WM8912 データシートの表示（PDF） - Cirrus Logic

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WM8912

Ultra Low Power DAC with Headphone Driver for Portable Audio Applications

Cirrus Logic 

WM8912

APPLICATIONS INFORMATION

RECOMMENDED EXTERNAL COMPONENTS

Production Data

Figure 56 Recommended External Components

Notes:

1. Decoupling Capacitors

X5R ceramic capacitor is recommended for capacitors C7, C8, C13, C14, C15, C17 and C18.

The positioning of C7 is very important - this should be as close to the WM8912 as possible.

Capacitors C17 and C18 should also be positioned as close to the WM8912 as possible.

2. Charge Pump Capacitors

Specific recommendations for C12, C17 and C18 are provided in Table 66. Note that two different recommendations are

provided for C17 and C18; either of these components is suitable, depending upon size requirements and availability.

The positioning of C12 is very important - this should be as close to the WM8912 as possible.

It is important to select a suitable capacitor type for the Charge Pump. Note that the capacitance may vary with DC voltage;

care is required to ensure that required capacitance is achieved at the applicable operating voltage, as specified in Table 66.

The capacitor datasheet should be consulted for this information.

COMPONENT

C12 (CPCA-CPCB)

C17 (CPVOUTP)

C18 (CPVOUTN)

REQUIRED

CAPACITANCE

 1F at 2VDC

 2F at 2VDC

Table 66 Charge Pump Capacitors

VALUE

2.2F

2.2F

4.7F

PART NUMBER

VOLTAGE TYPE

Kemet C0402C225M9PAC

6.3v

X5R

MuRata GRM188R61A225KE34D

10v

X5R

MuRata GRM155R60J475M_EIA

6.3v

X5R

SIZE

0402

0603

0402

3. ZOBEL NETWORKS

The Zobel network shown in Figure 56 is required on HPOUTL, HPOUTR, LINEOUTL and LINEOUTR whenever that output is

enabled. Stability of these ground-referenced outputs across all process corners cannot be guaranteed without the Zobel

network components. (Note that, if any ground-referenced output pin is not required, the zobel network components can be

omitted from the output pin, and the pin can be left floating.) The Zobel network requirement is detailed further in the

applications note WAN_0212 “Class W Headphone Impedance Compensation”.

Zobel networks (C9, C10, C11, C16, R3, R4, R5, R6) should be positioned reasonably close to the WM8912.

w

PD, Rev 4.1, February 2013

126

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