ISL12023IVZ Intersil, ISL12023IVZ Datasheet - Page 27

• Manufacturer Part Number: ISL12023IVZ
• Description: IC RTC/CLDR TEMP SNSR 14-TSSOP
• Manufacturer: Intersil
• Type: Clock/Calendarr

Specifications of ISL12023IVZ

• 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: 14-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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.
For further information on the operation of the ISL12023 and
temperature compensated RTC’s, see Intersil Application
Note AN1389, “Using Intersil’s High Accuracy Real Time
Clock Module”.
http://www.intersil.com/data/an/AN1389.pdf
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.
Table 27 shows an example setup for the ISL12023.
27
ISL12023
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
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 27. 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
June 24, 2009
84h
48h
00h
02h
10h
78h
00h
02h
VALUE
FN6682.2