WM8940_11 Datasheet, PDF (68/91 Pages) Wolfson Microelectronics plc – Mono CODEC with Speaker Driver

WM8940
Production Data
POWER MANAGEMENT
VMID
The analogue circuitry will not work when VMID is disabled (VMIDSEL[1:0] = 00b). The impedance of
the VMID resistor string, together with the decoupling capacitor on the VMID pin will determine the
start-up time of the VMID circuit.
REGISTER
ADDRESS
R1
Power
management 1
BIT LABEL DEFAULT
DESCRIPTION
1:0 VMIDSEL 00
Reference string impedance to VMID pin
(determines startup time):
00=off (open circuit)
01=50kΩ
10=250kΩ
11=5kΩ (for fastest startup)
Table 57 VMID Impedance Control
BIASEN
REGISTER
ADDRESS
R1
Power
management 1
BIT LABEL DEFAULT
DESCRIPTION
3
BIASEN 0
Analogue amplifier bias control
0=Disabled
1=Enabled
Table 58 BIASEN Control
ESTIMATED SUPPLY CURRENTS
When either the DAC or ADC are enabled it is estimated that approximately 4mA will be drawn from
DCVDD when fs=48kHz (This will be lower at lower sample rates). When the PLL is enabled an
additional 700 microamps will be drawn from DCVDD.
Table 59 shows the estimated 3.3V AVDD current drawn by various circuits, by register bit.
REGISTER BIT
MONOEN
PLLEN
MICBEN
BIASEN
BUFIOEN
VMIDSEL
BOOSTEN
INPPGAEN
ADCEN
MONOEN
SPKPEN
SPKNEN
MONOMIXEN
SPKMIXEN
DACEN
AVDD CURRENT (MILLIAMPS)
0.2mA
1.4mA (with clocks applied)
0.5mA
0.3mA
0.1mA
10K=>0.3mA, less than 0.1mA for 100k/500k
0.2mA
0.2mA
2.6mA
0.2mA
1mA from SPKVDD
1mA from SPKVDD
0.2mA
0.2mA
1.8mA
Table 59 AVDD Supply Current
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PD, Rev 4.3, November 2011
68