Overview

The PAM8403 is an ultra-compact 3W+3W3\text{W} + 3\text{W} filterless dual-channel (stereo) Class-D audio power amplifier IC manufactured by Diodes Incorporated. Available as a tiny 15×18 mm15 \times 18\text{ mm} green breakout module (often equipped with an integrated rotary volume potentiometer and power switch), it is the most popular audio amplifier module for USB-powered speakers, portable Bluetooth audio players, arcade cabinets, and Raspberry Pi handheld consoles.

Operating on a 2.5V2.5\text{V} to 5.5V5.5\text{V} DC supply (ideal for 5V5\text{V} USB or single-cell Li-ion battery power), the PAM8403 delivers up to 3.0 Watts3.0\text{ Watts} per channel into 4 Ω4\ \Omega speakers with 90%90\% electrical efficiency and filterless Bridge-Tied Load (BTL) architecture.

Quick reference

Operating voltage (VCC)2.5 V to 5.5 V DC (5.0 V USB nominal)
ChannelsDual Stereo (2×3W2 \times 3\text{W} Output Channels)
Output Power3.0W3.0\text{W} per channel into 4 Ω4\ \Omega at 5.0V5.0\text{V} / 1.8W1.8\text{W} into 8 Ω8\ \Omega
Efficiency>90%> 90\% Class-D switching efficiency
THD + Noise<0.1%< 0.1\% typical at POUT=1.0W,f=1 kHzP_{OUT} = 1.0\text{W}, f = 1\text{ kHz}
Quiescent Current10 mA10\text{ mA} typical at 5.0V5.0\text{V}
Shutdown Current<1.0 μA< 1.0\ \mu\text{A} (via /SHDN pin)
ArchitectureFilterless Bridge-Tied Load (BTL) output

Pinout (SOP-16 Package & Module Terminals)

text
        ┌──────────────────┐
        │     PAM8403      │  (SOP-16 Package)
        └─┬───┬───┬───┬────┘
Module Pin LabelNameTypeDescription
5V / VCCVDDPowerPositive supply power input (+2.5 V to +5.5 V DC)
GNDPGNDPowerGround reference (0 V)
LLINAnalog InputLeft Channel audio input
GAGNDAnalog InputAudio input signal ground
RRINAnalog InputRight Channel audio input
L+ / L-OUTL+ / OUTL-Speaker OutputLeft Channel Bridge-Tied Load (BTL) speaker outputs
R+ / R-OUTR+ / OUTR-Speaker OutputRight Channel Bridge-Tied Load (BTL) speaker outputs

Specifications

ParameterSymbolMinTypMaxUnitConditions
Supply VoltageVDDV_{DD}2.55.05.5VDC
Continuous Output PowerPOUT1P_{OUT1}—3.0—WRL=4 Ω,VDD=5.0V,THD=10%R_L = 4\ \Omega, V_{DD} = 5.0\text{V}, THD=10\%
Continuous Output PowerPOUT2P_{OUT2}—1.8—WRL=8 Ω,VDD=5.0V,THD=10%R_L = 8\ \Omega, V_{DD} = 5.0\text{V}, THD=10\%
Quiescent CurrentIQI_Q—1016mAVDD=5.0VV_{DD} = 5.0\text{V}, no load
Shutdown CurrentIsdI_{sd}—0.41.0µA/SHDN pulled Low to GND
Power Supply RejectionPSRRPSRR—64—dBf=1 kHzf = 1\text{ kHz}

Filterless BTL Output Topology

The PAM8403 uses a Bridge-Tied Load (BTL) output stage. Speaker leads (L+/L- and R+/R-) drive both sides of the speaker coil differentially.

Warning

Speaker Ground Rules:

  • DO NOT CONNECT L- OR R- TO SYSTEM GND.
  • DO NOT BRIDGING L- AND R- TOGETHER.
  • Each speaker must be wired independently across its dedicated + and - terminal pair. Connecting negative speaker terminals to GND or joining left/right negative leads short-circuits the BTL H-bridge output, instantly destroying the PAM8403.

Wiring

PAM8403 Module Pin→Power / Audio Source / SpeakerNotes
5V (VCC)5V DC (USB Power / Li-ion Boost)Do not exceed 5.5V
GNDPower GNDSystem ground
LLeft Audio Channel (3.5mm Headphone Jack Left)Input audio signal
GAudio Ground (3.5mm Headphone Jack Shield)Input signal ground
RRight Audio Channel (3.5mm Headphone Jack Right)Input audio signal
L+ / L-4 Ohm / 8 Ohm Left SpeakerIndependent Left Speaker
R+ / R-4 Ohm / 8 Ohm Right SpeakerIndependent Right Speaker

Common mistakes

  • Connecting power exceeding 5.5V: The PAM8403 has an absolute maximum supply rating of 6.0V6.0\text{V}. Supplying 9V or 12V DC causes immediate chip burnout.
  • Shorting speaker negative pins (L- / R-) to ground: Common ground 3.5mm headphone sockets cannot be connected directly to the output terminals. Connect speakers directly across L+/L- and R+/R-.

Notes

  • PAM8403 vs LM386 vs TPA3116D2: PAM8403 is 3W+3W3\text{W}+3\text{W} Class-D (5V USB); LM386 is 0.7W0.7\text{W} mono Class-AB (9V); TPA3116D2 is 50W+50W50\text{W}+50\text{W} Class-D (12V–24V).

Assets & downloads