High vs Low side switching.

Hello,

I'm looking for opinions on high side vs low side switching. My research has yielded no definitive answer, although the trend is toward high side. I understand the pros and cons of both and personally I lean towards low side. I look forwards to your responses.

Cheers,

Alec

Low side switching is my preference. Please tell us where you see this trend -- what exact ECU models?

High side switching tends to be used by OEMs and 'dumb' circuits for short safety, ECUs and other units with logic tend to be built with simpler N channel MOSFETs - though this doesn't mean that more will/are being built with P channels for high or low side switching.

So to David's point most ECUs will tend to switch low more often than not, though you'll still see bigassed 12v switches integrated in vehicles until we do away with standard switches altogether ;)

I was thinking of ECU's, but you make me realize that PDM outputs are always (?) high-side outputs. But the inputs or low-side switched.

Hi David, Let me rephrase that. When I perform a Google search on high vs low side switching, most of the information I find recommends high side, including Google AI. I agree, there is an inherent "safety" factor with high side 12V circuits, short to ground, fuse or breaker blows, circuit dead. A low side ground fault and something is turned on that you may not want. I still prefer that to +12V wires running all over my car. At some point every control circuit will be logic level or serial, and every switch CAN.

You still need to complete a circuit, so proper line side fusing means the fear of +12v wires 'all over' the car is as safe as low side switching from that standpoint. Either way this is why AI isn't in a vacuum isn't a particularly useful tool - it gets lost in nuance as well as changes in technologies and strategies over time such as how older OEM switching was all high side and now they're driving CAN and BCM integration.