SKU: TH1985
The Adafruit PAM8302 STEMMA Mono 2.5W Class D Audio Amplifier is a tiny yet capable audio amplifier designed to drive real speakers directly from low-voltage projects. Powered by an efficient Class D amplifier core, it delivers up to 2.5W of mono output into 4–8Ω speakers while operating from a wide 2.0V–5.5V supply, making it an excellent choice for battery-powered and portable builds.
The Adafruit PAM8302 STEMMA Mono 2.5W Class D Audio Amplifier is a tiny yet capable audio amplifier designed to drive real speakers directly from low-voltage projects. Powered by an efficient Class D amplifier core, it delivers up to 2.5W of mono output into 4–8Ω speakers while operating from a wide 2.0V–5.5V supply, making it an excellent choice for battery-powered and portable builds.
Unlike older LM386-based designs, this amplifier runs cool and efficiently (over 90% efficiency in typical use), with built-in thermal and over-current protection for reliable operation. An onboard trim potentiometer allows easy volume adjustment from the default 24dB gain, so you can fine-tune output levels without modifying your audio source.
This STEMMA version is designed for true plug-and-play use. Audio input is provided via a 3-pin JST-PH connector, allowing quick connections using pre-crimped cables, pin headers, or alligator clips—no soldering required. To simplify the design, the input is single-ended and referenced to the power/signal ground rather than using differential inputs.
The amplifier output uses a bridge-tied-load (BTL) configuration, meaning both speaker wires connect directly to the amplifier outputs with no connection to ground. Audio is delivered as a high-frequency (~250kHz) PWM signal that is naturally smoothed by the speaker coil, eliminating the need for bulky output filters. Because of this design, the board is intended to drive speakers directly and should not be connected to another amplifier stage.
(Speaker not included; use any speaker with 4Ω or higher impedance.)
Technical details for Adafruit PAM8302 STEMMA Mono 2.5W Class D Audio Amplifier.
| Specification | Details |
|---|---|
| Amplifier IC | PAM8302 |
| Amplifier Type | Class D (high-efficiency, filterless design) |
| Audio Channels | Mono |
| Operating Voltage | 2.0V – 5.5V DC |
| Output Power | 2.5W @ 4Ω, 10% THD (5.5V supply) 1.5W @ 8Ω, 10% THD (5.5V supply) |
| Recommended Speaker Impedance | 4Ω or higher (4–8Ω typical) |
| Output Configuration | Bridge-Tied Load (BTL) – speaker connects directly to OUT+ and OUT- |
| Switching Frequency | ~250 kHz PWM |
| Input Type | Single-ended audio input referenced to power/signal ground |
| Input Coupling | 1.0µF AC-coupled input capacitors |
| Gain | Fixed 24 dB gain with onboard trim potentiometer for volume adjustment |
| Power Supply Rejection Ratio (PSRR) | 50 dB @ 1 kHz |
| Efficiency | >90% efficiency (typical with 8Ω speaker at moderate output) |
| Quiescent Current | ~4 mA |
| Shutdown Current | ~0.5 mA (due to pull-up resistor on SD pin) |
| Protection Features | Thermal protection, short-circuit and over-current protection |
| Input Connector | 3-pin JST-PH connector (STEMMA compatible) |
| Speaker Connector | 3.5mm screw terminal block |
| Included Accessories | Breadboard header screw terminal block (color may vary) |
| Typical Applications | Portable audio projects, alerts, sound effects, embedded systems, battery-powered devices |
| Pin / Connector | Label | Description |
|---|---|---|
| Power | VIN | Power input pin. Supply the board with 3V–5V DC. Available via STEMMA connector and through-hole pad. |
| GND | Common ground for power and signal. Available via STEMMA connector and through-hole pad. | |
| Audio Input | SIGNAL | Line-level audio input (~1Vpp). AC-coupled via onboard capacitors, allowing DC offset if needed. Available via STEMMA connector and through-hole pad. |
| Audio Output (BTL) | VO+ | Positive speaker output. Connect directly to the positive terminal of a 4–8Ω speaker. |
| VO- | Negative speaker output. Connect directly to the negative terminal of a 4–8Ω speaker. Not connected to ground. | |
| STEMMA JST-PH Connector | SIGNAL (White) | Audio input pin. Accepts line-level AC or DC-coupled audio signal. |
| VIN (Red) | Power input pin. Supply 3V–5V DC to power the amplifier. | |
| GND (Black) | Ground reference for power and audio signal. | |
| Speaker Terminal Block | – | Speaker negative terminal. Electrically identical to VO-. |
| + | Speaker positive terminal. Electrically identical to VO+. | |
| Onboard Control | Volume Trimpot | Adjusts output volume from the default 24dB gain level. |
| Indicators & Jumpers | Power LED | Green LED labeled ON, indicates when the board is powered. |
| LED Jumper | Rear-side jumper to disable the power LED. Cut the trace to turn off LED; re-solder pads to re-enable. |
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SKU: TH1634
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