DS18B20

2 of 21

ORDER INFORMATION

ORDERING

NUMBER

PACKAGE

MARKING

DESCRIPTION

DS18B20

18B20

DS18B20 in 3-pin TO92

DS18B20/T&R

18B20

DS18B20 in 3-pin TO92, 2000 Piece Tape-and-Reel

DS18B20+

18B20 (See Note)

DS18B20 in Lead-Free 3-pin TO92

DS18B20+T&R

18B20 (See Note)

DS18B20 in Lead-Free 3-pin TO92, 2000 Piece Tape-

and-Reel

DS18B20U

18B20

DS18B20 in 8-pin uSOP

DS18B20U/T&R

18B20

DS18B20 in 8-pin uSOP, 3000 Piece Tape-and-Reel

DS18B20U+

18B20 (See Note)

DS18B20 in Lead-Free 8-pin uSOP

DS18B20U+T&R

18B20 (See Note)

DS18B20 in Lead-Free 8-pin uSOP, 3000 Piece Tape-

and-Reel

DS18B20Z

DS18B20

DS18B20 in 150 mil 8-pin SO

DS18B20Z/T&R

DS18B20

DS18B20 in 150 mil 8-pin SO, 2500 Piece Tape-and-

Reel

DS18B20Z+

DS18B20 (See Note)

DS18B20 in Lead-Free 150 mil 8-pin SO

DS18B20Z+T&R

DS18B20 (See Note)

DS18B20 in Lead-Free 150 mil 8-pin SO, 2500 Piece

Tape-and-Reel

Note: A “+” symbol will also be marked on the package.

DETAILED PIN DESCRIPTIONS Table 1

SO*

μSOP* TO-92 SYMBOL DESCRIPTION

5

4

1

GND

Ground.

4

1

2

DQ

Data Input/Output pin. Open-drain 1-Wire interface pin.

Also provides power to the device when used in parasite

power mode (see “Parasite Power” section.)

3

8

3

parasite power mode.

*All pins not specified in this table are “No Connect” pins.

OVERVIEW

Figure 1 shows a block diagram of the DS18B20, and pin descriptions are given in Table 1. The 64-bit

ROM stores the device’s unique serial code. The scratchpad memory contains the 2-byte temperature

register that stores the digital output from the temperature sensor. In addition, the scratchpad provides

register. The configuration register allows the user to set the resolution of the temperature-to-digital

they will retain data when the device is powered down.

The DS18B20 uses Dallas’ exclusive 1-Wire bus protocol that implements bus communication using one

control signal. 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 DS18B20). In this bus system, the

microprocessor (the master device) identifies and addresses devices on the bus using each device’s unique

64-bit code. Because each device has a unique code, the number of devices that can be addressed on one

bus is virtually unlimited. The 1-Wire bus protocol, including detailed explanations of the commands and

“time slots,” is covered in the 1-WIRE BUS SYSTEM section of this datasheet.