Pre-Production
WM8904
APPLICATIONS INFORMATION
RECOMMENDED EXTERNAL COMPONENTS
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
REQUIRED
VALUE
PART NUMBER
VOLTAGE
TYPE
SIZE
CAPACITANCE
C14 (CPCA-CPCB)
C15 (CPVOUTN)
C16 (CPVOUTP)
1F at 2VDC
2.2F
2.2F
4.7F
Kemet C0402C225M9PAC
MuRata GRM188R61A225KE34D
MuRata GRM155R60J475M_EIA
6.3v
10v
X5R
X5R
X5R
0402
0603
0402
2F at 2VDC
6.3v
Table 95 Charge Pump Capacitors
PP, Rev 3.3, September 2012
181
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
