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
Watch & Alarm
Oscillator
X2
V
CC
V
REG
V
Back
SCL/SCK
SDA/SO
SI
CS
CLKOUT
INT or IRQ
CLKOE
Power
Management
I2C
or SPI
- Seconds
- Minutes
- Hours
- Days
- Weekdays
- Months
- Years
Timer
Output
Control
EEPROM
Copyright
2011, EM Microelectronic-Marin SA
3027-DS.doc, Version 6.0, 20-Jun-11
1
www.emmicroelectronic.com
EM3027
Table of contents
Table of contents ..................................................................................................................................................................... 2
1 Packages / Pin Out Configuration .................................................................................................................................... 3
2 Absolute Maximum Ratings .............................................................................................................................................. 4
6 Definitions of terms in the memory mapping .................................................................................................................. 10
7 Serial communication ..................................................................................................................................................... 12
7.1
How to perform data transmission through I2C ....................................................................................................... 12
7.2
How to perform data transmission through SPI ....................................................................................................... 13
Start after power-up ................................................................................................................................................ 15
8.2
Normal Mode function ............................................................................................................................................. 15
8.3
Watch and Alarm function ....................................................................................................................................... 15
8.4
Timer function ......................................................................................................................................................... 16
8.5
Temperature measurement ..................................................................................................................................... 16
8.6
Frequency compensation ........................................................................................................................................ 16
RAM User Memory .................................................................................................................................................. 18
8.9
Status Register........................................................................................................................................................ 18
Self-Recovery System (SRS) ............................................................................................................................. 19
Crystal Oscillator and Prescaler ......................................................................................................................... 19
9
Power Management ................................................................................................................................................ 20
9.1
Power Supplies, Switchover and Trickle Charger ................................................................................................... 20
AC Characteristics .................................................................................................................................................. 22
10.1
AC characteristics – I2C ..................................................................................................................................... 22
AC characteristics – SPI ..................................................................................................................................... 24
11
Package Information ............................................................................................................................................... 26
Ordering Information ............................................................................................................................................... 28
Copyright
2011, EM Microelectronic-Marin SA
3027-DS.doc, Version 6.0, 20-Jun-11
2
www.emmicroelectronic.com
EM3027
1
Packages / Pin Out Configuration
Pin
1
2
3
4
5
6
7
8
Table 1
Name
X1
X2
V
Back
V
SS
SDA
SCL
IRQ/CLKOUT
V
CC
Function
32.768 kHz crystal input
32.768 kHz crystal output
Backup Supply
Ground Supply
Serial Data
Serial Clock
Interrupt Request/Clock output
Positive Supply
SO8-TSSOP8
X1
X2
Vcc
IRQ/CLKOUT
EM3027
V
Back
Vss
SCL
SDA
I2C
TSSOP14
X1
X2
SI
NC
CLKOE
V
CC
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
Name
X1
X2
SI
V
Reg
V
Back
INT
V
SS
SO
SCK
CS
IRQ/CLKOUT
V
CC
CLKOE
V
Reg
V
Back
INT
Vss
EM3027
IRQ/CLKOUT
CS
SCK
SO
SPI
14
NC
Table 2
Function
32.768 kHz crystal input
32.768 kHz crystal output
Serial Data input
Regulated Voltage – Reserved for
test purpose (This output must be
left unconnected)
Backup Supply
Interrupt Request output
(Open Drain active low)
Ground Supply
Serial Data output
Serial Clock input
Chip Select input
Interrupt Request/Clock output
Positive Supply
Clock Output Enable
CLKOE = „0‟ CLKOUT is low
CLKOE = „1‟ CLKOUT is output
Not Connected
Copyright
2011, EM Microelectronic-Marin SA
3027-DS.doc, Version 6.0, 20-Jun-11
3
www.emmicroelectronic.com
EM3027
2
Absolute Maximum Ratings
Symbol
V
CCmax
V
CCmin
V
max
V
min
T
STOmax
T
STOmin
V
Smax
Conditions
V
SS
+ 6.0V
V
SS
– 0.3V
V
CC
+ 0.3V
V
SS
– 0.3V
+150°C
-65°C
2000V
2.2
Operating Conditions
Symbol
Min
Typ
Max
Unit
Parameter
Maximum voltage at V
CC
Minimum voltage at V
CC
Maximum voltage at any
signal pin
Minimum voltage at any signal
pin
Maximum storage
temperature
Minimum storage temperature
Electrostatic discharge
maximum to MIL-STD-883C
method 3015.7 with ref. to V
SS
Table 3
Parameter
T
A
Operating Temp.
-40
Supply voltage
V
CC
,
1.4
5.0
V
Back
(Note 1)
Capacitor at V
CC
,
C
D
100
V
Back
Table 4
Note 1: Refer to paragraphs 9.1 and 9.2
+125
5.5
°C
V
nF
2.3
Crystal characteristics
Symbol
Min
Typ
Max
Unit
Parameter
Stresses above these listed maximum ratings may cause
permanent damages to the device.
Exposure beyond specified operating conditions may
affect device reliability or cause malfunction.
Frequency
Load capacitance
Series resistance
Table 5
f
C
L
R
S
7
32.768
kHz
8.2
12.5 pF
70
110 k
Crystal Reference :
Micro Crystal CC5V-T1A
web:
www.microcrystal.com
2.4
EEPROM Characteristics
Symbol
Min
Typ
Max
Unit
Parameter
2.1
Handling Procedures
This device has built-in protection against high static
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