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DS1921G

Thermochron iButton Device

EVALUATION KIT AVAILABLE

For pricing, delivery, and ordering information, please contact Maxim Direct at

1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.

General Description

The Thermochron

iButton

device (DS1921G) is a

rugged, self-sufficient system that measures temperature

and records the result in a protected memory section.

The recording is done at a user-defined rate, both as a

direct storage of temperature values as well as in the

form of a histogram. Up to 2048 temperature values

taken at equidistant intervals ranging from 1 to 255min

can be stored. The histogram provides 63 data bins with

a resolution of 2.0°C. If the temperature leaves a user-

programmable range, the DS1921G also records when

this happened, for how long the temperature stayed out-

side the permitted range, and if the temperature was too

high or too low. An additional 512 bytes of battery-

backed SRAM allow storing information pertaining to the

object to which the DS1921G is associated. Data is

transferred serially through the 1-Wire

protocol, which

requires only a single data lead and a ground return.

Every DS1921G is factory lasered with a guaranteed

unique, electrically readable, 64-bit registration number

that allows for absolute traceability. The durable stainless

steel package is highly resistant to environmental haz-

ards such as dirt, moisture, and shock. Accessories per-

mit the DS1921G to be mounted on almost any object

including containers, pallets, and bags.

Applications

Features

o Digital Thermometer Measures Temperature in

0.5°C Increments

o Accuracy ±1°C from -30°C to +70°C (See the

Electrical Characteristics

for Accuracy

Specification)

o Built-In Real-Time Clock (RTC) and Timer Has

Accuracy of ±2 Minutes per Month from 0°C to +45°C

o Water Resistant or Waterproof if Placed Inside

DS9107 iButton Capsule (Exceeds Water

Resistant 3 ATM Requirements)

o Automatically Wakes Up and Measures Temperature

at User-Programmable Intervals from 1 Minute to

255 Minutes

o Logs Consecutive Temperature Measurements in

2KB of Data-Log Memory

o Records a Long-Term Temperature Histogram

with 2.0°C Resolution

o Programmable Temperature High and

Temperature Low Alarm Trip Points

o Records Up to 24 Timestamps and Durations

When Temperature Leaves the Range Specified

by the Trip Points

o 512 Bytes of General-Purpose Battery-Backed SRAM

o Communicates to Host with a Single Digital Signal

at 15.4kbps or 125kbps Using 1-Wire Protocol

Common iButton Device Features

o Digital Identification and Information by

Momentary Contact

o 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

o Multidrop Controller for 1-Wire Net

o Chip-Based Data Carrier Compactly Stores Information

o Data Can Be Accessed While Affixed to Object

o Button Shape is Self-Aligning with Cup-Shaped

Probes

o Durable Stainless-Steel Case Engraved with

Registration Number Withstands Harsh

Environments

o Easily Affixed with Self-Stick Adhesive Backing,

Latched by Its Flange, or Locked with a Ring

Pressed Onto Its Rim

o Presence Detector Acknowledges When Reader

First Applies Voltage

Ordering Information

19-5101; Rev 8; 11/13

PART TEMP RANGE PIN-PACKAGE

DS1921G-F5# -40°C to +85°C F5 Can

DS1921G-F5N# -40°C to +85°C F5 Can

Examples of Accessories

PART ACCESSORY

DS9096P Self-Stick Adhesive Pad

DS9101 Multipurpose Clip

DS9093RA Mounting Lock Ring

DS9093A Snap-In Fob

DS9092 iButton Probe

Pin Configuration appears at end of data sheet.

Thermochron, iButton, and 1-Wire are registered trademarks of

Maxim Integrated Products, Inc.

#Denotes a RoHS-compliant device that may include lead(Pb)

that is exempt under the RoHS requirements.

A NIST traceability certificate is available for the DS1921G-F5N.

See Application Note 4629 for details.

Temperature Logging in Cold Chain, Food Safety,

Pharmaceutical, and Medical Products

Summary of content (42 pages)

PAGE 1
EVALUATION KIT AVAILABLE DS1921G Thermochron iButton Device General Description Features The Thermochron® iButton® device (DS1921G) is a o Digital Thermometer Measures Temperature in 0.
PAGE 2
DS1921G Thermochron iButton Device ABSOLUTE MAXIMUM RATINGS IO Voltage Range Relative to GND ..........................-0.5V to +6V IO Sink Current....................................................................20mA Operating Temperature Range ..........................-40°C to +85°C* Storage Temperature Range..............................-40°C to +50°C* *Storage or operation above +50°C significantly reduces battery life.
PAGE 3
DS1921G Thermochron iButton Device ELECTRICAL CHARACTERISTICS (continued) (VPUP = +2.8V to +5.25V, TA = -40°C to +85°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS IO PIN: 1-Wire WRITE Write-Zero Low Time (Notes 1, 12, 13) Write-One Low Time (Notes 1, 13) tW0L tW1L Standard speed 60 120 Overdrive speed, VPUP > 4.5V 6 15 Overdrive speed 8.
PAGE 4
DS1921G Thermochron iButton Device ELECTRICAL CHARACTERISTICS (continued) (VPUP = +2.8V to +5.25V, TA = -40°C to +85°C.) Note 17: WARNING: Maxim data-logger products are 100% tested and calibrated at time of manufacture to ensure that they meet all data sheet parameters, including temperature accuracy. As with any sensor-based product, user shall be responsible for occasionally rechecking the temperature accuracy of the product to ensure it is still operating properly.
PAGE 5
DS1921G Thermochron iButton Device RTC Deviation vs. Temperature 4 UPPER LIMIT RTC DEVIATION (MINUTES/MONTH) 2 0 LOWER LIMIT -2 -4 -6 -8 -10 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 TEMPERATURE (°C) Minimum Product Lifetime vs. Temperature at Different Sample Rates 11.00 10.00 MINIMUM PRODUCT LIFETIME (YEARS) 9.00 8.00 7.00 6.00 5.00 4.00 EVERY MINUTE NO SAMPLES EVERY 3 MINUTES OSCILLATOR OFF EVERY 10 MINUTES 3.00 2.00 1.00 0.
PAGE 6
DS1921G Thermochron iButton Device Minimum Product Lifetime vs. Sample Rate at Different Temperatures 11.00 +15°C 10.00 -20°C MINIMUM PRODUCT LIFETIME (YEARS) 9.00 -40°C 8.00 +40°C 7.00 +45°C 6.00 +50°C 5.00 +55°C 4.00 +60°C 3.00 2.00 +70°C 1.00 +85°C 0.00 1 10 100 1000 MINUTES BETWEEN SAMPLES Accuracy Limits 2.0 1.5 UPPER LIMIT 1.0 ACCURACY (°C) 0.5 0 -0.5 LOWER LIMIT -1.0 -1.5 -2.
PAGE 7
DS1921G Thermochron iButton Device Detailed Description The DS1921G is an ideal device to monitor the temperature of any object it is attached to or shipped with, such as perishable goods or containers of temperaturesensitive chemicals. The general-purpose batterybacked SRAM can store an electronic copy of shipping information, date of manufacture and other important data written as clear as well as encrypted files. Note that the initial sealing level of the DS1921G achieves IP56.
PAGE 8
DS1921G Thermochron iButton Device ory. Except for the ROM and the scratchpad, all other memory is arranged in a single linear address space. All memory reserved for logging purposes, including counter registers and several other registers, is readonly for the user. The timekeeping and control registers are write protected while the device is programmed for a mission. The hierarchical structure of the 1-Wire protocol is shown in Figure 2.
PAGE 9
DS1921G Thermochron iButton Device MSB LSB 8-BIT CRC CODE MSB 8-BIT FAMILY CODE (21h) 48-BIT SERIAL NUMBER LSB LSB MSB LSB MSB Figure 3. 64-Bit Lasered ROM POLYNOMIAL = X8 + X5 + X4 + 1 1ST STAGE X0 2ND STAGE X1 3RD STAGE X2 4TH STAGE X3 5TH STAGE X4 6TH STAGE X5 7TH STAGE X6 8TH STAGE X7 X8 INPUT DATA Figure 4. 1-Wire CRC Generator 64-Bit Lasered ROM Memory Each DS1921G contains a unique ROM code that is 64 bits long. The first 8 bits are a 1-Wire family code.
PAGE 10
DS1921G Thermochron iButton Device 32-BYTE INTERMEDIATE STORAGE SCRATCHPAD ADDRESS 0000h to 01FFh GENERAL-PURPOSE SRAM (16 PAGES) PAGES 0 to 15 0200h to 021Fh 32-BYTE REGISTER PAGE PAGE 16 0220h to 027Fh ALARM TIMESTAMPS AND DURATIONS PAGES 17 to 19 0280h to 07FFh (RESERVED FOR FUTURE EXTENSIONS) PAGES 20 to 63 0800h to 087Fh TEMPERATURE HISTOGRAM MEMORY PAGES 64 to 67 0880h to 0FFFh (RESERVED FOR FUTURE EXTENSIONS) PAGES 68 to 127 1000h to 17FFh DATA-LOG MEMORY (64 PAGES) PAGES128 to 1
PAGE 11
DS1921G Thermochron iButton Device ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FUNCTION ACCESS* 0210h (No function, reads 00h) — R R** 0211h Temperature Read-Out (Forced Conversion) Temperature R R** 0212h Low Byte 0213h High Byte Mission Start Delay R/W R/W** Status R/W R/W Mission Timestamp R R Mission Samples Counter R R Device Samples Counter R R 0214h TCB MEMCLR MIP SIP 0 0215h Minutes 0216h Hours 0217h Date 0218h Month 0219h Year 021A
PAGE 12
DS1921G Thermochron iButton Device RTC and RTC Alarm Registers Map ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 0200h 0 10 Seconds Single Seconds 0201h 0 10 Minutes Single Minutes 0202h 0 12/24 20 Hour AM/PM 10 Hour 0203h 0 0 0 0 0204h 0 0 0205h CENT 0 0206h Single Hours 0 10 Date 0 BIT 0 Day of Week Single Date 10 Months Single Months 10 Years Single Years 0207h MS 10 Seconds Alarm Single Seconds Alarm 0208h MM 10 Minutes Alarm Single Minutes Alarm 0209
PAGE 13
DS1921G Thermochron iButton Device Temperature Alarm Register Map ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 020Bh Temperature Low Alarm Threshold 020Ch Temperature High Alarm Threshold BIT 2 BIT 1 BIT 0 Sample Rate Register Map ADDRRESS BIT 7 BIT 6 BIT 5 020Dh BIT 3 BIT 2 BIT 1 BIT 0 Sample Rate Temperature Conversion The DS1921G measures temperatures with a resolution of 0.5°C.
PAGE 14
DS1921G Thermochron iButton Device Control Register Map ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 020Eh EOSC EMCLR 0 EM RO TLS THS TAS Control Register The DS1921G is set up for its operation by writing appropriate data to its special function registers that are located in the register page. Several functions that are controlled by a single bit only are combined into a single byte called the Control register (address 020Eh). This register can be read and written.
PAGE 15
DS1921G Thermochron iButton Device Status Register Map ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0214h TCB MEMCLR MIP SIP 0 TLF THF TAF Status Register The Status register holds device status information and alarm flags. The register is located at address 0214h. Writing to this register does not necessarily end a mission. The functional assignments of the individual bits are explained below. The bits MIP, TLF, THF, and TAF can only be written to 0.
PAGE 16
DS1921G Thermochron iButton Device Mission Timestamp Register Map ADDRESS BIT 7 0215h 0 10 Minutes 0 20 Hour AM/PM 0216h BIT 6 12/24 0217h 0 0 0218h 0 0 0219h BIT 5 BIT 4 BIT 3 BIT 1 BIT 0 Single Minutes 10 Hour Single Hours 10 Date 0 BIT 2 Single Date 10 Months Single Months 10 Years Single Years Mission Samples Counter Register Map ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 021Ah Low Byte 021Bh Center Byte 021Ch High Byte BIT 2 BIT 1 BIT 0 Device Samples Counter Re
PAGE 17
DS1921G Thermochron iButton Device TEMPERATURE READING TEMPERATURE EQUIVALENT IN °C 00h -40.0 or lower 0 800h to 801h 01h -39.5 0 800h to 801h 02h -39.0 0 800h to 801h 03h -38.5 0 800h to 801h 04h -38.0 1 802h to 803h 05h -37.5 1 802h to 803h 06h -37.0 1 802h to 803h 07h -36.5 1 802h to 803h 08h -36.0 2 804h to 805h … … … … F3h +81.5 60 878h to 879h F4h +82.0 61 87Ah to 87Bh F5h +82.5 61 87Ah to 87Bh F6h +83.0 61 87Ah to 87Bh F7h +83.
PAGE 18
DS1921G Thermochron iButton Device ADDRESS DESCRIPTION 0220h Mission Samples Counter, Low Byte 0221h Mission Samples Counter, Center Byte 0222h Mission Samples Counter, High Byte ALARM EVENT Low Alarm 1 0223h Alarm Duration Counter 0224h to 0227h Alarm Timestamp and Duration Low Alarm 2 0228h to 024Fh Alarm Timestamp and Durations Low Alarms 3 to 12 0250h Mission Samples Counter, Low Byte 0251h Mission Samples Counter, Center Byte 0252h Mission Samples Counter, High Byte 0253h Alar
PAGE 19
DS1921G Thermochron iButton Device Next, the low temperature and high temperature thresholds that specify the temperature tolerance band must be defined. The Temperature Conversion section describes how to convert a temperature value into the binary code to be written to the threshold registers. The state of the search condition bits in the Control register does not affect the mission.
PAGE 20
DS1921G Thermochron iButton Device BIT NUMBER 7 6 5 4 3 2 1 0 TARGET ADDRESS (TA1) T7 T6 T5 T4 T3 T2 T1 T0 TARGET ADDRESS (TA2) T15 T14 T13 T12 T11 T10 T9 T8 ENDING ADDRESS WITH DATA STATUS (E/S) (READ-ONLY) AA 0 PF E4 E3 E2 E1 E0 Figure 9. Address Registers write command was not recognized by the device. If everything went correctly, both flags are cleared and the ending offset indicates the address of the last byte written to the scratchpad.
PAGE 21
DS1921G Thermochron iButton Device Read Scratchpad [AAh] This command is used to verify scratchpad data and target addresses. After issuing the Read Scratchpad command, the master begins reading. The first 2 bytes are the target address. The next byte is the ending offset/data status byte (E/S) followed by the scratchpad data beginning at the byte offset T[4:0], as shown in Figure 9.
PAGE 22
DS1921G Thermochron iButton Device MASTER Tx MEMORY OR CONTROL FUNCTION COMMAND 0Fh WRITE SCRATCHPAD? FROM ROM FUNCTIONS FLOWCHART (FIGURE 13) AAh READ SCRATCHPAD? N Y 55h COPY SCRATCHPAD N TO FIGURE 10b N Y Y DS1921G SETS EMCLR = 0 DS1921G SETS EMCLR = 0 DS1921G SETS EMCLR = 0 MASTER Tx TA1 [T7:T0], TA2 [T15:T8] MASTER Rx TA1 [T7:T0], TA2 [T15:T8] MASTER Tx TA1 [T7:T0], TA2 [T15:T8] DS1921G SETS SCRATCHPAD OFFSET = [T4:T0] AND CLEARS (PF, AA) MASTER Rx ENDING OFFSET WITH DATA STATUS (E/
PAGE 23
DS1921G Thermochron iButton Device FROM FIGURE 10a F0h READ MEMORY? A5h READ MEMORY WITH CRC N Y Y DS1921G SETS EMCLR = 0 MASTER Rx TA1 [T7:T0], TA2 [T15:T8] 3Ch CLEAR MEMORY N EMCLR = 1? N Y MASTER Tx TA1 [T7:T0], TA2 [T15:T8] DS1921G SETS MEMORY ADDRESS = [T15:T0] TO FIGURE 10c Y DS1921G SETS EMCLR = 0 DECISION MADE BY DS1921G N DS1921G CLEARS MISSION TIMESTAMP, MISSION SAMPLES COUNTER, MISSION START DELAY, SAMPLE RATE REGISTER DS1921G SETS MEMORY ADDRESS = [T15:T0] DECISION MADE BY MA
PAGE 24
DS1921G Thermochron iButton Device FROM FIGURE 10b 44h CONVERT TEMPERATURE? N Y DS1921G SETS EMCLR = 0 Y MISSION IN PROGRESS? N TEMPERATURE CONVERSION PROCESS DS1921G SETS TCB = 0 DS1921G PERFORMS A TEMPERATURE CONVERSION DS1921G STARTS TEMPERATURE CONVERSION PROCESS DS1921G COPIES RESULT TO ADDRESS 0211h N MASTER Tx RESET? DS1921G SETS TCB = 1 Y END OF PROCESS N MASTER Tx RESET? Y TO FIGURE 10b Figure 10c.
PAGE 25
DS1921G Thermochron iButton Device Read Memory with CRC [A5h] The Read Memory with CRC command is used to read memory data that cannot be packetized, such as the register page and the data recorded by the device during a mission. The command works the same way as the simple Read Memory command, except for the 16bit CRC that the DS1921G generates and transmits following the last data byte of a memory page.
PAGE 26
DS1921G Thermochron iButton Device LOGGING PROCESS MISSION START PROCESS MIP = 1? N EM = 0? DS1921G COPIES RTC TO MISSION TIMESTAMP Y DS1921G SETS MIP = 0 DS1921G SETS DATA-LOG ADDRESS = 1000h N DS1921G MEASURES TEMPERATURE Y MEMCLR = 1? N DS1921G UPDATES HISTOGRAM, DEVICE SAMPLES COUNTER, MISSION SAMPLES COUNTER AND ALARM, IF APPLICABLE Y NEW SAMPLE RATE = 0? Y N N DS1921G COPIES NEW SAMPLE RATE FROM SCRATCHPAD TO SAMPLE RATE REGISTER Y Y RO = 1? DATA-LOG ADDRESS = 1800h? N DS1921G SET
PAGE 27
DS1921G Thermochron iButton Device a maximum data rate of 16.3kbps. The speed can be boosted to 142kbps by activating the overdrive mode. The DS1921G is not guaranteed to be fully compliant to the iButton device standard. Its maximum data rate in standard speed is 15.4kbps and 125kbps in overdrive. The value of the pullup resistor primarily depends on the network size and load conditions. The DS1921G requires a pullup resistor of maximum 2.2kΩ at any speed. The idle state for the 1-Wire bus is high.
PAGE 28
DS1921G Thermochron iButton Device Initialization All transactions on the 1-Wire 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 DS1921G is on the bus and is ready to operate. For more details, see the 1-Wire Signaling section.
PAGE 29
DS1921G Thermochron iButton Device MASTER Tx RESET PULSE FROM MEMORY/CONTROL FUNCTIONS FLOWCHART (FIGURE 10) FROM FIGURE 13b SHORT RESET PULSE? N OD = 0 Y MASTER Tx ROM FUNCTION COMMAND 33h READ ROM COMMAND? * N DS1921G Tx PRESENCE PULSE 55h MATCH ROM COMMAND? Y ** F0h SEARCH ROM COMMAND? N Y ECh CONDITIONAL SEARCH COMMAND? N Y N TO FIGURE 13b Y N CONDITION MET? Y DS1921G Tx FAMILY CODE (1 BYTE) DS1921G Tx BIT 0 * MASTER Tx BIT 0 DS1921G Tx BIT 0 * MASTER Tx BIT 0 BIT 0 MATCH
PAGE 30
DS1921G Thermochron iButton Device TO FIGURE 13a FROM FIGURE 13a CCh SKIP ROM COMMAND? N Y 3Ch OVERDRIVESKIP ROM? N 69h OVERDRIVEMATCH ROM? Y Y OD = 1 OD = 1 MASTER Tx RESET PULSE? Y N MASTER Tx BIT 0 *** N BIT 0 MATCH? N Y MASTER Tx BIT 1 BIT 1 MATCH? *** N Y MASTER Tx BIT 63 BIT 63 MATCH? FROM FIGURE 13a *** N Y TO FIGURE 13a ***ALWAYS TO BE TRANSMITTED AT OVERDRIVE SPEED. Figure 13b.
PAGE 31
DS1921G Thermochron iButton Device Overdrive-Skip ROM [3Ch] standard speed at the next reset pulse of minimum 480µs duration. The Overdrive-Match ROM command can be used with a single or multiple devices on the bus. On a single-drop bus this command can save time by allowing the bus master to access the memory/control functions without providing the 64-bit ROM code. Unlike the normal Skip ROM command, the Overdrive-Skip ROM command sets the DS1921G in the overdrive mode (OD = 1).
PAGE 32
DS1921G Thermochron iButton Device A tRSTL duration of 480µs or longer exits the overdrive mode, returning the device to standard speed. If the DS1921G is in overdrive mode and tRSTL is no longer than 80µs, the device remains in overdrive mode. After the bus master has released the line, it goes into receive mode (Rx). Now the 1-Wire bus is pulled to V PUP through the pullup resistor or, in case of a DS2480B driver, through active circuitry.
PAGE 33
DS1921G Thermochron iButton Device WRITE-ONE TIME SLOT tW1L VPUP VIHMASTER VTH VTL VILMAX 0V ε tF tSLOT RESISTOR MASTER WRITE-ZERO TIME SLOT tW0L VPUP VIHMASTER VTH VTL VILMAX 0V ε tF tREC tSLOT RESISTOR MASTER READ-DATA TIME SLOT tMSR tRL VPUP VIHMASTER VTH MASTER SAMPLING WINDOW VTL VILMAX 0V δ tF tREC tSLOT RESISTOR MASTER DS1921G Figure 15.
PAGE 34
DS1921G Thermochron iButton Device With the Read Scratchpad command, the CRC is generated by first clearing the CRC generator and then shifting in the command code, the target addresses TA1 and TA2, the E/S byte, and the scratchpad data starting at the target address. The DS1921G transmits this CRC only if the reading continues through the end of the scratchpad, regardless of the actual ending offset.
PAGE 35
DS1921G Thermochron iButton Device Command-Specific 1-Wire Communication Protocol—Legend (continued) SYMBOL DESCRIPTION Transfer of an undetermined amount of data CRC-16 Transfer of an inverted CRC-16 FF loop Indefinite loop where the master reads FFh bytes AA loop Indefinite loop where the master reads AAh bytes Interval during Copy Scratchpad where the DS1921G does not respond. Any bits read during this time are logic 1.
PAGE 36
DS1921G Thermochron iButton Device 1-Wire Communication Examples (continued) Read Memory with CRC (Success) RST PD Select RMC TA CRC-16 <32 bytes> CRC-16 Loop The “32 bytes” are either valid page data or 00h bytes when reading reserved pages 20 through 63 or 68 through 127 or pages 192 and higher (beyond data-log memory). Read Memory with CRC (Invalid Address) RST PD Select RMC TA <00 to EOP> CRC-16 The “32 bytes” are all 00h.
PAGE 37
DS1921G Thermochron iButton Device Step 1: Set the RTC Let the actual time be 15:30:00 hours on Monday, the 1st of April in 2002.
PAGE 38
DS1921G Thermochron iButton Device Step 2: Clear the data of the previous mission Set the EMCLR bit to 1, enable the RTC, and then execute the Clear Memory command. The RTC oscillator must be stable before the Clear Memory command is issued. Wait 500µs after issuing the Clear Memory command before proceeding to step 3.
PAGE 39
DS1921G Thermochron iButton Device Step 3: Set the search condition and Mission Start Delay and clear the alarm flags In this example, the rollover is disabled and the search condition is set for a high temperature only. The mission is to start with a delay of 90min (005Ah) and the alarm flags TLF, THF, and TAF are cleared.
PAGE 40
DS1921G Thermochron iButton Device Step 4: Set the temperature alarms and write the Sample Rate to start the mission In this example, the temperature alarms are set to -5°C for the low temperature threshold and 0°C for the high temperature threshold. The sample rate is once every 10min, allowing the mission to last up to 14 days.
PAGE 41
DS1921G Thermochron iButton Device Pin Configuration 5.89mm 0.51mm t o n ®. c 89 ® 21 YY 1-Wire® ® 50 om iB BRANDING ut Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. 16.
PAGE 42
DS1921G Thermochron iButton Device Revision History REVISION DATE DESCRIPTION PAGES CHANGED Added bullet “Water resistant or waterproof if placed inside DS9107 iButton capsule (Exceeds Water Resistant 3 ATM requirements)” Deleted “application pending” from UL bullet and safety statement Added text to Detailed Description section: Note that the initial sealing level of DS1921G achieves IP56.