ISL12023IVZ Intersil, ISL12023IVZ Datasheet - Page 17

• 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

ALPHA Register (ALPHA)
The Alpha variable is 8 bits and is defined as the
temperature coefficient of Crystal from -40°C to T0, or the
Alpha Cold (there is an Alpha Hot register that must be
programmed as well). It is normally given in units of
ppm/°C
device uses a scaled version of the absolute value of this
coefficient in order to get an integer value. Therefore,
Alpha<7:0> is defined as the (|Actual Alpha Value| x 2048)
and converted to binary. For example, a crystal with Alpha of
-0.034ppm/°C
then converted to a binary number of 01000110b.
The practical range of Actual Alpha values is from
-0.020 to -0.060.
The ALPHA register should only be changed while the TSE
(Temp Sense Enable) bit is “0”. Note that both the ALPHA
and the ALPHA Hot registers need to be programmed with
values for full range temperature compensation.
BETA Register (BETA)
TEMPERATURE SENSOR ENABLED BIT (TSE)
This bit enables the Temperature Sensing operation, including
the temperature sensor, A/D converter and AT/DT register
adjustment. The default mode after power-up is disabled
(TSE = 0). To enable the operation, TSE should be set to 1
(TSE = 1). When temperature sense is disabled, the initial
values for IATR and IDTR registers are used for frequency
control.
All changes to the IDTR, IATR, ALPHA and BETA registers
must be made with TSE = 0. After loading the new values,
TSE can be enabled and the new values are used. When TSE
is set to 1, the temperature conversion cycle begins and will
end when two temperature conversions are completed. The
average of the two conversions is in the TEMP registers.
IATR05 IATR04 IATR03 IATR02 IATR01 IATR00
ADDR
ADDR
0Dh
0Ch
1
1
1
1
TABLE 12. IATRO TRIMMING RANGE (Continued)
2
TSE BTSE BTSR BETA4 BETA3 BETA2 BETA1 BETA0
, with a typical value of -0.034. The ISL12023
7
7
D
1
1
1
1
2
ALPHA6 ALPHA5 ALPHA4 ALPHA3 ALPHA2 ALPHA1 ALPHA0
is first scaled (|2048*(-0.034)| = 70d) and
6
6
TABLE 13. ALPHA REGISTER
1
1
1
1
5
5
TABLE 14.
1
1
1
1
17
4
4
0
0
1
1
3
3
2
0
1
0
1
2
TRIMMING
RANGE
1
1
-28
-29
-30
-31
ISL12023
0
0
TEMP SENSOR CONVERSION IN BATTERY MODE BIT
(BTSE)
This bit enables the Temperature Sensing and Correction in
battery mode. BTSE = 0 (default) no conversion, Temp Sensing
or Compensation in battery mode. BTSE = 1 indicates Temp
Sensing and Compensation enabled in battery mode. The
BTSE is disabled when the battery voltage is lower than 2.7V.
No temperature compensation will take place with V
FREQUENCY OF TEMPERATURE SENSING AND
CORRECTION BIT (BTSR)
This bit controls the frequency of Temp Sensing and
Correction. BTSR = 0 default mode is every 10 minutes,
BTSR = 1 is every 1.0 minute. Note that BTSE has to be
enabled in both cases. See Table 15.
The temperature measurement conversion time is the same
for battery mode as for V
battery mode current will increase during this conversion time
to typically 68µA. The average increase in battery current is
much lower than this due to the small duty cycle of the
ON-time versus OFF-time for the conversion.
To figure the average increase in battery current, we take the
the change in current times the duty cycle. For the 1 minute
temperature period the average current is shown in Equation 1:
For the 10 minute temperature period the average current is
shown in Equation 2:
If the application has a stable temperature environment that
doesn’t change quickly, the 10 minute option will work well
and the backup battery lifetime impact is minimized. If quick
temperature variations are expected (multiple cycles of more
than 10° within an hour), then the 1 minute option should be
considered and the slightly higher battery current figured into
overall battery life.
GAIN FACTOR OF AT BIT (BETA<4:0>)
Beta is specified to take care of the Cm variations of the
crystal. Most crystals specify Cm around 2.2fF. For example, if
Cm > 2.2fF, the actual AT steps may reduce from 1ppm/step
to approximately 0.80ppm/step. Beta is then used to adjust for
this variation and restore the step size to 1ppm/step.
ΔI
ΔI
TABLE 15. FREQUENCY OF TEMPERATURE SENSING AND
BAT
BAT
=
=
BTSE
0.022s
----------------- -
0.022s
----------------- -
600s
60s
0
0
1
1
CORRECTION BIT
×
×
68μA
68μA
=
=
250nA
25nA
DD
mode, approximately 22ms. The
BTSR
0
1
0
1
BATTERY MODE
TC PERIOD IN
10 Minutes
1 Minute
OFF
OFF
BAT
June 24, 2009
<2.7V.
FN6682.2
(EQ. 1)
(EQ. 2)