DS1722

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OVERVIEW

A block diagram of the DS1722 is shown in Figure 1. The DS1722 consists of four major components:

1. Precision temperature sensor

2. Analog-to-digital converter

3. SPI/3-wire interface electronics

4. Data registers

The factory-calibrated temperature sensor requires no external components. The DS1722 is in a power-

conserving shutdown state upon power-up. After power-up, the user may alter the configuration register

to place the device in a continuous temperature conversion mode or in a one-shot conversion mode. In

the continuous conversion mode, the DS1722 continuously converts the temperature and stores the result

in the temperature register. As conversions are performed in the background, reading the temperature

register does not affect the conversion in progress. In the one-shot temperature conversion mode, the

DS1722 will perform one temperature conversion, store the result in the temperature register, and then

return to the shutdown state. This conversion mode is ideal for power sensitive applications. More

information on the configuration register is contained in the “OPERATION-Programming” section.

The temperature conversion results will have a default resolution of 9 bits. In applications where small

incremental temperature changes are critical, the user can change the conversion resolution from 9 bits to

8, 10, 11, or 12. This is accomplished by programming the configuration register. Each additional bit of

resolution approximately doubles the conversion time.

The DS1722 can communicate using either a Motorola Serial Peripheral Interface (SPI) or standard 3-

wire interface. The user can select either communication standard through the SERMODE pin, tying it to

respectively). The analog supply powers the device for operation while the digital supply provides the

top rails for the digital inputs and outputs. The DS1722 was designed to be 1.8V Logic-Ready.