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3 W filter-free class-D audio power amplifier
  • active Active

The A21SP16 is a differential class-D BTL power amplifier. It is able to drive up to 2.3 W into a 4 Ω load and 1.4 W into a 8 Ω load at 5 V. It achieves outstanding efficiency (88% typ.) compared to classical Class-AB audio amps.

The gain of the device can be controlled via two external gain-setting resistors. Pop & click reduction circuitry provides low on/off switch noise while allowing the device to start within 5 ms. A standby function (active low) allows the reduction of current consumption to 10 nA typ.

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Errata Sheet
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Key Features

  • Operating from VCC = 2.4 V to 5.5 V
  • Standby mode active low
  • Output power: 3 W into 4 Ω and 1.75 W into 8 Ω with 10% THD+N max and 5 V power supply
  • Output power: 2.3 W @ 5 V or 0.75 W @ 3 V into 4 Ω with 1% THD+N max
  • Output power: 1.4 W @ 5 V or 0.45 W @ 3 V into 8 Ω with 1% THD+N max
  • Adjustable gain via external resistors
  • Low current consumption 2 mA @ 3 V
  • Efficiency: 88% typ.
  • Signal to noise ratio: 85 dB typ.
  • PSRR: 63 dB typ. @ 217 Hz with 6 dB gain
  • PWM base frequency: 250 kHz
  • Low pop & click noise
  • Thermal shutdown protection
  • Available in flip-chip 9 x 300 μm (Pb-free)

Design Resources


Technical Documentation

Product Specifications

Description Version Size
DS10233: 3 W filter-free class-D audio power amplifier
1.0 857 KB

Presentations & Training Material


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ST offering in Wearable - Analog and Mixed Signal Portfolio
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Publications and Collaterals


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Sample & Buy

Part Number Marketing StatusPackagePacking TypeOperating Temperature (min) Operating Temperature (max) Automotive GradeOrder From STUnit Price (US$)*
@ 1000
Distributor AvailabilityRoHS Compliance GradeDownload
Material Declaration**
A21SP16JActiveChip Scale Package 0.5mm pitchTape And Reel_Free Samples.4Distributor reported inventory date: 2016-02-29
Distributor NameRegionStockMin. order
ARROWOrder NowAMERICA50005000
Farnell Element14Order NowEUROPE49971

(*) Suggested Resale Price per unit (USD) for BUDGETARY USE ONLY. For quotes, prices in local currency, please contact your local ST Sales Office or our Distributors
(**) The Material Declaration forms available on may be generic documents based on the most commonly used package within a package family. For this reason, they may not be 100% accurate for a specific device. Please contact our sales support for information on specific devices.