S-8426AAA-J8T1X Datasheet, PDF (12/37 Pages) Seiko Instruments Inc – BATTERY BACKUP SWITCHING IC

BATTERY BACKUP SWITCHING IC
S-8426A Series
Rev.2.0_02
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).
VOUT
V_dif
VIN
REG2
M1
VBAT
Figure 15 Definition of Vdif
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