I wrote ...

> I my recent design, I have 16 bright leds and they need a lot of current. If I
> switch them very fast (2kHz or so) the PIC resets. It happens after some time
> and it seems to be a problem with the power supply to the PIC. If I insert a
> capacitor in parallell, the problem goes away until I raise the supply current
> even more to the leds (I use buffers to control the leds so the PIC doesn't
 need
> that much current).

Scott Stephens wrote ...

> How much did you raise the LED current?
> How are you raising the supply current to the LED's?
> What device is the buffer for the LED's?
> Describe the trace lengths/locations of the supply, PIC, buffer & LED's?
> What are the V and I spec's for the supply, PIC, LED's & buffer?
> How much did you increase the filter cap?

The problem is that I don't want sixteen resistors on my board so I use
"built in" current limiting in two 74HC244:s. Yesterday I checked the
voltage drop over the PIC with my osc. and deltaV = 2V (too much I guess).
The simplest solution to this was to place a couple of diodes from
V+ to Vdd of the 74HC244 and now it works with deltaV = 0.2V (but with
a little less power output from the leds.)
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Conny Andersson / LiTH