Which H-Bridge?

[Christopher Cole]

For a simple, powerful H-bridge using a few FETs, check out:
http://coledd.com/electronics/robot/h-bridge.php
You can drive this with PWM if you wish.
Take care,
-Chris

 

[Winfield Hill]

Christopher Cole wrote...

For a simple, powerful H-bridge using a few FETs, check out:
http://coledd.com/electronics/robot/h-bridge.php
You can drive this with PWM if you wish.

Whew, bad news, supply-rail shoot-through city!

Thanks,
- Win

whill_at_picovolt-dot-com

 

[Klaus Vestergaard Kragelund]

Christopher Cole wrote...

Whew, bad news, supply-rail shoot-through city!

Will there be shoot-through if he drives the two control line independently?

Cheers

Klaus

 

[Christopher Cole]

Christopher Cole wrote...
Whew, bad news, supply-rail shoot-through city!
Thanks,
- Win
whill_at_picovolt-dot-com

Hehe, yes one needs to take care not to enable both lines at once.
Arguably even allow some dead time between directional changes.

Take care,
-Chris

 

[Winfield Hill]

Klaus Vestergaard Kragelund wrote...

Winfield wrote ...

Will there be shoot-through if he drives the two control
line independently?

Yes, because although T3 and T4 may be properly driven (we
aren't told), R1 and R2 have such a high value (10k) that
the FETs they are driving will turn off too slowly. An
IRF9510 has 200pF of gate capacitance, and the gate will
take several time constants to get below threshold, which
translates to say 5us of FET turn-off delay (the actual
calculation is more complex, as I've detailed many times
in these pages). The circuit will experience high rail-
to-rail shoot-through currents (e.g., over 10A) during this
time. It may survive the experience, but it's a severe
stress that should be avoided. It's a poor circuit.

Thanks,
- Win

whill_at_picovolt-dot-com

 

[Jan Panteltje]

You got the reverse diodes in such a way that if a bottom MOSFET switches on,
it shorts the supply!
No matter how you drive it (drawing error, the P and N you put upside down, but you
also reversed the diodes).
IRF9510 diodes are the other way around!
JP

 

[Winfield Hill]

Jan Panteltje wrote...

You got the reverse diodes in such a way that if a bottom MOSFET
switches on, it shorts the supply! No matter how you drive it
(drawing error, the P and N you put upside down, but you also
reversed the diodes). IRF9510 diodes are the other way around!

Right, he has the p-channel S and D labels in the right place,
but has wrongly drawn the p-channel symbol S and D orientation.

Thanks,
- Win

whill_at_picovolt-dot-com