CHI035A High Power Board Outputs

[RussellS]

Hi, I hope someone can offer me some advice please.

I have a project ongoing for the car which uses the CHI035A high power board. It is driven by 12v and has the 78L05 regulator fitted (and link removed) and also has the L293D motor driver IC fitted to drive a motor in either direction.

Everything is working well except for one thing. I am using FET output B.0 to provide 12v power to a reversing camera but unfortunately it is not working as I had hoped because the output is connected between B.0 and V2+ and NOT referenced to GND. Therefore when the camera is off then there is 12v on both the supply wires going to the camera instead of both being 0v which is causing issues elswhere in the system.
I have temporarily got around the issue by using a miniature relay to switch 12v & GND to the camera and using the B.0 & V2+ to switch the relay on/off. This is working well and has solved the issue but is not a particular elegant solution especially as the relay is just connected to some flying leads and not on a circuit board.

Can anyone suggest a better solution to use the B.0 output to switch 12v (referenced to GND) instead of the relay.


Many thanks

Russell Spearing

 

[inglewoodpete]

When I want to connect and disconnect 12v power without using a relay, I use a P-channel MOSFET. Refer to the attached circuit that I have snipped out of a much larger diagram.

I have included the 1 ohm resistor in my circuit so that I could easily measure load current. The daughter board that I am using has 5v and 3.3v regulators, so small voltage losses can be tolerated. For your purpose omit the resistor but include a fuse near the MOSFET, since you are running power around your vehicle.

 

[RussellS]

That's great, thanks for the advice.
I already have a small breadboard with a logic level converter circuit to convert the 12v signals to 5v so I can incorporate this circuit on it as well.

Thanks again.