MEMORY DATABOOK - Al Kossow's Bitsavers

_______________________ • APPLICATIONS.7. MEMORY COMPARISONSTANDARDIn general, power, speed, and usability are required formemory elements. At present, 64K bit dynamic RAMscan be supplied by a lot of manufacturers, and theseelements have almost unified specifications.In designing a circuit board to achieve stable systemoperation, however, considerations must be given to thespecification values and margins against the spacificationvalues, pertaining to the points shown in the followingtable. Factors that will affact the stable system opera·tion are power, tempereture, aging, clock skew, unevenoperation of peripheral ICs, and so forth.Pointto be notedActual item to be consideredReasonPower o Currents (lcc1, Icc3, and Icc4) at the operating The power system must be noted.time and current (lcc2) at the standby time (example: with battery backup)TimingmarginVoltagemargino Current waveform (especially the peak currentvalue)o Address setup (tASR, tASe) and hold (tRAH,tCAH) timingo Data setup (tOS) timing and write pulse width(tyVp)Voltage, temperature, and dependability of eachtiming (especially the tREF and tRAcIIt is impossible to achieve the ideal voltage statuswhen used with ina system.The noise margin must be strict formemories with large peak current.In system designing, these timing pulsesare directly related to the access time.These timing pulses are related to thecycle time in writing.The temperature inclination must belittle for the timing pulses tREF andtRAC·A sufficient voltage margin must beprovided under consideration of variousfactors which will affact the systemoperation stability.Attached drawing 1Frequency characteristics of capacitor and O!PAC50(n)10Z5a/PAC sactional viewJrr.1Pin 3 Pin 1 Pin 2---Model CB tantalum 1.01'Fcapacitor (manufacturedby the Oki Seramic)Model CB(1.0I'F)a·PAC(between pins1 and 2)a·PAC/V'-