WM8350GEB/V Wolfson Microelectronics, WM8350GEB/V Datasheet - Page 191

• Manufacturer Part Number: WM8350GEB/V
• Description: Audio CODECs Audio CODEC plus pwr management
• Manufacturer: Wolfson Microelectronics

Specifications of WM8350GEB/V

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Production Data
21 VOLTAGE REFERENCES
21.1 MAIN REFERENCE (VREF)
21.2 LOW-POWER REFERENCE
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The WM8350 generates several reference voltages used for different purposes.
The main reference voltage VREF, and additional internal references derived from it, are used in the
DC-DC converters, the LDO regulators and the auxiliary ADC. VREF is highly stable, accurate, and
independent of the supply voltage. It can be trimmed for improved accuracy.
The VRTC regulator (see Section 17.6) uses a separate, low-power reference at start-up.
The mid-rail reference VMID is used in the audio CODEC. It is generated from AVDD.
Each reference voltage is internally provided to those parts of the WM8350 where it is needed.
The main reference generates a highly accurate reference voltage VREF. It requires a decoupling
capacitor on the CREF pin; a 2.2uF X5R capacitor is recommended, as noted in Section 29.2; and
an accurate resistor on the RREF pin; a 100kΩ (1%) resistor is recommended, as noted in
Section 29.2.
The WM8350 will malfunction if those components are omitted.
The accuracy of supply voltages generated by the WM8350 depends on VREF, and can be improved
by trimming. This scales VREF by up to +15/-16% in 1% steps, to compensate for deviations from
the nominal value.
The main reference can be overdriven with an externally generated reference voltage, if desired.
The low-power reference determines the accuracy of VRTC on start-up. Once the main bandgap has
been trimmed and has settled VRTC switches across to the main bandgap for greater accuracy.
PD, March 2010, Rev 4.2
WM8350
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