Cirrus-logic CS4353 Manuel d'utilisateur télécharger pdf (Page 17)

DS803F3 17

CS4353

4.8 Initialization

When power is first applied, the DAC enters a reset (low power) state at the beginning of the initialization

sequence. In this state, the AOUTx pins are weakly pulled to ground and VBIAS is connected to VA.

The device will remain in the reset state until the RESET

pin is brought high. Once the RESET pin is high,

the internal digital circuitry is reset and the DAC enters a power-down state until MCLK is applied. Alterna-

tively, if no external reset control is required, the internal power-on reset can be used by tying the RESET

pin to VL (see Section 4.7).

Once MCLK is valid, the device enters an initialization state in which the charge pump powers up and charg-

es the capacitors for both the positive and negative high-voltage supplies.

Once LRCK and SCLK are valid, the number of MCLK cycles is counted relative to the LRCK period to de-

termine the MCLK/LRCK frequency ratio. Next, the device enters the power-up state in which the interpo-

lation and decimation filters and delta-sigma modulators are turned on, the internal voltage reference,

VBIAS, powers up to normal operation, the analog output pull-down resistors are removed, and power is

applied to the output amplifiers.

After this power-up state sequence is complete, normal operation begins and analog output is generated.

If valid MCLK, LRCK, and SCLK are applied to the DAC before RESET

is set high, the total time from RE-

SET being set high to the analog audio output from AOUTx is less than 50 ms.

See Figure 9 for a diagram of the device’s states and transition conditions.

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Cirrus-logic CS4353 Manuel d'utilisateur Page 17