MB3888 Fuji Electric, MB3888 Datasheet - Page 18

no-image

MB3888

Manufacturer Part Number
MB3888
Description
DC/DC Converter IC for Charging Li-ion Battery
Manufacturer
Fuji Electric
Datasheet
18
MB3888
(2) Setting constant current mode soft-start
For preventing rush current upon activation of IC, the IC allows soft-start using the capacitor (C
the CS terminal (pin 20) .
When CTL terminal (pin 3) is placed under “H” level and IC is activated (V
turned off and the external soft-start capacitor (C
Error Amp output (FB1 terminal (pin 15) ) is determined by comparison between the lower voltage of the two
non-inverted input terminals ( INE1 terminal (pin 13) and CS terminal voltage) and inverted input terminal voltage
( INE1 terminal (pin 14) voltage) . Within the soft-start period (CS terminal voltage
by comparison between INE1 terminal voltage and CS terminal voltage, and DC/DC converter output voltage
goes up proportionately with the increase of CS terminal voltage caused by charging on the soft-start capacitor.
Soft-start time is obtained from the following formula :
Soft-start time : ts (time to output 100
t
S
(s) : = INE2 10 ( A)
4.9 V
INE2
0 V
C
Soft-start time : t
S
INE1
INE1
FB1
CS
15
14
20
13
C
S
S
( F)
VREF
10 A
)
Soft-start circuit
Q2
S
) connected to the CS terminal is charged at 10 A.
CS terminal voltage
Comparison with Error Amp block
voltage.
10 A
Amp1
Error
CC
UVLO threshold voltage) , Q2 is
UVLO
INE1) , FB1 is determined
S
) connected to
INE1

Related parts for MB3888