memory products - Al Kossow's Bitsavers

ETC2732DEVICE OPERATIONThe five modes of operation of the ETC 2732 arelisted in the Operating Modes table. A single 5 Vpower supply is required in the read mode. All inputsare TTL levels except for OENpp during programming.In the program mode the OENpp inputis pulsed from a TTL level to 25V.READ MODEThe ETC2732 has two control functions, both ofwich must be logically active in order to obtain dataat the ouputs. Chip Enable (CE) is the power controland should be used for device selection. OutputEnable (OE) is the output control and shouldbe used to gate data to the output pins, independentof device selection. Assuming that addressesare stable, address access time (tACC) is equal tothe delay from CE to output (tCE). Data is availableat the ou.!mJts after the falling edge of OE,assuming that CE has been low and addresses havebeen stable for at least tACC-tOE.STANDBY MODEThe ETC2732 has a standby mode which reducesthe active power dissipation by 98%, from 26.25mW to 0.53mW. The ETC 2732 is placed in thestandby mode, by applying a TTL high signal to theCE input when in standby mode the outputsare in a high impedance state, independant of theOE input.OUTPUT OR-TYINGBecause EPROMS are usually used in larger memoryarrays, we have provided a 2-line control functionthat accomodates this use of multiple memoryconnection. The 2-line control function allows for.a) the lowest possible memory power dissipation,andb) complete assurance that output bus contentionwill not occur.To most efficiently us~hese two control lines, itis recommended that CE (pin 18) be decoded andused as the primary device selecting function, whileOE (pin 20) be made a common connection to alldevices in the array and connected to the READline from the system control bus. This assures thatall deselected memory devices are in their low powerstandby modes and that the output pins areactive only when data is desired from a particularmemory device.PROGRAMMINGCAUTION: Exceeding 26.5V on pin 20 (Vpp) willdamage the ETC2732.Initially, and after each erasure, all bits of the ETC2732 are in the" 1" state. Data is introduced byselectively programming "Os" into the desired bitlocations. Although only "Os" will be programmed,both "1s" and "Os" can be presented in the dataword. The only way to change a "0" to a "1" isby ultraviolet light erasure.The~C2732 is in the programming mode whenthe OENpp input is at 25V. It is reqUired that a 0.1ftF capacitor be placed across OENpp, and groundto suppress spurious voltage transients which maydamage the device. The data to be programmedis applied 8 bits in parallel to the data output pins.The levels required for the address and data inputsare TTL.When the address and data are stable, a 50 msactive low TTL program pulse is applied to the CEinput. A program pulse must be applied at eachaddress location to be programmed. You can programany location at any time-either individually,sequentially, or at random. The program pulse hasa maximum width of 55 ms. The ETC 2732 mustnot be programmed with a DC signal applied to theCE input.Programming of multiple ETC 2732s in parallel withthe same data can be easily accomplished due tothe simplicity of the programming requirements. likeinputs of the paralleled ETC 2732s may be connectedtogether when they are programmed withthe same data. A low level TTL pulse applied tothe CE input programs the paralleled.OPERATING MODES~ CEMODE (18)READVILOElVpp vee OUTPUTS(20) (24) (9-11,13-17)VIL 5 DourSTANDBY VIH Don't Care 5 Hi-ZPROGRAMVILVpp5 DINPROGRAM VERIFYVILVIL5 DourPROGRAM INHIBITVIHVpp5 Hi-Z~ SIiS-1HOMSON.., I. Ul1JO(i:;OO©~~~(i:;VOO©fiIIlO(i:;i\l5/10105