LP3927 Datasheet, PDF (10/16 Pages) National Semiconductor (TI) – Cellular/PCS System Power Management IC

Keyboard Start-Up/Shut-Down
Note: Diagram indicates Open Drain IRQ tied to V_DD.
*** = Internal signal
1. Keyboard de-bounce delay, 32 msec typ.
2. Delay between LDO1 reaching 95% of its output voltage and LDO2 enable, 125 µsec typical.
3. Both LDO1 and LDO2 outputs reach 95% of respective output voltage, start RST timer.
4. RST delay, 20 msec typical.
5. IRQ is active low.
6. Keyboard press must be greater than 32 msec.
7. PS_HOLD timer begins upon RST going high.
8. Maximum of 500 msec period from RST going high to PS_HOLD going high.
9. Response time from PS_HOLD going low to RST going low.
10. Delay between RST high-low transition to LDO2 disable.
11. Delay between LDO2 disable and LDO1 disable.
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