MK41T56 STMICROELECTRONICS | Alldatasheet
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Technical content
512 bit (64b x8) Serial Access TIMEKEEPER® SRAM March 1999 1/15 COUNTERS for SECONDS, MINUTES, HOURS, DAY , DATE, MONTH and YEARS SOFTWARE CLOCK CALIBRATION AUTOMATIC POWER-FAIL DETECT and SWITCH CIRCUITRY I2C BUS COMPATIBLE
56 BYTES of GENERAL PURPOSE RAM
ULTRA-LOW BATTERY SUPPLY CURRENT of 500nA OPERATING TEMPERATURE: – MK41T56: 0 to 70°C – MKI41T56: –40 to 85°C AUTOMATIC LEAP YEAR COMPENSATION
DESCRIPTION
The MK41T56 TIMEKEEPER ® is a low power 512 bit static CMOS RAM organized as 64 words by 8 bits. A built-in 32.768 kHz oscillator (external crystal controlled) and the first 8 bytes of the RAM are used for the clock/calendar function and are configured in binary coded decimal (BCD) format. Addresses and data are transferred serially via a two-line bi-directional bus. The built-in address register is incremented automatically after each write or read data byte. The MK41T56 clock has a built-in power sense circuit which detects power failures and automatically switches to the battery supply during power failures. The energy needed to sustain the RAM and clock operations can be supplied from a small lithium button cell. AI02304 OSCI VCC MK41T56 MKI41T56 VSS SCL OSCO SDA FT/OUT VBAT Figure 1. Logic Diagram Table 1. Signal Names
CAUTION: Negative undershoots below –0.3 volts are not allowed on any pin while in the Battery Back-up mode. Table 2. Absolute Maximum Ratings
0 ST 10 Seconds Seconds Seconds 00-59
1 X 10 Minutes Minutes Minutes 00-59
2 X X 10 Hours Hours Hour 00-23
3 X X X X X Day Day 01-07
4 X X 10 Date Date Date 01-31
7 OUT FT S Calibration Control
Keys: S = SIGN Bit; FT = FREQUENCY TEST Bit; ST = STOP Bit; OUT = Output level; X = Don’t care. Table 3. Register Map
Note: 1. The RAYOVAC BR1225 or equivalent is recommended as the battery supply. Table 6. DC Characteristics Notes:1. Effective capacitance measured with power supply at 5V.
- Sampled, not 100% tested.
Table 5. Capacitance (1,2) Note: 1. All voltages referenced to VSS . Table 7. Power Down/Up Trip Points DC Characteristics (1) minimum trace lengths and isolation from RF generating signals should be taken into account. STMicroelectronics recommends the ECS-.327-12.5-8SP-2 quartz crystal is recommended for industrial temperature operations. ESC Inc. can be contacted at 800-237-1041 or 913-782-7787 for further information on this crystal type. Table 8. Crystal Electrical Characteristics
Table 9. Power Down/Up Mode AC Characteristics Figure 5. Power Down/Up Mode AC Waveforms current mode of operation to conserve battery life. stable whenever the clock line is High. High will be interpreted as control signals.
Note: 1. Transmitter must internally provide a hold time to bridge the undefined region (300ns max.) of the falling edge of SCL. Table 10. AC Characteristics defines the START condition. one clock pulse per bit of data. that has been clocked out of the slave transmitter. the master to generate the STOP condition.
would represent 10.7 seconds per month. much calibration a given MK41T56 may require. utility that accessed the Calibration byte. quency shift at the test temperature. Frequency test output frequency. and then the FT/OUT pin will be driven low. an external pull-up resistor. Figure 13. Clock Calibration
Figure 14. Crystal Accuracy Across Temperature
ORDERING INFORMATION SCHEME Operating Temp. blank 0 to 70 °C I –40 to 85 °C Package N PSDIP8 0.4mm Frame S SO8 0.15mm Frame Speed
00 No Speed Options
TR Tape & Reel Example: MKI41T56 N 00 TR For a list of available options or for further information or any aspect of this device, please contact the STMicroelectronics Sales Office nearest to you. MK41T56, MKI41T56
A L D E1 E N C eA eB B Symb mm inches Typ Min Max Typ Min Max A 4.80 0.189 A1 0.70 – 0.028 – A2 3.10 3.60 0.122 0.142 B 0.38 0.58 0.015 0.023 B1 1.15 1.65 0.045 0.065 C 0.38 0.52 0.015 0.020 D 9.20 9.90 0.362 0.390 E1 6.30 7.10 0.248 0.280 eA 8.40 – 0.331 – eB 9.20 0.362 L 3.00 3.80 0.118 0.150 N8 8 Drawing is not to scale. PSDIP8 - 8 pin Plastic Skinny DIP, 0.4mm lead frame MK41T56, MKI41T56
E N CP B e A D C LA1 α H h x 45˚ Symb mm inches Typ Min Max Typ Min Max A 1.35 1.75 0.053 0.069 A1 0.10 0.25 0.004 0.010 B 0.33 0.51 0.013 0.020 C 0.19 0.25 0.007 0.010 D 4.80 5.00 0.189 0.197 E 3.80 4.00 0.150 0.157 e1 . 2 7– – 0 . 0 5 0 – – H 5.80 6.20 0.228 0.244 h 0.25 0.50 0.010 0.020 L 0.40 0.90 0.016 0.035 α 0° 8° 0° 8° N8 8 CP 0.10 0.004 Drawing is not to scale. SO8 - 8 lead Plastic Small Outline, 150 mils body width MK41T56, MKI41T56
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics © 1999 STMicroelectronics - All Rights Reserved All other names are the property of their respective owners STMicroelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - France - Germany - Italy - Japan - Korea - Malaysia - Malta - Mexico - Morocco - The Netherlands - Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A. http://www.st.com MK41T56, MKI41T56