ISL12026IBZ Intersil, ISL12026IBZ Datasheet - Page 8

• 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

X1, X2
The X1 and X2 pins are the input and output, respectively, of
an inverting amplifier. An external 32.768kHz quartz crystal
is used with the ISL12026 to supply a timebase for the real
time clock. Internal compensation circuitry provides high
accuracy over the operating temperature range from
-40°C to +85°C. This oscillator compensation network can
be used to calibrate the crystal timing accuracy
over-temperature either during manufacturing or with an
external temperature sensor and microcontroller for active
compensation. X2 is intended to drive a crystal only, and
should not drive any external circuit.
Real Time Clock Operation
The Real Time Clock (RTC) uses an external 32.768kHz
quartz crystal to maintain an accurate internal representation
of the second, minute, hour, day, date, month and year. The
RTC has leap-year correction. The clock also corrects for
months having fewer than 31 days and has a bit that controls
24 hour or AM/PM format. When the ISL12026 powers up
after the loss of both V
operate until at least one byte is written to the clock register.
Reading the Real Time Clock
The RTC is read by initiating a Read command and specifying
the address corresponding to the register of the Real Time
Clock. The RTC Registers can then be read in a Sequential
Read Mode. Since the clock runs continuously and a read
takes a finite amount of time, there is the possibility that the
clock could change during the course of a read operation. In
this device, the time is latched by the read command (falling
edge of the clock on the ACK bit prior to RTC data output) into
a separate latch to avoid time changes during the read
operation. The clock continues to run. Alarms occurring during
a read are unaffected by the read operation.
Writing to the Real Time Clock
The time and date may be set by writing to the RTC
registers. RTC Register should be written ONLY with Page
Write. To avoid changing the current time by an incomplete
write operation, write to the all 8 bytes in one write operation.
When writing the RTC registers, the new time value is
loaded into a separate buffer at the falling edge of the clock
during the Acknowledge. This new RTC value is loaded into
the RTC Register by a stop bit at the end of a valid write
sequence. An invalid write operation aborts the time update
procedure and the contents of the buffer are discarded. After
a valid write operation, the RTC will reflect the newly loaded
data beginning with the next “one second” clock cycle after
the stop bit is written. The RTC continues to update the time
FIGURE 7. RECOMMENDED CRYSTAL CONNECTION
DD
and V
8
BAT
X1
X2
, the clock will not
ISL12026, ISL12026A
while an RTC register write is in progress and the RTC
continues to run during any non-volatile write sequences.
Accuracy of the Real Time Clock
The accuracy of the Real Time Clock depends on the
accuracy of the quartz crystal that is used as the time base
for the RTC. Since the resonant frequency of a crystal is
temperature dependent, the RTC performance will also be
dependent upon temperature. The frequency deviation of
the crystal is a function of the turnover temperature of the
crystal from the crystal’s nominal frequency. For example, a
>20ppm frequency deviation translates into an accuracy of
>1 minute per month. These parameters are available from
the crystal manufacturer. Intersil’s RTC family provides
on-chip crystal compensation networks to adjust
load-capacitance to tune oscillator frequency from -34ppm to
+80ppm when using a 12.5pF load crystal. For more detailed
information, see “Application Section” on page 19.
Clock/Control Registers (CCR)
The Control/Clock Registers are located in an area separate
from the EEPROM array and are only accessible following a
slave byte of “1101111x” and reads or writes to addresses
[0000h:003Fh]. The clock/control memory map has memory
addresses from 0000h to 003Fh. The defined addresses are
described in the Table 1. Writing to and reading from the
undefined addresses are not recommended.
CCR Access
The contents of the CCR can be modified by performing a
byte or a page write operation directly to any address in the
CCR. Prior to writing to the CCR (except the status register),
however, the WEL and RWEL bits must be set using a three
step process (see “Writing to the Clock/Control Registers” on
page 12).
The CCR is divided into 5 sections. These are:
Each register is read and written through buffers. The
non-volatile portion (or the counter portion of the RTC) is
updated only if RWEL is set and only after a valid write
operation and stop bit. A sequential read or page write
operation provides access to the contents of only one section
of the CCR per operation. Access to another section requires
a new operation. A read or write can begin at any address in
the CCR.
It is not necessary to set the RWEL bit prior to writing the
status register. See “Status Register (SR)” on page 9.
supports a single byte read or write only. Continued reads or
writes from this section terminates the operation.
1. Alarm 0 (8 bytes; non-volatile)
2. Alarm 1 (8 bytes; non-volatile)
3. Control (5 bytes; non-volatile)
4. Real Time Clock (8 bytes; volatile)
5. Status (1 byte; volatile)
November 30, 2010
FN8231.9