DS1923-F5# Maxim Integrated Products, DS1923-F5# Datasheet

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... Presence Detector Acknowledges When Reader First Applies Voltage ♦ Meets UL 913 (4th Edit.); Intrinsically Safe Apparatus: Approved Under Entity Concept for Use in Class I, Division 1, Group and D Locations PART DS1923-F5# #Denotes a RoHS-compliant device that may include lead(Pb) that is exempt under the RoHS requirements. DS9096P DS9101 DS9093RA ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory ABSOLUTE MAXIMUM RATINGS IO Voltage Range Relative to GND ..........................-0.3V to +6V IO Sink Current....................................................................20mA *See the Safe Operating Range graph. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory ELECTRICAL CHARACTERISTICS (continued +3.0V to +5.25V -20°C to +85°C.) PUP A PARAMETER SYMBOL Presence-Detect Low Time Presence-Detect Sample Time (Note 1) IO PIN: 1-Wire WRITE Write-Zero Low Time ...

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... Note 21: Response time is determined by measuring the 1/e point as the device transitions from 40%RH to 90%RH or 90%RH to 40%RH, whichever is slower. Test was performed at 5L/min airflow. Note 22: All DS1923 humidity measurements are 12-bit readings. Missioning determines 8-bit or 16-bit data logging. Battery life- time is the same no matter what RH resolution is logged. ...

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... Note 24: Software-corrected accuracy is accomplished using the method detailed in the Software Correction Algorithm for Temperature section. Note 25: Every DS1923 device is measured and calibrated in a controlled, NIST-traceable RH environment. Note 26: Higher accuracy versions may be available. Contact the factory for details. Note 27: If this device is exposed to a high humidity environment (> 70%RH), and then exposed to a lower RH environment, the device reads high for a period of time ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory 100 STORAGE ONLY 20 0 -40 -20 2.0 1.5 1.0 0.5 0 -0.5 -1.0 -20 -10 NOTE: THE GRAPHS ARE BASED ON 11-BIT DATA. 6 _______________________________________________________________________________________ SAFE OPERATING ZONE ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory Minimum Lifetime vs. Temperature, Slow Sampling (Temperature Only) EVERY MINUTE EVERY 60 MINUTES -20 -10 0 EVERY MINUTE EVERY 60 MINUTES ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory Minimum Lifetime vs. Temperature, Fast Sampling (Temperature Only) EVERY SECOND EVERY 30 SECONDS 350 300 250 200 150 100 50 0 -20 -10 EVERY SECOND EVERY 30 SECONDS 100 ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory Minimum Lifetime vs. Temperature, Slow Sampling EVERY MINUTE EVERY 60 MINUTES -20 - Minimum Lifetime vs. Temperature, Fast Sampling ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory Minimum Product Lifetime vs. Sample Rate (Temperature Only 0.1 0.01 0.01 NOTE: WITH HUMIDITY LOGGING ACTIVATED, THE LIFETIME IS REDUCED BY LESS THAN 11% FOR THE SAMPLE RATES OF 3MIN. ...

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... The rest of the electronics inside the DS1923 is sealed so that it is not exposed to ambient humidity. Note that the initial sealing level of the DS1923 achieves the equivalent of IP56. Aging and use ...

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... SENSE HUMIDITY SENSOR AND ADC2 Figure 1. Block Diagram 12 ______________________________________________________________________________________ ROM 64-BIT IO FUNCTION LASERED CONTROL ROM MEMORY FUNCTION CONTROL DS1923 GENERAL-PURPOSE SRAM (512 BYTES) INTERNAL TIMEKEEPING, REGISTER PAGES CONTROL REGISTERS, (64 BYTES) AND COUNTERS CALIBRATION MEMORY ADC1 (64 BYTES) CONTROL DATA-LOG MEMORY LOGIC 8KB ...

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... STAGE STAGE Figure 4. 1-Wire CRC Generator ______________________________________________________________________________________ OTHER DEVICES DS1923 AVAILABLE COMMANDS: DATA FIELD AFFECTED: READ ROM 64-BIT ROM, RC-FLAG MATCH ROM 64-BIT ROM, RC-FLAG SEARCH ROM 64-BIT ROM, RC-FLAG CONDITIONAL SEARCH ROM 64-BIT ROM, RC-FLAG, ALARM FLAGS, SEARCH CONDITIONS SKIP ROM ...

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... Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory Figure 5 shows the DS1923 memory map. Pages contain 512 bytes of general-purpose SRAM. The various registers to set up and control the device fill pages 16 and 17, called register pages 1 and 2 (see Figure 6 for details). Pages 18 and 19 can be used as storage space for calibration data ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory ADDRESS BIT 7 BIT 6 0200h 0 10 Seconds 0201h 0 10 Minutes 20 Hour 0202h 0 12/24 AM/PM 0203h 0 0 0204h CENT 0 0205h 10 Years 0206h 0207h 0 0 ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory ADDRESS BIT 7 BIT 6 0219h 0 10 Seconds 021Ah 0 10 Minutes 20 Hour 021Bh 0 12/24 AM/PM 021Ch 0 0 021Dh CENT 0 021Eh 10 Years 021Fh 0220h 0221h 0222h ...

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... These bits always read 0 regardless of how they are written. The number representation of the RTC registers is binary-coded decimal (BCD) format. The DS1923’s RTC can run in either 12hr or 24hr mode. Bit 6 of the Hours register (address 0202h) is defined as the 12hr or 24hr mode select bit. When high, the 12hr mode is selected ...

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... Forced Conversion command is executed (see the Memory and Control Function Commands section) or during a mission if the device is set up to log humidi- ty data. Regardless of its setup, the DS1923 always reads 16 bits from the humidity sensor. The result of the latest humidity reading is found at address 020Eh (low byte) and 020Fh (high byte) ...

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... H10 During a mission, if humidity logging is enabled, the HRH byte (H11 to H4) is always recorded. The HRL byte is only recorded if the DS1923 is set up for 16-bit humidity logging. The logging mode (8-bit or 16-bit) is selected through the HLFS bit at the Mission Control register, address 0213h. ...

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... Humidity Low Alarm Threshold register. If EHLA is 1, humidity low alarms are enabled. If EHLA is 0, humidity low alarms are not generated. To minimize the power consumption of a DS1923, the RTC oscillator should be turned off when the device is not in use. The oscillator on/off bit is located in the RTC Control register ...

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... An addition- al control bit can be set to tell the DS1923 to wait with logging data until a temperature alarm is encountered. Bit 5: Start Mission Upon Temperature Alarm (SUTA) ...

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... The information in the General Status register tells the host computer whether a mission-related command was executed successfully. Individual status bits indi- cate whether the DS1923 is performing a mission, wait- ing for a temperature alarm to trigger the logging of data or whether the data from the latest mission has been cleared ...

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... For a typical mission, the Mission Start Delay mission is too long for a single DS1923 to store all read- ings at the selected sample rate, one can use several devices and set the Mission Start Delay for the second device to start recording as soon as the memory of the first device is full, and so on ...

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... BIT 5 BIT 4 BIT 3 EPW Other Indicators The DS1923 is designed to use two passwords that control read access and full access. Reading from or writing to the scratchpad as well as the Forced Conversion command does not require a password. The password must be transmitted immediately after the command code of the memory or control function. If password checking is enabled, the password transmit- ted is compared to the passwords stored in the device ...

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... FP0, FP1…FP62, FP63. It affects the commands Read Memory with CRC, Copy Scratchpad, Clear Memory, Start Mission, and Stop Mission. The DS1923 executes the command only if the password transmitted by the master was correct or if password checking is not enabled. Due to the special behavior of the write-access logic, the Password Control register and both passwords must be written at the same time ...

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... Before the device can per- form this function, it needs to be set up properly. This procedure is called missioning. First, the DS1923 must have its RTC set to a valid time and date. This reference time can be the local time, or, when used inside of a mobile unit, UTC (also called GMT, Greenwich Mean Time), or any other time stan- dard that was agreed upon ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory ETL = 1; EHL = 0 OR ETL = 0; EHL = 1 TLFS = HLFS = 0 1000h 8192 8-BIT ENTRIES TEMPERATURE OR HUMIDITY DATA 2FFFh Figure 7a. 1-Channel Logging ETL ...

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... Sample Rate register and the EHSS bit. If the start upon temperature alarm mode is chosen (SUTA = 1) and temperature logging is enabled (ETL = 1), the DS1923 first waits until the start delay is over. Then the device wakes up in intervals as specified by the sample rate and EHSS bit and measures the tem- perature ...

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... Figure 9 shows the protocols necessary for accessing the memory and the special function registers of the DS1923. An example on how to use these and other functions to set up the DS1923 for a mission is included in the Mission Example: Prepare and Start a New Mission section. The communication between the mas- ...

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... CRC generator and then shift- ing in the contents of the data memory page. After the 16-bit CRC of the last page is read, the bus master receives logic 1s from the DS1923 until a reset pulse is issued. The Read Memory with CRC command sequence can be ended at any point by issuing a reset pulse ...

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... FLOWCHART (FIGURE 11) 0Fh N WRITE SCRATCHPAD? Y MASTER Tx TA1 [T7:T0] MASTER Tx TA2 [T15:T8] DS1923 SETS SCRATCHPAD OFFSET = [T4:T0] AND CLEARS (PF, AA) MASTER Tx DATA BYTE TO SCRATCHPAD OFFSET DS1923 DS1923 SETS [E4:E0] = INCREMENTS SCRATCHPAD OFFSET SCRATCHPAD OFFSET Y MASTER Tx RESET SCRATCHPAD OFFSET = 11111b? PARTIAL Y BYTE WRITTEN? Y ...

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... DS1923 SETS MEMCLR = MASTER Tx RESET MASTER Rx "1"s N 55h N N FORCED CONVERSION? Y MASTER Tx FFh DUMMY BYTE Y MISSION IN PROGRESS DS1923 PERFORMS A TEMPERATURE CONVERSION DS1923 COPIES RESULT TO Y ADDRESS 020C/Dh DS1923 PERFORMS A HUMIDITY CONVERSION DS1923 COPIES RESULT TO ADDRESS 020E/Fh N MASTER Tx RESET FIGURE 9c FROM FIGURE 9c ...

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... DELAY PROCESS MASTER Tx START DELAY COUNTER = 0? MASTER Tx N DS1923 WAITS FOR 1 MINUTE DS1923 DECREMENTS START DELAY COUNTER Y MISSION IN SUTA = DS1923 SETS WFTA = 1 DS1923 WAITS ONE SAMPLE PERIOD Y MIP = 1, Y MIP = 0? N DS1923 PERFORMS 8-BIT TEMPERATURE CONVERSION TEMPERATURE ALARM DS1923 SETS WFTA = 0 ...

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... During a mission there is only read access to the regis- ter pages. Stop Mission [with Password] [33h] The DS1923 uses a control function command to stop a mission. Only a mission that is in progress can be stopped. After the command code, the master must transmit the 64-bit full access password followed by a FFh dummy byte ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory Memory Access Conflicts While a mission is in progress or while the device is waiting for a temperature alarm to start a mission, peri- odically a temperature and/or humidity sample is taken ...

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... Data-Log Memory 1-Wire Bus System The 1-Wire bus is a system that has a single bus mas- ter and one or more slaves. In all instances the DS1923 is a slave device. The bus master is typically a micro- controller. The discussion of this bus system is broken ...

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... The presence pulse lets the bus master know that the DS1923 is on the bus and is ready to operate. For more details, see the 1-Wire Signaling section. 1-Wire ROM Function Commands ...

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... AND result). The Overdrive-Match ROM command followed by a 64-bit ROM sequence transmitted at overdrive speed allows the bus master to address a specific DS1923 on a multidrop bus and to simultaneously set it in overdrive mode. Only the DS1923 that exactly matches the 64-bit ROM sequence responds to the subsequent memory/control function command ...

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... DS1923 Tx BIT 0 MASTER Tx BIT 0 MASTER Tx BIT BIT 0 MATCH? BIT 0 MATCH? BIT 0 MATCH DS1923 Tx BIT 1 DS1923 Tx BIT 1 MASTER Tx BIT 1 DS1923 Tx BIT 1 DS1923 Tx BIT 1 MASTER Tx BIT 1 MASTER Tx BIT BIT 1 MATCH? BIT 1 MATCH? BIT 1 MATCH DS1923 Tx BIT 63 DS1923 Tx BIT 63 MASTER Tx BIT 63 DS1923 Tx BIT 63 DS1923 Tx BIT 63 ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory TO FIGURE 11a CCh FROM FIGURE 11a SKIP ROM COMMAND FROM FIGURE 11a TO FIGURE 11a NOTE: THE OD FLAG REMAINS THE DEVICE WAS ALREADY ...

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... ILMAX determining a logical level, not triggering any events. The initialization sequence required to begin any com- munication with the DS1923 is shown in Figure 12. A reset pulse followed by a presence pulse indicates the DS1923 is ready to receive data, given the correct ROM and memory function command. If the bus master uses ...

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... When responding with a 1, the DS1923 does not hold the data line low at all, and the voltage starts rising as soon The sum of t ...

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... WRITE-ONE TIME SLOT t W1L V PUP V IHMASTER ILMAX RESISTOR WRITE-ZERO TIME SLOT V PUP V IHMASTER ILMAX RESISTOR READ-DATA TIME SLOT PUP V IHMASTER ILMAX RESISTOR Figure 13. Read/Write Timing Diagrams ______________________________________________________________________________________ t SLOT MASTER t W0L t SLOT MASTER MSR MASTER SAMPLING WINDOW t SLOT MASTER t REC t REC DS1923 43 ...

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... X Figure 15. CRC-16 Hardware Description and Polynomial CRC Generation The DS1923 uses two types of CRCs. One CRC is an 8-bit type and is stored in the most significant byte of the 64-bit ROM. The bus master can compute a CRC value from the first 56 bits of the 64-bit ROM and com- pare it to the value stored within the DS1923 to deter- mine if the ROM data has been received error-free ...

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... Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory ing in the command code, the target addresses TA1 and TA2, and all the data bytes. The DS1923 transmits this CRC only if the data bytes written to the scratchpad include scratchpad ending offset 11111b. The data can start at any location within the scratchpad ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory Command-Specific 1-Wire Communication Protocol—Color Codes Master-to-Slave Slave-to-Master Write Scratchpad, Reaching the End of the Scratchpad (Cannot Fail) RST PD Select WS TA <Data to EOS> Read Scratchpad (Cannot Fail) RST PD Select ...

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... To verify success, read the General Status register at address 0215h. If MIP is 0, the command was executed successfully. Mission Example: Prepare and Start a New Mission Assumption: The previous mission has been ended by using the Stop Mission command. Passwords are not enabled. The device is a DS1923. Starting a mission requires three steps: MASTER MODE ...

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... Alarm Controls (Response to Conditional Search ROM) • General Mission Parameters (e.g., Channels to Log and Logging Format, Rollover, Start Mode) • Mission Start Delay The following data sets up the DS1923 for a mission that logs temperature and humidity using 8-bit format for both. EXAMPLE VALUES ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory With only a single device connected to the bus master, the communication of step 2 looks like this: MASTER MODE ...

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... The software correction algorithm requires two addition- al values, which are not stored in the device. For the DS1923 these values are Tr1 = 60°C and Offset = 41. The correction algorithm consists of two steps, prepara- tion and execution. The preparation step first converts temperature data from binary to decimal °C format. ...

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... Next, three coefficients A, B, and C are computed. In the exe- cution step the humidity reading as delivered by the DS1923 (raw data) is first converted from the low/high- byte format (HcL, HcH) to %RH (Hc) and then correct Hcorr. Once step 1 is performed, the three coefficients can be used repeatedly to correct any humidity reading and humidity log of the same device ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory Step 1: Preparation For the humidity data in the calibration memory, the lower 4 bits of each low byte are set to 0. This simplifies the con- version from the binary data ...

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... This shift continues to increase while the device remains at 70%RH and above. This effect is called sat- uration drift, or hysteresis. This drift is reversible. Readings return to their regular level when the DS1923 is removed from a high-humidity environment possible to compensate for most of the error intro- ...

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Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory SAMPLE INPUT DATA ( (HOUR) T (° 25.1 2 25.0 3 24.9 4 25.0 5 25.1 6 25.1 7 25.0 8 24.9 HTcorr = 93.70207%RH HScorr = ...

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... DS1923 achieves IP56. Aging and use conditions can degrade the integrity of the seal over time, so for applications with significant exposure to liquids, sprays, or other similar environments recommended to place the Hygrochron under a shield to protect it. (See www.maxim-ic.com/AN4126). The hydrophobic filter may not protect the DS1923 from destruction in the event of full submersion in liquid. 2 4/09 Created newer template-style data sheet ...