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 freely — used where the credential itself must carry a record, such as service history, meter data or route information.
Rewrite it forever — no write-cycle limit
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; the DS1992/DS1993 does not — you can rewrite the same byte every minute for ten years. That makes it the carrier 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, use the DS1982 or DS1985 add-only EPROM instead.
Key features
- Battery-backed NV SRAM — freely and repeatedly rewritable, with no EEPROM-style write-cycle wear limit.
- DS1992 = 1 Kbit (4 pages); DS1993 = 4 Kbit (16 pages); each page 256 bits for packetized, CRC-checked transfers.
- Parasite-powered ROM: the 64-bit ID stays readable even if the internal battery is exhausted.
- Family codes: DS1992 = 08h, DS1993 = 06h. Full ROM command set for true multidrop operation.
- Over 10 years data retention; −40 to +70 °C; UL 913 intrinsically-safe rated.
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 |
| Package | F5 can |
| Protocol | 1-Wire® |
Inside the stainless can
A 0.25 mm solid stainless shell, a UV-stable polypropylene grommet isolating lid from base, and the die bonded inside. Lid = data contact, base = ground return.
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 | Largest battery-free memory; production travellers |
| DS1982 | 09h | 1 Kbit (128 B) | EPROM — add-only, cannot be erased | Tamper-evident checkpoints and certificates |
| DS1985 | 0Bh | 16 Kbit (2 KB) | EPROM — add-only, cannot be erased | Full append-only service history |
| DS1992 / DS1993 | 08h / 06h | 1 Kbit / 4 Kbit | NV RAM — battery-backed, unlimited writes | Data that changes constantly on the key |
| DS1996 | 0Ch | 64 Kbit (8 KB) | NV RAM — battery-backed, unlimited writes | Portable database — the largest capacity here |
| DS1994 | 04h | 4 Kbit + RTC | NV RAM + clock, timer, counter, alarms | Time- or usage-limited access that expires by itself |
| DS1904L | 24h | No user memory | Real-time clock only | Give a microcontroller an accurate 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 | The anti-cloning choice — proves it knows a secret |
Ordering information
| MOQ | 100 pcs |
|---|---|
| Lead time | 3–7 days for stock items, 10–15 days for OEM |
| Packing | Bulk ESD bags (100–200 pcs/bag, 2 bags/carton); blister or header cards for retail on request |
| Samples | Free samples for volume buyers — courier at cost |
| Payment | T/T bank transfer; other terms negotiable for repeat orders |
| Shipping | DHL / FedEx / UPS air express; sea or rail freight for pallet volumes |
| Customization | ROM ranges · housing colours · laser logo · private label |
Typical applications
Frequently asked questions
DS1992, DS1993 or DS1996 — how much memory do I actually need?
They are the same device 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. 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. All three rewrite without limit and hold data for over ten years.
What happens to the data when the battery runs out?
It is lost — this is battery-backed SRAM, not EEPROM. 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. 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.