ISL12057 Datasheet, PDF (7/17 Pages) Intersil Corporation – Low Cost and Low Power I2C RTC Real Time Clock/Calendar

ISL12057
Typical Performance Curves Temperature is +25°C unless otherwise specified
0.7
1.0
0.6
0.5
0.4
0.3
0.2
0.1
0
1.4
1.9
2.4
2.9
3.4
V_DD (V)
FIGURE 2. I_DD1 vs V_DD
0.8
3.6
0.6
3.0
0.4
1.8
1.4
0.2
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
FIGURE 3. I_DD1 vs TEMPERATURE
1.2
1.1
32768Hz
1.0
0.9
0.8
0.7
8192Hz
0.6
4096Hz
0.5
0.4
0.3
1Hz
0.2
1.4
1.9
2.4
2.9
3.4
V_DD (V)
FIGURE 4. I_DD vs V_DD vs F_OUT
General Description
The ISL12057 device is a low power real time clock with
clock/calendar, power fail indicator, and alarm function.
The oscillator uses an external, low-cost 32.768kHz crystal.
The real time clock tracks time with separate registers for
hours, minutes, and seconds. The device has calendar
registers for date, month, year and day of the week. The
calendar is accurate through 2099, with automatic leap year
correction.
The ISL12057 has two flexible alarms; each can be set to any
clock/calendar value for a match. For example, every minute,
every Tuesday or at 5:23 AM on 1st day of a month. The alarm
status is available by checking the Status Register, or the
device can be configured to provide a hardware interrupt via the
IRQ1/F_OUT or IRQ2 pin. There is a repeat mode for the alarm
allowing a periodic interrupt every second or every minute.
32769.0
32768.8
32768.6
32768.4
32768.2
32768.0
32767.8
32767.6
32767.4
32767.2
32767.0
1.4
1.9
2.4
2.9
3.4
V_DD (V)
FIGURE 5. F_OUT VS V_DD WITH A TYPICAL 32.768kHZ CRYSTAL
Pin Description
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 ISL12057 to supply a timebase for the real
time clock. Refer to Figure 6.
The device can also be driven directly from a 32.768kHz
square wave source with peak-to-peak voltage from 0V to
VDD at X1 pin with X2 pin floating.
X1
X2
FIGURE 6. RECOMMENDED CRYSTAL CONNECTION
7
FN6755.0
June 15, 2009