WM8980CGEFL/RV WOLFSON [Wolfson Microelectronics plc], WM8980CGEFL/RV Datasheet - Page 20

• Manufacturer Part Number: WM8980CGEFL/RV
• Description: Stereo CODEC with Speaker Driver and Video Buffer
• Manufacturer: WOLFSON [Wolfson Microelectronics plc]

WM8980
Figure 8 Typical Power up Sequence where DVDD is Powered before AVDD
w
Table 3 Typical POR Operation (typical values, not tested)
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
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
Notes:
1.
2.
3.
pora
SYMBOL
V
V
V
V
V
, there is enough voltage for the circuit to guarantee PORB is asserted low and the chip is held in
pora_on
pora_off
pord_on
pord_off
If AVDD and DVDD suffer a brown-out (i.e. drop below the minimum recommended operating
level but do not go below V
operation 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
MIN
0.4
0.9
0.4
0.5
0.4
por
pord_off
period is maintained even if DVDD and AVDD have zero rise time. This
TYP
0.6
1.2
0.6
0.7
0.6
.
pora_off
MAX
0.8
1.6
0.8
0.9
0.8
or V
pord_off
UNIT
V
V
V
V
V
) then the chip will not reset and will resume normal
PP, Rev 3.8, May 2012
pora_off
or V
Pre-Production
pord_off
pora_on
. This
,
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