ISL12026IBZ Intersil, ISL12026IBZ Datasheet - Page 20

• Manufacturer Part Number: ISL12026IBZ
• Description: IC RTC/CALENDAR EEPROM 8-SOIC
• Manufacturer: Intersil
• Type: Clock/Calendar/EEPROMr

Specifications of ISL12026IBZ

• Memory Size: 4K (512 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: 8-SOIC (3.9mm Width)
• Clock Format: HH
• Clock Ic Type: RTC
• Interface Type: I2C, Serial
• Memory Configuration: 512 X 8
• Supply Voltage Range: 2.7V To 5.5V
• Digital Ic Case Style: SOIC
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

A final application for the ATR control is in-circuit calibration
for high accuracy applications, along with a temperature
sensor chip. Once the RTC circuit is powered up with battery
backup, the IRQ/F
frequency drift is measured. The ATR control is then
adjusted to a setting which minimizes drift. Once adjusted at
a particular temperature, it is possible to adjust at other
discrete temperatures for minimal overall drift, and store the
resulting settings in the EEPROM. Extremely low overall
temperature drift is possible with this method. The Intersil
evaluation board contains the circuitry necessary to
implement this control.
For more detailed operation see Intersil’s application note
AN154 on Intersil’s website at www.intersil.com.
Layout Considerations
The crystal input at X1 has a very high impedance and will
pick up high frequency signals from other circuits on the
board. Since the X2 pin is tied to the other side of the crystal,
it is also a sensitive node. These signals can couple into the
oscillator circuit and produce double clocking or mis-
clocking, seriously affecting the accuracy of the RTC. Care
needs to be taken in layout of the RTC circuit to avoid noise
pickup. In Figure 23 is a suggested layout for the ISL12026
or ISL12027 devices in 8 pin SO package.
Frequency
Frequency Tolerance
Turnover Temperature
Operating Temperature Range
Parallel Load Capacitance
Equivalent Series Resistance
Citizen
Epson
Raltron
SaRonix
Ecliptek
ECS
Fox
MANUFACTURER
PARAMETER
OUT
output is set at 32.768kHz and
CM201, CM202, CM200S
MC-405, MC-406
RSM-200S-A or B
32S12A or B
ECPSM29T-32.768K
ECX-306/ECX-306I
FSM-327
20
TABLE 6. CRYSTAL PARAMETERS REQUIRED FOR INTERSIL RTCs
PART NUMBER
MIN
-40
20
TABLE 7. CRYSTAL MANUFACTURERS
32.768
TYP
12.5
25
ISL12026
MAX
±100
30
85
50
The X1 and X2 connections to the crystal are to be kept as
short as possible. A thick ground trace around the crystal is
advised to minimize noise intrusion, but ground near the X1
and X2 pins should be avoided as it will add to the load
capacitance at those pins. Keep in mind these guidelines for
other PCB layers in the vicinity of the RTC device. A small
decoupling capacitor at the V
with a solid connection to ground.
The ISL12026 product has a special consideration. The IRQ/
F
X2 pin. When this pin is used as a frequency output (IRQ/
F
X2 pins and cause double-clocking. The layout in Figure 23
TEMP RANGE
FIGURE 23. SUGGESTED LAYOUT FOR INTERSIL RTC IN SO-8
-40 to +85°C
-40 to +85°C
-40 to +85°C
-40 to +85°C
-10 to +60°C
-10 to +60°C
-40 to +85°C
OUT
OUT
- pin on the 8-lead SOIC package is located next to the
) and is set to 32.768kHz noise can couple to the X1 or
UNITS
ppm
kHz
k
°C
°C
pF
Ω
Down to 20ppm if desired
Typically the value used for most crystals
For best oscillator performance
+25°C FREQUENCY TOLERANCE
DD
pin of the chip is mandatory,
NOTES
±20ppm
±20ppm
±20ppm
±20ppm
±20ppm
±20ppm
±20ppm
October 23, 2006
FN8231.5