DS1621 Datasheet, PDF (2/16 Pages) Dallas Semiconductor – Digital Thermometer and Thermostat

ORDERING INFORMATION
ORDERING
PACKAGE
NUMBER
MARKING
DS1621
DS1621
DS1621+
DS1621 (See Note)
DS1621S
DS1621
DS1621S+
DS1621 (See Note)
DS1621S/T&R DS1621
DS1621S+T&R DS1621 (See Note)
DS1621V
DS1621V
DS1621V+
DS1621V (See Note)
DS1621V/T&R DS1621V
DS1621V+T&R DS1621V (See Note)
DS1621
DESCRIPTION
DS1621 in 300 mil DIP
DS1621 in Lead-Free 300 mil DIP
DS1621 in 150 mil SOIC
DS1621 in Lead-Free 150 mil SOIC
DS1621 in 150 mil SO, 2500 Piece Tape-and-Reel
DS1621 in Lead-Free 150 mil SO, 2500 Piece Tape-and-Reel
DS1621 in 208 mil SOIC
DS1621 in Lead-Free 208 mil SOIC
DS1621 in 208 mil SO, 2500 Piece Tape-and-Reel
DS1621 in Lead-Free 208 mil SO, 2500 Piece Tape-and-Reel
Note: A “+” symbol will also be marked on the package near the Pin 1 indicator.
Table 1. DETAILED PIN DESCRIPTION
PIN SYMBOL DESCRIPTION
1
SDA
Data input/output pin for 2-wire serial communication port.
2
SCL
Clock input/output pin for 2-wire serial communication port.
3
T_OUT
Thermostat output. Active when temperature exceeds TH; will reset when
temperature falls below TL.
4
GND
Ground pin.
5
A2
Address input pin.
6
A1
Address input pin.
7
A0
Address input pin.
8
V_DD
Supply voltage input power pin. (2.7V to 5.5V)
OPERATION
Measuring Temperature
A block diagram of the DS1621 is shown in Figure 1.
The DS1621 measures temperature using a bandgap-based temperature sensor. A delta-sigma analog-to-
digital converter (ADC) converts the measured temperature to a digital value that is calibrated in °C; for
°F applications, a lookup table or conversion routine must be used.
The temperature reading is provided in a 9-bit, two’s complement reading by issuing the READ
TEMPERATURE command. Table 2 describes the exact relationship of output data to measured
temperature. The data is transmitted through the 2-wire serial interface, MSB first. The DS1621 can
measure temperature over the range of -55°C to +125°C in 0.5°C increments.
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