Epson RX8900SA/CE - 8.8. Battery Backup Switchover Function; 8.8.1. Description of Battery Backup Switchover Function

RX8900 SA / CE
Page - 24 ETM45E-01
8.8. Battery backup switchover function
8.8.1. Description of Battery backup switchover function
It consists of the power-source detector "VDET" which detect the power down of the main power source "VDD", and built-in
MOS switches located between the main power-source pin "VDD" and the backup power supply pin "VBAT".
In turning off a MOS switch according to the supply-voltage detection result of VDET, when an drive power source changes
to VDD OFF ->VBAT (it shifts to a backup operation from a normal operation), it becomes possible to prevent a
reverse-current (VBAT->VDD) of an electric current.
[Connection example]
VDD
V
BAT
VDD
C
VDD
V
BAT
secondary
batter
y
VDD
EDLC
o
r
R
C
C
VDD
V
BAT
primary
battery
VDD
R
C
C
[Connection example when not using the battery backup switchover function]
If you do not want to use the feature, please connect to both the VBAT pin and VDD pin main power.
If you have this connection, interface voltage is 1.6V to 5.5V.
Ex.1 Not use a backup circuit Ex.2 Connected a second battery Ex.3 Connected a primary battery