MB39A119 Datasheet, PDF (20/53 Pages) Fujitsu Component Limited. – DC/DC Converter IC of Synchronous Rectification for charging Li-ion battery

MB39A119
■ SETTING THE CHARGE VOLTAGE
The charge voltage (DC/DC output voltage) can be set by connecting external output voltage setting resistors
(R1 and R2) to the -INE3 terminal (pin 15) . Be sure to select a resistor value that allows you to ignore the on-
resistance (35 Ω at 1 mA) of internal FET connected to the OUTD terminal (pin 16).
Battery charge voltage : VO
VO (V) =
R1 + R2
× − INE3 (V)
R2
B ^VO
R1
−INE3
15
R2
16
OUTD
<Error Amp3>
−
+
4.2 V
■ SETTING THE CHARGE CURRENT
The charge current value can be set at the analog voltage value of the +INE2 terminal (pin 12) .
Charge current formula : Ichg (A) = ^{+ INE2 (V)}
24.5 × RS1 (Ω)
Battery charge current setting voltage : + INE2
+ INE2 (V) = 24.5 × Ichg (A) × RS1 (Ω)
It is recommended that the filter should be connected to an input terminal of Current Amp2 as shown below in order
to reduce the switching noise and increase the charge current accuracy.
Ichg
RS1
10 Ω
10 Ω
0.22 0.22
µF µF
+INC2
10
−INC2 ₁₁
<Current Amp2>
+
× 24.5
−
20