WM8912
Production Data
APPLICATIONS INFORMATION
RECOMMENDED EXTERNAL COMPONENTS
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
REQUIRED
VALUE
PART NUMBER
VOLTAGE
TYPE
SIZE
CAPACITANCE
C12 (CPCA-CPCB)
C17 (CPVOUTP)
C18 (CPVOUTN)
≥ 1μF at 2VDC
2.2μF
2.2μF
4.7μF
Kemet C0402C225M9PAC
MuRata GRM188R61A225KE34D
MuRata GRM155R60J475M_EIA
6.3v
10v
X5R
X5R
X5R
0402
0603
0402
≥ 2μF at 2VDC
6.3v
Table 66 Charge Pump Capacitors
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.
PD, Rev 4.0, September 2010
w
126
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
