S1F76540 Series

Power-off Control Function

The S1F76540 has the power-off function and turns on or off each circuit function when control signals are entered in the POFF1 and POFF2 pins from an external system (such as microprocessor) as defined on Table 2.7. This power-off function can also cut the reactive current

in parallel connection and other application circuits. To use the dual-state, power-off control (all ON and all OFF states) only, connect pin POFF2 to pin VI and use only pin POFF1 for power-off control.

Table 2.7 Available combination of power-off control

 

 

 

 

 

 

 

 

 

 

 

 

 

POFF1

 

POFF2

 

Functions

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(High = VDD)

(High = VDD)

Oscillator

Booster

Regulator

Applications

Mode

(Low = VI)

(Low = VI)

 

circuit

circuit

 

 

 

 

 

 

 

 

 

 

 

 

PS1

 

High

 

Low

ON

ON

ON

All circuits are turned on.

 

 

 

 

 

 

 

 

 

 

 

PS2

 

Low

 

Low

OFF

OFF (*1)

OFF (*2)

All circuits are turned off.

 

 

 

 

 

 

 

 

 

 

 

PS3

 

High

 

High

OFF

ON

ON

Slave unit side of parallel connection

 

 

(Booster and regulator)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PS4

 

Low

 

High

ON

ON

OFF

Master unit side of parallel

 

 

connection (Booster only)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

*1 When the booster circuit is off, approximately VI + 0.6 V voltage appears at VO pin. *2 When the regulator is off, the VREG pin becomes high-impedance state.

Application notes on power-off function:

•When using external system signals for power-on control, start to control the power only when VI voltage becomes stable after power-on. Unstable VI voltage may destroy the IC permanently during on/off control.

VI

VI

 

POFF1

POFF1

 

POFF2

POFF2

Figure 2.6 Start timing of power-off control

2–28

EPSON

S1F70000 Series Technical Manual