WM8351 datasheet(112/330 Pages) WOLFSON

112 / 330 page

WM8351

Production Data

PD, April 2012, Rev 4.5

112

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R6 (06h)

Interface

Control

USE_DEV_

PINS

Selects which pins to use for the 2-wire

control:

0 = Use 2-wire I/F pins as 2-wire interface

1 = Use GPIO 10 and 11 as 2-wire interface,

e.g. to download settings from PIC.

Only applies when CONFIG pins[1:0] = 00.

14:13

DEV_ADDR

[1:0]

Selects device address (only valid when

CONF_STS = 00)

00 = 0x34

01 = 0x36

10 = 0x3C

11 = 0x3E

Note:

In custom modes (CONF[1:0]≠00), the secondary control interface is never used and the

control bits described here have no effect.

Table 62 Control Interface Switching in Development Mode

14.4.2

STARTING UP IN DEVELOPMENT MODE

In Development mode, the GPIO1 pin is configured as a DO_CONF output (see Section 20), which is

asserted high to indicate that the WM8351 is about to start up. This may be used to trigger the ‘genie’

to configure the WM8351 via the secondary control interface.

Figure 65 Configuration Timing in Development Mode

On completion of the register configuration, the power-up sequence is initiated by writing a logic 1 to

the CONFIG_DONE bit. If the CONFIG_DONE bit is not set before the maximum set-up time has

elapsed (see Figure 65), then the WM8351 will revert to the OFF state.

An alternative implementation is to start up the WM8351 by setting CONFIG_DONE to ‘1’ without first

programming the converter/LDO settings. By this method, the rising edge of the /RST signal may be

used to trigger the WM8351 configuration process after the device has entered the ACTIVE state. In

this case, the DC-DC converters and LDOs turn on immediately when they are enabled (time slots are

no longer relevant because the WM8351 is already in the ACTIVE state). To reduce in-rush current,

any configuration sequence triggered by /RST should therefore include supply staggering in software

(i.e. time delays between powering up individual supply domains).

Note that, whether using DO_CONF or /RST to trigger configuration, the on-chip watchdog imposes a

time-out for configuration; if the WM8351 watchdog is not serviced, it restarts the system. This can be

prevented, if necessary, by disabling the watchdog.

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