WM8904 データシートの表示（PDF） - Wolfson Microelectronics plc

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WM8904

Ultra Low Power CODEC for Portable Audio Applications

Wolfson Microelectronics plc 

Pre-Production

APPLICATIONS INFORMATION

RECOMMENDED EXTERNAL COMPONENTS

WM8904

Figure 71 Recommended External Components

Notes:

1. Decoupling Capacitors

X5R ceramic capacitor is recommended for capacitors C1, C2, C3, C4, C5, C15, C16, C17 and C18.

The positioning of C17 and C18 is very important - these should be as close to the WM8904 as possible.

Capacitors C15 and C16 should also be positioned as close to the WM8904 as possible.

2. Charge Pump Capacitors

Specific recommendations for C14, C15 and C16 are provided in Table 95. Note that two different recommendations are

provided for C15 and C16; either of these components is suitable, depending upon size requirements and availability.

The positioning of C14 is very important - this should be as close to the WM8904 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 95.

The capacitor datasheet should be consulted for this information.

COMPONENT

C14 (CPCA-CPCB)

C15 (CPVOUTN)

C16 (CPVOUTP)

REQUIRED

CAPACITANCE

 1F at 2VDC

 2F at 2VDC

Table 95 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

w

PP, Rev 3.3, September 2012

181

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