Highest and Lowest voltage PROMs? - Page 1
Forum section: electronics / general

author: colejohnson66
author_rank: Unknown
timestamp: November 10, 2019, 05:50:23 pm
content: I’m curious what the highest and lowest voltages required to program a PROM are.According toWikipedia(and thelinked data sheet), first generation Intel 1702A EPROMs required -48V(!) applied to the substrate to program. The article then mentions that second generation EPROMs required +25V programming voltage pulses.Is there any PROM (one time programmable, EPROMs, E2PROMs, etc.) that required even higher or lower voltages than those two early EPROMs?

author: SeanB
author_rank: Super Contributor
timestamp: November 10, 2019, 06:16:20 pm
content: Probably not, the first generation devices were really weird with supply voltage, and also were picky about supply sequencing as well. Later ones simplified it by having on die bias generators to simplify things, and also easing the need to have power rail sequencing, plus they were not as prone to latch up and self destruction. As a bonus they also got more erase cycle endurance, the originals were rather notorious for getting flaky with only 100 cycles on them or less, simply because they were so new, and also for getting bits that would never program down to a 0 level either.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 10, 2019, 07:46:02 pm
content: Lowest is easy, modern Flash runs on quite low external voltages, and 2.7V (and lower?) stuff has been around for many years.Although, there's an internal charge pump which boosts this to whatever is still required (I think 4-6V for the highest density stuff??), which may be what you're after.Programming current is another excellent question; as far as I know, fuse PROMs required quite a gulp (~100mA?). Others?Tim

author: colejohnson66
author_rank: Unknown
timestamp: November 10, 2019, 08:52:07 pm
content: I probably should’ve been more clear when I said “lowest.” I meant lower below ground than -45V. But 2.7V would probably be theclosestto ground. Unless there’s 1.8V and below flash memories.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 10, 2019, 09:06:50 pm
content: I don't know of any PROM/EPROM requiring lower than -48V (as with the earlier PROMs), at least for commercial chips.As to modern Flash memory, as T3sl4co1l said, they usually have an internal charge pump, so they are actually programmed with around 5V at least internally. I don't think you can reliably program Flash memory cells with current technology *directly* with 2.7V or lower. There *are* 1.8V Flash chips (eg: W25Q32JW). But they are using internal charge pumps as well.

author: edavid
author_rank: Super Contributor
timestamp: November 11, 2019, 04:14:09 am
content: The MM5203 required -50V for programming.The 2708 required a nominal +26V, but +25V would also work.

author: techman-001
author_rank: Frequent Contributor
timestamp: November 11, 2019, 06:23:46 am
content: Quote from: edavid on November 11, 2019, 04:14:09 amThat brings back memories from 1975I've had to build programmers for both these chips, but the MM5203 was the most nerve wracking because they were so expensive to blow up back in the day.And I blew up a few getting the programmer working properly.The programmer had to be made with TTL and analog parts because I didn't have a handy MCU to throw at it like nowadays.Here is a online scan of the MM5203 programming process for any other 'greyhairs' wanting a walk down memory lane.https://archive.org/stream/bitsavers_nationaldaMemoryDatabook_43572148/1977_National_Memory_Databook_djvu.txtOperation of the MM4203/MM5203 in program modeInitially, all 2048 bits of the MM4203/MM5203are in the HIGH state. Information is introducedby selectively programming LOWS in the properbit locations. (Note!)Word address selection is done by the same decod-ing circuitry used in the Read mode. The eightoutput terminals are used as data inputs to deter-mine the information pattern in the eight bits ofeach word. A LOW data input level (-50V) willleave a HIGH and a HIGH data input level willallow programming of a LOW All eight bits of oneword are programmed simultaneously by settingthe desired bit information patterns on the datainput terminals. The duty cycle of the Vdd pulse(amplitude and width as specified on page 4)should be limited to 2%. The address should beapplied for at least 1 jus before application of theProgram pulse. In programming mode, data inputs1-8 are pins 4-11 respectively regardless of thelogic state of Ag and mode control. Chip selectshould be disabled (HIGH).Positive logic is used during the read miode foraddresses and data out. Address 0 corresponds toall address inputs at V,l and address 255|o cor-responds to all address Inputs at V|^^. A “1" or aP at a data output corresponds to Vqh- A "0” oran N at a data output corresponds to \/Q^_. Posi-tive logic is also used during the programming modefor addresses. Address 0 corresponds to all addressinputs at V,Lp and address 255 iq corresponds toall address inputs at V|Hp.Negative logic is used during the programming modefor data in. A "1" or a P at a data input corres-ponds to V|L,p. A "0” or an N at a data inputcorresponds to V|Hp.