DS18B20-SL DALLAS [Dallas Semiconductor], DS18B20-SL Datasheet - Page 6

• Manufacturer Part Number: DS18B20-SL
• Description: Programmable Resolution 1-Wire Digital Thermometer
• Manufacturer: DALLAS [Dallas Semiconductor]

Figure 4. Supplying the Parasite-Powered DS18B20 During Temperature Conversions
Figure 5. Powering the DS18B20 with an External Supply
64-BIT LASERED ROM CODE
Each DS18B20 contains a unique 64–bit code (see Figure 6) stored in ROM. The least significant 8 bits
of the ROM code contain the DS18B20’s 1-Wire family code: 28h. 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. A detailed explanation of the CRC bits is provided in
the CRC Generation section. The 64-bit ROM code and associated ROM function control logic allow the
DS18B20 to operate as a 1-Wire device using the protocol detailed in the 1-Wire Bus System section.
Figure 6. 64-Bit Lasered ROM Code
MSB
8-BIT CRC
μP
μP
LSB
V
PU
V
MSB
PU
4.7k
4.7k
48-BIT SERIAL NUMBER
1-Wire BUS
6 of 22
V
PU
1-Wire BUS
GND
DS18B20
DQ
LSB
V
DD
GND
DS18B20
MSB
DQ
V
8-BIT FAMILY CODE (28h)
DD
V
(EXTERNAL SUPPLY)
DD
TO OTHER
1-WIRE DEVICES
TO OTHER
1-WIRE DEVICES
DS18B20
LSB