MoTeC Global Forum

Hi,

I see the DHB drives 20A (total). If I want to PWM a Fan and a Fuel pump separately with it.....does this in effect mean that I have 10A on the Fuel pump driver and 10A for the Fan?

Also, If I turn on a Fan at 100% DC, will the DHB....

1. Clamp current at 10A
2. Shutdown on over current
3. Or will it fry?


Thanks
M

Hi,
The DHB will not current limit at 10A. It will protect its self if the maximum internal temperature is exceeded.
The continuous current of the DHB is specified under worst possible conditions (running at high voltage near its maximum ambient temperature).
If the case temperature is maintained at a relatively low temperature then the DHB would be able to drive significantly higher current.

A big fan will draw about 40A for 0,5sec and then settle at 18A.


This will surely exceed one half of a DHB? (DHB fitted on Heatsink)

Will you suggest using both Half bridges?

DavidC wrote:Hi,
It will protect its self if the maximum internal temperature is exceeded.
higher current.

Clamping current or shutting down?

I rang my local dealer to inquire about price for the DHB but apparently there are none available at the moment. Have they sold out ? Whats the price for these units in Australia ? When are we likely to be able to purchase them ?

Martin wrote:

DavidC wrote:Hi,
It will protect its self if the maximum internal temperature is exceeded.
higher current.

Clamping current or shutting down?

Higher temprature is acheived by higher current

That of course will depend on if a person added any active cooling (say like a computer fan or two, kinf od what they do in custom stereo amplifier installs in cars).

With that said, The DHB should be used and considered as one for higher current useage.

Your initial post

the DHB (as David said) does not current limit. If you pull 12 amps from output 1 (say the fuel pump) and 18 amps on the output 2 (the fan) the DHB will work until the thermal limit is reached and then shut the party down. At that point I would do one DHB for each item (1 for fan and 1 for fuel pump).

adding a heatsink and active cooling will help (no different than adding a heatsink to MOSFET's) in carrying an increase in current but don't expect to much an increase. Send a PWM singal from either the M800 or SDL/ADL2/ADL3, and now you have speed control built in.

I consider the DHB like a solid state relay except the relay only has one output.