DS18S20-SL+T&R Maxim Integrated Products, DS18S20-SL+T&R Datasheet
DS18S20-SL+T&R
Specifications of DS18S20-SL+T&R
Related parts for DS18S20-SL+T&R
DS18S20-SL+T&R Summary of contents
Page 1
... 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. ...
Page 2
... The control line requires a weak pullup resistor since all devices are linked to the bus via a 3-state or open-drain port (the DQ pin in the case of the DS18S20). In this bus system, the microprocessor (the master device) identifies and addresses devices on the bus using each device’s unique 64-bit code ...
Page 3
... Convert T command and the DS18S20 will respond by transmitting 0 while the temperature conversion is in progress and 1 when the conversion is done. If the DS18S20 is powered with parasite power, this notification technique cannot be used since the bus must be pulled high by a strong pullup during the entire temperature conversion ...
Page 4
... The master device can check the alarm flag status of all DS18S20s on the bus by issuing an Alarm Search [ECh] command. Any DS18S20s with a set alarm flag will respond to the command, so the master can determine exactly which DS18S20s have experienced an alarm condition ...
Page 5
... 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. The stolen charge powers the DS18S20 while the bus is high, and some of the charge is stored on the parasite power capacitor (C low ...
Page 6
... 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. The next 48 bits contain a unique serial number. The most significant 8 bits contain a cyclic redundancy check (CRC) byte that is calculated from the first 56 bits of the ROM code ...
Page 7
... Data is written to bytes 2 and 3 of the scratchpad using the Write Scratchpad [4Eh] command; the data must be transmitted to the DS18S20 starting with the least significant bit of byte 2. To verify data integrity, the scratchpad can be read (using the Read Scratchpad [BEh] command) after the data is written ...
Page 8
... 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 ...
Page 9
... 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 “single-drop” system; the system is “multidrop” if there are multiple slaves on the bus. ...
Page 10
... The presence pulse lets the bus master know that slave devices (such as the DS18S20) are on the bus and are ready to operate. Timing for the reset and presence pulses is detailed in the 1-Wire Signaling section ...
Page 11
... In parasite power mode this notification technique cannot be used since the bus is pulled high by the strong pullup during the conversion. WRITE SCRATCHPAD [4Eh] This command allows the master to write 2 bytes of data to the DS18S20’s scratchpad. The first byte is written into the T register (byte 2 of the scratchpad), and the second byte is written into the T H (byte 3 of the scratchpad) ...
Page 12
... READ POWER SUPPLY [B4h] The master device issues this command followed by a read-time slot to determine if any DS18S20s on the bus are using parasite power. During the read-time slot, parasite powered DS18S20s will pull the bus low, and externally powered DS18S20s will let the bus remain high ...
Page 13
... There are two types of write time slots: “Write 1” time slots and “Write 0” time slots. The bus master uses a Write 1 time slot to write a logic 1 to the DS18S20 and a Write 0 time slot to write a logic 0 to the DS18S20. All write time slots must be a minimum of 60µs in duration with a minimum of a 1µs recovery time between individual write slots ...
Page 14
... Figure 11). After the master initiates the read-time slot, the DS18S20 will begin transmitting bus. The DS18S20 transmits leaving the bus high and transmits pulling the bus low. When transmitting a 0, the DS18S20 will release the bus by the end of the time slot, and the bus will be pulled back to its high idle state by the pullup resister. Output data from the DS18S20 is valid for 15µ ...
Page 15
... Figure 12. Detailed Master Read 1 Timing V PU 1-WIRE BUS GND T INT Figure 13. Recommended Master Read 1 Timing V PU 1-WIRE BUS GND INT RC small small > 1µ 15µs VIH of Master 15µs LINE TYPE LEGEND Bus master pulling low Resistor pullup DS18S20 VIH of Master Master samples Master samples ...
Page 16
... BIT BIT 0 BIT 0 MATCH? MATCH DS18S20 T BIT 1 X MASTER T X DS18S20 T BIT 1 X BIT 1 MASTER T BIT BIT 1 BIT 1 MATCH? MATCH DS18S20 T BIT 63 X MASTER T DS18S20 T BIT BIT 63 MASTER T BIT BIT 63 BIT 63 MATCH? MATCH MASTER T X FUNCTION COMMAND (FIGURE 15 CCh ECh N N SKIP ROM ...
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... Figure 15. DS18S20 Function Commands Flowchart 44h MASTER T CONVERT X FUNCTION TEMPERATURE COMMAND ? Y N PARASITE POWER ? DS18S20 BEGINS CONVERSION DEVICE N CONVERTING TEMPERATURE ? Y MASTER MASTER R “0s” R “1s” B4h N READ POWER SUPPLY ? PARASITE POWERED ? MASTER MASTER R “1s” R “0s” MASTER ENABLES STRONG PULLUP ON DQ ...
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... Tx 64-bit ROM code data bytes DS18S20 OPERATION EXAMPLE 2 In this example there is only one DS18S20 on the bus and it is using parasite power. The master writes to the T and T registers in the DS18S20 scratchpad and then reads the scratchpad and recalculates the H L CRC to verify the data. The master then copies the scratchpad contents to EEPROM. ...
Page 19
... 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
... Parasite Power +3.0 Local Power +3.0 -10°C to +85°C -55°C to +125°C -0.3 Local Power +2.2 Parasite Power +3 0.4V 4.0 I spec of the DS18S20, the actual supply rail for the strong IH . Figure 5.5V MAX UNITS +5 ±0.5 °C ±2 +0.8 ...
Page 21
... Start Convert T t SPON Command Issued t SLOT t REC t LOW0 t LOW1 t RDV t RSTH t RSTL t PDHIGH t PDLOW C IN/OUT > 960µs, a power-on reset may occur. DS18S20 Typical Error Curve Mean Error Temperature (° MIN TYP MAX 2 10 50k 10 MIN TYP MAX UNITS 750 ms µs 10 µs 60 120 µ ...
Page 22
... RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE TO-92 (straight leads) 3 TO-92 (formed leads) to www.maxim-ic.com/packages. PACKAGE CODE OUTLINE NO. S8-2 Q3-1 Q3 Note that a “+”, “#”, or “-” LAND PATTERN NO. 21-0041 90-0096 21-0248 21-0250 DS18S20 — — ...
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... Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time © 2010 Maxim Integrated Products DESCRIPTION Maxim is a registered trademark of Maxim Integrated Products, Inc. DS18S20 PAGES CHANGED ...