wm8400 Wolfson Microelectronics plc, wm8400 Datasheet - Page 154

• Manufacturer Part Number: wm8400
• Description: Wolfson Audioplustm Hi-fi Audio Codec And Power Management Unit For Mobile Multimedia
• Manufacturer: Wolfson Microelectronics plc

WM8400
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DEVICE SHUTDOWN
The WM8400 can be programmed to initiate a device shutdown in response to selected
overtemperature or undervoltage conditions. These conditions are referenced in Table 93, Table 97
and Table 100. Setting the applicable _ERRACT register bits detailed in these tables will cause a
device shutdown to be initiated if the corresponding condition occurs.
A device shutdown is performed in the event of a CDELAY error condition (see “Power Sequencing
and Control”). A CDELAY error condition will occur if the CDELAY pin is shorted to GND or if an
unsuitable CDELAY capacitor is connected. Suitable CDELAY components are detailed in the
“Applications Information” section.
The WM8400 will also initiate a device shutdown in response to a logic low level on the NPDN pin
(referenced to the HBVDD power domain) or by setting the Register bit CHIP_SOFTSD. Either of
these events will command the WM8400 to execute a ‘soft shutdown’, where the CODEC and Power
Management functions are disabled in a controlled manner, avoiding audio pops and other
undesirable effects. The definition of CHIP_SOFTSD is provided in Table 101.
Following a Shutdown caused by setting CHIP_SOFTSD, the chip will ignore the status of the NPDN
pin until it has been restored to a logic low level. Therefore, re-starting the chip following a
CHIP_SOFTST requires NPDN to be toggled low and then high again.
Table 101 Chip Soft Shutdown
When a Shutdown has been initiated, the cause of this shutdown can be read from Register R82
(52h), as described in Table 102. Note that register read/write operations are still supported following
shutdown, provided that NPDN remains asserted.
R76 (4Ch)
R82 (52h)
REGISTER
REGISTER
ADDRESS
ADDRESS
BIT
BIT
13
13
11
10
9
8
7
6
5
4
CHIP_SOFTSD
SDR_CHIP_SOFTS
D
SDR_NPDN
SDR_CDEL_TO
SDR_CHIP_GT150
SDR_CHIP_GT115
SDR_LINE_CMP
SDR_UVLO
SDR_DC2_UV
SDR_DC1_UV
LABEL
LABEL
DEFAULT
0b
DEFAULT
0b
0b
0b
0b
0b
0b
0b
0b
0b
CHIP_SOFTSD shutdown status
0 = Disabled
1 = Enabled
NPDN shutdown status
0 = Disabled
1 = Enabled
CDELAY time shutdown status
0 = Disabled
1 = Enabled
Temperature Level 2 shutdown status
0 = Disabled
1 = Enabled
Temperature Level 1 shutdown status
0 = Disabled
1 = Enabled
Battery Comparator shutdown status
0 = Disabled
1 = Enabled
UVLO shutdown status
0 = Disabled
1 = Enabled
DC2 Undervoltage shutdown status
0 = Disabled
1 = Enabled
DC1 Undervoltage shutdown status
Chip Soft Shutdown Sequence
0 = Disabled
1 = Enabled
DESCRIPTION
DESCRIPTION
PP, April 2009, Rev 3.0
Pre-Production
154