Difference between pic16Lf and pic16f

[Jeff Stevens]

Hello.
My PIC16F877 project wrapped up successfully a few months ago, and the first production run is in. Our board manufacturer opted to use the PIC16LF877 instead (not sure why). VDD is a rock-steady 5v. Can anyone tell me if this could cause any problems anyhow?
Obviously, I wouldn't be asking if there were none. I'm using the counter on the micro, and expect the reported counts to be about 15\% higher than I'm seeing. The only obvious deviation from print is that it's a low-voltage micro.

Thanks in advance. ~ Jeff
___________________________
This message was ported from CCS's old forum
Original Post ID: 144515151

[PCM programmer]

:=Hello.
:= My PIC16F877 project wrapped up successfully a few months ago, and the first production run is in. Our board manufacturer opted to use the PIC16LF877 instead (not sure why). VDD is a rock-steady 5v. Can anyone tell me if this could cause any problems anyhow?
:= Obviously, I wouldn't be asking if there were none. I'm using the counter on the micro, and expect the reported counts to be about 15\% higher than I'm seeing. The only obvious deviation from print is that it's a low-voltage micro.
:=
--------------------------------------------------------------

The LF version is rated at 10 MHz max. What frequency are
you running it at ?

If you go through the data sheet in the electrical section,
there are lots of differences in setup and hold times for
the LF chips. They're longer than the regular chip.

The first thing I would do is pull out the LF chip from
one of your problem boards and put in the regular chip.
-- Just to confirm that it's really causing the problem.

Then if it's the problem, I would have your manufacturer
rework the boards and put in the specified chip.
___________________________
This message was ported from CCS's old forum
Original Post ID: 144515153

[Jeff Stevens]

:=:=Hello.
:=:= My PIC16F877 project wrapped up successfully a few months ago, and the first production run is in. Our board manufacturer opted to use the PIC16LF877 instead (not sure why). VDD is a rock-steady 5v. Can anyone tell me if this could cause any problems anyhow?
:=:= Obviously, I wouldn't be asking if there were none. I'm using the counter on the micro, and expect the reported counts to be about 15\% higher than I'm seeing. The only obvious deviation from print is that it's a low-voltage micro.
:=:=
:=--------------------------------------------------------------
:=
:=The LF version is rated at 10 MHz max. What frequency are
:=you running it at ?
:=
:=If you go through the data sheet in the electrical section,
:=there are lots of differences in setup and hold times for
:=the LF chips. They're longer than the regular chip.
:=
:=The first thing I would do is pull out the LF chip from
:=one of your problem boards and put in the regular chip.
:=-- Just to confirm that it's really causing the problem.
:=
:=Then if it's the problem, I would have your manufacturer
:=rework the boards and put in the specified chip.

We're running the chip at 4MHz. I'm checking a debugging trigger I put in during development to see if the timing is correct.
Thanks for the info on the timing charts. I'll post my final findings.
___________________________
This message was ported from CCS's old forum
Original Post ID: 144515156

[Terry Giles]

My understanding is that the LF parts are the same silicon as the standard parts, but are characterised and so guaranteed to work below 5V. If you use them at 5V I would not expect any difference in performance. Yes, the data sheets do show slower operation but that is what you would expect of a CMOS device at a lower supply voltage.

I have a product working at 3v and 10MHz clock that I developed with the standard F part ( could not get any LF at the time). In production we are using the LF and have not noticed any change in performance but I do sleep better at night knowing the 3v operation is guaranteed!

Regards


Terry Giles
:=:=:=Hello.
:=:=:= My PIC16F877 project wrapped up successfully a few months ago, and the first production run is in. Our board manufacturer opted to use the PIC16LF877 instead (not sure why). VDD is a rock-steady 5v. Can anyone tell me if this could cause any problems anyhow?
:=:=:= Obviously, I wouldn't be asking if there were none. I'm using the counter on the micro, and expect the reported counts to be about 15\% higher than I'm seeing. The only obvious deviation from print is that it's a low-voltage micro.
:=:=:=
:=:=--------------------------------------------------------------
:=:=
:=:=The LF version is rated at 10 MHz max. What frequency are
:=:=you running it at ?
:=:=
:=:=If you go through the data sheet in the electrical section,
:=:=there are lots of differences in setup and hold times for
:=:=the LF chips. They're longer than the regular chip.
:=:=
:=:=The first thing I would do is pull out the LF chip from
:=:=one of your problem boards and put in the regular chip.
:=:=-- Just to confirm that it's really causing the problem.
:=:=
:=:=Then if it's the problem, I would have your manufacturer
:=:=rework the boards and put in the specified chip.
:=
:=We're running the chip at 4MHz. I'm checking a debugging trigger I put in during development to see if the timing is correct.
:=Thanks for the info on the timing charts. I'll post my final findings.
___________________________
This message was ported from CCS's old forum
Original Post ID: 144515197