
1
Low Power RTC with Battery Backed SRAM, Integrated
±5ppm Temperature Compensation and Auto Daylight
Saving
ISL12022MR5421
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
FIGURE 1. TYPICAL APPLICATION CIRCUIT
FIGURE 2. PERFORMANCE CURVE
GND
NC
GND
NC
GND
NC
VBAT
VDD
GND IRQ/FOUT
NC
SCL
SDA
ISL12022MR5421
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
SCHOTTKY DIODE
BAT54
BATTERY
3.0V
3.3V
C2
0.1F
C1
0.1F
R1
10k
R2
10k
R3
10k
VDO
SCL
SDA
GND
MCU
INTERFACE
IRQ/FOUT
-5
-4
-3
-2
-1
0
1
2
3
4
5
-40
-20
0
20
406080
TEMPERATURE (°C)
F
OU
T
FRE
Q
UENCY
ERROR
(ppm
)
VDD = 2.7V
VBAT = 5.5V
VDD = 3.3V
OSCILLATOR ERROR vs TEMPERATURE
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774
|Copyright Intersil Americas Inc. 2010-2012. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
June 7, 2012
FN7576.3