MAX98357A I2S amplifier: specs and pinout
A mono amplifier that takes digital I2S audio (BCLK, LRCLK, DIN) and drives a speaker directly through a Class D output stage, with no separate DAC and no MCLK needed. This page covers the MAX98357A chip; the module board around it is not covered by an official document.
Specs
| Spec | Value | Source |
|---|---|---|
| Supply voltage VDD | 2.5 V to 5.5 V | source Electrical Characteristics, Supply Voltage Range (p.4); Features (p.1) |
| Output power | 3.2 W into 4 ohm at 5 V (feature-list figure); power into other loads and supplies is in the datasheet output-power table | source Features (p.1) |
| Quiescent current IDD | 2.75 mA typ, 3.35 mA max at VDD 5 V; 2.4 mA typ at VDD 3.7 V | source Electrical Characteristics (p.4) |
| Shutdown current | 0.6 uA typ, 2 uA max (SD_MODE = 0 V) | source Electrical Characteristics (p.4) |
| Digital audio input levels | VIH 1.3 V min; VIL 0.6 V max | source Electrical Characteristics (p.6-7) |
| Audio interface | MAX98357A takes I2S data (MAX98357B takes left-justified); both also accept 8-channel TDM; no MCLK required | source General Description (p.1) |
| Supported LRCLK sample rates | 8, 16, 32, 44.1, 48, 88.2 and 96 kHz only; 11.025, 12, 22.05 and 24 kHz are NOT supported | source Features (p.1); LRCLK note in the I2S/LJ operation text |
| Gain in I2S mode | 15 dB: GAIN_SLOT to GND through 100 kohm; 12 dB: GND; 9 dB: unconnected; 6 dB: VDD; 3 dB: VDD through 100 kohm | source Table 8 Gain Selection (p.28) |
| Channel select in I2S mode | SD_MODE high = left word; high through a small resistor = right word; high through a large resistor = (left + right) / 2; low = shutdown | source SD_MODE and Shutdown Operation (p.17) |
| Operating temperature | -40 C to +85 C | source Absolute Maximum Ratings (p.4) |
Power
| Value | Source | |
|---|---|---|
| Supply | VDD 2.5 V to 5.5 V single supply | source Electrical Characteristics (p.4) |
| Current | 2.75 mA quiescent at VDD 5 V (speaker current not included) | source Electrical Characteristics (p.4) |
Chip pins
These are the pins of the chip on the module, from the chip datasheet. The module's own header may label or expose them differently.
Rows are the chip's TQFN-16 pins. The module board (header order and labels, which pins it brings out, any resistor on SD_MODE or GAIN_SLOT) is not covered by an official document, so check the printed labels on your board.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| DIN | Digital input signal (I2S data) | VIH 1.3 V min, VIL 0.6 V max | TQFN pin 1 | source Pin Description (p.15); Electrical Characteristics (p.6-7) |
| GAIN_SLOT | Gain select in I2S mode (Table 8); channel select with SD_MODE in TDM mode | TQFN pin 2 | source Pin Description (p.15); Table 8 (p.28) | |
| SD_MODE | Shutdown and channel select | Low = shutdown | TQFN pin 4 | source Pin Description (p.15); SD_MODE section (p.17) |
| VDD | Power-supply input | 2.5-5.5 V | TQFN pins 7 and 8 | source Pin Description (p.15); Electrical Characteristics (p.4) |
| OUTP | Positive speaker amplifier output | TQFN pin 9 | source Pin Description (p.15) | |
| OUTN | Negative speaker amplifier output | TQFN pin 10 | source Pin Description (p.15) | |
| LRCLK | Frame clock: left/right clock in I2S and left-justified mode | TQFN pin 14 | source Pin Description (p.15) | |
| BCLK | Bit clock input | TQFN pin 16; BCLK must be 32, 48 or 64 times LRCLK | source Pin Description (p.15); Electrical Characteristics (p.6) | |
| GND | Ground | TQFN pins 3, 11 and 15 | source Pin Description (p.15) |
Build with it
Project ideas for the MAX98357A I2S amplifier. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- ESP32 doorbell chime: The ESP32 has I2S and 3.3 V logic, above the amplifier's 1.3 V input-high level; power the amplifier from the 5 V pin, inside its 2.5-5.5 V range. Power the board from a USB supply that can provide the speaker current. An 8 ohm speaker gets less than the 3.2 W quoted for 4 ohm.
- Record and play back toy: Both the microphone and the amplifier use I2S on the ESP32. Keep the speaker away from the microphone to avoid feedback. Learning project.
- Network audio player: Resample audio to 8, 16, 32, 44.1, 48, 88.2 or 96 kHz before it reaches the amplifier; the datasheet says 11.025, 12, 22.05 and 24 kHz LRCLK are not supported, and many web streams use 22.05 or 24 kHz. Power the board from a USB supply that can provide the speaker current.
- Pi Zero desk speaker: The Pi's 3.3 V I2S pins are above the amplifier's input-high level; the Pi needs its I2S audio output enabled in software. Learning project. Power the board from a USB supply that can provide the speaker current. An 8 ohm speaker gets less than the 3.2 W quoted for 4 ohm.
Common mistakes
- Powering the amplifier from more than 5.5 V: the supply range is 2.5-5.5 V; the digital inputs need only VIH 1.3 V, so 3.3 V logic from an ESP32 or Pico is enough (source)
- Expecting the 3.2 W headline on an 8 ohm speaker: the 3.2 W figure is for a 4 ohm load at 5 V, so an 8 ohm speaker receives less power (source)
- Stopping LRCLK while BCLK keeps running: the datasheet warns this can cause unexpected output behaviour including a large DC output voltage, so stop both clocks together (source)
Not covered by the official source
- Module board is not covered by an official document: header labels, resistors on SD_MODE and GAIN_SLOT, and the factory gain and channel setting are unknown.
- Only the 3.2 W / 4 ohm / 5 V feature line is quoted; the output-power table is not given.
- Listing says MAX98357A (I2S input); the MAX98357B is the left-justified variant. Check the chip marking on your module.
- Datasheet is Rev 7, a copy hosted on a mirror; a newer Analog Devices revision may exist.
Sources
- link (Maxim Integrated MAX98357A/MAX98357B datasheet, 19-6779 Rev 7, 2/16)