High-Performance 56W Audio Power Amplifier - LM3875


High-Performance 56W Audio Power Amplifier


The LM3875 is a high-performance audio power amplifier capable of delivering 56W of continuous average power to an 8Ω load with 0.1% THD+N from 20Hz to 20kHz.

The performance of the LM3875, utilizing its Self Peak Instantaneous Temperature (°Ke) (SPiKe) protection circuitry, puts it in a class above discrete and hybrid amplifiers by providing an inherently, dynamically protected Safe Operating Area (SOA). SPiKe protection means that these parts are completely safeguarded at the output against overvoltage, undervoltage, overloads, caused by shorts to the supplies, thermal runaway, and instantaneous temperature peaks.

The LM3875 maintains an excellent signal-to-noise ratio of greater than 95dB(min) with a typical low noise floor of 2.0μV. It exhibits extremely low THD+N values of 0.06% at the rated output into the rated load over the audio spectrum, and provides excellent linearity with an IMD (SMPTE) typical rating of 0.004%.


  • 56W Continuous Average Output Power Into 8Ω
  • 100W Instantaneous Peak Output Power Capability
  • Signal-to-Noise Ratio >95dB (min)
  • Output Protection From A Short to Ground or to the Supplies Via Internal Current Limiting Circuitry
  • Output Over-Voltage Protection Against Transients From Inductive Loads
  • Supply Under-Voltage Protection, Not Allowing Internal Biasing to Occur When |V+| + |V−| ≤ 12V, Thus Eliminating Turn-On and Turn-Off Transients
  • 11 Lead PFM Package
  • Wide Supply Voltage Range: |V+| + |V−| = 20V to 84V

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Parametrics Compare all products in Mid/High-Power Class D Amplifiers

Max. Power to Single-Ended Load
Max. Power to Bridge Tied Load
Max. Power to Parallel Bridge Tied Load
Min. Supported Single-Ended Load
Min. Supported Bridge Tied Load
Min. Supported Parallel Bridge Tied Load
Closed/Open Loop
Max Speaker Outputs (#)
Input Type
Control Type
Analog Supply Min [V]
Analog Supply Max [V]
Power Stage Supply Min (V)
Power Stage Supply Max (V)
Operating Temperature Range (C)
Approx. Price (US$)
LM3875 LM4780
75     65    
4     4    
Open     Open    
3     2    
Analog     Analog    
Hardware     Hardware    
20     20    
94     94    
20     20    
94     94    
Catalog     Catalog    
0 to 70     -20 to 85    
3.21 | 1ku     5.52 | 1ku    
Class AB     Class AB    

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