DS1992 / DS1993 Memory iButton
1 Kb and 4 Kb NV RAM tokens for carrying data on the key.
Battery-backed NV RAM you can read and rewrite — a fit where the credential itself must carry a record, such as service history, meter data or route information.
Ordering information
| MOQ | Confirmed by model and order when quoting |
|---|---|
| Preparation time | Availability and lead time are confirmed by model and order when quoting |
| Packing | Confirm pack quantity, protection and labelling for the selected model. |
| Samples | Sample quantity, fees and shipping are confirmed for the selected model. |
| Payment | Agree payment terms and the payee in the quotation and invoice. |
| Shipping | Confirm the shipping method, cost and timing for your destination and order. |
| Customization | State ROM, colour, marking and packing needs; feasibility and cost require confirmation. |
SRAM-based: no EEPROM write-cycle limit (per datasheet)
This is SRAM kept alive by a lithium cell, not EEPROM, and that single fact decides the choice. An EEPROM part such as the DS1972 has a finite number of write cycles per page; per the original manufacturer's datasheet the DS1992/DS1993 has no such write-cycle limit, so frequent rewrites of the same byte are within its design (confirm for the supplied version). That makes it a candidate for data that changes constantly on the token itself: meter readings, service history, a running balance, route progress. The trade-off is the battery: once it is exhausted the data is gone, so for a write-once record that must outlive the device, consider the DS1982 or DS1985 add-only EPROM instead.
Key features
- Original model references: DS1992 has 1 Kbit of nonvolatile memory; DS1993 has 4 Kbit.
- The original devices use 256-bit memory pages and a 256-bit scratchpad for the verified write sequence.
- Select capacity for the host’s memory map; for battery-backed units, ask whether production-date and storage-history information is available for the quoted lot.
Specifications
| Chip / compatibility | DS1992 (1 Kb, family code 08h) / DS1993 (4 Kb, family code 06h) |
|---|---|
| Memory | Battery-backed NV RAM in 256-bit pages (DS1992: 4 pages / DS1993: 16 pages) + 256-bit scratchpad with verified copy |
| Operating temperature | −40 to +70 °C · over 10 years data retention (per the original manufacturer's datasheet; confirm for the supplied version) |
| Package | F5 can |
| Protocol | 1-Wire® |
Inside the stainless can
Typical construction of this can format: a stainless-steel shell, an insulating grommet separating lid from base, and the chip bonded inside. Lid = data contact, base = ground return. Wall thickness, grommet material and other construction details: confirm for the supplied version.
Which memory iButton do you need?
The whole memory range side by side, grouped by storage technology — capacities and family codes per the Analog Devices datasheets.
| Model | Family code | Capacity | Memory technology | Pick it for |
|---|---|---|---|---|
| DS1971 | 14h | 256 bit + 64-bit OTP | EEPROM — battery-free | Asset tag: a locked ID beside rewritable data |
| DS1972 | 2Dh | 1 Kbit (128 B) | EEPROM — battery-free | Per-page write-protect or EPROM-emulation modes |
| DS1973 | 23h | 4 Kbit (512 B) | EEPROM — battery-free | Battery-free rewritable memory (4 Kbit); production travellers |
| DS1982 | 09h | 1 Kbit (128 B) | EPROM — add-only; written data is not erasable (per datasheet) | Add-only records such as checkpoints and certificates |
| DS1985 | 0Bh | 16 Kbit (2 KB) | EPROM — add-only; written data is not erasable (per datasheet) | Append-only service history (16 Kbit) |
| DS1992 / DS1993 | 08h / 06h | 1 Kbit / 4 Kbit | NV RAM — battery-backed, high write endurance (per datasheet) | Data that changes constantly on the key |
| DS1996 | 0Ch | 64 Kbit (8 KB) | NV RAM — battery-backed, high write endurance (per datasheet) | Portable database — 64 Kbit NV RAM |
| DS1994 | 04h | 4 Kbit + RTC | NV RAM + clock, timer, counter, alarms | Time- or usage-limited access with the expiry held in the key |
| DS1904L | 24h | No user memory | Real-time clock only | Give a microcontroller a real-time timebase |
| DS1991 | 02h | 1152 bit = 3 × 384 bit | Secure NV RAM — three password zones | Legacy multi-tenant systems (not for new secure designs) |
| DS1961S | 33h | 1 Kbit + 64-bit secret | EEPROM + SHA-1 challenge–response | Authentication: proves it knows a secret (assess cloning risk for your own system) |
Typical applications
Frequently asked questions
DS1992, DS1993 or DS1996 — how much memory do I actually need?
Per the original manufacturer's datasheet they are one device type in three sizes: 1 Kbit (128 bytes), 4 Kbit (512 bytes) and 64 Kbit (8 KB) of battery-backed NV RAM, with family codes 08h, 06h and 0Ch; confirm for the supplied version. A few identifiers and a status field fit comfortably in a DS1992; a service history or a route with dozens of checkpoints wants the DS1993; a full personnel record or a machine's complete parameter set needs the DS1996. Rewrite endurance and data retention are datasheet figures (retention quoted at over ten years) and depend on the battery; confirm both for the supplied version.
What happens to the data when the battery runs out?
It is lost — this is battery-backed SRAM, not EEPROM. Per the original manufacturer's datasheet, data retention is specified at over ten years, and the 64-bit ROM ID stays readable regardless because it is parasite-powered, but the user memory does depend on the cell; confirm for the supplied version. If your record must outlive the device by design, use an add-only EPROM part (DS1982 or DS1985) or a battery-free EEPROM part (DS1972 or DS1973) instead.
Related products
DS1991 MultiKey iButton
Three password-protected 384-bit subkeys in one button.
DS1996 64 Kb Memory iButton
The large-memory token — 64 Kb of rewritable NV RAM.
DS1961S SHA-1 Authentication iButton
1 Kb EEPROM with on-chip SHA-1 challenge–response.
DS1971 EEPROM iButton
256-bit EEPROM — non-volatile without a battery.