LP3927ILQ-AH National Semiconductor, LP3927ILQ-AH Datasheet - Page 13

• Manufacturer Part Number: LP3927ILQ-AH
• Description: Cellular/PCS System Power Management IC
• Manufacturer: National Semiconductor

VEXT Detect W/Keyboard Interrupts
20037928
Note: Diagram indicates Open Drain IRQ tied to V
.
DD
***
= Internal signal
1. VEXT goes active low.
2. VEXT 32 msec de-bounce period.
3. Delay between LDO1 and LDO2 enable.
4. Both LDO1 and LDO2 outputs reach 95% of respective output voltage, start Reset timer.
5. Reset delay.
6. Keyboard de-bounce delay.
7. Keyboard pulse must be a minimum of 32 msec.
8. PS_HOLD may go low after Key press, but LDOs stay on since VEXT is low.
9. VEXT goes high, begin shutdown since PS_HOLD is low.
10. Delay between RST going low and LDO2 disabled.
11. Delay between LDO2 disable and LDO1 disabled.
13
www.national.com