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MAX98357A I²S 3 W Amp

ET-A21

MAX98357A I²S 3 W Amp

Digital audio straight to a speaker — no DAC needed

AED 19.00

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Download datasheet (PDF)

OverviewKey featuresSpecificationsPerformancePinout

Overview

Digital audio straight to a speaker — no DAC needed

The ET-A21 is built around the Maxim MAX98357A — I²S DAC + class-D amp, 3.2W into 4Ω at 5V, filterless, click/pop suppression. It talks over I2S / left-justified / TDM, 8–96kHz, no MCLK needed and runs from 2.5–5.5V.

Designed in Dubai by ElectroTrical — the full schematic, BOM and design notes are published below.

Good for

  • ESPHome voice assistants
  • Sound effects and alarms
  • Internet radio

Key features

What makes it different

Amplifier

Maxim MAX98357A: I²S DAC + class-D amp, 3.2W into 4Ω at 5V, filterless, click/pop suppression

Interface

I2S / left-justified / TDM, 8–96kHz, no MCLK needed

Supply

2.5–5.5V

Output

Bridge-tied speaker 4–8Ω on a screw terminal (don't ground either side)

Open documentation

Schematic, BOM and layout notes published for every board.

Breadboard friendly

Standard 2.54 mm pitch and M2.5 mounting holes.

Specifications

Technical specifications

Device
AmplifierMaxim MAX98357A: I²S DAC + class-D amp, 3.2W into 4Ω at 5V, filterless, click/pop suppression
InterfaceI2S / left-justified / TDM, 8–96kHz, no MCLK needed
Supply2.5–5.5V
OutputBridge-tied speaker 4–8Ω on a screw terminal (don't ground either side)
Board
Size25.4 × 17.8 mm
Mounting4 × M2.5 holes, 2.54 mm from each corner
Connectors7-pin 2.54 mm header · Screw terminal 2P 5.0mm 17A (THT) — Speaker 4–8Ω
Main ICMAX98357AETE+T (LCSC C910544)
RevisionRev A
Software
LibrariesESP32 I2S / ESP-ADF, ESPHome i2s_audio speaker, CircuitPython audiobusio, Raspberry Pi hifiberry-dac overlay
Solder jumpers
JP1 (default Open)3-way: GAIN to VIN (6dB) / open (9dB) / GND (12dB)

Performance

Output

Maximum output power at 5 VFrom the MAX98357A datasheet.

Pinout

Pin map and connections

MAX98357A I²S 3 W Amp pinout: VIN, GND, BCLK, LRC, DIN, SD, GAIN
PinNameTypeFunction
1VINPower2.5–5.5V (5V for 3W)
2GNDGroundGround
3BCLKControlI²S bit clock
4LRCSignalI²S word select
5DINSPII²S data
6SDSignalLow = shutdown; float/1M = mono mix
7GAINSignalFloat = 9dB · GND = 12dB · VIN = 6dB (or JP1)

Mechanical

Dimensions and what's in the box

Board 25.4 × 17.8 mm with M2.5 holes
Top view · 25.4 × 17.8 mm

In the box

  • 1 × ET-A21 MAX98357A I²S 3 W Amp (assembled)
  • 1 × 7-pin 2.54 mm male header, unsoldered

Getting started

  • Wire the header: VIN, GND, BCLK, LRC, DIN, SD
  • Libraries: ESP32 I2S / ESP-ADF, ESPHome i2s_audio speaker, CircuitPython audiobusio, Raspberry Pi hifiberry-dac overlay

Compare

Which audio board?

MAX98357A I²S 3 W Amp (this board)This boardET-S73 MAX9814 AGC MicrophoneET-S47 ICS-43434 I²S MEMS Microphone
What it doesDigital audio straight to a speaker — no DAC neededMicrophone amplifier with automatic gain, analog out24-bit digital microphone for ESP32 and Pi
InterfaceI2S / left-justified / TDM, 8–96kHz, no MCLK…Analog audio out (DC-biased) to any ADCStandard I2S (Philips), slave: host provides…
Best forESPHome voice assistantsSound-reactive LEDsVoice and audio capture on ESP32
Price19 AED25 AED22 AED

Downloads

Documents and design files

PDFET-A21 schematicRev ALCSCMAX98357AETE+T datasheet and stockC910544
STEP3D modelComing soon

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