© 2011 Microchip Technology Inc.

DS21743B-page 11

TC72

4.0

FUNCTIONAL DESCRIPTION

TC72 consists of a band-gap type temperature sensor,

a 10-bit Sigma Delta Analog-to-Digital Converter

(ADC), an internal conversion oscillator and a double

buffer digital output port. The 10-bit ADC is scaled from

-128°C to +127°C; therefore, the resolution is 0.25°C

per bit. The ambient temperature operating range of

the TC72 is specified from -55°C to +125°C.

This device features a four-wire serial interface that is

fully compatible with the SPI specification and, there-

fore, allows simple communications with common

microcontrollers and processors. TC72 can be used

either in a Continuous Temperature Conversion mode

or a One-Shot Conversion mode. TC72 temperature

measurements are performed in the background and,

therefore, reading the temperature via the serial I/O

lines does not affect the measurement in progress.

The Continuous Conversion mode measures the

temperature approximately every 150 ms and stores

the data in the temperature registers. TC72 has an

internal clock generator that controls the automatic

temperature conversion sequence. The automatic

temperature sampling operation is repeated indefinitely

until TC72 is placed in Shutdown mode by a write

operation to the Control register. TC72 will remain in

Shutdown mode until the shutdown bit in the Control

register is reset.

In contrast, the One-Shot mode performs a single

temperature measurement and returns to the power-

saving shut down mode. This mode is especially useful

for low power applications.

FIGURE 4-1:

Temperature-To-Digital Transfer Function (Non-Linear Scale).

Temp

Temp

Output

Code

+125°C

-55°C

+25°C

-25°C

+0.25°C

-0.125°C

0111 1101 / 0000 0000

MSB

LSB

Note:

The ADC converter is scaled from -128°C to +127°C, but the operating range of the

TC72 is specified from -55°C to +125°C.

0001 1001 / 0000 0000

MSB

LSB

0000 0000 / 0100 0000

MSB

LSB

0000 0000 / 0000 0000

MSB

LSB

1111 1111 / 1100 0000

MSB

LSB

1110 0111 / 0000 0000

MSB

LSB

1100 1001 / 0000 0000

MSB

LSB

0°C