説明

The DS2401 enhanced silicon serial number is a low-cost, electronic registration number that provides an absolutely unique identity which can be determined with a minimal electronic interface (typically, a single port pin of a microcontroller). The DS2401 consists of a 64-bit ROM that includes a unique 48-bit serial number, an 8-bit CRC, and an 8-bit Family Code (01h). Data is transferred serially via the 1-Wire protocol that requires only a single data lead and a ground return. Power for reading and writing the device is derived from the data line itself with no need for an external power source. The DS2401 is an upgrade to the DS2400. The DS2401 is fully reverse-compatible with the DS2400 but provides the additional multi-drop capability that enables many devices to reside on a single data line. The familiar TO-92, SOT-223, or TSOC package provides a compact enclosure that allows standard assembly equipment to handle the device easily.

 

アプリケーション

PCB Identification

Network Node ID

Equipment Registration

 

メリットと特徴

Guaranteed Unique 64-Bit ROM ID Chip for Absolute Traceability

Unique, 64-Bit Registration Number (8-Bit Family Code + 48-Bit Serial Number + 8-Bit CRC Tester)

8-Bit Family Code Specifies DS2401 Communications Requirements to Reader

Minimalist 1-Wire® Interface Lowers Cost and Interface Complexity

Multiple DS2401 Devices Can Reside on a Common 1-Wire Net

Built-In Multidrop Controller Ensures Compatibility with Other 1-Wire Net Products

Reduces Control, Address, Data, and Power to a Single Pin and Communicates at up to 16.3kbps

Presence Pulse Acknowledges When the Reader First Applies Voltage

Low-Cost TO-92, SOT-223, and TSOC Surface-Mount Packages

TO-92 Tape-and-Reel Version with Leads Bent to 100-mil Spacing (Default) or with Straight Leads (DS2401-SL)

Wide Voltage and Temperature Operating Ranges Enables Robust System Performance

Extended 2.8V to 6.0V Range (DS2401)

Zero Standby Power Required

-40°C to +85°C Industrial Temperature Range

 

Operation

The DS2401’s internal ROM is accessed via a single data line. The 48-bit serial number, 8-bit family code and 8-bit CRC are retrieved using the 1-Wire protocol. This protocol defines bus transactions in terms of the bus state during specified time slots that are initiated on the falling edge of sync pulses from the bus controller. All data is read and written least significant bit first.

 

 

1-Wire Bus System

The 1-Wire bus is a system which has a single bus controller system and one or more peripherals. In all instances, the DS2401 is a peripheral device. The bus controller is typically a microcontroller. The discussion of this bus system is broken down into three topics: hardware configuration, transaction sequence, and 1-Wire signaling (signal type and timing).

 

Hardware Configuration

The 1-Wire bus has only a single line by definition; it is important that each device on the bus be able to drive it at the appropriate time. To facilitate this, each device attached to the 1-Wire bus must have an open-drain connection or 3-state outputs. The DS2401 is an open-drain part with an internal circuit equivalent. The bus controller can be the same equivalent circuit. If a bidirectional pin is not available, separate output and input pins can be tied together. The bus controller requires a pullup resistor at the controller end of the bus. The value of the pullup resistor should be approximately 5kΩ (DS2401) or 2.2kΩ (DS2401A) for short line lengths. A multidrop bus consists of a 1-Wire bus with multiple peripherals attached. The 1-Wire bus has a maximum data rate of 16.3kbits per second.

The idle state for the 1-Wire bus is high. If, for any reason, a transaction needs to be suspended, the bus MUST be left in the idle state if the transaction is to resume. If this does not occur and the bus is left low for more than 120µs, one or more of the devices on the bus may be reset.