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Author Topic: PIC18F2620 input high voltage of only 2V..?  (Read 2476 times)
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mrnobody
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« on: December 14, 2007, 01:30:14 01:30 »

Hi,
Refering to PIC18F2620 datasheet, section 26.3 on DC characteristics, it says that the INPUT HIGH voltage is only 2V for VDD between 4.5V and 5.5V.

BTW I am doing a project using PIC18F2620 and ENC28J60 and i was wondering, if the input high voltage is only 2V, then why would i still need additional CMOS chip to act as voltage level translator/shifter for ENC28J60's output pin SO, CLKOUT and INT. I mean, shouldn't the output voltage of 3.3V be sufficient to change the PIC pin from a LOW state to a HIGH state..?

Any thoughts..
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mylogin
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« Reply #1 on: December 14, 2007, 04:48:10 04:48 »

I theory it should work without CMOS level shifter, vdd-0.7v min. o/p  should be able to drive the 2v min. I/p of PIC.  for noise margin consideration it is in margin.  You can try it without CMOS LEVEL translator, if not good enough, try add pull-up resistor to these o/p signals from ENC28J60. a 10k resistor to the VCC supply of PIC (5V system) to pull  the o/p level higher.
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kiemsidatinh
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« Reply #2 on: December 14, 2007, 08:17:12 08:17 »

        I test it, it Ok, but the rate is slow . . . .
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