CS4525 datasheet(44/98 Pages) CIRRUS

44 / 98 page

DS726PP1

CS4525

6.1.6

Serial Audio Delay & Warning Input Port

The CS4525 includes a configurable delay and warning port to allow easy system integration of external

lip-sync delay devices or warning inputs from external amplifiers. The port can be configured as a serial

audio delay interface, an external warning input port, or disabled by the DlyPortCfg[1:0] bits in the Aux

Config register. When disabled, the DLY_SDOUT and DLY_SDIN/EX_TWR pins become high-imped-

ance.

6.1.6.1

Serial Audio Delay Interface

Video processing and reproduction circuitry in digital video display devices can often introduce noticeably

more delay than is introduced by the device’s audio processing and reproduction circuitry. This can result

in a phenomenon known as lip-synch delay - a delay present between the video and audio content being

reproduced.

To help overcome this problem, the CS4525 delay and warning port can be configured as serial audio

delay interface. This interface consists of a serial audio input/output port to facilitate the use of an external

serial audio delay device. The port routes the serial data from the selected input source (the ADC or the

serial input port) out to an external serial audio delay device, and then back in to the CS4525 internal dig-

ital sound processing blocks. The delay serial audio interface signals include DLY_SDOUT and

DLY_SDIN/EX_TWR and are clocked from AUX_LRCK and AUX_SCLK. The serial data is output on the

DLY_SDOUT pin and input on the DLY_SDIN/EX_TWR in the format specified by the AuxI²S/LJ bits in

the Aux Config register. Because the delay interface uses the auxiliary port clock signals, the auxiliary se-

rial port must be enabled using the EnAuxPort bit in the Aux Port Configuration register to allow the delay

interface to operate properly.

6.1.6.2

External Warning Input Port

When implementing external PWM power stage devices with thermal warning indicator outputs, it can be

useful to provide these warning signals as an input to the internal thermal foldback algorithm. This allows

the CS4525 to automatically respond to the external devices’ thermal warning conditions without com-

pletely disrupting the system’s operation.

When configured as an external warning input port, the DLY_SDIN/EX_TWR is an active-low thermal

warning input to the foldback algorithm and the DLY_SDOUT pin becomes high-impedance.

In order for the foldback algorithm to act on the external thermal warning input signal, the thermal foldback

algorithm must be enabled by the EnTherm bit in the Foldback Cfg register. See “Thermal Foldback” on

page 40 for more information.

Referenced Control

DlyPortCfg........................... “Delay & Warning Port Configuration (DlyPortCfg[1:0])” on page 72

Referenced Control

AuxI²S/LJ............................. “Aux/Delay Serial Port Digital Interface Format (AuxI²S/LJ)” on page 72

EnAuxPort ........................... “Enable Aux Serial Port (EnAuxPort)” on page 72

Referenced Control

EnTherm ............................. “Enable Thermal Foldback (EnTherm)” on page 74

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