S-8424AAAFT-TB-X Datasheet, PDF (22/46 Pages) Seiko Instruments Inc – BATTERY BACKUP SWITCHING IC

BATTERY BACKUP SWITCHING IC
S-8424A Series
Rev.3.0_01
3.4 Switch Transistor M1
Voltage regulator 2 is also used to switch from VIN pin to VOUT pin. Therefore, no reverse current flows
from VOUT pin to VIN pin when voltage regulator 2 is OFF. The output voltage of voltage regulator 2 can
be selected from between 2.3 V and 5.4 V in 0.1 V steps.
The on-resistance of switch transistor M1 is 60 Ω or lower (I_OUT = 10 to 500 μA).
Therefore, when M1 is switched ON and VOUT pin is connected to VBAT pin, the voltage drop (V_dif)
caused by M1 is 60 × I_OUT (output current) at maximum., and V_BAT – V_dif (max.) is output to the VOUT pin at
minimum.
When voltage regulator 2 is ON and M1 is OFF, the leakage current of M1 is kept below 0.1 μA max. (V_IN
= 6 V, Ta = 25°C) with the VBAT pin grounded (VSS pin).
VIN
REG2
VOUT
V_dif
VBAT
M1
Figure 9 Definition of V_dif
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