DS1972 1 Kbit EEPROM iButton
Rewritable 1 Kbit EEPROM with per-page write-protect — no battery.
1024 bits of EEPROM in four 256-bit pages, written through an 8-byte scratchpad for verified transfers. Each page can be permanently write-protected or put in EPROM-emulation ("write-to-0") mode to guard against accidental erasure or tampering. Battery-free — it draws power from the 1-Wire line. Shares its die with the DS2431 chip.
Choose page by page: rewritable, locked, or write-once
Its four pages are not all-or-nothing. Each 256-bit page can be left freely rewritable, permanently write-protected, or switched into EPROM-emulation mode where bits can only be cleared, never set back — three different behaviours inside one battery-free button. That lets a single device hold a locked configuration block, an append-only usage counter and a rewritable status field at the same time, which neither the plain-EEPROM DS1973 nor the fully add-only DS1982 can do.
Key features
- Rewritable 1 Kbit EEPROM over 1-Wire — non-volatile with no battery.
- Four 256-bit pages, written through an 8-byte scratchpad with a verified copy protocol.
- Each page can be permanently write-protected or set to EPROM-emulation mode against tampering.
- High endurance: 200,000 write cycles at +25 °C; 40-year retention at +85 °C; Overdrive to 125 kbit/s.
- Family code 2Dh; unique 64-bit ROM; shares its die with the DS2431 chip; 2.8–5.25 V.
- Switchpoint hysteresis and input filtering optimise performance in electrically noisy environments; Level-4 ESD protection — ±8 kV contact, ±15 kV air-gap discharge.
- Original imported dies, canned and assembled at our own line — original-chip reliability at a sharper price; laser-etched custom marking and logos to order.
Specifications
| Chip / compatibility | DS1972 · family code 2Dh · chip-form DS2431 |
|---|---|
| Memory | 1 Kbit EEPROM (4 pages × 256 bits) + 8-byte scratchpad |
| Protocol | 1-Wire, 16.3 kbit/s (Overdrive ~125 kbit/s) |
| Package | F3 / F5 can |
| Operating temperature | −40 to +85 °C; 2.8–5.25 V |
| Options | Laser-etched custom marking / logo on the can |
Product dimensions
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
Related products
DS1991 MultiKey iButton
Three password-protected 384-bit subkeys in one button.
DS1992 / DS1993 Memory iButton
1 Kb and 4 Kb NV RAM tokens for carrying data on the key.
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.