Pre-Production
WM8904
POWER CONSUMPTION
The WM8904 power consumption is dependent on many parameters. Most significantly, it depends
on supply voltages, sample rates, mode of operation, and output loading.
The power consumption on each supply rail varies approximately with the square of the voltage.
Power consumption is greater at fast sample rates than at slower ones. When the digital audio
interface is operating in Master mode, the DBVDD current is significantly greater than in Slave mode.
(Note also that power savings can be made by using MCLK as the BCLK source in Slave mode.) The
output load conditions (impedance, capacitance and inductance) can also impact significantly on the
device power consumption.
COMMON TEST CONDITIONS
Unless otherwise stated, the following test conditions apply throughout the following sections:
Ambient temperature = +25°C
Audio signal = quiescent (zero amplitude)
Sample rate = 48kHz
MCLK = 12.288MHz
Audio interface mode = Slave (LRCLK_DIR=0, BCLK_DIR=0)
SYSCLK_SRC = 0 (system clock comes direct from MCLK, not from FLL)
Additional, variant test conditions are quoted within the relevant sections below. Where applicable,
power dissipated in the headphone or line loads is included.
POWER CONSUMPTION MEASUREMENTS
Single-ended Stereo Line Record - IN1L/R, IN2L/R or IN3L/R pins to ADC output.
Test conditions:
L_MODE = R_MODE = 00b (Single ended)
LIN_VOL = RIN_VOL = 00101 = +0.0 dB
ADC_OSR128 = 0 (64*fs), ADC_128_OSR_TST_MODE = 1, ADC_BIASx1P5 = 1
MICBIAS = disabled
Variant test conditions
AVDD
DCVDD
DBVDD
CPVDD
MICVDD
TOTAL
mW
V
mA
4.38
4.25
4.41
V
mA
0.80
0.14
0.80
V
mA
0.02
0.00
0.03
V
mA
0.01
0.01
0.01
V
mA
0.01
0.01
0.01
48kHz sample rate
8kHz sample rate
1.80
1.80
1.80
1.00
1.00
1.00
1.80
1.80
1.80
1.80
1.80
1.80
1.80
1.80
1.80
8.72
7.81
48kHz -6dBV sine wave
8.81
Differential Stereo Record from Analogue Microphones - IN1L/R, IN2L/R or IN3L/R pins to ADC out.
Test conditions:
L_MODE = R_MODE = 10b (Differential mic)
LIN_VOL = RIN_VOL = 00111 = +30.0 dB
ADC_OSR128 = 0 (64*fs), ADC_128_OSR_TST_MODE = 1, ADC_BIASx1P5 = 1
MICBIAS_ENA = 1, MICBIAS_SEL = 000, No load connected to MICBIAS
Variant test conditions
AVDD
DCVDD
DBVDD
CPVDD
MICVDD
TOTAL
mW
V
mA
4.38
4.25
4.39
V
mA
0.80
0.14
0.81
V
mA
0.02
0.00
0.03
V
mA
0.01
0.01
0.01
V
mA
0.01
0.01
0.01
48kHz sample rate
8kHz sample rate
1.80
1.80
1.80
1.00
1.00
1.00
1.80
1.80
1.80
1.80
1.80
1.80
1.80
1.80
1.80
8.73
7.81
48kHz -30dBV sine wave
8.78
PP, Rev 3.3, September 2012
21
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
