wm8351 Wolfson Microelectronics plc, wm8351 Datasheet - Page 108

• Manufacturer Part Number: wm8351
• Description: Wolfson Audioplus? Stereo Codec With Power Management
• Manufacturer: Wolfson Microelectronics plc

WM8351
w
R39 (27h)
Comparator
Interrupt
Status Mask
Table 55 Wake-Up Interrupts
14.3.2
The WM8351 power supply blocks can be commanded to start up according to a defined sequence
when the WM8351 is commanded into the ACTIVE state. This sequence comprises fourteen
timeslots, where the enabling of each DC-DC converter, LDO voltage regulator and the current limit
switch is associated with one timeslot. In order to minimise supply in-rush current at power-up time,
the start-up of these power supply blocks should be staggered in time by the use of this feature.
The WM8351 proceeds from one time slot to the next after a delay of approximately 1.28ms,
provided that all power supply blocks started up in the current time slot (if any) have reached 90% of
their programmed output voltage. See Section 14.3.4 for details of the WM8351 behaviour if any
power supply block fails to achieve 90% of its programmed output voltage.
14.3.3
The WM8351 goes from ACTIVE or HIBERNATE to the OFF state when a shutdown event occurs.
Shutdown events include:
•
•
•
•
•
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As part of the start-up sequence, the CHIP_ON bit is set to 1. The software shutdown is commanded
by writing 0 to the CHIP_ON register field as described in Table 56.
ADDRESS
Software shutdown (setting CHIP_ON = 0)
A trigger signal on a GPIO pin configured as PWR_OFF lasting more than 40ms. The active
polarity of this input is set by GPn_CFG for the applicable GPIO pin (see Section 20).
A trigger signal on the ON pin lasting more than 10 seconds. The active polarity of this input is
set by the register field ON_POL. If required, the de-bounce time can be set to 5 seconds using
the ON_DEB_T register bit.
Watchdog time-out (see Section 23) after 7 previous faults.
Fault conditions programmed to trigger a shutdown (see Section 18).
Thermal shutdown (see Section 25)
SHUTDOWN
POWER-UP SEQUENCING
BIT
6:0
2
1
0
WKUP_GP_PWR_ON_EINT
WKUP_ONKEY_EINT
WKUP_GP_WAKEUP_EINT
“IM_” + name of respective
bit in R31
LABEL
PWR_ON (Alternate GPIO function) pin
has been pressed for longer than
specified time.
(Rising Edge triggered)
Note: This bit is cleared once read.
ON key has been pressed for longer than
specified time.
(Rising Edge triggered)
Note: This bit is cleared once read.
has been pressed for longer than
specified time.
(Rising Edge triggered)
Note: This bit is cleared once read.
Interrupt mask.
0 = Do not mask interrupt.
1 = Mask interrupt.
Each bit in R39 enables or masks the
corresponding bit in R31. The default
value for these bits is 0 (unmasked).
WAKEUP (Alternate GPIO function) pin
DESCRIPTION
PD, June 2009, Rev 4.1
Production Data
108