MB3888 Datasheet, PDF (16/30 Pages) Fujitsu Component Limited. – DC/DC Converter IC for Charging Li-ion Battery

MB3888
s SETTING THE CHARGING VOLTAGE
The charging voltage (DC/DC output voltage) can be set by connecting external voltage setting resistors (R3,
R4) to the −INE2 terminal (pin 7) according to the voltage at the +INE2 terminal (pin 8) . Be sure to select a
resistor value that allows you to ignore the on resistor (35 Ω, 1 mA) of the internal FET connected to the OUTD
terminal (pin 9) .In standby mode, the charging voltage is applied to OUTD termial. Therefore, output voltage
must be adjusted so that voltage applied to OUTD terminal is 17 V or less.
Battery charging voltage : VO
VO (V) = (R3 + R4) / R4 × +INE2 (V)
VO
R3
−INE2
7
R4
9
OUTD
<Error Amp2>
−
+
+
20
CS
8
+INE2
s METHOD OF SETTING THE CHARGING CURRENT
The charge current (output limit current) value can be set with the voltage at the +INE1 terminal (pin 13) .
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 : +INE1
+INE1 (V) = 20 × I1 (A) × RS (Ω)
s METHOD OF SETTING THE TRIANGULAR WAVE OSCILLATION FREQUENCY
The triangular wave oscillation frequency can be set by the timing resistor (RT) connected the RT terminal (pin 2) .
Triangular wave oscillation frequency : fOSC
fOSC (kHz) =: 12690 / RT (kΩ)
16