8. FUNCTIONAL DESCRIPTION
S1F76980 Technical Manual (Rev.1.0)
EPSON
9
8.3 Switching Control Circuit
This circuit controls output of a signal that selects optimum input power supply according to input conditions of
three power supplies (V
CC
, V
BUS
, and V
BAT
) and in the priority sequence set in the IC.
(1) Power input control logic
V
CC
V
BUS
V
BAT
V
OUT
Output selection system
L L L
OFF
L L H
L H L
L H H
(
)
H L L
H L H
H H L
H H H
(Note 5) The priority sequence may be changed with the BSEL pin.
It can be switched even during operation of IC.
(Note 6) L: Input disabled, H: Input enabled
(2) Switch
configuration
Fig.8.4.1 shows the configuration diagram of power supply selection switches, that are configured outside the
IC.
The O*1 (OC1, OU1, and OB1) pin performs over voltage limiter control while the O*2 (OC2, OU2, and OB2)
pin controls backflow prevention.
Fig.8.4.1 Switch configuration
OC2
OC1
V
CC
OU2
OU1
V
BUS
OB2
OB1
V
BAT
V
OUT
