DS641F4

9

CS8421

Pin Name

#

Pin Description

VD

1

Digital Power

(Input) - Digital core power supply. Typically +2.5 V.

GND

2

Ground

(Input) - Ground for I/O and core logic.

RST

3

Reset

(Input) - When RST is low, the CS8421 enters a low-power mode and all internal states are

reset. On initial power-up, RST must be held low untilthe power supply is stable and all input clocks

are stable in frequency and phase.

BYPASS

4

Sample Rate Converter Bypass

(Input) - When BYPASS is high, the sample-rate converter will be

bypassed, and any data input through the serial audio input port will be directly output on the serial

audio output port. When BYPASS is low, the sample rate converter will operate normally.

ILRCK

5

Serial Audio Input Left/Right Clock

(Input/Output) - Word-rate clock for the audio data on the

SDIN pin.

ISCLK

6

Serial Audio Bit Clock

(Input/Output) - Serial-bit clock for audio data on the SDIN pin.

SDIN

7

Serial Audio Input Data Port

(Input) - Audio data serial input pin.

MCLK_OUT

8

Master Clock Output

(Output) - Buffered and level-shifted output for Master clock. If MCLK_OUT

is not required, this pin should be pulled high through a 47 kΩ resistor to turn the output off. See

“Master Clock” on page 21.

TDM_IN

9

Serial Audio TDM Input

(Input) - Time Division Multiplexing serial audio data input. Grounded

when not used. See “Time Division Multiplexing (TDM) Mode” on page 22.

SDOUT

10

Serial Audio Output Data Port

(Output) - Audio data serial output pin. Optionally this pin may be

pulled low through a 47 kΩ resistor, but should not be pulled high.

OSCLK

11

Serial Audio Bit Clock

(Input/Output) - Serial bit clock for audio data on the SDOUT pin.

OLRCK

12

Serial Audio Input Left/Right Clock

(Input/Output) - Word rate clock for the audio data on the

SDOUT pin.

MS_SEL

13

Master/Slave Select

(Input) - Used to select Master or Slave for the input and output serial audio

ports at startup and reset. See Table 1 on page 19 for settings.

GND

14

Ground

(Input) - Ground for I/O and core logic.

VL

15

Logic Power

(Input) - Input/Output power supply. Typically +3.3 V or +5.0 V.

SAOF

16

Serial Audio Output Format Select

(Input) - Used to select the serial audio output format at star-

tup and reset. See Table 3 on page 19 for format settings.

SAIF

17

Serial Audio Input Format Select

(Input) - Used to select the serial audio input format at startup

and reset. See Table 2 on page 19 for format settings.

SRC_UNLOCK

18

SRC Unlock Indicator

(Output) - Indicates when the SRC is unlocked. See “SRC Locking and

Varispeed” on page 20.

XTO

19

Crystal Out

(Output) - Crystal output for Master clock. See “Master Clock” on page 21.

XTI

20

Crystal/Oscillator In

(Input) - Crystal or digital clock input for Master clock. See “Master Clock” on

page 21.

Thermal Pad

-

Thermal Pad

- Thermal relief pad for optimized heat dissipation. This pad must be electrically con-

nected to GND. See “Power Supply, Grounding, and PCB Layout” on page 24 for more information.