Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsSensorsTemperature sensor -55 up to +125 °C Radial lead

AVAILABLE

Functional Diagrams

Pin Configurations appear at end of data sheet.

Functional Diagrams continued at end of data sheet.

UCSP is a trademark of Maxim Integrated Products, Inc.

For pricing, delivery, and

ordering information, please contact Maxim Direct

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

FEATURES

 Unique 1-Wire

Interface Requires Only One

Port Pin for Communication

 Each Device has a Unique 64-Bit Serial Code

Stored in an On-Board ROM

 Multidrop Capability Simplifies Distributed

Temperature Sensing Applications

 Requires No External Components

 Can Be Powered from Data Line. Power

Supply Range is 3.0V to 5.5V

 Measures Temperatures from -55°C to

+125°C (-67°F to +257°F)

 ±0.5°C Accuracy from -10°C to +85°C

 9-Bit Thermometer Resolution

 Converts Temperature in 750ms (max)

 User-Definable Nonvolatile (NV) Alarm

Settings

 Alarm Search Command Identifies and

Addresses Devices Whose Temperature is

Outside Programmed Limits (Temperature

Alarm Condition)

 Applications Include Thermostatic Controls,

Industrial Systems, Consumer Products,

Thermometers, or Any Thermally Sensitive

System

PIN CONFIGURATIONS

DESCRIPTION

The DS18S20 digital thermometer provides 9-bit Celsius temperature measurements and has an alarm

function with nonvolatile user-programmable upper and lower trigger points. The DS18S20

communicates over a 1-Wire bus that by definition requires only one data line (and ground) for

communication with a central microprocessor. It has an operating temperature range of –55°C to +125°C

and is accurate to ±0.5°C over the range of –10°C to +85°C. In addition, the DS18S20 can derive power

directly from the data line (“parasite power”), eliminating the need for an external power supply.

Each DS18S20 has a unique 64-bit serial code, which allows multiple DS18S20s to function on the same

1-Wire bus. Thus, it is simple to use one microprocessor to control many DS18S20s distributed over a

large area. Applications that can benefit from this feature include HVAC environmental controls,

temperature monitoring systems inside buildings, equipment, or machinery, and process monitoring and

control systems.

1-Wire is a registered trademark of Maxim Integrated Products, Inc.

TO-92

(DS18S20)

(BOTTOM VIEW)

MAXIM

DS1820

GND

SO (150 mils)

(DS18S20Z)

N.C.

GND

N.C.

DS1820

19-5474; Rev 8/10

DS18S20

High-Precision 1-

Wire Digital Thermometer

Summary of content (23 pages)

PAGE 1
LE AVAILAB DS18S20 High-Precision 1-Wire Digital Thermometer FEATURES          MAXIM DS1820 1 2 3 N.C. 1 N.C. 2 VDD 3 DQ 4 DS1820   Unique 1-Wire Interface Requires Only One Port Pin for Communication Each Device has a Unique 64-Bit Serial Code Stored in an On-Board ROM Multidrop Capability Simplifies Distributed Temperature Sensing Applications Requires No External Components Can Be Powered from Data Line. Power Supply Range is 3.0V to 5.
PAGE 2
DS18S20 ORDERING INFORMATION PART TEMP RANGE –55°C to +125°C –55°C to +125°C –55°C to +125°C –55°C to +125°C –55°C to +125°C –55°C to +125°C –55°C to +125°C –55°C to +125°C –55°C to +125°C –55°C to +125°C DS18S20 DS18S20+ DS18S20/T&R DS18S20+T&R DS18S20-SL/T&R DS18S20-SL+T&R DS18S20Z DS18S20Z+ DS18S20Z/T&R DS18S20Z+T&R PIN-PACKAGE 3 TO-92 3 TO-92 3 TO-92 (2000 Piece) 3 TO-92 (2000 Piece) 3 TO-92 (2000 Piece)* 3 TO-92 (2000 Piece)* 8 SO 8 SO 8 SO (2500 Piece) 8 SO (2500 Piece) +Denotes a lead(Pb)-free/R
PAGE 3
DS18S20 Figure 1. DS18S20 Block Diagram VPU PARASITE POWER CIRCUIT 4.7k MEMORY CONTROL LOGIC DS18S20 DQ TEMPERATURE SENSOR INTERNAL VDD GND VDD 64-BIT ROM AND 1-Wire PORT CPP SCRATCHPAD ALARM HIGH TRIGGER (TH) REGISTER (EEPROM) ALARM LOW TRIGGER (TL) REGISTER (EEPROM) POWERSUPPLY SENSE 8-BIT CRC GENERATOR OPERATION—MEASURING TEMPERATURE The core functionality of the DS18S20 is its direct-to-digital temperature sensor. The temperature sensor output has 9-bit resolution, which corresponds to 0.
PAGE 4
DS18S20 Figure 2. Temperature Register Format LS BYTE BIT 7 26 BIT 6 25 BIT 5 24 BIT 4 23 BIT 3 22 BIT 2 21 BIT 1 20 BIT 0 2-1 MS BYTE BIT 15 S BIT 14 S BIT 13 S BIT 12 S BIT 11 S BIT 10 S BIT 9 S BIT 8 S S = SIGN Table 1. Temperature/Data Relationship TEMPERATURE (°C) +85.0* +25.0 +0.5 0 -0.5 -25.0 -55.
PAGE 5
DS18S20 POWERING THE DS18S20 The DS18S20 can be powered by an external supply on the VDD pin, or it can operate in “parasite power” mode, which allows the DS18S20 to function without a local external supply. Parasite power is very useful for applications that require remote temperature sensing or those with space constraints. Figure 1 shows the DS18S20’s parasite-power control circuitry, which “steals” power from the 1-Wire bus via the DQ pin when the bus is high.
PAGE 6
DS18S20 Figure 4. Supplying the Parasite-Powered DS18S20 During Temperature Conversions VPU DS18S20 GND DQ VDD VPU µP 4.7k TO OTHER 1-WIRE DEVICES 1-Wire BUS Figure 5. Powering the DS18S20 with an External Supply DS18S20 VPU µP VDD (EXTERNAL SUPPLY) GND DQ VDD 4.7k TO OTHER 1-WIRE DEVICES 1-Wire BUS 64-BIT LASERED ROM CODE Each DS18S20 contains a unique 64-bit code (see Figure 6) stored in ROM. The least significant 8 bits of the ROM code contain the DS18S20’s 1-Wire family code: 10h.
PAGE 7
DS18S20 MEMORY The DS18S20’s memory is organized as shown in Figure 7. The memory consists of an SRAM scratchpad with nonvolatile EEPROM storage for the high and low alarm trigger registers (TH and TL). Note that if the DS18S20 alarm function is not used, the TH and TL registers can serve as general-purpose memory. All memory commands are described in detail in the DS18S20 Function Commands section. Byte 0 and byte 1 of the scratchpad contain the LSB and the MSB of the temperature register, respectively.
PAGE 8
DS18S20 CRC GENERATION CRC bytes are provided as part of the DS18S20’s 64-bit ROM code and in the 9th byte of the scratchpad memory. The ROM code CRC is calculated from the first 56 bits of the ROM code and is contained in the most significant byte of the ROM. The scratchpad CRC is calculated from the data stored in the scratchpad, and therefore it changes when the data in the scratchpad changes. The CRCs provide the bus master with a method of data validation when data is read from the DS18S20.
PAGE 9
DS18S20 1-WIRE BUS SYSTEM The 1-Wire bus system uses a single bus master to control one or more slave devices. The DS18S20 is always a slave. When there is only one slave on the bus, the system is referred to as a “single-drop” system; the system is “multidrop” if there are multiple slaves on the bus. All data and commands are transmitted least significant bit first over the 1-Wire bus.
PAGE 10
DS18S20 TRANSACTION SEQUENCE The transaction sequence for accessing the DS18S20 is as follows: Step 1. Initialization Step 2. ROM Command (followed by any required data exchange) Step 3. DS18S20 Function Command (followed by any required data exchange) It is very important to follow this sequence every time the DS18S20 is accessed, as the DS18S20 will not respond if any steps in the sequence are missing or out of order. Exceptions to this rule are the Search ROM [F0h] and Alarm Search [ECh] commands.
PAGE 11
DS18S20 SKIP ROM [CCh] The master can use this command to address all devices on the bus simultaneously without sending out any ROM code information. For example, the master can make all DS18S20s on the bus perform simultaneous temperature conversions by issuing a Skip ROM command followed by a Convert T [44h] command. Note that the Read Scratchpad [BEh] command can follow the Skip ROM command only if there is a single slave device on the bus.
PAGE 12
DS18S20 COPY SCRATCHPAD [48h] This command copies the contents of the scratchpad TH and TL registers (bytes 2 and 3) to EEPROM. If the device is being used in parasite power mode, within 10µs (max) after this command is issued the master must enable a strong pullup on the 1-Wire bus for at least 10ms as described in the Powering the DS18S20 section.
PAGE 13
DS18S20 1-WIRE SIGNALING The DS18S20 uses a strict 1-Wire communication protocol to ensure data integrity. Several signal types are defined by this protocol: reset pulse, presence pulse, write 0, write 1, read 0, and read 1. All these signals, with the exception of the presence pulse, are initiated by the bus master.
PAGE 14
DS18S20 READ-TIME SLOTS The DS18S20 can only transmit data to the master when the master issues read-time slots. Therefore, the master must generate read-time slots immediately after issuing a Read Scratchpad [BEh] or Read Power Supply [B4h] command, so that the DS18S20 can provide the requested data. In addition, the master can generate read-time slots after issuing Convert T [44h] or Recall E2 [B8h] commands to find out the status of the operation as explained in the DS18S20 Function Commands section.
PAGE 15
DS18S20 Figure 12. Detailed Master Read 1 Timing VPU VIH of Master 1-WIRE BUS GND TINT > 1µs TRC Master samples 15µs Figure 13.
PAGE 16
DS18S20 Figure 14.
PAGE 17
DS18S20 Figure 15.
PAGE 18
DS18S20 DS18S20 OPERATION EXAMPLE 1 In this example there are multiple DS18S20s on the bus and they are using parasite power. The bus master initiates a temperature conversion in a specific DS18S20 and then reads its scratchpad and recalculates the CRC to verify the data. MASTER MODE Tx Rx Tx Tx Tx Tx Rx Tx Tx Tx DATA (LSB FIRST) Reset Presence 55h 64-bit ROM code 44h DQ line held high by strong pullup Reset Presence 55h 64-bit ROM code BEh Rx 9 data bytes Tx COMMENTS Master issues reset pulse.
PAGE 19
DS18S20 DS18S20 OPERATION EXAMPLE 3 In this example there is only one DS18S20 on the bus and it is using parasite power. The bus master initiates a temperature conversion then reads the DS18S20 scratchpad and calculates a higher resolution result using the data from the temperature, COUNT REMAIN and COUNT PER °C registers.
PAGE 20
DS18S20 ABSOLUTE MAXIMUM RATINGS Voltage Range on Any Pin Relative to Ground........................................................................................ -0.5V to +6.0V Continuous Power Dissipation (TA = +70°C) 8-Pin SO (derate 5.9mW/°C above +70°C).......................................................................................... 470.6mW 3-Pin TO-92 (derate 6.3mW/°C above +70°C).....................................................................................
PAGE 21
DS18S20 AC ELECTRICAL CHARACTERISTICS—NV MEMORY (VDD = 3.0V to 5.5V, TA = -55°C to +100°C, unless otherwise noted.) PARAMETER NV Write Cycle Time EEPROM Writes EEPROM Data Retention SYMBOL tWR NEEWR tEEDR CONDITIONS MIN -55°C to +55°C -55°C to +55°C TYP 2 MAX 10 50k 10 UNITS ms writes years AC ELECTRICAL CHARACTERISTICS (VDD = 3.0V to 5.5V; TA = -55°C to +125°C, unless otherwise noted.
PAGE 22
DS18S20 Figure 17. Timing Diagrams PACKAGE INFORMATION For the latest package outline information and land patterns, go to www.maxim-ic.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. PACKAGE TYPE 8 SO 3 TO-92 (straight leads) 3 TO-92 (formed leads) PACKAGE CODE S8-2 OUTLINE NO. 21-0041 LAND PATTERN NO.
PAGE 23
DS18S20 REVISION HISTORY REVISION DATE 042208 8/10 DESCRIPTION In the Ordering Information table, added TO-92 straight-lead packages and included a note that the TO-92 package in tape and reel can be ordered with either formed or straight leads Removed the Top Mark column from the Ordering Information table; added the continuous power dissipation and lead and soldering temperatures to the Absolute Maximum Ratings section PAGES CHANGED 2 2, 20 Maxim cannot assume responsibility for use of any circuitry