CS47L35 datasheet(224/300 Pages) CIRRUS

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DS1085F3

CS47L35

4.22 Power-On Reset (POR)

4.21.2 Short Circuit Protection

The short-circuit detection function for the Class D speaker outputs is triggered when the respective output drivers are

enabled (see Table 4-64). If a short circuit is detected at this time, the enable does not succeed, and the respective output

driver is not enabled.

The Class D speaker short-circuit detection provides inputs to the interrupt control circuit and can be used to trigger an

interrupt event; see Section 4.15. If the Class D speaker short-circuit condition is detected, the respective drivers are

automatically disabled in order to protect the device. When the speaker driver shutdown is complete, a further interrupt,

SPK_SHUTDOWN_EINTn, is asserted.

To enable the Class D speaker outputs following a short-circuit detection, the host processor must disable and reenable

the output drivers. Note that the short-circuit status bits are always cleared when the drivers are disabled.

The short-circuit detection function for the headphone and earpiece output paths operates continuously if the respective

output driver is enabled. If a short circuit is detected on the headphone or earpiece output, current limiting is applied to

protect the respective output driver. Note that the driver continues to operate, but the output is current-limited.

The headphone and earpiece short-circuit detection functions provide input to the interrupt control circuit and can be used

to trigger an interrupt event when a short-circuit condition is detected; see Section 4.15.

4.21.3 Timer-Controlled Speaker Shutdown

The general-purpose timers (see Section 4.5.3) can also be used to trigger a shutdown of the Class D speaker drivers.

This is configured using the SPK_SHUTDOWN_TIMER_SEL field, as described in Table 4-114.

If one of the general-purpose timers is selected for the speaker shutdown function, and the respective timer reaches its

final count value, the Class D speaker drivers are automatically disabled. When the driver shutdown is complete, an

interrupt event (SPK_SHUTDOWN_EINTn) is signaled.

To enable the Class D speaker outputs following a timeout condition, the host processor must disable and reenable the

output drivers.

4.21.4 GPIO Output

The thermal status, Class D speaker short-circuit protection, and Class D speaker shutdown flags can be output directly

on a GPIO pin as an external indication of the associated events. See Section 4.14 to configure a GPIO pin for this

function.

4.22 Power-On Reset (POR)

The CS47L35 remains in the reset state until AVDD, DBVDD1, and DCVDD are above their respective reset thresholds.

Note that specified device performance is not assured outside the voltage ranges defined in Table 3-3.

After the initial power-up, the POR is rescheduled following an interruption to the DBVDD1 or AVDD supplies.

If the CS47L35 SLIMbus component is in its operational state, it must be reset before scheduling a POR. See Section 4.10

for details of the SLIMbus reset control messages.

Table 4-114. Speaker Shutdown—Timer Control

Bit

Label

Default

Description

R620 (0x026D)

SPK_Watchdog_1

3:0

SPK_

SHUTDOWN_

TIMER_SEL[3:0]

0x0

Speaker Shutdown Timer select. Unlisted codes are reserved

0x0 = Disabled

0x1 = Timer 1

0x2 = Timer 2

0x3 = Timer 3

0x4 = Timer 4

All other codes are reserved

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