memory products - Al Kossow's Bitsavers

M9346FUNCTIONAL DESCRIPTIONThe input and output pins are controlled byseparate serial formats. Eight 9-bit instructions canbe executed. The instruction format has a logical"1" as a start bit, two bits as an op code, and sixbits of address. The on-chip programming voltagegenerator allows the user to use a single power supply(Vccl. It only generates high voltage during theprogramming modes (write, erase, chip-erase, chipwrite)to prevent spurious programming duringother modes.The programming cycle is self timed, with the dataout (DO) pin indicating the ready/busy state of thechip. The serial output (DO) pin is valid as data outduring the read mode, and if initiated, as aready/busy status indicator during a programmingcycle. During all other modes the DO pin is in highimpedance state eliminating bus contention. TheBulk programming instructions (ERAL, WRAL) areenabled or disabled by the BPE pin. This pin connectedto V 1H enables the executions of previousmentioned instructions. The BPE pin connected toV1L causes the same instructions to be ignored. Ifthe BPE pin is not connected, it is pulled-up to Veeby an on-chip pull-up and the Bulk programminginstructions are enabled. Execution of the EWEN,EWDS, WRITE and ERASE instructions are independentfrom the state of the BPE pin.READThe read instruction is the only instruction whichoutputs serial data on the DO pin. After a READinstruction is received, the instruction and addressare decoded, followed by data transfer from thememory register into a 16 bit serial out shift register.A dummy bit (logical "0") precedes the 16 bit dataoutput string. The output data changes during thehigh state of the system clock.ERASEIWRITE ENABLE AND DISABLEWhen Vee is applied to the part it powers up in theprogramming disable (EWDS) state, programmingmust be preceded by programming enable (EWEN)instruction. Programming remains enabled until aprogramming disable (EWDS) instruction is executedor Vee is removed from the part. The programmingdisable instruction is provided to protectagainst accidental data disturb. Execution of aREAD instruction is independent of both EWENand EWDS instructions.ERASE (Note 2)Like most EEPROMs, the register must first beerased (all bits set to logical' 1 ') before the registercan be written (certain bits set to logical '0'). Afteran ERASE instruction is input, es is dropped low.This falling edge of es determines the start ofthe self-timed programming cycle. If es is broughthigh subsequently (after observing the tes specification),the DO pin will indicate the ready/busy statusof the chip. The DO pin will go low if the chipis still programming. The DO pin will go high whenall bits of the register at the address specified inthe instruction have been set to a logical' 1'. Thepart is now ready for the next instruction sequence.WRITE (Note 2)The WRITE instruction is followed by 16 bits of datato be written into the specified address. After thelast bit of data (DO) is put on the data in (DI) pin,es must be brought low before the next rising edgeof the SK clock. This falling edge of es initiatesthe self-timed programming cycle. Like all programmingmodes, DO indicates the ready/busy statusof the chip if es is brought high after a minimumof 1 fls (tes). DO = logical '0' indicates thatprogramming is still in progress. DO = logical '1'indicates that the register at the address specifedin the instruction has been written with the data patternspecified in the instruction and the part is readyfor another instruction. The register to be writteninto must have been previously erased.WRITE WITH AUTOERASE (Note 2)The WRITE instruction is followed by 16 bits of datato be written into the specified address. After thelast bit of data (DO) is put on the data in (DI) pines must be brought low before the next falling edgeof the SK clock.This falling edge of es initiates the self-timedprogramming cycle. Like all programming modes,DO indicates the ready/busy status of the chip ifes is brought high after a minimum of 1 fls (tcs).DO = logical '0' indicates that programming is stillin progress. DO = logical '1' indicates that theregister at the address specifed in the instructionhas been written with the data pattern specified inthe instruction and the part is ready for another instruction.4/9220