• Features/Applications/Description
  • Key Specifications
  • Packaging/Pricing/Samples
  • Design Notes
  • Additional Resource


• True RMS response
• Wide dynamic range
• High crest factor
• Wide bandwidth
• Logarithmic output scaling
• Low cost
• Single in-line package
• Matches THAT 2180 and 2181 Series VCAs


• Meters
• Spectrum Analyzers
• Compressors
• Expanders
• Oscillators
• Psychoacoustic Modeling
• Noise Measurement

Datasheet Download
2252 Datasheet(227 kB) RMS Level Detector


The THAT 2252 integrated-circuit rms level detector is designed to convert an AC input current into a DC output voltage. The output is proportional to the log of the true rms value of the input signal.

Fabricated in a super low-noise process, the 2252 combines wide dynamic range with frequency response to beyond 20 kHz. The logarithmic output is especially convenient for audio applications requiring decibel-linear scaling. The integration time is adjustable via an external R/C pair. With some external circuitry, response to DC is also possible.

Key Specifications(see2252 datasheetfor complete specifications)

Conditions Typical Units
Dynamic Range > 80  dB
Crest Factor 1 dB error
Bandwidth 20 kHz
Output Scale Factor 6.1 mV/dB
Supply Voltage Range ± 4 ~ ± 15  V
Supply Current No signal mA

Packaging / Pricing / Samples

Model Package Order Number Pricing
Min Order
2252 No longer available  
Demo Board
No longer available
All 2252 parts areRoHS compliant.

Design Notes(as PDF files)

Design Note 00A Basic Compressor/Limiter Design (113k) 

Design Note 01A The Mathematics of Log-Based Dynamic Processors (64k)

Design Note 03 Signal Limiter for Power Amplifiers (95k)

Design Note 04 Improving Loudspeaker Signal Handling Capability (217k)

Design Note 05 A Low Parts Count, Two-Slope Compressor (78k)

Design Note 100 A Fully Adjustable Noise Gate (69k)

Design Note 102 Adjustable Ducker using the THAT 4301 (76k)

Design Note 107/111 A Simple Effective Soft-Knee Compressor / Limiter (81k)

Design Note 112 LED Bar-Graph Compression Indicator (83k)

Design Note 113 THAT4301 Gain Reduction Indicator

Design Note 114 Adaptive Attack and Release Rates using THAT RMS Detectors

Design Note 115 Fully Adjustable Compressor/Limiter (46k)

Design Note 116 Techniques for Stereo Volume Control (126k)

Design Note 117 Input Limited for ADCs (120k)

Design Note 118 High Performance Stereo AGC (90k)

Design Note 119 Wide Ranging dB Meter (177k)

Design Note 125 The “One Knob Squeezer” (90k)

Design Note 128 What’s a PTAT Temp. Coefficient, & Where Does It Come From? (64k)

Design Note 131 Dealing with the PTAT Coefficient (75k)

Design Note 132 Alternate Method of Indicating Compression (52k)

Analog Secrets Your Mother Never Told You(1528k)
Originally presented at the 123rd AES Convention, this seminar provides tips and techniques to achieve optimal performance in the analog signal path. Topics covered range from inputs (balanced line and mic level) to outputs (balanced to single-ended), and include analog signal processing (VCAs, RMS detection, and Analog Engines).

Related Products

 Voltage Controlled Amplifiers (VCAs)
THAT 2180 Series Pre-trimmed Blackmer VCAs 2180 Series Datasheet
THAT 2181 Series Trimmable Blackmer VCAs 2181 Series Datasheet
THAT 2162 Dual Pre-trimmed Blackmer VCA 2162 Datasheet
  Analog Engine® Dynamics Processors
THAT 4305 Low-cost basic Analog Engine for dual supply voltages 4305 Datasheet
THAT 4320 Low-voltage, low-power versatile Analog Engine for single supply voltages 4320 Datasheet
THAT 4315 Low-voltage, low-power basic Analog Engine for single supply voltages 4315 Datasheet
THAT 4316 Very Low-voltage, low-power basic Analog Engine for single supply voltages 4316 Datasheet

Additional Resources

2252 Device Model
Our SPICE macro models allow modeling of the important parameters of our ICs.

Harsh Environment Packaging – TT Semiconductor repackages THAT Corporation’s IC products in ruggidized plastic for the medical, aerospace, defense, and heavy industrial marketplaces.

2252 Material Data Declaration Sheet
Material Data Declaration Sheets (MDDS) disclose the hazardous materials in our integrated circuits as required by the European RoHS directive.