Datasheet

DS18B20
2 of 22
ORDERING INFORMATION
PART
TEMP RANGE
PIN-PACKAGE
TOP MARK
DS18B20
-55
°
C to +125
°
C
3 TO-92
18B20
DS18B20+
-55°C to +125°C
3 TO-92
18B20
DS18B20/T&R
-55°C to +125°C
3 TO-92 (2000 Piece)
18B20
DS18B20+T&R
-55°C to +125°C
3 TO-92 (2000 Piece)
18B20
DS18B20-SL/T&R
-55
°
C to +125
°
C
3 TO-92 (2000 Piece)*
18B20
DS18B20-SL+T&R
-55°C to +125°C
3 TO-92 (2000 Piece)*
18B20
DS18B20U
-55°C to +125°C
8 µSOP
18B20
DS18B20U+
-55°C to +125°C
8 µSOP
18B20
DS18B20U/T&R
-55
°
C to +125
°
C
8
µ
SOP (3000 Piece)
18B20
DS18B20U+T&R
-55
°
C to +125
°
C
8
µ
SOP (3000 Piece)
18B20
DS18B20Z
-55
°
C to +125
°
C
8 SO
DS18B20
DS18B20Z+
-55°C to +125°C
8 SO
DS18B20
DS18B20Z/T&R
-55
°
C to +125
°
C
8 SO (2500 Piece)
DS18B20
DS18B20Z+T&R
-55°C to +125°C
8 SO (2500 Piece)
DS18B20
+Denotes a lead-free package. A “+” will appear on the top mark of lead-free packages.
T&R = Tape and reel.
*TO-92 packages in tape and reel can be ordered with straight or formed leads. Choose “SL” for straight leads. Bulk TO-92 orders are straight
leads only.
PIN DESCRIPTION
PIN
NAME FUNCTION
SO
µ
SOP
TO-92
1, 2, 6,
7, 8
2, 3, 5,
6, 7
— N.C. No Connection
3 8 3 V
DD
Optional V
DD
. V
DD
must be grounded for operation in
parasite power mode.
4 1 2 DQ
Data Input/Output. Open-drain 1-Wire interface pin. Also
provides power to the device when used in parasite power
mode (see the Powering the DS18B20 section.)
5 4 1 GND Ground
OVERVIEW
Figure 1 shows a block diagram of the DS18B20, and pin descriptions are given in the Pin Description
table. 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 access to the 1-byte upper and lower alarm trigger registers (T
H
and T
L
) and the 1-byte
configuration register. The configuration register allows the user to set the resolution of the temperature-
to-digital conversion to 9, 10, 11, or 12 bits. The T
H
, T
L
, and configuration registers are nonvolatile
(EEPROM), so they will retain data when the device is powered down.
The DS18B20 uses Maxim’s 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