8. FUNCTIONAL DESCRIPTION
8
EPSON
S1F76980 Technical Manual (Rev.1.0)
Fig.8.2.3 Block diagram for V
BAT
power voltage monitoring circuit
(Note 3) The power switch built in the output guarantee circuit may be turned ON/OFF by the PSW pin only for
the V
BAT
-system power supply.
(Note 4) The detecting voltage dead time of power voltage monitoring may be specified by external capacitor
only for the V
BAT
-system power supply. The recommended value of the capacitor is approximately 1s
for 6800pF. However, when the voltage is temporarily below the output guarantee voltage, low voltage
is detected even during the dead time.
Typ.
For detecting voltage = 1.6V, detecting voltage dead setting time TBDLY [S] = Set coefficient (147)
×
C [
µ
F]
In case of the recommended C=6800[pF], the release delay time is TBDLY=1[S].
Typ.
For detecting voltage = 2.8V, detecting voltage dead setting time TBDLY [S] = Set coefficient (250)
×
C [
µ
F]
In case of the recommended C=6800[pF], the release delay time is TBDLY=1.7[S].
V
BAT
CMP
+
-
BDET
V
REF
R2
R3
The power is turned off when the voltage is below the
output guarantee voltage.
R1
Output
guarantee
V
REG
XOFF
CBDLY
PSW
(Note 3)
(Note 4)
