wm8351 Wolfson Microelectronics plc, wm8351 Datasheet - Page 324

• Manufacturer Part Number: wm8351
• Description: Wolfson Audioplus? Stereo Codec With Power Management
• Manufacturer: Wolfson Microelectronics plc

WM8351
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29.3.3
USB mode is selected by setting DC2_FBSRC[1:0] = 11 as described in Section 14.6.4. This mode
generates a 5V output, suitable for USB interfaces. The recommended connections to the DC-DC
(Step-Up) Converter in this mode are illustrated in Figure 91.
Figure 91 DC-DC (Step-Up) Converter External Components - USB Mode
In the USB mode, the DC-DC (Step-Up) Converter uses an internal resistor chain to control the
output voltage. This results in a fixed 5V output, suitable for USB interfaces.
The DC-DC (Step-Up) Converter may be configured as USB OTG supplement by setting
USB_MSTR = 1 as described in Section 17.4. (The DC-DC Converter USB mode must also be
selected by setting DC2_FBSRC[1:0] = 11). The output of the DC-DC Converter should be
connected to the USB pin in order to provide voltage feedback.
The choice of Capacitors, Inductor and FET in constant current mode is the same as for the constant
voltage mode; see Section 29.3.4 for specific recommended component details.
29.3.4
Wolfson recommends the following external components for use with DC-DC Converter 2. Note that
the choice of output capacitor should be determined as described in Section 29.3.1.
Table 158 Recommended External Components - DC-DC2
COMPONENT
C
FET
C
OUT
L
IN
DC-DC (STEP-UP) CONVERTER - USB MODE
DC-DC (STEP-UP) CONVERTER RECOMMENDED COMPONENTS
VALUE
0.47μF
4.7μF
4.7μF
10μH
10μF
Taiyo Yuden NR4012T100M (0.7A)
Murata GRM21BR71E474KC01L
Murata GRM188R60J475KE19D
Murata GRM188R60J475KE19D
Murata GRM219R60J106KE19B
On Semiconductor NTHD4N02F
N-Channel FETKY
PART NUMBER
PD, June 2009, Rev 4.1
Production Data
SIZE
0805
0603
0805
0603
324