WM8311 datasheet(102/302 Pages) WOLFSON

102 / 302 page

WM8311

Pre-Production

PP, May 2012, Rev 3.1

102

When the Current Sinks output drive is enabled or disabled using CS1_DRIVE or CS2_DRIVE, the

current ramps up or down at a programmable rate. The ramp durations are programmed using the

and the Current Sinks, then the following switch-off sequence may be used:



Disable Boost Converter (DC4_ENA = 0)



Disable Current Sink and Current Drive (CSn_ENA = 0; CSn_DRIVE = 0)

When the Current Sinks are enabled, the status of each is indicated using the CSn_STS bits. If the

Current Sinks are unable to sink the demanded current (eg. if the power source is too low or if the

load is open circuit), then the respective CSn_STS bit will be set to 1. When the Current Sink circuit is

correctly regulated, then the respective CSn_STS bits are set to 0.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R16462

(404Eh)

Current Sink 1

CS1_ENA

Current Sink 1 Enable (ISINK1 pin)

0 = Disabled

1 = Enabled

Note - this bit is reset to 0 when the OFF

power state is entered.

CS1_DRIVE

Current Sink 1 output drive enable

0 = Disabled

1 = Enabled

CS1_STS

Current Sink 1 status

0 = Normal

1 = Sink current cannot be regulated

CS1_SLPENA

Current Sink 1 SLEEP Enable

0 = Disabled

1 = Controlled by CS1_ENA

R16463

(404Fh)

Current Sink 2

CS2_ENA

Current Sink 2 Enable (ISINK2 pin)

0 = Disabled

1 = Enabled

Note - this bit is reset to 0 when the OFF

power state is entered.

CS2_DRIVE

Current Sink 2 output drive enable

0 = Disabled

1 = Enabled

CS2_STS

Current Sink 2 status

0 = Normal

1 = Sink current cannot be regulated

CS2_SLPENA

Current Sink 2 SLEEP Enable

0 = Disabled

1 = Controlled by CS2_ENA

Table 48 Enabling ISINK1 and ISINK2

16.2.2 PROGRAMMING THE SINK CURRENT

The sink currents for ISINK1 and ISINK2 can be independently programmed by writing to the

CS1_ISEL and CS2_ISEL register bits. The current steps are logarithmic to match the logarithmic

light sensitivity characteristic of the human eye. The step size is 1.51dB (i.e. the current doubles

every four steps).

Note that the maximum programmable sink current is 27.6mA. The maximum current that can be

supported by the DC-DC4 Boost Converter varies with the output voltage; the maximum ISINK current

that can be supported by the Boost Converter will depend upon the forward voltage required by the

current sink load(s).

WM8311 Datasheet(PDF) 102 Page - Wolfson Microelectronics plc

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