1.7.1 Device Resets on Wake-Up from Sleep (PIC16LF1938/1939 devices only)

This issue affects only the PIC16LF1938/1939 devices. These devices may undergo a BOR Reset when waking up from Sleep and BOR is re-enabled. A BOR Reset may also occur the moment the software BOR is enabled.

Under certain voltage and temperature conditions and when either SBODEN or BOR_NSLEEP is selected, the devices may occasionally reset when waking up from Sleep or BOR is enabled.

Work around

Method 1:

In applications where BOR use is not critical, turn off the BOR in the Configuration Word.

Method 2:

Set the FVREN bit of the FVRCON register. Maintain this bit 'ON' at all times.

Method 3:

When BOR module is needed only during run-time, use the software-enabled BOR by setting the SBODEN option in the Configuration Word. BOR should be turned off by software before Sleep, then follow the sequence below for turning BOR on after wake-up:
  1. Wake-up event occurs.
  2. Turn on the FVR (FVREN bit of the FVRCON register).
  3. Wait until the FVRRDY bit is set.
  4. Wait 15 μs after the FVRRDY bit is set.
  5. Manually turn on the BOR.

Method 4:

Use the software-enabled BOR as described in Method 3, but use the following sequence:
  1. Switch to the internal 32 kHz oscillator immediately before Sleep.
  2. Upon wake-up, turn on the FVR (FVREN bit of the FVRCON register).
  3. Manually turn on the BOR.
  4. Switch the clock back to the preferred clock source.
Note: When using the software BOR follow the steps in Methods 3 or 4 above when enabling BOR for the first time during program execution.

Affected Silicon Revisions

A1 A2 A3
X X