M41T83RMY6E STMicroelectronics, M41T83RMY6E Datasheet - Page 32

• Manufacturer Part Number: M41T83RMY6E
• Description: IC RTC SERIAL W/BATT SW SOX18
• Manufacturer: STMicroelectronics
• Type: Clock/Calendar/Alarmr

Specifications of M41T83RMY6E

• Memory Size: 32B
• Time Format: HH:MM:SS:hh (24 hr)
• Date Format: YY-MM-DD-dd
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 18-SOX, 18-SOIC with Crystal (7.5mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Clock operation
Note:
Figure 19. Clock divider chain and calibration circuits
32/61
32KHz
Two methods are available for ascertaining how much calibration a given M41T8x may
require:
●
●
Setting or changing the digital calibration byte does not affect the frequency test, square
wave, or watchdog timer frequency, but changing the analog calibration byte DOES affect all
functions derived from the low current oscillator (see
The first involves setting the clock, letting it run for a month and comparing it to a known
accurate reference and recording deviation over a fixed period of time. This allows the
designer to give the end user the ability to calibrate the clock as the environment
requires, even if the final product is packaged in a non-user serviceable enclosure. The
designer could provide a simple utility that accesses either or both of the calibration
bytes.
The second approach is better suited to a manufacturing environment, and uses the
512 Hz frequency test output. This is the IRQ1/FT/OUT pin on the M41T83, and the
FT/RST pin on the M41T82 (see
enabling the FT output). The 512 Hz frequency test signal can be measured using a
highly accurate timing device such as a frequency counter. The measured value is then
compared to 512 Hz and the oscillator error in ppm is then determined.
Any deviation from 512 Hz indicates the degree and direction of oscillator frequency
shift at the test temperature. For example, a reading of 512.010124 Hz would indicate a
+20 ppm oscillator frequency error, requiring either a –10 (xx001010) to be loaded into
the digital calibration byte, or +6 pF (00011000) into the analog calibration byte for
correction.
C XO
C XI
Low Current
Analog Calibration
Circuitry
Oscillator
Doc ID 12578 Rev 12
÷64
÷64
Section 3.14
Frequency Test
512Hz Output
Digital Calibration Circuitry
(divide by 511/512/513)
and
Figure
Section 3.15
1Hz Signal
÷2
19).
for more information on
Remainder of
Divider Circuit
Watchdog Timer
Counters
Square Wave
Clock
8-bit Timer
M41T82-M41T83
AI11806c