PIC16F1455 voltage levels - Page 1
Forum section: electronics / general

author: RUWO1
author_rank: Newbie
timestamp: February 05, 2019, 01:47:32 pm
content: hello all,So for the PIC16F1455(http://ww1.microchip.com/downloads/en/DeviceDoc/40001639B.pdf), the absolute max voltage rating is 6.5v, and the recommended range goes up to 5.5v. however, all figures in the datasheet are given for 3v, suggesting that 5v is not the recommended operating voltage. do you think I could run it at 5v without any issues? and I know this is for the supply voltage, but can I pump 5v into an I/O line? can it handle that? (couldn't find that in the datasheet) also, the chip has built-in USB, can I just connect those to the USB differential lines or do these need extra protection components/filtering?thanks a lot!

author: hli
author_rank: Frequent Contributor
timestamp: February 05, 2019, 02:14:28 pm
content: Which figures are you referring to? Every place I looked at where the supply voltage might be a factor lists 1.8V, 3V and 5V as supply voltage. Note that the PIC16LF1455 is a 3.6V part, so in places where only this part is described no 5V apply.

author: KL27x
author_rank: Super Contributor
timestamp: February 05, 2019, 02:23:22 pm
content: I wouldn't supply it at more than 5.1V or thereabouts.Be sure you use the F version, and not the LF. The F has an LDO built in, which is why it can handle 5V. The LF variant takes only up to 3.3V.QuoteIf the supply is 5V, you can put 5V on the I/O pins. But you should not put more than 0.3V over Vsupply on the I/O... at least not without current limiting. There's ESD protection circuitry on the pins. Basically, there are a couple diodes in there that clamp the pins to the rails.QuoteYes, you can connect USB D+- lines, directly to the micro pins. You do not need any special filtering for USB.

author: RUWO1
author_rank: Newbie
timestamp: February 05, 2019, 03:10:01 pm
content: Quote from: hli on February 05, 2019, 02:14:28 pmpage 342/344 of the datasheet I linked. note I quoted max figures.Quote from: KL27x on February 05, 2019, 02:23:22 pmthx, the LDO is nice. I won't give it more than 5V volts under normal operation. and this is a really easy circuit then, with the built in ldo and no USB filtering required.

author: NorthGuy
author_rank: Super Contributor
timestamp: February 05, 2019, 03:38:35 pm
content: Quote from: RUWO1 on February 05, 2019, 03:10:01 pmMore importantly, you do not need a crystal or external oscillator. All you need is a capacitor for LDO and a decoupling capacitor. Also, you can power it from USB (which is usually 4.5 to 5 V).

author: hli
author_rank: Frequent Contributor
timestamp: February 06, 2019, 09:02:54 am
content: Quote from: RUWO1 on February 05, 2019, 03:10:01 pmPage 342 is chapter 29.0, absolute max ratings, right? It says the PIC16F1455 can hande 6.5V Vdd, and the PIC16LF1455 4.0V. The USB Lines cannot handle more than 0.5V above the USB3V3 voltage (see the USB description where this comes from). I see no mentioning of 3V Vdd on this page.Page 344 is chapter 29.1, DC characteristics. Same here - the specs for the PIC16F1455 are with 5V, for the PIC16LF1455 for 3.3V. The specs in the 'typical' column are for 3.0V, but they are just for 'guidance', so you should not rely on them anyway.Which additional information would you need for 5.0V?

author: Ian.M
author_rank: Super Contributor
timestamp: February 06, 2019, 10:04:04 am
content: The abs. max. ratings only tell you what the PIC will survive without damage. It may not operate correctly at 6.5V Vdd, and may require being completely powered down to recover.FIGURE 29-1: PIC16F1454/5/9 VOLTAGE FREQUENCY GRAPH shows you its actual operating Vdd range, and that's max. 5.5V.