LP3913 Datasheet, PDF (29/70 Pages) Texas Instruments – Power Management IC for Flash Memory-Based Portable Media Players

LP3913
www.ti.com
SNVS489I – NOVEMBER 2006 – REVISED SEPTEMBER 2013
Power On Timing
Each timeout T1 thru to T5 are factory programmed from 0 ms to 63 ms. The following defaults are shown below.
Symbol
T1
T2
T3
T4
T5
Description
Programmable Delay for LDO1 and
LDO2
Programmable Delay to Buck1
Programmable Delay for Buck2
Programmable Delay for Buck3
Programmable Delay for NRST
Time
5
15
20
25
60
Units
ms
ms
ms
ms
ms
Power Off Timing
The timing delays during a power off sequence are equal to 63 ms minus the timing delay during the power on
sequence.
Symbol
T1
T2
T3
T4
T5
Description
Programmable delay for LDO1 and LDO2
Programmable delay to Buck1
Programmable delay for Buck2
Programmable delay for Buck3
Programmable delay for NRST
Time
58
48
43
38
3
Units
ms
ms
ms
ms
ms
Transitioning from Standby to Active Mode (Power Up) Battery Power Present Only
When only battery power is present and the battery voltage V_BATT > V_BATTLOW, the LP3913 is waiting for one of
three valid wakeup signals. The first is the ONOFF pin. The second and third wakeups are the Wall Adapter and
USBPWR. The ONOFF pin is factory programmable wakeup source. It can be a rising edge, a falling edge, a
level high, or a level low event. Regardless of the mode, the signal requires a 32 ms deglitch time. A deglitched
version of the ONOFF pin is output on the open-drain output pin ONSTAT. ONOFF is usually connected to a
push button. Asserting the ONOFF pin starts the power on sequencer. This enables the DC/DC converters
including the Buck1 DC/DC converter that supplies power to the system processor. The system processor then
needs to set bit D4 (PACK bit) in the Power On Event Register through the I²C interface or apply a logic high to
the POWERACK pin to keep the LP3913 in the Active mode. These serve as a Power Acknowledgment,
confirming the power on request initiated by the ONOFF pin. If neither the PACK bit (D4) in the PON register or
the POWERACK pin is set within 128 ms (max) of the start of the power-up sequencer, then the LP3913 will
automatically turn off, as the system failed to acknowledge the power on request. Connecting the battery will be
considered a Power on event. However hot insertion of the battery with the adapter connected is NOT permitted.
Copyright © 2006–2013, Texas Instruments Incorporated
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