FEATURES

Fully Differential Input-to-Output Architecture

Digitally Controlled Gain Using Serial Port

Interface:

? Gain Range: 10dB through 65dB, 1dB per

step

? Unity (0dB) Gain Setting via Serial Port or

Dedicated Control Pin

Dynamic Performance:

? Equivalent Input Noise with ZS = 150Ω and

Gain = 30dB: ?128dBu

? Total Harmonic Distortion plus Noise

(THD+N) with Gain = 30dB: 0.0004%

Zero Crossing Detection Minimizes Audible

Artifacts when Gain Switching

Integrated DC Servo Minimizes Output Offset

Voltage

Common-Mode Servo Improves CMRR

Four-Wire Serial Control Port Interface:

? Simple Interface to Microprocessor or

DSP Serial Ports

? Supports Daisy-Chaining of Multiple

PGA2500 Devices

Dedicated Input Pin for Selecting Unity Gain

Overload Output Pin Provides Clipping

Indication

Four General-Purpose Digital Output Pins

Requires ±5V Power Supplies

Available in an SSOP-28 Package

APPLICATIONS

Microphone Preamplifiers and Mixers

Digital Mixers and Recorders

DESCRIPTION

The PGA2500 is a digitally controlled, analog microphone

preamplifier designed for use as a front end for highperformance

audio analog-to-digital converters (ADCs). The

PGA2500 features include low noise, wide dynamic range,

and a differential signal path. An on-chip DC servo loop is

employed to minimize DC offset, while a common-mode

servo function may be used to enhance common-mode

rejection.

The PGA2500 features a gain range of 10dB through 65dB

(1dB/step), along with a unity gain setting. The wide gain

range allows the PGA2500 to be used with a variety of

microphones. Gain settings and internal functions are

programmed using a 16-bit control word, which is loaded

using a simple serial port interface. A serial data output pin

provides support for daisy-chained connection of multiple

PGA2500 devices. Four programmable digital outputs are

provided for controlling the external switching of input pads,

phantom power, high pass filters, and polarity reversal

functions. The PGA2500 requires both +5V and ?5V power

supplies and is available in a small SSOP-28 package.