piclist 1998\11\09\140829a >
Thread: Write voltage and MAX232
picon face BY : Peter L. Peres email (remove spam text)

On Mon, 9 Nov 1998, Dave VanHorn wrote:

{Quote hidden}

I was thinking of using a PIC to program a PIC of course. This is a cheat
on bootstrapping ;)

> Handling the flyback pulse could be interesting as well. Can we spell
> CMOS latchup?
> I think that FET would be well advised.

The OD PIC pin can switch a coil at 5V Vdd without the latchup becoming
dangerous (of course you use a zener or diode to limit it just in case).

> I've heard processors discussed as SMPS controllers before, but never
> seen it implemented.. That's interesting, because they have the

;) About 50% of the camcorders on the market use the PWM outputs of a
processor to control a pair of choppers directly. These drive the drum and
capstan motor, with the control loops closed through the resp. sensors and
the processor algorythm.

There are several schematics of special purpose DC/DC converters built
with PIC16C71/711s, with four channels each and serial control. Need I go
on ?

> potential to be a lot more intelligent than existing analog chips.
> External drivers are not a problem, but driving the drivers might be.
> The CS3844 for example, provides 1A in either direction to rapidly
> charge/discharge the switching FET's gate capacitance. Any processor is
> going to have a hard time with that!

As long as we talk small, a PIC output can drive a small VFET (like a
BSS175 etc) directly properly and this leads to outputs of the order of
0.8 A per channel. Driving VFETs too fast without a reason is painful in
the RFI domain. You almost always end up trying to slow it down



In reply to: <36471563.B88ACAAB@cedar.net>
See also: www.piclist.com/techref/power.htm?key=voltage
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