wm8982gefl-v Wolfson Microelectronics plc, wm8982gefl-v Datasheet - Page 17

• Manufacturer Part Number: wm8982gefl-v
• Description: Mono Codec With Speaker Driver And Video Buffer
• Manufacturer: Wolfson Microelectronics plc

Pre-Production
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Figure 8 Typical Power up Sequence where DVDD is Powered before AVDD
Figure 8 shows a typical power-up sequence where DVDD comes up first. First it is assumed that
DVDD is already up to specified operating voltage. When AVDD goes above the minimum threshold,
V
in reset. In this condition, all writes to the control interface are ignored. When AVDD rises to V
PORB is released high and all registers are in their default state and writes to the control interface
may take place.
On power down, where DVDD falls first, PORB is asserted low whenever DVDD drops below the
minimum threshold V
Table 2 Typical POR operation (simulated values)
Notes:
If AVDD and DVDD suffer a brown-out (i.e. drop below the minimum recommended operating level
but do not go below V
when the voltage is back to the recommended level again.
The chip will enter reset at power down when AVDD or DVDD falls below V
may be important if the supply is turned on and off frequently by a power management system.
The minimum t
specification is guaranteed by design rather than test.
pora
SYMBOL
V
V
V
V
V
pora_on
pora_off
pord_on
pord_off
, there is enough voltage for the circuit to guarantee PORB is asserted low and the chip is held
pora
MIN
0.4
0.9
0.4
0.5
0.4
por
period is maintained even if DVDD and AVDD have zero rise time. This
pord_off
pora_off
TYP
0.6
1.2
0.6
0.7
0.6
.
or V
pord_off
MAX
0.8
1.6
0.8
0.9
0.8
) then the chip will not reset and will resume normal operation
UNIT
V
V
V
V
V
PP, Rev 3.2, September 2008
pora_off
or V
WM8982
pord_off
pora_on
. This
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