WM8311GEB/V Wolfson Microelectronics, WM8311GEB/V Datasheet - Page 284

• Manufacturer Part Number: WM8311GEB/V
• Description: POWER MANAGEMENT SUBSYSTEM, 121BGA
• Manufacturer: Wolfson Microelectronics

Specifications of WM8311GEB/V

• Supply Voltage: 5.5V
• No. Of Step-down Dc - Dc Converters: 4
• No. Of Ldo Regulators: 7
• Digital Ic Case Style: BGA
• No. Of Pins: 121
• No. Of Regulated Outputs: 9
• Operating Temperature Range: -40°C To
• Rohs Compliant: Yes
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

WM8311
w
When selecting a suitable output inductor, the inductance value and the saturation current must be
compatible with the operating conditions of the converter.
The magnitude of the inductor current ripple is dependent on the inductor value and can be
determined by the following equation:
The inductor current is also a function of the DC-DC Converter maximum input current, which can be
determined by the following equation:
As a minimum requirement, the DC current rating should be equal to the maximum input current plus
one half of the inductor current ripple.
To be suitable for the application, the chosen inductor must have a saturation current that is higher
than the peak inductor current given by the above equation. To maximise the converter efficiency,
the inductor should also have a low DC Resistance (DCR), resulting in minimum conduction losses.
Care should also be taken to ensure that the component’s inductance is suitable at the applicable
operating temperature.
When ISINK1 or ISINK2 is used in conjunction with DC-DC Converter 4, the ISINK should always be
switched on before the DC-DC Converter is switched on. Conversely, the DC-DC Converter should
always be switched off before the ISINK is switched off.
Wolfson recommends the following external components for use with DC-DC Converter 4.
The output capacitor C
4.7μF is recommended. For 15V output, 3.3μF is recommended. For 20-30V output, 1.5μF is
recommended.
The resistors R1 and R2 must be selected according to the required output voltage - refer to the
equations above. The values quoted below are suitable for 20V output.
Table 117 Recommended External Components - DC-DC4
I
COMPONENT
schottky diode
L
=
V
FET +
C
L . F
OUT
C
R1
R2
OUT
L
IN
- V
SW
IN
OUT
VALUE
1.8MΩ
4.7μF
3.3μF
1.5μF
2.2μF
10μH
47kΩ
must be selected according to the required output voltage. For 10V output,
Multicomp MIC 0.063W 0603 1% 47K
V
V
L
F
MuRata GRM31CR71H225KA88
Murata GRM31CR61C475KA01
Murata GRM31CR71C335KA01
SW
OUT
IN
MuRata GRM188R61A5KE34
I
Taiyo-Yuden NR3015T100M
L
Phycomp 2322 7046 1805
Vishay SIA814DJ-T1-GE3
= Inductor ripple current
= Output voltage
= Input voltage
= Inductance
= Switching frequency
PART NUMBER
PP, December 2009, Rev 3.0
3 x 3 x 1.5mm
2.05 x 2.05 x
SC-70-6
0.75mm
Pre-Production
SIZE
1206
1206
1206
0603
0603
0603
284