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WTS701

Publication Release Date: May 2003

- 17 -

Revision 3.09

VFS (CODEC Synchronization Line)

The CODEC synchronization line supplies a frame synchronization signal to the internal CODEC. This

is a digital input. After receipt of a synchronization pulse, the CODEC will output data on the VDX line.

The VFS line expects an 8kHz sample rate and supports both short frame and long frame

synchronization signal.

VDX (CODEC Data Transmit Line)

The CODEC data transmit line is a digital output that places digital audio data onto the CODEC bus.

The line is in a tri-state condition until the device is due to transmit data. The data output from the VDX

line is selected by the SCOD Command. When WTS701 places data on the VDX line, it is required

that the VFS line should be in tri-state condition when another device is connected to the CODEC as

well.

7.2.7 The Analog Interface

The WTS701 provides an on-chip analog interface for audio output via an 8

Ω speaker driver or an

output buffer capable of driving a 5k

Ω load. Additionally, an analog input (AUXIN) allows an audio

signal to be fed through the WTS701 chip to either output device. The command SAUD configures the

analog path. A digitally controlled attenuator provides volume control via the SVOL command.

The following is a description of the analog pins:

AUXIN (Analog Input)

The AUXIN is an additional audio input to the WTS701. This input has a nominal 694 mV p-p level at

its minimum gain setting (0 dB) (See Table 2). Additional gain is available in 3 dB steps (controlled by

the SAUD Command) up to 9 dB. The use and equivalent circuit of the input amplifier is shown in

Figure 7. (Must be AC coupled)

Internal to the device

COUP

0.1 µF

aCCOUP

NOTE:

fCUTOFF=

Figure 7. AUXIN Input Amplifier.

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