Datasheet

 2012-2018 Microchip Technology Inc. DS20002300C-page 31
MCP7951X/MCP7952X
5.6.2 COARSE TRIM MODE
When CRSTRIM = 1, Coarse Trim mode is enabled.
While in this mode, the MCP795XX will apply trimming
every second. If SQWEN is set, the CLKOUT pin will
output a trimmed 1 Hz nominal clock signal.
Because trimming is applied every second rather than
every minute, each step of the TRIMVAL<7:0> value
has a larger effect on the resulting time deviation and
output clock frequency.
By monitoring the CLKOUT output frequency while in
this mode, the user can easily observe the
TRIMVAL<7:0> value affecting the clock timing.
TABLE 5-10: SUMMARY OF REGISTERS ASSOCIATED WITH DIGITAL TRIMMING
Note 1: The 1 Hz Coarse Trim mode square
wave output is not available while
operating from the backup power supply.
2: With Coarse Trim mode enabled, the
TRIMVAL<7:0> value has a larger effect
on timing. Leaving the mode enabled
during normal operation will likely result
in inaccurate time.
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Register
on Page
RTCHOUR TRIMSIGN
12/24 AM/PM
HRTEN1
HRTEN0 HRONE3 HRONE2 HRONE1 HRONE0 18
CONTROL
—SQWENALM1EN ALM0EN EXTOSC CRSTRIM SQWFS1 SQWFS0 28
OSCTRIM TRIMVAL7 TRIMVAL6 TRIMVAL5 TRIMVAL4 TRIMVAL3 TRIMVAL2 TRIMVAL1 TRIMVAL0 29
Legend: — = unimplemented location, read as ‘0’. Shaded cells are not used by digital trimming.l