PAM8403 stereo amplifier: specs and pinout

A stereo class-D audio amplifier built around the PAM8403 chip, which drives speakers directly without an output filter. The facts below are for the chip; the module board is not covered by an official document. Diodes Incorporated marks the PAM8403 as not recommended for new design.

Every value cites its sourceChip-level pinout

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Specs

Spec	Value	Source
Supply voltage range	2.5 V to 5.5 V (absolute maximum 6.0 V)	source Recommended Operating Conditions p.3; Absolute Maximum Ratings p.3
Output power, 4 ohm, THD+N 10 %	3.2 W at 5.0 V; 1.6 W at 3.6 V; 1.3 W at 3.2 V	source Electrical Characteristics, p.4
Output power, 8 ohm, THD+N 10 %	1.8 W at 5.0 V; 0.9 W at 3.6 V; 0.6 W at 3.2 V	source Electrical Characteristics, p.4
Closed-loop gain	24 dB	source Electrical Characteristics, p.4
Quiescent current, no load	16 mA at 5.0 V; 10 mA at 3.6 V; 8 mA at 3.0 V	source Electrical Characteristics, p.4
Shutdown current	less than 1 uA	source Electrical Characteristics, p.4
Efficiency	87 % into 8 ohm and 83 % into 4 ohm (f = 1 kHz, THD 10 %)	source Electrical Characteristics, p.4
Enable and mute input levels	High 1.5 V min; low 0.4 V max	source Electrical Characteristics, p.4; Pin Descriptions p.2 (both active low)
Operating temperature	-40 C to +85 C	source Recommended Operating Conditions, p.3

Power

	Value	Source
Supply	2.5 V to 5.5 V (chip)	source Electrical Characteristics, p.4
Current	16 mA quiescent at 5.0 V, no load	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.

These are the SOP-16 chip pins. The module board's terminal labels, input coupling, volume pot and power connector are not covered by an official document; read the silkscreen of the board you receive.

Pin	Function	Voltage	Notes	Source
1 +OUT_L	Left channel positive output			source Pin Descriptions, p.2
2 PGND	Power ground			source Pin Descriptions, p.2
3 -OUT_L	Left channel negative output			source Pin Descriptions, p.2
4 PVDD	Power VDD	2.5 V to 5.5 V		source Pin Descriptions, p.2
5 MUTE	Mute control input, active low			source Pin Descriptions, p.2
6 VDD	Analog VDD	2.5 V to 5.5 V		source Pin Descriptions, p.2
7 INL	Left channel input			source Pin Descriptions, p.2
8 VREF	Internal analog reference		Connect a bypass capacitor from VREF to GND	source Pin Descriptions, p.2
9 NC	No connect			source Pin Descriptions, p.2
10 IN_R	Right channel input		The pin table prints this name without the underscore (IN and R run together)	source Pin Descriptions, p.2
11 GND	Analog ground			source Pin Descriptions, p.2
12 SHND	Shutdown control input, active low		Printed SHND in the pin table; the block diagram writes SHDN	source Pin Descriptions, p.2
13 PVDD	Power VDD	2.5 V to 5.5 V		source Pin Descriptions, p.2
14 -OUT_R	Right channel negative output			source Pin Descriptions, p.2
15 PGND	Power ground			source Pin Descriptions, p.2
16 +OUT_R	Right channel positive output			source Pin Descriptions, p.2

Build with it

Project ideas for the PAM8403 stereo amplifier. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.

Sound-effect box: At 5 V the chip gives 1.8 W into 8 ohm, within a 3 W speaker (about 0.4 A at full power). Power the amplifier and the Uno side from the 5 V 5 A supply's output terminals, not a GPIO pin, with grounds joined; keep the supply at 5 V, never above the chip's 5.5 V limit.
ESP32 tone player: The ESP32 DAC output (0 to 3.3 V, with a DC offset) goes to a channel input. The chip needs AC coupling at its inputs (series capacitor CI in the sheet's application circuit); the module's input capacitors are not documented, so check the board has them or add a series capacitor. Power the amplifier from the ESP32 board's 5 V pin (USB-powered) at moderate volume: full power into 8 ohm is about 0.4 A on top of the board's own current, so for loud use take 5 V from the stocked 5 V 5 A supply instead. Keep the amplifier at 5 V (limit 5.5 V) and the ESP32 on its own 3.3 V.
Microphone to speaker demo: Learning project. The microphone module output is DC-biased, so the amplifier input needs a series capacitor; check the module has input capacitors or add one (the sheet's circuit shows CI in series with the input). Keep the microphone away from the speaker to avoid feedback squeal. Power both modules from the 5 V 5 A supply's output terminals (never above 5.5 V), with grounds joined.

Common mistakes

Do not feed more than 5.5 V: the absolute maximum is 6.0 V, so a 9 V or 12 V supply will damage the chip (source: link, p.3).
A speaker connects across the + and - outputs of a channel; the sheet lists both as outputs, so neither is a ground (source: link, Pin Descriptions, p.2).
The sheet recommends supply decoupling and a 0.47 to 1.0 uF bypass capacitor on VREF; a weak or noisy supply gives noise and pops (source: link, Application Information).

Not covered by the official source

The datasheet is marked NOT RECOMMENDED FOR NEW DESIGN (use PAM8406); the module still uses the PAM8403 name.
The module board is not documented; the chip is assumed fitted per the product name.

Sources

link (Diodes Incorporated PAM8403, DS36439 Rev. 2-3, September 2020)