Information

 2008-2013 Microchip Technology Inc. DS80000425K-page 11
PIC18F24K20/25K20/44K20/45K20
39. Module: Wake-up from Low-Power Sleep
mode
The device may not wake from Sleep when both of
the following conditions are met:
1. The device is in Sleep mode for <1 ms;
2. On waking, the device executes a SLEEP
instruction within 100 µs.
Under these conditions, the oscillator may stop
before completing execution of the SLEEP
instruction. The device will enter Sleep mode but
will not wake-up on any enabled wake-up event,
including the Watchdog Timer.
Work around
1. Disable High-Speed Start-up
Disabling High-Speed Start-up in the Configuration
Word will delay the device executing code on
wake-up by 250 µs, nominally, allowing the
oscillator to stabilize.
The wake-up time from Sleep will increase by
about 250 µs, nominally.
2. BOR enabled during Sleep
Configuring the device for hardware only BOR or
software-controlled BOR and enabling SBOREN,
the voltage reference is on during Sleep.
The device will wake-up and the oscillator will be
stable. This will add 20 µA (nominal) to the Sleep
current.
3. Enable the FVR during Sleep
In the same manner as the BOR, the FVR will keep
the voltage reference on during Sleep, causing the
oscillator to be stable on wake-up.
4. Avoid executing SLEEP within 100 µs of any
wake-up event
This can be achieved by adding more instructions
(NOP) before executing the SLEEP instruction. This
minimizes the probability of the SLEEP instruction
only partially executing.
Affected Silicon Revisions
40. Module: Low-Voltage Detect
If Low-Voltage Detect is enabled, the band gap is
disabled in Sleep, and the part is put to Sleep for a
short period of time, the LVD will trigger
immediately upon waking-up from Sleep.
Work around
Do not disable the band gap in Sleep when using
the LVD.
Affected Silicon Revisions
0xA 0xC
0xE
0x11
0x16 0x18 0x19
0x1B 0x1C
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0xA 0xC
0xE
0x11
0x16 0x18 0x19
0x1B
0x1C
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