WM8781 Datasheet, PDF (15/20 Pages) Wolfson Microelectronics plc – 24-Bit, 192kHz Stereo ADC

Production Data
WM8781
Test Conditions
AVDD = 5V, DVDD = 3.3V, AGND = DGND = 0V, TA = +25°C
PARAMETER
SYMBOL
TEST CONDITIONS
Power Supply Input Timing Information
DVDD level to activate POR –
power on
Vpora
Measured from DGND
AVDD level to activate POR –
power on
Vpora
Measured from AGND
VMID level to activate POR –
power on
Vpora
Measured from AGND
DVDD level to release POR –
Vporr
power on (see notes 1 and 2)
Measured from DGND
AVDD level to release POR –
Vporr
power on (see notes 1 and 2)
Measured from AGND
VMID level to release POR –
Vporr
power on (see notes 1 and 2)
Measured from AGND
POR active period (see notes 1
tpor
and 2)
Measured from POR active to
POR release
DVDD level to activate POR –
power off (see note 5)
AVDD level to activate POR –
power off (see note 5)
VMID level to activate POR –
power off (see note 5)
Power on - POR propagation
delay through device
Power down - POR propagation
delay through device
Vpor_off
Vpor_off
Vpor_off
tpon
tpoff
Measured from DGND
Measured from AGND
Measured from AGND
Measured from rising EDGE of
POR
Measured from falling EDGE of
POR
MIN
30
(note 6)
TYP
MAX
0.7
0.7
0.7
DVDD Min
AVDD Min
1
Defined by DVDD/AVDD/
VMID Rise Time
0.8
0.8
0.7
30
30
UNIT
V
V
V
V
V
V
µs
V
V
V
µs
µs
Notes:
1. POR is activated when DVDD or AVDD or VMID reach their stated Vpora level (Figure 10).
2. POR is only released when DVDD and AVDD and VMID have all reached their stated Vporr levels (Figure 10).
3. The rate of rise of VMID depends on the rate of rise of AVDD, the internal 50kΩ resistance and the external decoupling
capacitor. Typical tolerance of 50K resistor can be taken as +/-20%.
4. If AVDD, DVDD or VMID suffer a brown-out (i.e. drop below the minimum recommended operating level but do not go
below Vpor_off,), then the chip will not reset and will resume normal operation when the voltage is back to the
recommended level again.
5. The chip will enter reset at power down when AVDD or DVDD or VMID falls below Vpor_off. This may be important if the
supply is turned on and off frequently by a power management system.
6. The minimum tpor period is maintained even if DVDD, AVDD and VMID have zero rise time. This specification is
guaranteed by design rather than test.
w
PD, April 2006, Rev 4.1
15