+INE2
OUTD
−INC
+INC
OUTC
+INE1
−INE1
FB1
VCC
VH
OUT
VCC (O)
CS
I
O
I
O
I
I
O
I
I
O
I
I
O
O
O
4
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