S-8425AAAFT-TB-X Datasheet, PDF (14/45 Pages) Seiko Instruments Inc – BATTERY BACKUP SWITCHING IC

BATTERY BACKUP SWITCHING IC
S-8425 Series
Rev.3.1_01
3.4 Switch Transistor M1
Voltage regulator 2 is also used to switch from the VIN
pin to the VOUT pin. Therefore, no reverse current _VIN
flows from the VOUT pin to the 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.
REG2
VOUT
Vdif
M1
VBAT
The on-resistance of switch transistor M1 is 60 Ω or
Figure 9 Definition of V_dif
lower (I _OUT = 10 to 500 μA).
Therefore, when M1 is switched ON and the VOUT pin is connected to the 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).
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