m48t212a STMicroelectronics, m48t212a Datasheet
m48t212a
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m48t212a Summary of contents
Page 1
... MICROPROCESSOR POWER-ON RESET PROGRAMMABLE ALARM OUTPUT ACTIVE in the BATTERY BACKED-UP MODE DESCRIPTION The M48T212A is a self-contained device that in- cludes a real time clock (RTC), programmable alarms, a watchdog timer, and two external chip enable outputs which provide control four (two in parallel) external low-power static RAMs. ...
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... Byte 1h contains century information. Byte 0h contains additional flag information pertaining to the watchdog timer, alarm and battery status. The M48T212A also has its own Power-Fail De- tect circuit. This control circuitry constantly moni- tors the supply voltage for an out of tolerance condition. When V ...
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... ( ( Low Low Low High High X ( M48T212A Value –55 to 125 260 –0.3 to 4.6 –0 DQ7-DQ0 Power X High-Z Standby V D Active Active IH OUT V High-Z Active IH X High-Z ...
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... 100pF or 5pF includes JIG capacitance Note: 1. DQ0-DQ7 2. E1 and E2 CON CON 3. Excluding open-drain output pins 4/20 A0-A18 A0-A3 V CCSW OUT A E M48T212A CON Note CON WDI RSTIN1 RSTIN2 RST DQ0-DQ7 IRQ/FT V CAP external SRAM should be as short as possible. ...
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... V –0.3 OUT1 CC V > V –0.3 OUT2 BAT through 100K resistor. WDI internally pulled-down can only sustain CMOS leakage currents in the battery back-up mode. Higher leakage cur- CON specification. CC M48T212A Min Max Min Typ Max ±1 ± 575 ...
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... M48T212A Figure 5. Power Down/Up AC Waveform PFD (max) V PFD (min INPUTS VALID OUTPUTS VALID RST V CCSW Table 8. Power Down/Up AC Characteristics ( 70°C) A Symbol V (max PFD PFD F V (min PFD (min PFD PFD t V (max) to RST High ...
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... GHQZ t Address Transition to Output Transition AXQX Note 5pF L Parameter (Low or High) CON (Low or High) CON tEXPD tEXPD Parameter M48T212A M48T212A -85 Unit Min Max tAPD AI02639 M48T212A -85 Unit Min Max 7/20 ...
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... goes low simultaneously with W going low, the outputs remain in the high impedance state. 8/20 the address presented to the M48T212A is in the range of 0h-Fh, one of the on-board TIMEKEEP- ER registers is accessed and valid data will be available to the eight data output drivers within ...
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... DATA OUT VALID WRITE WRITE tAVAV tAVAV tAVEH tAVWH tELEH tEHAX tWHAX tEHDX tWLWH tEHQZ tDVEH tDVWH DATA IN VALID M48T212A WRITE tAVAV tAVWL tWHAX tWLWH tGHQZ DATA OUT DATA IN VALID VALID AI02640 READ tAVAV tAVQV tGLQV tWHQX tWLQZ tWHDX DATA IN ...
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... A0-A3 ACTIVE FLAG BIT IRQ/FT WRITE MODE The M48T212A is in the Write Mode whenever W (Write Enable) and E (Chip Enable) are in a low state after the address inputs are stable. The start of a write is referenced from the latter occurring falling edge write is terminated by the earlier rising edge ...
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... The RST signal also remains active during this time (see Figure 5). Note: Most low power SRAMs on the market to- day can be used with the M48T212A TIMEKEEP- ER Controller. There are, however some criteria which should be used in making the final choice of an SRAM to use. The SRAM must be designed in a way where the chip enable input disables all oth- er inputs to the SRAM ...
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... It can also be pro- grammed to go off while the M48T212A is in the battery back-up to serve as a system wake-up call. Bits RPT5-RPT1 put the alarm in the repeat mode of operation ...
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... Watchdog Reg- ister = 3 seconds). If the processor does not reset the timer within the specified period, the M48T212A sets the WDF (Watchdog Flag) and generates a watchdog interrupt or a microproces- sor reset. The most significant bit of the Watchdog Register is the Watchdog Steering Bit (WDS). When set to a ‘ ...
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... V through a 100K resistor. CC Calibrating the Clock The M48T212A is driven by a quartz controlled os- cillator with a nominal frequency of 32,768 Hz. The devices are tested not to exceed ±35 ppm (parts per million) oscillator frequency error at 25°C, which equates to about ±1.53 minutes per month. ...
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... Load Capacitance L Note: Load capacitors are integrated within the M48T212A. Circuit board layout considerations for the 32kHz crystal of minimum trace lengths and isolation from RF generating signals should be taken into account. ST recommends the KDS DT-38 Tuning Fork Type quartz crystal for all temperature operations. KDS can be contacted at 913-491-6825 or at http://www.kdsj.co.jp for forther information on this crystal type ...
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... M48T212A Figure 11. Calibration Waveform NORMAL POSITIVE CALIBRATION NEGATIVE CALIBRATION Figure 12. RSTIN1 & RSTIN2 Timing Waveforms RSTIN1 tR1 RSTIN2 (1) RST Note: 1. With pull-up resistor. Table 16. Default Values Condition Initial Power-up (2) (Battery Attach for SNAPHAT) (3) RESET (4) Power-down Subsequent Power-up Note: 1. WDS, BMB0-BMB4, RB0, RB1. ...
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... To protect from these voltage spikes, ST recom- mends connecting a schottky diode from V V (cathode connected (Schottky diode 1N5817 is recommended for through hole and MBRS120T3 is recommended for surface mount). Figure 13. Supply Voltage Protection bus. These CC bus. The anode M48T212A 0.1 F DEVICE V SS AI02169 17/20 ...
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... Date October 1999 First Issue SNAPHAT Battery & Crystal removed Hardware Hookup scheme changed (Figure 3) 03/01/00 Back-Up Mode Alarm Waveforms changed (Figure 10) Default Values Table added (Table 16) SOH44 package silhouette, mechanical drawings and mechanical data changed (Figure 14) 18/20 M48T212A = 2.7V to 3.0V Revision Details - ...
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... Drawing is not to scale. mm Min Max 3.05 0.05 0.36 2.34 2.69 0.36 0.46 0.15 0.32 17.71 18.49 8.23 8.89 – – 11.51 12.70 0.41 1.27 0° 8° M48T212A inches Typ Min 0.002 0.092 0.014 0.006 0.697 0.324 0.032 – 0.453 0.016 0° Max 0.120 0.014 0.106 0.018 0.012 0.728 0.350 – 0.500 0.050 8° 0.004 ...
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... M48T212A 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 ...