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LM73-Q1

SNIS194 – DECEMBER 2016

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Feature Description (continued)

•

Temperature Register

•

Configuration Register

•

THIGH Register

•

TLOW Register

•

Control/Status Register

•

Identification Register

7.3.1 Power-On Reset

The power-on reset (POR) state is the point at which the supply voltage rises above the power-on reset

threshold (specified in the Electrical Characteristics), generating an internal reset. Each of the registers contains

a defined value upon POR and this data remains there until any of the following occurs:

•

The first temperature conversion is completed, causing the Temperature Register and various status bits to

be updated internally, depending on the value of the measured temperature.

•

The master writes different data to any Read/Write (R/W) bits, or

•

The LM73-Q1 is powered down.

7.3.2 One-Shot Conversion

The LM73-Q1 features a one-shot conversion bit, which is used to initiate a single conversion and comparison

cycle when the LM73-Q1 is in shutdown mode. While the LM73-Q1 is in shutdown mode, writing a 1 to the One-

Shot bit in the Configuration Register will cause the LM73-Q1 to perform a single temperature conversion and

update the Temperature Register and the affected status bits. Operating the LM73-Q1 in this one-shot mode

allows for extremely low average-power consumption, making it ideal for low-power applications.

When the One-Shot bit is set, the LM73-Q1 initiates a temperature conversion. After this initiation, but before the

completion of the conversion and resultant register updates, the LM73-Q1 is in a "one-shot" state. During this

state, the Data Available (DAV) flag in the Control/Status register is 0 and the Temperature Register contains the

value 8000h (-256°C). All other registers contain the data that was present before initiating the one-shot

conversion. After the temperature measurement is complete, the DAV flag will be set to 1 and the temperature

register will contain the resultant measured temperature.

7.3.3 Temperature Data Format

The resolution of the temperature data and the size of the data word are user-selectable through bits RES1 and

RES0 in the Control/Status Register. By default, the LM73-Q1 temperature stores the measured temperature in

an 11-bit (10 bits plus sign) word with one least significant bit (LSB) equal to 0.25°C. The maximum word size is

14 bits (13-bits plus sign) with a resolution of 0.03125 °C/LSB.

CONTROL BIT

DATA FORMAT

RES1

RES0

WORD SIZE

RESOLUTION

0

0

11 bits

0.25 °C/LSB

0

1

12 bits

0.125 °C/LSB

1

0

13 bits

0.0625 °C/LSB

1

1

14 bits

0.03125 °C/LSB

The temperature data is reported in 2's complement format. The word is stored in the 16-bit Temperature

Register and is left justified in this register. Unused temperature-data bits are always reported as 0.

Table 1. 11-Bit (10-Bit Plus Sign)

TEMPERATURE

DIGITAL OUTPUT

BINARY

HEX

150°C

0100 1011 0000 0000

4B00h

25°C

0000 1100 1000 0000

0C80h

1°C

0000 0000 1000 0000

0080h

0.25°C

0000 0000 0010 0000

0020h