Datasheet

MCP7940N
DS80000611B-page 2  2014-2015 Microchip Technology Inc.
Silicon Errata Issues
1. Issue: Date Increment
When operating in 12-hour mode
(RTCHOUR<6> is set) if the application loads
an hour value before 12:00 PM while the oscilla-
tor is running then the date and day of week may
increment at 12:00 PM. When this occurs, the
month and year will also increment according to
the normal rollover rules. The date will incre-
ment again at 12:00 AM.
Work around
Disable the oscillator by ensuring both the ST
and EXTOSC bits are cleared and wait for the
OSCRUN bit to clear before loading the new
hour value.
Affected Silicon Revisions
2. Issue: Spurious Minute-Match Alarm
Interrupt
When using an alarm to match on minutes
(ALMxMSK<2:0> = 001) and digital trimming is
being used to slow down the time
(TRIMVAL<6:0> > 0 and SIGN = 0), spurious
alarm interrupts may occur at incorrect minutes.
Work around
When an alarm interrupt occurs, read the
RTCMIN register and confirm the minute
matches the desired value for the alarm.
Affected Silicon Revisions
Note: This document summarizes all silicon
errata issues from all revisions of silicon,
previous as well as current. Only the
issues indicated by the shaded column in
the following tables apply to the current
silicon revision.
All
X
All
X