ds1200 serial ram chip ds1200 030598 1/1 features ? 1024 bits of read/write memory ? low data retention current for battery backup applica- tions ? 4 million bits/second data rate ? single byte or multiple byte data transfer capability ? no restrictions on the number of write cycles ? low-power cmos circuitry ? applications include: software authorization computer identification system access control secure personnel areas calibration automatic system setup traveling work record pin assignment nc dq clk nc nc gnd nc nc nc gnd nc nc nc rst v cc v bat 16-pin soic (300 mil) see mech. drawings section v cc dq clk gnd nc gnd nc nc rst v bat 10-pin dip (300 mil) see mech. drawings section 1 2 3 4 56 7 10 9 8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 pin description v cc +5 volts rst reset dq data input/output clk clock gnd ground v bat battery (+) nc no connection description the ds1200 serial ram chip is a miniature read/write memory which can randomly access individual 8-bit strings (bytes) or sequentially access the entire 1024-bit contents (burst). interface cost to a microprocessor is minimized by on-chip circuitry which permits data trans- fers with only three signals: clock, rst , and data in- put/output. nonvolatility can be achieved by connecting a battery of 2 to 4 volts at the battery input v bat . a load of 0.5 m a should be used to size the external battery for the re- quired data retention time. if nonvolatility is not required the v bat pin should be grounded. for a complete description of operating conditions, electrical characteristics, bus timing, and signal de- scriptions other than v bat , see the ds1201 electronic tag 1024-bit data sheet.
|
