DS18B20 Maxim Integrated Products, DS18B20 Datasheet - Page 18

• Manufacturer Part Number: DS18B20
• Description: IC THERM MICROLAN PROG-RES TO-92
• Manufacturer: Maxim Integrated Products

Specifications of DS18B20

• Function: Thermometer, Thermostat
• Topology: Register Bank, Scratchpad
• Sensor Type: Internal
• Sensing Temperature: -55°C ~ 125°C
• Output Type: 1-Wire®
• Output Alarm: Yes
• Output Fan: No
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -55°C ~ 125°C
• Mounting Type: Through Hole
• Package / Case: TO-92-3 (Standard Body), TO-226
• Full Temp Accuracy: +/- 2 C
• Digital Output - Bus Interface: Serial (1-Wire)
• Digital Output - Number Of Bits: 12 bit
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 55 C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

DS18B20 OPERATION EXAMPLE 1
In this example there are multiple DS18B20s on the bus and they are using parasite power. The bus
master initiates a temperature conversion in a specific DS18B20 and then reads its scratchpad and
recalculates the CRC to verify the data.
DS18B20 OPERATION EXAMPLE 2
In this example there is only one DS18B20 on the bus and it is using parasite power. The master writes to
the T
recalculates the CRC to verify the data. The master then copies the scratchpad contents to EEPROM.
MASTER MODE
MASTER MODE
H
, T
Tx
Rx
Tx
Tx
Tx
Tx
Tx
Rx
Tx
Tx
Tx
Rx
Tx
Rx
Tx
Tx
Tx
Tx
Rx
Tx
Tx
Rx
Tx
Rx
Tx
Tx
Tx
L
, and configuration registers in the DS18B20 scratchpad and then reads the scratchpad and
DATA (LSB FIRST)
DQ line held high by
DATA (LSB FIRST)
DQ line held high by
64-bit ROM code
64-bit ROM code
strong pullup
3 data bytes
9 data bytes
strong pullup
9 data bytes
Presence
Presence
Presence
Presence
Presence
Reset
Reset
Reset
CCh
CCh
CCh
BEh
4Eh
48h
Reset
Reset
BEh
55h
44h
55h
Master issues reset pulse.
DS18B20 responds with presence pulse.
Master issues Skip ROM command.
Master issues Write Scratchpad command.
Master sends three data bytes to scratchpad (T
Master issues reset pulse.
DS18B20 responds with presence pulse.
Master issues Skip ROM command.
Master issues Read Scratchpad command.
Master reads entire scratchpad including CRC. The master then
recalculates the CRC of the first eight data bytes from the
scratchpad and compares the calculated CRC with the read CRC
(byte 9). If they match, the master continues; if not, the read
operation is repeated.
Master issues reset pulse.
DS18B20 responds with presence pulse.
Master issues Skip ROM command.
Master issues Copy Scratchpad command.
Master applies strong pullup to DQ for at least 10ms while copy
operation is in progress.
Master issues reset pulse.
DS18B20s respond with presence pulse.
Master issues Match ROM command.
Master sends DS18B20 ROM code.
Master issues Convert T command.
Master applies strong pullup to DQ for the duration of the
conversion (t
Master issues reset pulse.
DS18B20s respond with presence pulse.
Master issues Match ROM command.
Master sends DS18B20 ROM code.
Master issues Read Scratchpad command.
Master reads entire scratchpad including CRC. The master
then recalculates the CRC of the first eight data bytes from the
scratchpad and compares the calculated CRC with the read
CRC (byte 9). If they match, the master continues; if not, the
read operation is repeated.
18 of 22
CONV
).
COMMENTS
COMMENTS
H
, T
L
, and config).
DS18B20