Wolfson WM8978, Manual, Page: 12 / 119

WM8978
Production Data
w
PD, Rev 4.5, October 2011
12
POWER CONSUMPTION
Typical current consumption for various scenarios is shown below.
MODE AVDD
(3.0V)
(mA)
DCVDD
(1.8V)
(mA)
DBVDD
1
(3.0V)
(mA)
TOTAL
POWER
(mW)
Off 0.04
3
0.0008 <0.0001 0.12
Sleep (VREF maintained, no clocks) 0.04 0.0008 <0.0001 0.12
Stereo Record (8kHz)
2
4.1 1.0 0.001 14.1
Stereo 16 Ω HP Playback (44.1kHz, quiescent)
2
3.3 6.2 0.004 21.1
Stereo 16 Ω HP Playback (44.1kHz, white noise)
2
5.4 7.3 0.004 29.4
Stereo 16 Ω HP Playback (44.1kHz, sine wave)
2
18 6.7 0.004 66.1
Notes:
1. DBVDD Current will increase with greater loading on digital I/O pins.
2. 5 Band EQ is enabled.
3. AVDD standby current will fall to nearer 15uA when thermal shutdown sensor is disabled.
Table 1 Power Consumption
ESTIMATING SUPPLY CURRENT
When either the DAC or ADC is enabled approximately 7mA will be drawn from DCVDD when
DCVDD=1.8V and fs=48kHz. When the PLL is enabled approximately 1.5mA additional current will
be drawn from DCVDD.
As a general rule, digital supply currents will scale in proportion to sample rates. Supply current for
analogue and digital blocks will also be lower at lower supply voltages.
Power consumed by the output drivers will depend greatly on the signal characteristics. A quiet
signal, or a signal with long periods of silence will consume less power than a signal which is
continuously loud.
Estimated supply current for the analogue blocks is shown in Table 2. Note that power dissipated in
the load is not shown.