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Description

Request Full Data Sheet The DS1961S combines 1024 bits of EEPROM, a 64-bit secret, an 8-byte register/control page with up to five user read/write bytes, a 512-bit SHA-1 engine and a fully featured 1-Wire® interface in a rugged iButton®. Data is transferred serially via the 1-Wire protocol, which requires only a single data lead and a ground return. The DS1961S has an additional memory area called the scratchpad that acts as a buffer when writing to the main memory, the register page or when installing a new secret. Data is first written to the scratchpad from where it can be read back. After the data has been verified, a copy scratchpad command will transfer the data to its final memory location, provided that the DS1961S receives a matching 160-Bit message authentication code (MAC). The computation of the MAC involves the secret and additional data stored in the DS1961S including the device's Identity Register. Only a new secret can be loaded without providing a MAC. The SHA-1 engine can also be activated to compute 160-bit MAC when reading a memory page or to compute a new secret, instead of loading it. The DS1961S understands a unique command "Refresh Scratchpad." Proper use of a refresh sequence (see Writing with Verification section) after a copy scratchpad operation reduces the number of weak bit failures in a touch environment. The refresh sequence also provides a means to restore functionality in a device with bits in a weak state. Each DS1961S has its own 64-bit ROM registration number that is factory lasered into the chip to provide a guaranteed unique identity for absolute traceability. The durable stainless steel package is highly resistant to environmental hazards such as dirt, moisture, and shock. Its compact coin-shaped profile is self-aligning with mating receptacles, allowing the DS1961S to be easily used by human operators. Accessories permit the DS1961S to be mounted on almost any surface including plastic key fobs and photo-ID badges.

Key Features

1128 bits of 5V EEPROM memory partitioned into four pages of 256 bits, a 64-bit write-only secret and up to five general purpose read/write registers Write access requires knowledge of the secret and the capability of computing and transmitting a 160-bit MAC as authorization Secret and data memory can be write-protected (all or page 0 only) or put in EPROM-emulation mode ("write to 0", page 1) On-chip 512-bit SHA-1 engine to compute 160-bit MAC and to generate secrets Reads and writes over a wide voltage range of 2.8V to 5.25V from -40°C to +85°C Communicates to host with a single digital signal at 14.1kb per second using 1-Wire protocol On-chip 16-bit CRC generator for safeguarding data transfers Overdrive mode boosts communication speed to 125kbps Operating temperature range from -40°C to +85°C Minimum 10 years of data retention at 85°C Common iButton Features Unique, factory-lasered and tested 64-bit registration number (8-bit family code + 48-bit serial number + 8-bit CRC tester) assures absolute traceability because no two parts are alike Multidrop controller for 1-Wire net Digital identification and information by momentary contact Chip-based data carrier compactly stores information Data can be accessed while affixed to object Button shape is self-aligning with cup-shaped probes Durable stainless steel case engraved with registration number withstands harsh environments Easily affixed with self-stick adhesive backing, latched by its flange, or locked with a ring pressed onto its rim Presence detector acknowledges when reader first applies voltage

Key Specifications:   iButton Products
Part Number	Overview	Memory Type	Memory Size	Security Features	UniqueWare	Real-Time Clock	Features	Price**
DS1961S	Secure iButton	EEPROM	1K bits	SHA-1 Write-Only Secrets	No	No	• Monetary Ecash	$2.18 @ 1k
See All iButton Products (26)

Notes: **This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

Diagram

Application Notes

Application Note 148: Guidelines for Reliable Long Line 1-Wire® Networks - DS1961S Application Note 151: Maxim Digital Monetary Certificates - DS1961S Application Note 154: Passwords in SHA Authentication - DS1961S Application Note 159: Software Methods to Achieve Robust 1-Wire® Communication in iButton® Applications - DS1961S Application Note 190: Challenge and Response with 1-Wire® SHA Devices - DS1961S Application Note 244: Advanced 1-Wire Network Driver - DS1961S Application Note 1098: White Paper 3: Why are 1-Wire SHA-1 Devices Secure? - DS1961S Application Note 1099: White Paper 4: Glossary of 1-Wire SHA-1 Terms - DS1961S Application Note 1201: White Paper 8: 1-Wire® SHA-1 Overview - DS1961S Application Note 1770: Securing Electronic Transactions Using SHA-1 Secure Hash Algorithm - DS1961S Application Note 1820: White Paper 1: SHA Devices Used in Small Cash Systems - DS1961S Application Note 3522: White Paper 9: Are SHA-1 Devices Still Secure Enough? - DS1961S Application Note 3675: Protecting the R&D Investment—Two-Way Authentication and Secure Soft-Feature Settings - DS1961S Application Note 3808: What Is an iButton? - DS1961S Application Note 4255: How to Power the Extended Features of 1-Wire® Devices - DS1961S Application Note 4421: Alternatives to the DS1991L MultiKey iButton® - DS1961S

Evaluation Kits

none

Design Guides

1-Wire® Products (PDF)

Reliability Reports

Reliability Report: DS1961S.pdf

Software/Models

none

Ordering Information
Notes: Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales. Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day. Part number suffixes: T or T&R = tape and reel; + = RoHS/lead-free; # = RoHS/lead-exempt. More: SeeFull Data Sheet or Part Naming Conventions. * Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.
Devices: 1-5 of 5
DS1961S	Free Sample	Buy	Package: TYPE PINS FOOTPRINT   DRAWING CODE/VAR *	Temp	RoHS/Lead-Free? Materials Analysis
DS1961S-F5#W			µCAN(F5);2 pin;0 mm² Outline Drawing: 21-0266 (PDF) Land Pattern: Not Available Use pkgcode/variation: IB#5NT*	0°C to +70°C	RoHS/Lead-Free: RoHS Qualified Materials Analysis
DS1961S-F5+			µCAN(F5);2 pin;0 mm² Outline Drawing: 21-0266 (PDF) Land Pattern: Not Available Use pkgcode/variation: IB+5NT*	-40°C to +85°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS1961S-F3+			µCAN(F3);2 pin;0 mm² Outline Drawing: 21-0252 (PDF) Land Pattern: Not Available Use pkgcode/variation: IB+3NT*	-40°C to +85°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS1961S-F3#			µCAN(F3);2 pin;0 mm² Outline Drawing: 21-0252 (PDF) Land Pattern: Not Available Use pkgcode/variation: IB#3NT*	-40°C to +85°C	RoHS/Lead-Free: RoHS Qualified Materials Analysis
DS1961S-F5#			µCAN(F5);2 pin;0 mm² Outline Drawing: 21-0266 (PDF) Land Pattern: Not Available Use pkgcode/variation: IB#5NT*	-40°C to +85°C	RoHS/Lead-Free: RoHS Qualified Materials Analysis

More Information

New Product Press Release 2002-09-04

Related Products

DS1963S SHA iButton

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