TAS5012

SLES006A – SEPTEMBER 2001 – REVISED DECEMBER 2001

6

www.ti.com

functional description (continued)

digital interpolation filter

The 24-bit high-performance linear phase FIR interpolation filter up-samples the input digital data at a rate of two

times (quad speed mode = 176.4 kHz or 192 kHz), four times (double speed mode = 88.2 kHz or 96 kHz), or eight

times (normal mode = 32 kHz, 44.1 kHz, or 48 kHz) the incoming sample rate. This filter provides very low pass-band

ripple and optimized time domain transient response for accurate music reproduction.

digital PWM modulator

The interpolation filter output is sent to the modulator. This modulator consists of a high performance fourth order

digital noise shaper and a PCM-to-PWM converter. Following the noise shaper, the PCM signal is fed into a very low

distortion PCM-to-PWM conversion block, buffered, and output from the chip. The modulation scheme is based on

a 2-state control of the H-bridge output.

control, status, and operational modes

The TAS5012 control section consists of several control-input pins. Three serial mode pins (MOD0, MOD1, and

MOD2) are provided to select various serial data formats. During normal operating conditions if any of the MOD0,

MOD1, or MOD2 pins changes state, a reset sequence is initiated. Also provided are separate power-down (PDN),

reset (RESET), and mute (MUTE) pins.

power up

At power up the VALID_L and VALID_R pins are asserted low and the PWM outputs go to the hard mute state in which

the P outputs are held low and the M outputs are held high. Following initialization, the TAS5012 comes up in the

operational state (differential PWM audio). There are two cases of power-up timing. The first case is shown in Figure 1

with RESET preceding PDN. The second case is shown in Figure 2 with PDN preceding RESET.

Initialization Time = 100 ms max

RESET

PDN

VALID_L

VALID_R

Figure 1. Power-Up Timing (RESET Preceding PDN)

Initialization Time = 5 ms max

RESET

PDN

Greater Than 16 MCLK Periods

VALID_L

VALID_R

Figure 2. Power-Up Timing (PDN Preceding RESET)