R
EM MICROELECTRONIC -
MARIN SA
EM3027
Real Time Clock with I2C or SPI, Crystal Temperature
Compensation, Battery Switchover and Trickle Charger
Description
The EM3027 is an Ultra Low Power CMOS real-time
clock IC with two serial interface modes: I2C or SPI. The
interface mode is selected by the chip version (see §12).
The basic clock is obtained from the 32.768 kHz crystal
oscillator. A thermal compensation of the frequency is
based on the temperature measurement and calculation
of the correction value. The temperature can be
measured internally or be input by an external application
to the register.
The chip provides clock and calendar information in BCD
format with alarm possibility. The actual contents are
latched at the beginning of a read transmission and
afterwards data are read without clock counter data
corruption.
An integrated 16-bit timer can run in Zero-Stop or Auto-
Reload mode.
An interrupt request signal can be provided through
INT/IRQ pin generated from alarm, timer, voltage
detector and Self-Recovery system.
An integrated trickle charger allows recharging backup
supply V
Back
from the main supply voltage V
CC
through
internal resistor(s). The internal device supply will
switchover to V
CC
when V
CC
is higher than V
Back
and vice
versa.
The device operates over a wide 1.4 to 5.5V supply
range and requires only 900 nA at 5V. It can detect
internally two supply voltage levels.
Applications
Utility meters
Battery operated and portable equipment
Consumer electronics
White/brown goods
Pay phones
Cash registers
Personal computers
Programmable controller systems
Data loggers
Features
Fully operational from 2.1 to 5.5V
Supply current typically 600 nA at 1.4V
Thermal compensated crystal frequency
Oscillator stability 0.5 ppm / Volt
Counter for seconds, minutes, hours, day of week,
date months, years in BCD format and alarm
Leap year compensation
16-bits timer with 2 working modes
Two low voltage detection levels V
Low1
, V
Low2
Automatic supply switchover
2
Serial communication via I2C (I C-bus specification
Rev. 03 compatible – see §10.2) or SPI (3-line SPI-
bus with separate combinable data input and output)
Thermometer readable by the host
Trickle charger to maintain battery charge
Integrated oscillator capacitors
Two EEPROM and 8 RAM data bytes for application
Digital Self-Recovery system
No busy states and no risk of corrupted data while
accessing
One hour periodical configuration registers refresh
Support for standard UL1642 for Lithium batteries
Standard temperature range: -40°C to +85°C
Extended temperature range: -40°C to +125°C
Packages: TSSOP8, TSSOP14, SO8.
Block Diagram
EM3027
Temperature
Sensor
X1
Oscillator
X2
V
CC
V
REG
V
Back
SCL/SCK
SDA/SO
SI
CS
CLKOUT
INT or IRQ
CLKOE
Watch & Alarm
- Seconds
- Minutes
- Hours
- Days
- Weekdays
- Months
- Years
Timer
Power
Management
I2C
or SPI
Output
Control
EEPROM
Copyright © 2009, EM Microelectronic-Marin SA
12/09 – rev D
1
www.emmicroelectronic.com
EMMICRO [ EM MICROELECTRONIC - MARIN SA ]
