MCP795WXX Family Silicon Errata and Data Sheet Clarification

MCP795WXX
MCP795WXX Family Silicon Errata
The MCP795WXX family devices that you have
received conform functionally to the current Device
Data Sheet (DS22280C), except for the anomalies
described in this document.
TABLE 1:
AFFECTED PART NUMBERS
The silicon issues discussed in the following pages are
for devices listed in Table 1. The silicon issues are
summarized in Table 2.
The errata described in this document will be addressed
in future revisions of the MCP795WXX silicon.
Note:
This document summarizes all silicon
errata issues from all revisions of silicon,
previous as well as current. Only the
issues indicated in the last column of
Table 2 apply to the current silicon
revision.
Note:
For more information on identifying the
product date code, refer to Packaging
Information section of the product Data
Sheet or contact your local Microchip
sales office.
TABLE 2:
SILICON ISSUE SUMMARY
Part Number
MCP795W10
MCP795W11
MCP795W12
MCP795W20
MCP795W21
MCP795W22
Affected Date Codes(1, 2)
Issue Number
Issue Summary
All
1
Time running fast when VCC > 3.6V.
X
2
Incorrect square wave clock output frequency when VCC > 3.6V.
X
3
Incorrect EVLS debounce period when VCC > 3.6V.
X
4
Incorrect WDT time-out period and pulse width when VCC > 3.6V.
X
5
Incorrect alarm interrupt output pulse width when using the WDO
pin and VCC > 3.6V.
X
6
Date incrementing at noon.
X
Month write resetting date to 1.
X
7
Note 1:
2:
Only those issues indicated in the last column apply to the current silicon revision.
The date codes are presented in YYWW format.
 2012-2015 Microchip Technology Inc.
DS80000542B-page 1
MCP795WXX
4. Issue:
Silicon Errata Issues
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.
Incorrect WDT Timings
When VCC is greater than 3.6V, the Watchdog
Timer time-out period and output pulse width will
not match the data sheet-specified values.
Work around
Operate the device at or below 3.6V.
Affected Silicon Revisions
1. Issue:
Time Running Fast
When VCC is greater than 3.6V, the internal time
keeping registers do not count correctly,
resulting in fast operation.
All
X
5. Issue:
Work around
Operate the device at or below 3.6V.
Affected Silicon Revisions
All
X
2. Issue:
Incorrect Clock Output
Frequency
When Vcc is greater than 3.6V, selecting a
square wave frequency for the CLKOUT pin
other than 32.768 kHz will result in the incorrect
frequency being outputted.
Work around
Operate the device at or below 3.6V or select
32.768 kHz output.
Affected Silicon Revisions
All
X
3. Issue:
Incorrect EVLS Debounce
Timing
Incorrect Alarm Output Pulse
Width
When VCC is greater than 3.6V, if the WDO pin
is selected as the alarm interrupt output pin, the
output pulse width will not match the data sheetspecified value.
Work around
Operate the device at or below 3.6V.
Affected Silicon Revisions
All
X
6. 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
oscillator 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 increment again at 12:00 AM.
Work around
When VCC is greater than 3.6V, the low-speed
event detect debounce period will not match the
data sheet-specified values.
Disable the oscillator by ensuring both the ST
and EXTOSC bits are cleared and wait for the
OSCON bit to clear before loading the new hour
value.
Work around
Affected Silicon Revisions
Operate the device at or below 3.6V.
Affected Silicon Revisions
All
X
All
X
DS80000542B-page 2
 2012-2015 Microchip Technology Inc.
MCP795WXX
7. Issue:
Date Reset after Month Write
If the application writes a new month value to the
timekeeping registers, some combinations of
date and month values may result in the date
being reset to 1, even if the date is also written
with the month.
Work around
When writing the month, always write the date
first, using a separate Write command, even if
the date value is not being changed. Avoid
writing date and month values within the same
Write command. Instead, terminate the Write
command after loading the date and begin a
new command to write the month. In addition,
disable the oscillator before loading the new
values. This is done by ensuring both the ST
and EXTOSC bits are cleared and waiting for
the OSCON bit to clear before loading the new
values.
Affected Silicon Revisions
All
X
 2012-2015 Microchip Technology Inc.
DS80000542B-page 3
MCP795WXX
APPENDIX A:
DOCUMENT
REVISION HISTORY
Rev A Document (03/2012)
Initial release of this document.
Rev B Document (12/2015)
Adopted new document format. Added silicon issues 6
(date incrementing at noon) and 7 (month write resetting date to 1). Removed MCP795BXX part numbers.
DS80000542B-page 4
 2012-2015 Microchip Technology Inc.
MCP795WXX
Note the following details of the code protection feature on Microchip devices:
•
Microchip products meet the specification contained in their particular Microchip Data Sheet.
•
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
•
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
•
Microchip is willing to work with the customer who is concerned about the integrity of their code.
•
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device
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and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
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Trademarks
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Analog-for-the-Digital Age, BodyCom, chipKIT, chipKIT logo,
CodeGuard, dsPICDEM, dsPICDEM.net, ECAN, In-Circuit
Serial Programming, ICSP, Inter-Chip Connectivity, KleerNet,
KleerNet logo, MiWi, motorBench, MPASM, MPF, MPLAB
Certified logo, MPLIB, MPLINK, MultiTRAK, NetDetach,
Omniscient Code Generation, PICDEM, PICDEM.net, PICkit,
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ViewSpan, WiperLock, Wireless DNA, and ZENA are
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© 2012-2015, Microchip Technology Incorporated, Printed in
the U.S.A., All Rights Reserved.
ISBN: 978-1-5224-0090-5
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DS80000542B-page 5
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DS80000542B-page 6
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