Overloading an LM317

Aug 07, 2010 25 Replies

Bit of an odd thing to say, isn't the just stated performance of the fan controller an exact counter-example to that assertion?

Pay for such smarts? We buy lots of fans, and I've stopped a lot of them by hand, and I've never seen one blow up. We don't even pay extra for non-blowing-up fans. Even the cheapest ones self-protect.

I remain surprised that nobody makes a good general-purpose current limiter chip. It wouldn't even have to be a single-purpose part, just one more current-set pin on an LDO.

John

Those fans are quasi-stepper... kick, look for a commutation voltage, then continue, with some kind of minimum frequency start oscillator.

I've used the game at nearly 1/4hp levels (Bosch/Mercedes A/C fan motor). No current limit needed, though I've done that too. ...Jim Thompson

| James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Spice is like a sports car... Performance only as good as the person behind the wheel.

Aren't the hot-swap controller chips pretty much that?

Best regards, Spehro Pefhany

"it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com

Yep. Good observation. I should have remembered... I've designed them :-) ...Jim Thompson

| James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Spice is like a sports car... Performance only as good as the person behind the wheel.

Some are, but there's very little above 5 volts. Fairchild (or is it ON?) has a specific current limiter part but it's, pretty well, limited. And expensive.

John

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