Re: MCLR circuit with in-circuit programmer --- beginner question
☄ Helpfulby PowerDuck 2017/06/16 13:53:57
Agree with NorthGuy, with resistor R16 between MCLR pin and capacitor C30, 470 Ohm is sufficient isolation for the Programmer to drive /MCLR signal when needed.
I have seen R16 with values between 470 Ohm and 1000 Ohm successfully used.
Reset switch indicated in diagram is in the wrong place.
Reset switch should be in parallel with capacitor C30, connecting to GP.
There have been mixed experiences reported with Tantalum capacitors for VCAP regulator stabilisation.
It seem some types of tantalum capacitors may have higher ESR than good aluminium electrolytics,
but I am not sure about frequency dependencies.
10 uF Ceramic capacitors seem to have much better ESR properties at high frequencies.
Ceramic capacitors loose capacitance when biased by DC voltage, thus ceramic capacitor rated for 16 V is preferred, even if VCAP voltage is only about 2 V.