MAX98357 Module

MAX98357 I2S 5V 3W Audio Amplifier Amp

Class D Digital Audio Music Amplifier Amplificator DAC Decoder 4-8 Ohm Speaker Raspberry Pi Arduino ESP32

     The MAX98357 Module is a single channel (mono) Class D amplifier board that receives audio digitally over the I2S bus, converts it to analog internally and drives a speaker directly. It measures 18mm x 19mm and weighs approximately 3gr. It operates from 2.5V - 5.5V; at 5V it delivers up to 3.2W into a 4Ω speaker and up to 1.8W into an 8Ω speaker. No separate DAC or preamplifier is needed: digital audio from a controller with an I2S output goes straight to the speaker.

     The board has 7 pins - LRC, BCLK, DIN, GAIN, SD, GND and Vin - and a place for a 2 pin speaker terminal block. Only 3 lines (LRC, BCLK, DIN) carry the audio data; no separate master clock (MCLK) is required. Sample rates from 8kHz to 96kHz are supported. Gain is selected with the GAIN pin connection as 3dB, 6dB, 9dB, 12dB or 15dB; with the pin left open the gain is 9dB. The SD pin shuts the amplifier down and selects which channel is played (left, right or left+right mix).

     A 1MΩ (105) resistor on the board connects SD to Vin; at 5V the board plays the mix of the left and right channels from one speaker by default. For stereo sound two modules are used, one set to the left and one to the right channel. The output is filterless and drives the speaker in bridge-tied (BTL) mode; it suits small speaker audio devices, internet radios and projects that give notification sounds.

Key features:

     Digital audio input (I2S): Audio arrives digitally from the controller and is converted to analog inside the module, so there is no noise or hum picked up on an analog cable. No separate DAC board is needed.

     3.2W from a small board: The 18mm x 19mm board delivers up to 3.2W into 4Ω and 1.8W into 8Ω at 5V. Thanks to its Class D design it is efficient (92% at 1W into 8Ω, chip value); it runs cool and needs no heatsink.

     Adjustable gain: The GAIN pin gives 9dB when open; connecting it to Vin or GND directly or through 100kΩ selects 3dB, 6dB, 12dB and 15dB. No software setting is needed.

     Channel select and shutdown: The voltage on the SD pin selects left, right or mixed channel; pulling SD to GND shuts the amplifier down. Two modules make a stereo system.

     Wide supply range: Operates from 2.5V - 5.5V; the I2S pins accept 3.3V and 5V logic. A 5V supply is recommended for the highest output power.

Features:

• Product type: I2S digital input mono Class D amplifier module
• Chip: MAX98357A
• Operating voltage: DC 2.5V - 5.5V
• Output power (5V, 10% THD): 3.2W at 4Ω, 1.8W at 8Ω
• Output power (3.3V, 10% THD): approximately 1.3W at 4Ω, approximately 0.8W at 8Ω
• Audio input: I2S digital (LRC, BCLK, DIN); no MCLK required
• Sample rate: 8kHz - 96kHz
• Channel: Mono (left, right or left+right mix selected with the SD pin)
• Gain: 3dB / 6dB / 9dB / 12dB / 15dB (GAIN pin; 9dB when open)
• Speaker impedance: 4Ω - 8Ω (do not use below 4Ω)
• Output stage: Filterless Class D, bridge-tied (BTL) output
• Logic level: 3.3V and 5V compatible
• Current: up to 650mA at full power at 5V
• Protection: Short circuit and over temperature protection (on chip)
• Efficiency: 92% (8Ω, 1W output, chip value)
• Pins: LRC, BCLK, DIN, GAIN, SD, GND, Vin (7 pins, 2.54mm pitch) + speaker terminal place (- / +)
• Mounting: 2 mounting holes on the board
• Color: Purple board
• Dimensions: 18mm x 19mm
• Weight: approximately 3gr

Usage information:

• Connect Vin to 5V (2.5V - 5.5V) and GND to ground. Connect LRC to the I2S word clock (WS / LRCLK) pin of the controller, BCLK to the bit clock pin and DIN to the I2S data output.
• Connect the two speaker wires to the + and - outputs of the board. The terminal block and pin header come unsoldered; solder them to the board before use.
• Default gain is 9dB. If the sound is too low connect GAIN to GND (12dB), if it distorts connect it to Vin (6dB); power cycle the board after changing the gain.
• For stereo, connect the LRC, BCLK and DIN pins of the two modules together; with the resistor on the SD pin set one to the left and the other to the right channel.

Application areas:

•  Internet radio and wireless speaker
•  Voice assistant and voice command devices
•  MP3 / music player and sound box
•  Doorbell and notification sound devices
•  Talking toys and sound games
•  Announcement, warning and alarm systems
•  Talking robots and moving figures
•  Measuring devices with voice menu and warnings
•  Education and STEM audio projects

Precautions:

•  The speaker output is bridge-tied (BTL). Do not connect the speaker - wire to GND and do not connect the output to another amplifier input or to headphones; drive a speaker only.
•  Do not use speakers below 4Ω. Speaker power rating should be at least the output power (3W or more for 4Ω).
•  It draws up to 650mA at full power at 5V; use a supply that can deliver at least 800mA. A weak supply distorts the sound at high volume.
•  The supply must not exceed 5.5V. At 3.3V the output drops to approximately 1.3W at 4Ω; use 5V for loud sound.
•  This module does not accept analog audio input (AUX, 3.5mm jack); it only takes I2S digital audio. Make sure your controller has an I2S output.

Package contents:

•  1 Piece MAX98357 Module
•  1 Piece 7 pin male pin header (unsoldered)
•  1 Piece 2 pin terminal block (unsoldered)
•  Note: Speaker and controller board are not included in the package.