Working voltage range: AC7-18V, DC8-28V,

Boot delay time: 3 seconds (fixed time cannot be changed)

DC detection voltage threshold: 1V (±0.2V)

When the relay is not closed (protection state), the LED indicator flashes, when the relay is closed after normal operation, the LED indicator will be on

Port description:

1. Audio input: L and R are connected to the left and right channels of the power amplifier, and GND is the common end of the power amplifier output. For traditional OCL or OTL power amplifiers, both need to be connected to the GND common end, while BTL or most digital power amplifiers are output There is no common terminal, no need to connect to GND

2. Audio output: L and R are connected to the left and right channels of the speaker (speaker), GND is the common end of the speaker (speaker), for traditional OCL or OTL, both need to be connected to the GND common end, and BTL or most For digital power amplifier, there is no common terminal for output, so there is no need to connect to GND;

3. AC power supply: This port is the AC power supply interface of the protection board. It needs a single transformer or a single transformer winding to supply power. It cannot share power with the power amplifier board or other circuits. The power supply voltage range is 8-20V AC;

4. DC power supply: This port is the DC power supply interface of the protection board (welding is required for the pad), which can share power with the power amplifier board or other circuits, and the power supply voltage range is DC 9-28V;

5. JP1 jumper: It is a standard 1206 resistor. This function requires AC power supply and a single transformer or a single transformer winding. When the resistor jumper is removed, the shutdown power failure detection function is turned on. Once the power supply is detected to be off, the relay will be disconnected in a short time, which can effectively avoid the impact to the speaker during shutdown. This function is affected by the power amplifier board's own power supply and circuit, the effect will be different, and it may not completely solve the shutdown shock. Moreover, when DC power is supplied, this function cannot be realized, and the resistance jumper cannot be removed.

6. JP1 jumper: It is a standard 1206 resistor. This function is suitable for some power amplifiers with relatively large output power and relatively large output dynamics. Due to the relatively large dynamic range, it is easy to cause the protection board to jump and raise the sound frequently and cause malfunction. When the resistance jumper is removed, the detection sensitivity can be reduced, the misoperation can be reduced, and the misoperation cannot be completely avoided;

7. External expansion relay interface: This port can be connected to a relay of the same type, adding a channel control, suitable for 2.1 channel power amplifier;

System typical wiring diagram:

Note:  Many output structures of digital power amplifiers are BTL structures, and the negative end of the output is not the common end of the power amplifier, that is, the GND ground. The output of the power amplifier needs to be directly connected to the speaker (speaker) without passing through the protected GND.

The output structure of most digital power amplifiers is BTL, and the output voltage is not 0V, which will cause the protection board to detect a protection voltage threshold higher than 1V, and the relay will not be closed. The detection circuit needs to be modified and the two resistors R6 and R8 are removed.