Information

 2010-2013 Microchip Technology Inc. DS80000500F-page 7
PIC18F87K90 FAMILY
Work around
None.
Affected Silicon Revisions
7. Module: Ultra Low-Power Sleep
Entering Ultra Low-Power Sleep mode, by
setting RETEN = 0 and SRETEN = 1, will cause
the part not to be programmable through ICSP.
This issue occurs when the RETEN fuse bit in
CONFIG1L<0> is cleared to ‘0’, the SRETEN bit
in the WDTCON register is set to ‘1’ and a
SLEEP instruction is executed within the first
350 µs of code execution, or whenever the
above Sleep mode is entered and MCLR
is
disabled. Discontinue use of the MCLR
disabled
RG5 mode if ICSP reprogramming is necessary.
Work around
Use normal Sleep and Low-Power Sleep modes
only, or on any Reset, ensure at least 350 µs
passes before executing a SLEEP instruction
when ULP is enabled. To ensure the Ultra
Low-Power Sleep mode is not enabled, the
RETEN fuse bit in CONFIG1L<0> should be set
to a ‘1’, and the SRETEN bit in the WDTCON
register should be cleared to a ‘0’. The following
code can be used:
//This will ensure the RETEN fuse is
set to 1
#pragma config RETEN = OFF
//This will ensure the SRETEN bit is 0
WDTCONbits.SRETEN = 0;
If the Ultra Low-Power Sleep mode is needed,
then the user must ensure that the minimum
time, before the first SLEEP instruction is
executed, is greater than 350 µs.
Affected Silicon Revisions
8. Module: Resets (BOR)
An unexpected Reset may occur if the Brown-out
Reset module (BOR) is disabled, and then
re-enabled, when the High/Low-Voltage Detection
module (HLVD) is not enabled
(HLVDCON<4> = 0). This issue affects BOR
modes: BOREN<1:0> = 10 and
BOREN<1:0> = 01. In both of these modes, if the
BOR module is re-enabled while the device is
active, unexpected Resets may be generated.
Work around
If BOR is required, and power consumption is
not an issue, use BOREN<1:0> = 11. For
BOREN<1:0> = 10 mode, either switch to
BOREN<1:0> = 11 mode or enable the HLVD
(HLVDCON<4> = 1) prior to entering Sleep. If
power consumption is an issue and low power is
desired, do not use BOREN<1:0> = 10 mode.
Instead, use BOREN<1:0> = 01 and follow the
steps below when entering and exiting Sleep.
1. Disable BOR by clearing SBOREN
(RCON<6> = 0).
WDTCONbits.SBOREN = 0;
2. Enter Sleep mode (if desired).
Sleep();
3. After exiting Sleep mode (if entered), enable the
HLVD (HLVDCON<4> = 1).
HLVDCONbits.HLVDEN = 1;
4. Wait for the internal reference voltage (T
IRVST)
to stabilize (typically 25 us).
while(!HLVDCONbits.IRVST);
5. Re-enable BOR by setting SBOREN
(RCON<6> = 1).
WDTCONbits.SBOREN = 1;
6. Disable the HLVD by clearing HLVDEN
(HLVDCON<4> = 0).
HLVDCONbits.HLVDEN = 0;
Affected Silicon Revisions
A1 B1 B3 C1 C3
X
A1 B1 B3 C1 C3
XX
X
A1 B1 B3 C1 C3
XX
X X X