PCM1789-Q1

SBAS546

– MARCH 2011

www.ti.com

PRODUCT OVERVIEW

The PCM1789-Q1 is a high-performance stereo DAC targeted for consumer audio applications such as Blu-ray

Disc players and DVD players, as well as home multi-channel audio applications (such as home theater and A/V

receivers). The PCM1789-Q1 consists of a two-channel DAC. The DAC output type is fixed with a differential

configuration. The PCM1789-Q1 supports 16-/20-/24-/32-bit linear PCM input data in I2S and left-justified audio

formats, and 24-bit linear PCM input data in right-justified and DSP formats with various sampling frequencies

from 8 kHz to 192 kHz. The PCM1789-Q1 offers three modes for device control: two-wire I2C software,

three-wire SPI software, and hardware.

ANALOG OUTPUTS

The PCM1789-Q1 includes a two-channel DAC, with a pair of differential voltage outputs pins. The full-scale

output voltage is (1.6

× VCC1) VPP in differential output mode. A dc-coupled load is allowed in addition to an

ac-coupled load, if the load resistance conforms to the specification. These balanced outputs are each capable of

driving 0.8 VCC1 (4 VPP) typical into a 5-kΩ ac-coupled or 15-kΩ dc-coupled load with VCC1 = +5 V. The internal

output amplifiers for VOUTL and VOUTR are biased to the dc common voltage, equal to 0.5 VCC1.

The output amplifiers include an RC continuous-time filter that helps to reduce the out-of-band noise energy

present at the DAC outputs as a result of the noise shaping characteristics of the PCM1789-Q1 delta-sigma (

ΔΣ)

DACs. The frequency response of this filter is shown in the Analog Filter Characteristic (Figure 10) of the Typical

Characteristics. By itself, this filter is not enough to attenuate the out-of-band noise to an acceptable level for

most applications. An external low-pass filter is required to provide sufficient out-of-band noise rejection. Further

discussion of DAC post-filter circuits is provided in the Application Information section.

VOLTAGE REFERENCE VCOM

The PCM1789-Q1 includes a pin for the common-mode voltage output, VCOM. This pin should be connected to

the analog ground via a decoupling capacitor. This pin can also be used to bias external high-impedance circuits,

if they are required.

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