DS1721U Datasheet, PDF (2/17 Pages) Maxim Integrated Products – 2-Wire Digital Thermometer and Thermostat

DS1721
ORDERING INFORMATION
ORDERING
PACKAGE
DESCRIPTION
INFORMATION MARKING
DS1721S
DS1721
DS1721 in 150 mil 8-pin SO
DS1721S+
DS1721 (See Note) DS1721 in Lead-Free 150 mil 8-pin SO
DS1721S/T&R DS1721
DS1721 in 150 mil 8-pin SO, 2500 Piece Tape-and-Reel
DS1721S+T&R DS1721 (See Note) DS1721 in Lead-Free 150 mil 8-pin SO, 2500 Piece Tape-
and-Reel
DS1721U
1721
DS1721 in 8-pin uSOP
DS1721U+
1721 (See Note) DS1721 in Lead-Free 8-pin uSOP
DS1721U/T&R 1721
DS1721 in 8-pin uSOP, 3000 Piece Tape-and-Reel
DS1721U+T&R 1721 (See Note) DS1721 in Lead-Free 8-pin uSOP, 3000 Piece Tape-and-Reel
Note: A ”+” symbol will also be marked on the package near the Pin 1 indicator.
DETAILED PIN DESCRIPTION Table 1
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. 2.7V to 5.5V input power pin.
OVERVIEW
A block diagram of the DS1721 is shown in Figure 1.
The DS1721 consists of five major components:
1. Precision temperature sensor
2. Analog-to-digital converter
3. 2-wire interface electronics
4. Data registers
5. Thermostat comparator
The factory-calibrated temperature sensor requires no external components. Upon power-up, the DS1721
is in an idle mode. Upon issuance of a Start Convert T command [51h], the DS1721 begins temperature
conversions with the default resolution of 12 bits (0.0625°C resolution). Following an 8-bit command
protocol, temperature data can be read over the 2-wire interface. The host can periodically read the value
in the temperature register, which contains the last completed conversion. As conversions are performed
in the background, reading the temperature register does not affect the conversion in progress.
In power-sensitive applications, the user can put the DS1721 in a “one-shot” mode, under which the
sensor will complete and store one temperature conversion and return to a low-power standby state. In
time-sensitive applications, the user can change the conversion resolution from 12 bits to 9, 10, or 11.
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