DS1721

2 of 17

ORDERING INFORMATION

ORDERING

INFORMATION

PACKAGE

MARKING

DESCRIPTION

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

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

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.