《元器件》DS1302.【GHOE]
AVAILABLE For pricing delivery and ordering information please contact Maxim Direct at 1 888 629 4642 or visit Maxim s website at DS1302 Trickle Charge Timekeeping Chip REV 120208 FEATURES Real Time Clock Counts Seconds Minutes Hours Date of the Month Month Day of the Week and Year with Leap Year Compensation Valid Up to 2100 31 x 8 Battery Backed General Purpose RAM Serial I O for Minimum Pin Count 2 0V to 5 5V Full Operation Uses Less than 300nA at 2 0V Single Byte or Multiple Byte Burst Mode Data Transfer for Read or Write of Clock or RAM Data 8 Pin DIP or Optional 8 Pin SO for Surface Mount Simple 3 Wire Interface TTL Compatible VCC 5V Optional Industrial Temperature Range 40 C to 85 C DS1202 Compatible Underwriters Laboratories UL Recognized PIN CONFIGURATIONS ORDERING INFORMATION PART TEMP RANGE PIN PACKAGE TOP MARK DS1302 0 C to 70 C 8 PDIP 300 mils DS1302 DS1302N 40 C to 85 C 8 PDIP 300 mils DS1302 DS1302S 0 C to 70 C 8 SO 208 mils DS1302S DS1302SN 40 C to 85 C 8 SO 208 mils DS1302S DS1302Z 0 C to 70 C 8 SO 150 mils DS1302Z DS1302ZN 40 C to 85 C 8 SO 150 mils DS1302ZN Denotes a lead free RoHS compliant package An N anywhere on the top mark indicates an industrial temperature grade device A anywhere on the top mark indicates a lead free device UL is a registered trademark of Underwriters Laboratories Inc VCC1 SCLK I O CE VCC2 X1 X2 GND 8 7 6 5 1 2 3 4 DIP 300 mils DS1302 VCC2 X1 X2 GND VCC1 SCLK I O CE 8 7 6 5 1 2 3 4 SO 208 mils 150 mils DS1302 TOP VIEW DS1302 Trickle Charge Timekeeping Chip 2 of 13 DETAILED DESCRIPTION The DS1302 trickle charge timekeeping chip contains a real time clock calendar and 31 bytes of static RAM It communicates with a microprocessor via a simple serial interface The real time clock calendar provides seconds minutes hours day date month and year information The end of the month date is automatically adjusted for months with fewer than 31 days including corrections for leap year The clock operates in either the 24 hour or 12 hour format with an AM PM indicator Interfacing the DS1302 with a microprocessor is simplified by using synchronous serial communication Only three wires are required to communicate with the clock RAM CE I O data line and SCLK serial clock Data can be transferred to and from the clock RAM 1 byte at a time or in a burst of up to 31 bytes The DS1302 is designed to operate on very low power and retain data and clock information on less than 1 W The DS1302 is the successor to the DS1202 In addition to the basic timekeeping functions of the DS1202 the DS1302 has the additional features of dual power pins for primary and backup power supplies programmable trickle charger for VCC1 and seven additional bytes of scratchpad memory OPERATION Figure 1 shows the main elements of the serial timekeeper shift register control logic oscillator real time clock and RAM TYPICAL OPERATING CIRCUIT DS1302 CPU VCC V CC2 SCLK CE GND X2 X1 VCC I O V CC1 DS1302 Trickle Charge Timekeeping Chip 3 of 13 Figure 1 Block Diagram POWER CONTROL vCC1 vCC2 GND INPUT SHIFT REGISTERS I O SCLK COMMAND AND CONTROL LOGIC REAL TIME CLOCK 31 X 8 RAM X1X2 CE 1Hz CLCL DS1302 TYPICAL OPERATING CHARACTERISTICS VCC 3 3V TA 25 C unless otherwise noted ICC2T vs VCC2T 5 10 15 20 25 30 2 03 04 05 0 VCC2 V SUPPLY CURRENT uA ICC1T vs VCC1T 100 150 200 250 300 350 400 2 03 04 05 0 VCC1 V SUPPLY CURRENT nA DS1302 Trickle Charge Timekeeping Chip 4 of 13 PIN DESCRIPTION PIN NAME FUNCTION 1 VCC2 Primary Power Supply Pin in Dual Supply Configuration VCC1 is connected to a backup source to maintain the time and date in the absence of primary power The DS1302 operates from the larger of VCC1 or VCC2 When VCC2 is greater than VCC1 0 2V VCC2 powers the DS1302 When VCC2 is less than VCC1 VCC1 powers the DS1302 2 X1 3 X2 Connections for Standard 32 768kHz Quartz Crystal The internal oscillator is designed for operation with a crystal having a specified load capacitance of 6pF For more information on crystal selection and crystal layout considerations refer to Application Note 58 Crystal Considerations for Dallas Real Time Clocks The DS1302 can also be driven by an external 32 768kHz oscillator In this configuration the X1 pin is connected to the external oscillator signal and the X2 pin is floated 4 GND Ground 5 CE Input CE signal must be asserted high during a read or a write This pin has an internal 40k typ pulldown resistor to ground Note Previous data sheet revisions referred to CE as RST The functionality of the pin has not changed 6 I O Input Push Pull Output The I O pin is the bidirectional data pin for the 3 wire interface This pin has an internal 40k typ pulldown resistor to ground 7 SCLK Input SCLK is used to synchronize data movement on the serial interface This pin has an internal 40k typ pulldown resistor to ground 8 VCC1 Low Power Operation in Single Supply and Battery Operated Systems and Low Power Battery Backup In systems using the trickle charger the rechargeable energy source is connected to this 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