TAS5001

SLES009A – SEPTEMBER 2001 – REVISED DECEMBER 2001

7

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functional description (continued)

reset

The reset signal for the TAS5001 must be applied whenever toggling the M_S, DBSPD signal. This reset is

asynchronous. See Figure 3 for reset timing. To initiate the reset sequence the RESET pin is asserted low. As

long as the pin is held low the chip is in the reset state. During this reset time the PWM outputs are hard-muted

(P-outputs held low and M-outputs held high) and the PWM outputs valid pins (VALID_L. VALID_R) are held

low. Assuming PDN is high, the rising edge of the reset pulse begins chip initialization. After the initialization

time, the TAS5001 begins normal operation.

Initialization

Normal

Operation

RESET

PDN

Normal Operation

5 ms max

VALID_L

VALID_R

Figure 3. Reset Timing

power down

When PDN is low (see Figure 4), both the PLL and the oscillator are shut down. Note that power down is an

asynchronous operation. To place the device in total power-down mode, both RESET and PDN must be held

low. As long as these pins are held low, the chip is in the power-down state and the PWM outputs are hard muted

with the P outputs held low and the M outputs held high. To place the device back into normal mode, see the

power up section.

NOTE:In order for the dynamic logic to be properly powered down, the clocks should not be stopped

before the PDN pin goes low. Otherwise, the device may drain additional supply current.

Initialization

Chip

Power-Down

PDN and RESET

Normal Operation

Normal

Operation

VALID

Figure 4. Power-Down Timing

mute

The TAS5001 provides a mute function that is used when the MUTE pin is asserted low. See Table 2 for mute

description. This mute is a quiet mute; that is, the mute is accomplished by outputting a zero value waveform

in which both sides of the differential PWM outputs have a 50% duty cycle (see Figure 5 for mute timing).

Table 2. Mute Description

MUTE

PWM_P

PWM_M

DESCRIPTION

0

50% duty cycle

50% duty cycle

Mute

1

DATA

DATA

Normal operation