MAX98357A I2S Digital Amplifier Module

1. Example Code for ESP32 Play Music via Bluetooth

Enable ESP32-E Bluetooth function, create a Bluetooth node named bluetoothAmplifier, and use a phone with Bluetooth function to connect that node to play music. Users can learn how to interface the I2S digital amplifier with an ESP32 microcontroller, configure Bluetooth on the ESP32, and connect a speaker for audio output.

2. Example Code for ESP32 Play Music from SD Card

Connect to an SD card module to play music files from an SD card using the I2S amplifier and ESP32. Users can learn how to interface the SD card module with the ESP32, scan for music files on the SD card, and control audio playback using the I2S amplifier.

API Description

The article serves as a reference for the I2S Amplifier Library for Arduino, detailing its installation, communication protocol, and key functions such as audio playback, Bluetooth control, and SD card management.

Specification

Module Parameter

Parameter	Details
MCU	MAX98357A
Operating Voltage	DC 3.3V~5V
Output Power	8Ω 1.8W / 4Ω 2.5W (at 12db)
Output Channel	single channel
Communication Interface	I2S interface
Operating Temperature	-40℃ - ＋80℃
Storage Temperature	-40℃ - ＋80℃
Dimension (Without Packaging)	18mm × 18mm/ 0.059 × 0.059

Chip Audio-relevant Parameters

VDD = 5V, VGND = 0V, GAIN_SLOT = VDD. BCLK = 3.072MHz, LRCLK = 48kHz
speaker loads (ZSPK) connected between OUTP and OUTN, ZSPK = J, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.

Parameter	Details
Sample Rate	8kHz~96kHz
THD	0.02% (f = 1kHz, POUT = 1W, TA = +25NC, ZSPK = 4I + 33FH, TQFN); 0.013% (f = 1kHz, POUT = 0.5W, TA = +25NC, ZSPK = 8I + 68FH)
Dynamic Range	105DB (A-weighted, VRMS = 2.54V, 24- or 32-bit data)
Output Noise	25FVRMS (A-weighted, 24- or 32-bit data (Note 4))
Efficiency	92% (ZSPK = 8I + 68FH, THD+N = 10%, f = 1kHz, gain = 12dB)
DAC Gain Error	1%
Frequency Response	±0.2dB
Class D Switching Frequency	330kHz
Spread Spectrum Bandwidth	±12.5kHz

Gain (relative to reference level of 2.1dBV)

GAIN_SLOT Configuration	Min	Typical	Max
GAIN_SLOT = GND through 100kΩ	14.4dB	15dB	15.6dB
GAIN_SLOT = GND	11.4dB	12dB	12.6dB
GAIN_SLOT = unconnected	8.4dB	9dB	9.6dB
GAIN_SLOT = VDD	5.4dB	6dB	6.6dB
GAIN_SLOT = VDD through 100kΩ	2.4dB	3dB	3.6dB

Product Dimension

Dimension

Pinout

Board Overview

Pin	Function	Remark
SPK-	Speaker negative	4Ω/8Ω ＜3W
VCC	Power input	DC 3.3V-5V
GND	Ground
NC	Not connected pin
SD	Turn off amplifier, adjust sound channel	Refer to 4.1.2(SD Mode Description)
GAIN	Adjust amplifier gain	Default to 9dB/Refer to 4.1.1 Gain Control Description
SPK+	Speaker positive	4Ω/8Ω ＜3W
DIN	Digital input signal
BCLK	Bit clock input	Bit Clock Input
LRC	Frame clock	Left/right clock of I2S and LJ mode. Synchronized clock in TDM mode

Special Pin Function

4.1.1 Gain Control(Gain)

Gain is 15dB when there is a 100K resistor connected between GAIN and GND
Gain is 12dB when GAIN is directly connected to GND
Gain is 9dB(Default status) when nothing is connected to GAIN
Gain is 6dB when GAIN is directly connected to VCC
Gain is 3dB when there is a 100k resistor connected between Gain and VCC

SD Mode

Turn off amplifier when SD is connected to GND(Voltage below 0.16V)
Output mix channel(Default) when the voltage on SD is between 0.16V to 0.77V, R1 resistance is 680k.
Output right channel when the voltage on SD is between 0.77V to 1.4V, R1 resistance is 330K.
Output left channel when the voltage on SD is over 1.4V, R1 resistance is 100K

Channel setting