PWM Module Current Supply (>1A)

[Gizmaa]

The documentation for the cFP-PWM-520 says that there are 8 outputs which can be supplied with 5, 12, or 24 VDC and that each put out a max of 1 A per channel.  Will it work if I supply the module with 12 VDC and 8 A?

I'm worried I might burn out the module. 

[AnalogKid2DigitalMan]

Gizmaa:

You should be OK. Using a supply rated at 8A, you have the ability to provide the 8 PWM outputs at full load all at once. The load will determine how much current is drawn from each channel. What type of loads do you have, out of curiosity?

-AK2DM

[Gizmaa]

We have a 12 VDC, 6.5 A blower.  I was planning on using multiple channels in parallel to power the blower until we could get a speed controller.

[AnalogKid2DigitalMan]

Gizmaa:

I would highly advise not to parallel multiple outputs to drive loads needing more than 1A. Some of NI's devices have this capability, but I did not see any mention of this in 520 manual. Hopefully someone with knowledge or experience with the 520 can verify this.

You could probably use a power transistor or MOSFET with the appropriate protection circuitry (since a blower motor is an inductive device capable of generating back EMF) that is driven by 1 channel of the 520 to allow high current operation for your load.

-AK2DM

[Kevin_S]

Gizmaa,

I would also not advise connecting multiple PWM channels in parallel.  If you do want to experiment with any connections right now, I strongly advise putting a fuse in series with your power supply and load as shown in Figure 3 of the Operating Instructions Manual.

Kevin S.

Applications Engineer

National Instruments

[Gizmaa]

I managed to find a controllable voltage source until I can get a speed controller for it.  After the advice from the two of you I'd much rather be safe than sorry.  Thanks for the help.