The PGA2500 is a digitally controlled, analog microphone preamplifier designed for use as a front end for highperformance audio analog-to-digital (A/D) converters. 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.

• 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 Noise with ZS = 150 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

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