WM8321 datasheet(136/253 Pages) WOLFSON

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WM8321

Production Data

PD, February 2012, Rev 4.0

136

26 TEMPERATURE SENSING

The WM8321 provides temperature monitoring as status information and also for self-protection of the

device. Temperature monitoring is always enabled in the ON and SLEEP states.

The thermal warning temperature can be set using the THW_TEMP register field. The thermal

warning hysteresis ensures that the THW_TEMP is not reset until the device temperature has

dropped below the threshold by a suitable margin. The extent of the hysteresis can be selected using

the THW_HYST register field.

The Thermal Warning condition can be read using the THW_STS register bit. An overtemperature

condition causes the thermal warning interrupt (TEMP_THW_CINT) to be set. The thermal warning

interrupt is also set when the overtemperature condition clears, ie. when the device has returned to its

normal operating limits.

The thermal shutdown temperature is set at a fixed level. If a thermal shutdown condition is detected

whilst in the ON or SLEEP states, then a System Reset is triggered, as described in Section 24.1,

forcing a transition to the OFF state.

The temperature sensing circuit is configured and monitored using the register fields described in

Table 81.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R16386

(4002h)

THW_HYST

Thermal Warning hysteresis

0 = 8 degrees C

1 = 16 degrees C

1:0

THW_TEMP

[1:0]

Thermal Warning temperature

00 = 90 degrees C

01 = 100 degrees C

10 = 110 degrees C

11 = 120 degrees C

R16397

(400Dh)

THW_STS

Thermal Warning status

0 = Normal

1 = Overtemperature Warning

(warning temperature is set by THW_TEMP)

Table 81 Temperature Sensing Control

The thermal warning interrupt event is indicated by the TEMP_THW_CINT register field. This

secondary interrupt triggers a primary Thermal Interrupt, TEMP_INT (see Section 23). This can be

masked by setting the mask bit as described in Table 82.

ADDRESS

BIT

LABEL

DESCRIPTION

R16401

(4011h)

Interrupt Status

TEMP_THW_CINT

Thermal Warning interrupt

(Rising and Falling Edge triggered)

Note: Cleared when a ‘1’ is written.

R16410

(4019h)

Interrupt Status

1 Mask

IM_TEMP_THW_CINT

Interrupt mask.

0 = Do not mask interrupt.

1 = Mask interrupt.

Default value is 1 (masked)

Table 82 Thermal Interrupts

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