DS1990R-F5

DS1990R-F5 iButton (guaranteed presence pulse)

R-variant that guarantees a presence pulse the instant the key touches a live bus.

Electrically identical to the DS1990A — same 64-bit read-only ROM, same family code 01h. The documented difference is behavioural: the DS1990R guarantees a presence pulse on contact (after power-on reset) when the button touches an already-powered 1-Wire bus, so the reader detects the key reliably the moment it lands. Preferred where presence-on-contact detection has to be certain on every touch.

Key features

Guarantees a presence pulse on contact (after power-on reset) with a live 1-Wire bus — reliable detection the instant the key lands.
Electrically identical to DS1990A: same read-only 64-bit ROM, same family code 01h.
Preferred where presence-on-contact detection must be certain on every single touch.
Same F5 MicroCan, same 1-Wire interface and reader compatibility as the standard key.

Specifications

Chip / compatibility	DS1990R compatible · family code 01h
Memory	64-bit ROM, read-only (8-bit family + 48-bit serial + 8-bit CRC)
Package	F5 can
Protocol	1-Wire, 16.3 kbit/s
Operating temperature	−40 °C … +85 °C

Inside the stainless can

F5 can: Ø16.25 × 5.89 mm · F3 can: Ø16.25 × 3.10 mm

64-bit ROM: 8-bit family code + 48-bit serial + 8-bit CRC

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.

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

Access Control Guard Tour & Patrol Checkpoints

Frequently asked questions

What does the “R” in DS1990R actually change?

Behaviour, not data: the DS1990R guarantees a presence pulse on contact (after power-on reset) when the button touches an already-powered 1-Wire bus, so the reader detects the key with certainty the instant it lands. ROM contents and family code 01h are the same as the DS1990A.

Are DS1990A and DS1990R interchangeable?

For reading, yes — both present the same 64-bit read-only ROM and readers accept either. Specify the R only where the system depends on guaranteed presence-on-contact detection.

Which systems require the R variant?

Installations where a missed first touch is unacceptable — fast gates, turnstiles and controllers that poll briefly and must catch the key on the first landing rather than a re-present.