WM8311 datasheet(98/302 Pages) WOLFSON

98 / 302 page

WM8311

Pre-Production

PP, May 2012, Rev 3.1

Typical Connections

The typical connections to DC-DC Converter 1 are illustrated in Figure 20. The equivalent circuit

applies to DC-DC Converters 2 and 3 also.

The input voltage connection to DC-DC Converters 1, 2 and 3 is provided on DC1VDD, DC2VDD and

DC3VDD respectively; these are typically connected to the SYSVDD voltage node. Note that the

internal supply pins PVDD1 and PVDD2 must be connected to the same supply voltage as the DC-

DC Converters (ie. SYSVDD).

Figure 20 DC-DC Synchronous Buck Converter Connections

The recommended output capacitor COUT varies according to the required transient response. Note

that the DCm_CAP register field must be set according to the output capacitance on each DC-DC

Converter in order to achieve best performance.

In the case of DC-DC1 and DC-DC2, the recommended inductor component varies according to the

DCm_FREQ register field. This register supports a choice of different switching frequencies.

See Section 30.3 for details of specific recommended external components.

15.15.3 DC-DC STEP UP CONVERTER

DC-DC Converter 4 is a step-up DC-DC Converter designed to deliver high power efficiency across

full load conditions. It is designed to provide a voltage which is determined by the selected current of

either Current Sink 1 or Current Sink 2 through an external load - typically a string of LEDs.

DC-DC Converter 4 is designed with fixed frequency current mode architecture. The clock frequency

is set by an internal RC oscillator, which provides a 1MHz clock.

The typical connections to DC-DC Converter 4 are illustrated in Figure 21. The DC4_FBSRC register

field can select either ISINK1 or ISINK2 as input to the feedback circuit.

The input voltage connection, DC4VDD, is typically connected to the SYSVDD voltage node. Note

that the internal supply pins PVDD1 and PVDD2 should also be connected to SYSVDD.

WM8311 датащи(PDF) 98 Page - Wolfson Microelectronics plc