em3027 EM Microelectronic, em3027 Datasheet - Page 15

• Manufacturer Part Number: em3027
• Description: Real-time Clock With I2c Or Spi Interface, Crystal Temperature Compensation, Battery Switchover And Trickle Charger
• Manufacturer: EM Microelectronic

8.1
A The chip is in reset state when supply voltage (V
0x03 goes to ‘1’). When the supply level is higher than this threshold voltage, the reset is released.
B When the supply voltage is higher than the oscillator start voltage, the basic clocks for Watch and control logic become
active after the oscillator start time.
C With clocks present, the voltage detector starts in fast mode to measure the supply voltage. When a voltage higher than
Vlow2 is detected, the fast detection mode is stopped and the EEPROM read is enabled.
D The configuration registers are loaded with the configuration data read from the EEPROM (Addresses 0x29 to 0x33).
The EM3027 starts its normal function, depending on the supply voltage level applied.
8.2
The chip has following functions in Normal Mode:
8.3
The Watch part provides timing information in BCD format. The timing data is composed of seconds, minutes, hours, date,
weekdays, months and years. The corresponding values are updated every second.
The Watch part setup is provided by Write transmission into the Watch Page (Address 0x08h to 0x0Eh). After the
transmission, the Watch is restarted from the setup values after one second.
The Alarm function is activated by setting and enabling the alarm registers (Address 0x10h to 0x16h). Each Alarm byte has
its own enable bit. It is the bit 7. Recommended combinations of enabled bits are described in the table below.
8.4
The 16-bit count down timer can be enabled/disabled by TiOn bit.
It’s possible to select timer frequency by TD1, TD0 bits according to the following table:
Copyright © 2008, EM Microelectronic-Marin SA
07/08 – rev B
- Both Watch and Alarm parts must be set by an application before use
- The bits SecEq to YearEq enable the comparison of the corresponding registers
8
1.
2.
3.
4.
5.
6.
7.
8.
Functional Description
Start after power-up
Normal Mode function
Watch and Alarm functionality
Timer function
Voltage detection – The voltage detection is executed each 1 or 16 seconds (depending on ThPer bit)
Temperature measurement – It is executed if voltage is above Vlow1 and thermometer is enabled (ThEn bit).
With the temperature measurement result, the compensation value for frequency correction is computed.
Frequency compensation – The compensation of the oscillator frequency works continuously.
Configuration Registers refresh – The EEPROM is read each hour to refresh the content of the configuration
registers (supply voltage must be above Vlow2)
Watch/Alarm
activation.
Timer
Self-Recovery system
Serial interface
R
SecEq
1
1
1
1
1
1
MinEq
0
1
1
1
1
1
– The Watch function is continously active, whereas the Alarm function depends on its
– Is active when enabled.
– Is enabled by default (can be disabled by the application)
– The communication works if V
HrsEq
0
0
1
1
1
1
Table 9 – Alarm Period Selection
DateEq
CC
0
0
0
1
1
0
or V
Back
DaysEq
) is below an internal threshold level (PON in Status register
0
0
0
0
0
1
15
CC
> V
MonthEq
Back
0
0
0
0
1
0
YearEq
0
0
0
0
0
0
Al_period
month
year
week
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EM3027