5. FUNCTIONAL DESCRIPTION
S1F76540M0C Series Technical Manual
EPSON
9
(Rev.1.1)
5.5 Power-off Control Circuit
S1F76540 provides the power-off function, which turns each function on and off by issuing the signals shown in
Table 5.3 from the external system (microprocessor, etc.) to the POFF1X and POFF2X pins.
Using the power-off function, reactive current can be reduced in the application circuit connected in parallel.
When using the power-off function only in two states (all ON and all OFF), connect the POFF2X pin to VI;
power-on and -off can be controlled using only one POFF1X pin.
Table 5.3 Combination of power-on and -off modes
Function state
Mode name
POFF1X
(H=V
DD
)
(L=V
IN
)
POFF2X
(H=V
DD
)
(L=V
IN
)
Oscillation
circuit
Booster Regulator
Use
PS1
H
L
ON
ON
ON
All circuit ON state
PS2 L L OFF
OFF
(Note 1)
OFF
(Note 2)
All circuit OFF state
PS3 H H OFF ON ON
Slave side in parallel connection
(B Regulator)
PS4 L H ON ON
OFF
(Note 2)
Master side in parallel connection
(Booster only)
(Note 1)
When the booster is off, the voltage of approximately VI+0.6V is generated in the VO pin.
(Note 2)
When the regulator is off, the V
REG
pin is placed into the high impedance state.
[Notes on using the power-off function]
Before starting the power-off function with an external system signal, check that VI has been stabilized after
power-on. Turning the power on or off before the power is not stabilized will result in a permanent destruction
of this IC.
Figure 5.4 Power-off control start timing
VI
POFF1X
POFF2X
VI
POFF1X
POFF2X
