Is the VDD connection on ISCP header neccessary for ICD-40?

blak3r · Joined: 11 Jan 2004 Posts: 45

I have a small circuit with a small power supply that can only provide 10mA. Vdd on the circuit is 3.3V and my PIC is a 16LF628.

Since i have a ICD-40U which is self powered from the USB port. Is it okay to not connect the VDD Pin on a ICSP header?

Also, are there any other things i should know about since my operating voltage for all my ICs is 3.3V?
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Chas · Guest

Yes, you need to connect your Vdd to the ICD interface. It is used by the ICD for reference when it drives the MCLR line. Look at the post in this forum about about "different frequencies" which is a couple of lines below this one.

Guest · Posted: Fri Jul 16, 2004 2:40 pm

Hmm... So if VDD is operating at 3.3V then does it drive the MCLR line with a 3.3V logic level opposed to 5V?

Thanks

bdavis · Posted: Mon Aug 02, 2004 5:01 pm

I think /MCLR is driven to 12 to 13 volts from the ICD when programming, not 5V or 3.3V.