Power Supply

FMT1

Advanced

Segment

DAC

Modulator

Bias

and

Vref

´ 8

Oversampling

Digital

Filter

and

Function

Control

Audio

Data Input

I/F

LRCK

BCK

DATA

DEM

RST

Current

Segment

DAC

IREF

Function

Control

I/F

Zero

Detect

ZERO

System

Clock

Manager

FMT0

MUTE

Current

Segment

DAC

MONO

CHSL

VCOML

VCOMR

IOUTL+

IOUTL–

I/V and Filter

VOUTL

IOUTR+

IOUTR–

I/V and Filter

VOUTR

PCM1798

www.ti.com

SLES102B – DECEMBER 2003 – REVISED MARCH 2015

7 Detailed Description

7.1 Overview

The PCM1798 is a 24-bit, 192-kHz, differential current output DAC that comes in a 28-pin SSOP package. The

PCM1798 is a hardware controlled and utilizes the advanced segment DAC architecture from TI in order to

perform with a Stereo Dynamic Range of 123 dB (126 dB Mono) and SNR of 123 dB (126 dB Mono) with a THD

of 0.0005%. The PCM1798 will use the SCK input as its system clock and automatically detect the sampling rate

of the Digital Audio input and has a high tolerance for clock jitter. The internal filter can be bypassed to allow for

an external digital filter to be used.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 System Clock and Reset Functions

7.3.1.1 System Clock Input

The PCM1798 requires a system clock for operating the digital interpolation filters and advanced segment DAC

modulators. The system clock is applied at the SCK input (pin 7). The PCM1798 has a system clock detection

circuit that automatically senses the frequency at which the system clock is operating. Table 1 shows examples

of system clock frequencies for common audio sampling rates.

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Product Folder Links: PCM1798