TAS5012

SLES006A – SEPTEMBER 2001 – REVISED DECEMBER 2001

7

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functional description (continued)

reset

The reset signal for the TAS5012 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 TAS5012 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 TAS5012 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

P OUTPUTS

M OUTPUTS

DESCRIPTION

0

50% duty cycle

50% duty cycle

Mute

1

DATA

DATA

Normal operation