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FEATURES

§ Real-time clock with fully compatible 1-

Wire

MicroLAN interface

§ Uses the same binary time/date

representation as the DS2404 but with 1

second resolution

§ Clock accuracy ±2 minutes per month at

25°C

§ Communicates at 16.3kbits per second

§ 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

§ 8-bit family code specifies device

communication requirements to bus master

§ Built-in multidrop controller ensures

compatibility with other MicroLAN products

§ Operates over a wide V

voltage range of

2.5V to 5.5V from -40°C to +85°C

§ Low power, 200nA typically with oscillator

running

§ Compact, low cost 6-pin TSOC surface

mount package

PIN ASSIGNMENT

PIN DESCRIPTION

Pin 1 - GND

Pin 2 - 1-Wire

Pin 3 - V

Pin 4 - V

BAT

Pin 5 - X1

Pin 6 - X2

ORDERING INFORMATION

DS2415P 6-pin TSOC package

DS2415P/T&R Tape & Reel of DS2415P

DS2415X Chip Scale Pkg., Tape &

Reel

DESCRIPTION

The DS2415 1-Wire time chip offers a simple solution for storing and retrieving vital time information

with minimal hardware. The DS2415 contains a unique, lasered ROM and a real-time clock/calendar

implemented as a binary counter. Only one pin is required for communication with the device. Utilizing a

backup energy source, the data is nonvolatile and allows for stand-alone operation. The DS2415 features

can be used to add functions such as calendar, time and date stamp, and logbook to any type of electronic

device or embedded application that uses a microcontroller.

OVERVIEW

The DS2415 has two main data components: 1) 64-bit lasered ROM, and 2) real-time clock counter

(Figure 1). The real-time clock utilizes an on-chip oscillator that is connected to an external 32.768kHz

crystal. All data is read and written least significant bit first. The real-time clock functions will not be

DS2415

1-Wire

Time Chip

www.maxim-ic.com

6-Pin TSOC PACKAGE

TOP VIEW

Summary of content (14 pages)

PAGE 1
DS2415 1-Wire Time Chip www.maxim-ic.com FEATURES § § § § § § § § § § PIN ASSIGNMENT Real-time clock with fully compatible 1Wire® MicroLAN interface Uses the same binary time/date representation as the DS2404 but with 1 second resolution Clock accuracy ±2 minutes per month at 25°C Communicates at 16.
PAGE 2
DS2415 available until the ROM function protocol has been established. This protocol is described in the ROM functions flow chart (Figure 7). The master must first provide one of four ROM function commands: 1) Read ROM, 2) Match ROM, 3) Search ROM, 4) Skip ROM. After a ROM function sequence has been successfully executed, the real-time clock functions are accessible and the master may then provide a real time clock function command (Figure 5).
PAGE 3
DS2415 The functions required to exercise the control functions of the DS2415 are not accessible until the ROM function protocol has been satisfied. This protocol is described in the ROM functions flow chart (Figure 7). The 1-Wire bus master must first provide one of the four ROM function commands. After a ROM function sequence has been successfully executed, the bus master may then provide one of the function commands specific to the DS2415 (Figure 5).
PAGE 4
DS2415 TIMEKEEPING A 32.768kHz crystal oscillator is used as the time base for the real-time clock counter. The oscillator can be turned on or off under software control. The oscillator must be on for the real-time clock to function. The real-time clock counter is double-buffered. This allows the master to read time without the data changing while it is being read. To accomplish this, a snapshot of the counter data is transferred to a read/write buffer, which the user accesses.
PAGE 5
DS2415 READ CLOCK [66h] The Read Clock command is used to read the device control byte and the contents of the real-time clock counter. After having received the most significant bit of the command code the device copies the actual contents of the real-time clock counter to the read/write buffer. Now the bus master reads data beginning with the device control byte followed by the least significant byte through the most significant byte of the real-time clock.
PAGE 6
DS2415 CLOCK FUNCTION COMMAND FLOW CHART Figure 5 6 of 14
PAGE 7
DS2415 HARDWARE CONFIGURATION Figure 6 1-WIRE BUS SYSTEM The 1-Wire bus is a system that has a single bus master and one or more slaves. In all instances the DS2415 behaves as a slave. The discussion of this bus system is broken down into three topics: hardware configuration, transaction sequence, and 1-Wire signaling (signal types and timing).
PAGE 8
DS2415 INITIALIZATION All transactions on the 1-ire bus begin with an initialization sequence. The initialization sequence consists of a Reset Pulse transmitted by the bus master followed by Presence Pulse(s) transmitted by the slave(s). The Presence Pulse lets the bus master know that the DS2415 is on the bus and is ready to operate. For more details, see the “1-Wire Signaling” section. ROM FUNCTION COMMANDS Once the bus master has detected a presence, it can issue one of the four ROM function commands.
PAGE 9
DS2415 ROM FUNCTIONS FLOW CHART Figure 7 9 of 14
PAGE 10
DS2415 1-WIRE SIGNALING The DS2415 requires strict protocols to insure data integrity. The protocol consists of four types of signaling on one line: Reset Sequence with Reset Pulse and Presence Pulse, Write 0, Write 1, and Read Data. The bus master initiates all these signals, except Presence Pulse. The initialization sequence required to begin any communication with the DS2415 is shown in Figure 8.
PAGE 11
DS2415 READ/WRITE TIMING DIAGRAM Figure 9 Write-1 Time Slot 60ms £ tSLOT < 120ms 1ms £ tLOW1 < 15ms 1ms £ tREC < ¥ Write-0 Time Slot 60ms £ tLOW0 < tSLOT < 120ms 1ms £ tREC < ¥ 11 of 14
PAGE 12
DS2415 Read-data Time Slot RESISTOR MASTER DS2415 60ms £ tSLOT < 120ms 1ms £ tLOWR < 15ms 0 £ tRELEASE < 45ms 1ms £ tREC < ¥ tRDV = 15ms tSU < 1ms CRYSTAL PLACEMENT ON PCB Figure 10 LOCAL GROUND PLANE BENEATH SIGNAL PLANE OR ON OTHER SIDE OF PCB 12 of 14
PAGE 13
DS2415 ABSOLUTE MAXIMUM RATINGS* Voltage on 1-Wire to Ground Operating Temperature Range Storage Temperature Range Soldering Temperature * -0.5V to +7.0V -40°C to +85°C -55°C to +125°C See J-STD-020A Specification This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.
PAGE 14
DS2415 AC ELECTRICAL CHARACTERISTICS (-40°C to +85°C, VPUP = 2.5V to 6.0V, VBAT = 2.5V to 5.