Manual

DS566F1 15

CS4351

4. APPLICATIONS

4.1 Sample Rate Range/Operational Mode Detect

The device operates in one of three operational modes. The allowed sample rate range in each mode will

depend on whether the Auto-Detect Defeat bit is enabled/disabled.

4.1.1 Auto-Detect Enabled

The Auto-Detect feature is enabled by default. In this state, the CS4351 will auto-detect the correct mode

when the input sample rate (F

), defined by the LRCK frequency, falls within one of the ranges illustrated

in Table 1. Sample rates outside the specified range for each mode are not supported.

4.1.2 Auto-Detect Disabled

The Auto-Detect feature can be defeated only by the format bits in the control port register 02h. In this

state, the CS4351 will not auto-detect the correct mode based on the input sample rate (F

). The opera-

tional mode must then be set manually according to one of the ranges illustrated in Table 2. Please refer

to Section 6.2.3 for implementation details. Sample rates outside the specified range for each mode are

not supported. In stand-alone mode it is not possible to disable auto-detect of sample rates.

4.2 System Clocking

The device requires external generation of the master (MCLK), left/right (LRCK) and serial (SCLK) clocks.

The left/right clock, defined also as the input sample rate (F

), must be synchronously derived from the

MCLK according to specified ratios. The specified ratios of MCLK to LRCK, along with several standard au-

dio sample rates and the required MCLK frequency, are illustrated in Tables 3 through 5.

Refer to Section 4.3 for the required SCLK timing associated with the selected Digital Interface Format and

to the “Switching Specifications - Serial Audio Interface” section on page 10 for the maximum allowed clock

frequencies.

Input Sample Rate (F

)MODE

4 kHz - 50 kHz Single-Speed Mode

84 kHz - 100 kHz Double-Speed Mode

170 kHz - 200 kHz Quad-Speed Mode

Table 1. CS4351 Auto-Detect

FM1 FM0 Input Sample Rate (F

)MODE

0 0 Auto speed mode detect Auto

0 1 4 kHz - 50 kHz Single-Speed Mode

1 0 50 kHz - 100 kHz Double-Speed Mode

1 1 100 kHz - 200 kHz Quad-Speed Mode

Table 2. CS4351 Mode Select