DATASHEET
ISL12022MR5421
Low Power RTC with Battery Backed SRAM, Integrated ±5ppm Temperature
Compensation and Auto Daylight Saving
FN7576
Rev 3.00
June 7, 2012
The ISL12022MR5421 device is a low power real time clock
(RTC) with an embedded temperature sensor and crystal.
Device functions include oscillator compensation,
clock/calendar, power fail and low battery monitors, brownout
indicator, one-time, periodic or polled alarms, intelligent
battery backup switching, Battery Reseal™ function and 128
bytes of battery-backed user SRAM. The device is offered in a
20 Ld SOIC module that contains the RTC and an embedded
32.768kHz quartz crystal. The calibrated oscillator provides
less than ±5ppm drift over the full -40°C to +85°C
temperature range.
The RTC tracks time with separate registers for hours, minutes,
and seconds. The calendar registers track date, month, year
and day of the week and are accurate through 2099, with
automatic leap year correction.
Daylight Savings time adjustment is done automatically, using
parameters entered by the user. Power fail and battery
monitors offer user-selectable trip levels. The time stamp
function records the time and date of switchover from VDD to
VBAT power, and also from VBAT to VDD power.
The ISL12022MR5421 has redesign package to increase
Contact and Air Discharge ESD performance.
Related Literature
• See AN1549 “Addressing Power Issues in Real Time Clock
Applications”
Features
• Embedded 32.768kHz Quartz Crystal in the Package
• 20 Ld SOIC Package (for DFN version, refer to the
ISL12020M)
• Calendar
• On-chip Oscillator Temperature Compensation
• 10-bit Digital Temperature Sensor Output
• 15 Selectable Frequency Outputs
• Interrupt for Alarm or 15 Selectable Frequency Outputs
• Automatic Backup to Battery or Supercapacitor
• VDD and Battery Status Monitors
• Battery Reseal™ Function to Extend Battery Shelf Life
• Power Status Brownout Monitor
• Time Stamp for Battery Switchover
• 128 Bytes Battery-Backed User SRAM
• I2C-Bus™
• RoHS Compliant
Applications
• Utility Meters
• POS Equipment
• Printers and Copiers
• Digital Cameras
1 GND GND 20
2 GND GND 19
3 GND
4 NC
GND 18
NC 17
3.3V
SCHOTTKY DIODE
BAT54
BATTERY
3.0V
0.1µCF2
5
6
7
8
9
NC
GND
VBAT
GND
NC
NC
GND
VDD
IRQ/FOUT
SCL
16
15
14
13
12
C1
0.1µF
R1 R2 R3
10k 10k 10k
10 NC
SDA 11
ISL12022MR5421
VDO
SCL MCU
SDAINTERFACE
GND
IRQ/FOUT
FIGURE 1. TYPICAL APPLICATION CIRCUIT
5 OSCILLATOR ERROR vs TEMPERATURE
4
3
2
1
0 VBAT = 5.5V
-1 VDD = 2.7V
-2
-3 VDD = 3.3V
-4
-5
-40 -20
0 20 40
TEMPERATURE (°C)
60
80
FIGURE 2. PERFORMANCE CURVE
FN7576 Rev 3.00
June 7, 2012
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