ISL12020MIRZ Intersil, ISL12020MIRZ Datasheet - Page 29

• Manufacturer Part Number: ISL12020MIRZ
• Description: IC RTC/CALENDAR TEMP SNSR 20-DFN
• Manufacturer: Intersil
• Type: Clock/Calendarr

Specifications of ISL12020MIRZ

• Memory Size: 1K (128 x 8)
• Time Format: HH:MM:SS (12/24 hr)
• Date Format: YY-MM-DD-dd
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-DFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Temperature Compensation Operation
The ISL12020M temperature compensation feature
needs to be enabled by the user. This must be done in a
specific order as follows.
Note that every time the BETA register is written with the
TSE bit = 1, a temperature compensation cycle is
instigated and a new correction value will be loaded into
the FATR/FDTR registers (if the temperature changed
since the last conversion).
Also note that registers 0Bh and 0Ch, the ITR0 and
ALPHA registers, should not be changed. If they must be
written be sure to write the same values that are recalled
from initial power-up. The ITR0 register may be written if
the user wishes to re-calibrate the oscillator frequency at
room temperature for aging or board mounting. The
original recalled value can be re-written if desired after
testing.
Daylight Savings Time (DST) Example
DST involves setting the forward and back times and
allowing the RTC device to automatically advance the
time or set the time back. This can be done for current
year, and future years. Many regions have DST rules that
use standard months, weeks and time of the day, which
permit a pre-programmed, permanent setting.
An example setup for the ISL12020M is in Table 26.
1. Read register 0Dh, the BETA register. This register
2. Bit 7 of the BETA register is the master enable
3. Bits 5 and 6 of the BETA register control
4. Write back to register 0Dh making sure not to
contains the 5-bit BETA trimmed value, which is
automatically loaded on initial power-up. Mask off
the 5LSB’s of the value just read.
control for temperature sense operation. Set this to
“1” to allow continuous temperature frequency
correction. Frequency correction will then happen
every 60s with V
temperature compensation in battery-backup mode
(see Table 15 on page 20). Set the values for the
operation desired.
change the 5 LSB values, and include the desired
compensation control bits.
DD
applied.
29
ISL12020M
The Enable bit (DSTE) is in the Month forward register, so
the BCD value for that register is altered with the
additional bit. The Week and Day values along with
Week/Day vs Date select bit is in the Week/Day register,
so that value is also not straight BCD. Hour and Month
are normal BCD, but the Hour doesn’t use the MIL bit
since Military time PM values are already discretely
different from AM/PM time PM values. The DST reverse
setting utilizes the option to select the last week of the
month for October, which could have 4 or 5 weeks but
needs to have the time change on the last Sunday.
Note that the DSTADJ bit in the status register monitors
whether the DST forward adjustment has happened.
When it is “1”, DST forward has taken place. When it is
“0”, then either DST reverse has happened, or it has
been reset either by initial power-up or if the DSTE bit
has been set to “0”.
Month Forward and
DST Enable
Week and Day Forward
and select Day/Week,
not Date
Date Forward
Hour Forward
Month Reverse
Week and Day Reverse
and select Day/Week,
not Date
Date Reverse
Hour Reverse
VARIABLE
TABLE 26. DST EXAMPLE
April
1st Week and
Sunday
not used
2am
October
Last Week
and Sunday
not used
2am
VALUE
15h
16h
17h
18h
19h
1Ah
1Bh
1Ch
REGISTER
February 11, 2010
84h
48h
00h
02h
10h
78h
00h
02h
VALUE
FN6667.4