Basic stamp controller interface board- power requirements

Slater

I'm looking at the StampCi (item# 27945) board for some light automation projects at my job. Looking through the manual, I noticed that the power requirements are 9-12v 1000ma max. I also noticed that it uses a LM2937 regulator that, per the spec sheet I found at Digi-key, differs in that it says it can handle 26v (500ma max).

We have LOTS of 24v power supplies. I'd like to use them, which leads me to my question:If I keep the current across the board to <500ma can I safely run it at 24v? Or are there other limiting factors I'm not seeing?

Also, how does the life span of this product look? I don't want to start using it·if it's close to obsolesence.....

Thanks in advance,

Slater

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Mike Green

The datasheet for the LM2937 is a bit confusing. They do indicate that the maximum current is 500mA, but they have graphs showing output current in excess of 1A and some of the tables show output currents of 1A. That said, the power requirements are 9-12V at 1A for the input to the board. The reason for the limit on supply voltage is the limited power dissipation of the un-heatsinked regulator at the higher input voltages. It's quite possible that you could run the board from 24V if the total current drawn is 300mA or less since the board is supposed to run at 12V/1A = 7W dissipation and 24V/300mA = about 7W. That's still a lot of heat and I'd not recommend doing that without a good size added heatsink. You'd be better off using a switching regulator that either reduces the 24V input to something like 9V or goes directly to 5V and substitute that for the LM2937.

Parallax tends to keep products that they make themselves around for as long as there's a demand for them.

Slater

Thanks for the explaination, Mike. I'll look into the regulator you're suggesting.

Slater