WM8944BECSSLASHR datasheet(62/165 Pages) CIRRUS

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WM8944B

Rev 4.3

LDO_VSEL [4:0]

LDO OUTPUT

LDO_VSEL [4:0]

LDO OUTPUT

00h

Vref x 1.42

10h

Vref x 2.85

01h

Vref x 1.50

11h

Vref x 3.00

02h

Vref x 1.58

12h

Vref x 3.16

03h

Vref x 1.66

13h

Vref x 3.32

04h

Vref x 1.74

14h

Vref x 3.49

05h

Vref x 1.82

15h

Vref x 3.63

06h

Vref x 1.90

16h

Vref x 3.79

07h

Vref x 1.97

17h

Vref x 3.95

08h

Vref x 2.06

18h

Vref x 4.12

09h

Vref x 2.13

19h

Vref x 4.28

0Ah

Vref x 2.21

1Ah

Vref x 4.42

0Bh

Vref x 2.29

1Bh

Vref x 4.58

0Ch

Vref x 2.37

1Ch

Vref x 4.75

0Dh

Vref x 2.45

1Dh

Vref x 4.90

0Eh

Vref x 2.53

1Eh

Vref x 5.06

0Fh

Vref x 2.69

1Fh

Vref x 5.23

Note

– Vref is the applicable voltage reference, selected by LDO_REF_SEL.

Table 38 LDO Output Voltage Control

BG_VSEL [4:0]

BG VOLTAGE (V)

BG_VSEL [4:0]

BG VOLTAGE (V)

00h

1.200

08h

1.414

01h

1.227

09h

1.440

02h

1.253

0Ah

1.467

03h

1.280

0Bh

1.494

04h

1.307

0Ch

1.520

05h

1.334

0Dh

1.547

06h

1.360

0Eh

1.574

07h

1.387

0Fh

1.600

Table 39 Bandgap Voltage Control

REFERENCE VOLTAGES AND MASTER BIAS

This section describes the analogue reference voltage and bias current controls. It also describes the

VMID soft-start circuit for pop suppressed start-up and shut-down.

The analogue circuits in the WM8944B require a mid-rail analogue reference voltage, VMID. This

reference is generated via a programmable resistor chain. Together with the external decoupling

capacitor (connected to the VMIDC pin), the programmable resistor chain results in a slow, normal or

fast charging characteristic on the VMID reference. This is enabled using VMID_ENA and VMID_SEL.

The different resistor options controlled by VMID_SEL can be used to optimize the reference for

normal operation, low power standby or for fast start-up as described in Table 40.

The VMID resistor chain can be powered from the LDO output (LDOVOUT) or from the LDO supply

(LDOVDD). This is selected using VMID_REF_SEL.

Note that when VMID is selected as the LDO reference voltage, VMID cannot be generated from the

LDOVOUT supply voltage (VMID_REF_SEL = 1) and must be generated from the LDOVDD supply

voltage (VMID_REF_SEL = 0).

The VMID ratio can be selected using VMID_CTRL. This selects the ratio of VMID to the supply

voltage that has been selected by VMID_REF_SEL. VMID should be half of the LDOVOUT supply

voltage for maximum voltage swing. In the case where VMID_REF_SEL has selected the LDOVOUT

supply voltage

, then VMID_CTRL should select the ratio “1/2”. In the case where VMID_REF_SEL

WM8944BECS/R 数据表(PDF) 62 Page - Cirrus Logic

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