I'm trying to keep this as simple and small as possible since it will be mounted on a motorcycle.

The circuit is a PWM fan speed controller, it will monitor the analog gauge sensor voltage already on the bike but I could replace that with a simple NTC thermistor.

This IC does everything I want it to do including having a fault indicator output which, although not 100% essential, would be nice to have.

The bike has a regular 12V lead-acid battery with the usual charging system that can jump as high as 14V. The fan is rated 12V nominal, no more than 3A at full speed.

Where I'm at:

A TC642B driving a logic level FET
http://ww1.microchip.com/downloads/en/DeviceDoc/21756b.pdf

(Ignore the way they designed in the SENSE part, I'll get that pulse in a different manner thus eliminating the resistor.)

What I'm wondering:

Is there a similar chip produced that will run with 12-16V for the supply instead of me having to give it a separate +5V? The few extra components are really not that big of a deal, just wondering if anyone had seen anything similar. I'm also somewhat limited in that I'd like to stay away from surface mount components.

 

A 555? Joking.

 

You could probably figure out a solution using a quad op-amp as a PWM controller. You'd need a few additional components (more than the Microchip part probably.)

 

Yea, that's what I figured. Fairly interesting chip for its age and they made some variations with other integral features, can't recall the other part #s at the moment.

Haven't really thought about it yet but it could have other uses.