Mixed Switching Elements in H-Bridge

[DamoRC]

Is it crazy to think that I could use a combination of MOSFETs and BJTs as the switching elements in a single H-Bridge?

In an application for a radio controlled car, which would spend most of its time going forward, could I use MOSFETs for the forward control "arm" of the bridge and BJTs for the reverse "arm".

I am thinking primarily of the switching element costs, in that the cost of the bridge could be reduced significantly if BJTs could replace MOSFETs for one half of the bridge.

One complication might be braking, which I originally intended on achieving by switching on both of the low side MOSFETs together and, in the scenario proposed above, would now involve switching on a low side MOSFET and a low side BJT together.

Thought, comments welcome.

Thanks

 

[mneary]

Not really crazy, but the savings is minimal unless this is a mass produced product.

 

[DamoRC]

Thanks mneary,

No - I won't be mass producing - I am just a total cheapskate. However, on thinking further about this, I could just buy cheaper MOSFETs for the reverse arm and then I could put some quality into the forward arm.

 

[zevon8]

Using MosFET's and SCR's was common at one time, the SCR's would self commutate, simplifying their half of the H-Bridge. With cheap logic gates and H-Bridge driver/output chips, I really don't see the need.

 

[dknguyen]

Don't forget to include the costs fo the gate drive circuitry. Cheaper switches might need more expensive and/or complicated gate drives or heatsinking.