XH-M125 is a new a new Mono audio amplifier Board available in electronics market. This amplifier board using XPT8871 SMD audio amplifier IC. This IC is works in 5V DC power supply and deliver up to 6 watt audio power at the speaker output. This article shares the Circuit diagram and information’s regarding the XPT8871 IC.
XPT8871 Amplifier Circuit Diagram
Components Required
| Ref. Designator | Component Type | Value / Specification |
|---|---|---|
| U1 | Amplifier IC | XPT8871 |
| H1 | Connector | 2-pin AUX input |
| R1 | Resistor | 100 Ω |
| R2 | Resistor | 100 kΩ |
| R3 | Resistor | 100 kΩ |
| C1 | Capacitor | 0.39 µF |
| C2 | Capacitor | 0.1 µF |
| C3 | Capacitor | 100 nF |
| C4 | Capacitor (Electrolytic) | 470 µF |
| U2 | Speaker | 5 W / 2 Ω |
| VCC | Power Supply | Typically 3V – 5V |
| GND | Ground | — |
Additional Information’s
When there’s no input signal to the IC which means the average output voltage is 0 V. The amplifier’s two outputs pins generate a square waves with a 50% duty cycle. These signals swing between the VCC and −VCC and are slightly out of phase with each other. Because of this, the speaker only sees very narrow pulses, even though the voltage still swings across the full range.
As a result, the average voltage across the load stays at 0 V. But the average current is much lower. That means the amplifier draws very less power from the supply voltage and which will improves the overall efficiency.
When the input signal goes positive, the duty cycle of the VoP output becomes larger than VoN, so the load receives mostly positive pulses. When the input goes negative the VoP’s duty cycle becomes smaller than VoN. which will producing mostly negative pulses. In the end the waveform across the load follows the input signal.
Why This XPT8871 Amplifier No Need Inductor in Output
In traditional Class D amplifiers circuits usually need an output filter. Without filter the high frequency switching pulses carry a lot of energy, which gets wasted in the load and reduces its efficiency. Adding an LC filter will helps to smooth things out and reduces these losses.
The XPT8871 works a bit differently. Its modulation method produces much narrower pulses with lower amplitude, so even without an output filter it is very little energy is wasted in the load. Because of this, you don’t need add an external output filter when using the XPT8871.
