WM8948ECSSLASHR datasheet(111/189 Pages) WOLFSON

111 / 189 page

Production Data

WM8948

PD, May 2011, Rev 4.1

111

THERMAL SHUTDOWN

The WM8948 incorporates a temperature sensor which detects when the device temperature is

within normal limits. The temperature status can be read at any time from the TEMP_STS bit, as

described in Table 70. This bit can be polled at any time, or may output directly on a GPIO pin, or

may be used to generate Interrupt events.

The temperature sensor can be configured to shut down the speaker outputs in the event of an

overtemperature condition. This is configured using the THERR_ACT register field.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R17 (11h)

Status Flags

TEMP_STS

Thermal Sensor status

0 = Normal

1 = Overtemperature

R42 (2Ah)

Output ctrl

THERR_ACT

Thermal Shutdown enable

0 = Disabled

1 = Enabled

When THERR_ACT = 1, then an

overtemperature condition will

cause the speaker outputs to be

disabled.

Table 70 Thermal Shutdown Control

POWER ON RESET

The WM8948 includes a Power-On Reset (POR) circuit, which is used to reset the digital logic into a

default state after power up. The POR circuit derives its output from LDOVDD and DCVDD. The

internal POR

¯¯¯ signal is asserted low when either LDOVDD or DCVDD are below minimum thresholds.

The specific behaviour of the circuit will vary, depending on relative timing of the supply voltages.

Typical scenarios are illustrated in Figure 49 and Figure 50.

Figure 49 Power On Reset Timing – LDOVDD Enabled First

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