ISL12026IBZ Intersil, ISL12026IBZ Datasheet - Page 21

• 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

circuits in less than one second. Some circuits may take
slightly longer, but start-up should definitely occur in less
than 5 seconds. When testing RTC circuits, the most
common impulse is to apply a scope probe to the circuit at
the X2 pin (oscillator output) and observe the waveform. DO
NOT DO THIS! Although in some cases you may see a
usable waveform, due to the parasitics (usually 10pF to
ground) applied with the scope probe, there will be no useful
information in that waveform other than the fact that the
circuit is oscillating. The X2 output is sensitive to capacitive
impedance so the voltage levels and the frequency will be
affected by the parasitic elements in the scope probe.
Applying a scope probe can possibly cause a faulty oscillator
to start up, hiding other issues (although in the Intersil RTCs,
the internal circuitry assures start-up when using the proper
crystal and layout).
The best way to analyze the RTC circuit is to power it up and
read the real time clock as time advances, or if the chip has
the IRQ/F
oscilloscope (after enabling it with the control register, and
using a pull-up resistor for an open-drain output).
Alternatively, the ISL12026 device has an IRQ/F
which can be checked by setting an alarm for each minute.
Using the pulse interrupt mode setting, the once-per-minute
interrupt functions as an indication of proper oscillation.
Backup Battery Operation
Many types of batteries can be used with the Intersil RTC
products. 3.0V or 3.6V Lithium batteries are appropriate, and
sizes are available that can power a Intersil RTC device for
up to 10 years. Another option is to use a SuperCap for
applications where V
short periods of time. Depending on the value of SuperCap
used, backup time can last from a few days to two weeks
(with >1F). A simple silicon or Schottky barrier diode can be
used in series with V
connected to the V
very low leakages, <1
charge a battery (especially lithium batteries!)
There are two possible modes for battery backup operation;
Standard and Legacy mode. In Standard mode, there are no
operational concerns when switching over to battery backup
since all other devices functions are disabled. Battery drain
is minimal in Standard mode, and return to Normal V
powered operations is predictable. In Legacy mode, the
V
less than V
alarm and communicate with the device, unless SBI = 1, but
the supply current drain is much higher than the Standard
mode and backup time is reduced. In this case, if alarms are
used in backup mode, the IRQ/F
connected to V
BAT
pin can power the chip if the voltage is above V
OUT
TRIP
output, look at the output of that pin on an
BAT
. In this mode, it is possible to generate the
BAT
voltage source.
DD
DD
µA
pin. Try to use Schottky diodes with
to charge the SuperCap, which is
may disappear intermittently for
desirable. Do not use the diode to
21
OUT
pull-up resistor must be
OUT
ISL12026, ISL12026A
DD
DD
output,
and
Alarm Operation Examples
Following are examples of both Single Event and periodic
Interrupt Mode alarms.
EXAMPLE 1
Alarm 0 set with single interrupt (IM = ”0”)
A single alarm will occur on January 1 at 11:30am.
A. Set Alarm 0 registers as follows:
B. Also the AL0E bit must be set as follows:
After these registers are set, an alarm will be generated when
the RTC advances to exactly 11:30am on January 1 (after
seconds changes from 59 to 00) by setting the AL0 bit in the
status register to “1” and also bringing the IRQ/F
EXAMPLE 2
Pulsed interrupt once per minute (IM = ”1”)
Interrupts at one minute intervals when the seconds register
is at 30 seconds.
A. Set Alarm 0 registers as follows:
B. Set the Interrupt register as follows:
REGISTER
REGISTER
2.7V TO 5.5V
CONTROL
ALARM0
MNA0
MOA0
DWA0
HRA0
SCA0
DTA0
INT
FIGURE 24. SUPERCAPACITOR CHARGING CIRCUIT
7 6 5 4 3 2 1 0 HEX
0 0 0 0 0 0 0 0
1 0 1 1 0 0 0 0
1 0 0 1 0 0 0 1
1 0 0 0 0 0 0 1
1 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0
7 6 5 4 3 2 1 0 HEX
0 0 1 0 0 0 0 0
V
DD
V
BIT
BIT
SS
V
BAT
00h Seconds disabled
B0h Minutes set to 30,
91h Hours set to 11,
81h Date set to 1,
81h Month set to 1,
00h Day of week
x0h Enable Alarm
SUPERCAP
enabled
enabled
enabled
enabled
disabled
DESCRIPTION
DESCRIPTION
OUT
November 30, 2010
output low.
FN8231.9