TC72 datasheet(12/24 Pages) MICROCHIP

12 / 24 page

TC72

DS21743A-page 12

 2002 Microchip Technology Inc.

4.0

INTERNAL REGISTER

STRUCTURE

The TC72 registers are listed below.

TABLE 4-1:

REGISTERS FOR TC72

4.1

Control Register

The Control register is both a read and a write register

that is used to select either the Shutdown, Continuous

or One-Shot Conversion operating mode. The Temper-

ature Conversion mode selection logic is shown in

Table 4-2. The Shutdown (SHDN) bit is stored in bit 0

of the Control register. If SHDN is equal to ‘1’, the TC72

will go into the power-saving shutdown mode. If SHDN

is equal to ‘0’, the TC72 will perform a temperature

conversion approximately every 150 ms.

At power-up, the SHDN bit is set to ‘1’. Thus, the TC72

is in the shutdown operating mode at startup. The Con-

tinuous Temperature Conversion mode is selected by

writing a ‘0’ to the SHDN bit of the Control register.

The Shutdown mode can be used to minimize the

power consumption of the TC72 when active tempera-

ture monitoring is not required. The shutdown mode

disables the temperature conversion circuitry; how-

ever, the serial I/O communication port remains active.

A temperature conversion will be initialized by a Write

operation to the Control register to select either the

Continuous Temperature Conversion or the One-Shot

operating mode. The temperature data will be available

in the MSB and LSB Temperature registers approxi-

mately 150 ms after the Control register Write

operation.

The One-Shot mode is selected by writing a ‘1’ into bit

4 of the Control register. The One-Shot mode performs

a single temperature measurement and returns to the

power-saving shutdown mode. After completion of the

temperature conversion, the One-Shot bit (OS) is reset

to ‘0’ (i.e. “OFF”). The user must set the One-Shot bit

to ‘1’ to initiate another temperature conversion.

Bits 1, 3, 5, 6 and 7 of the Control register are not used

by the TC72. Bit 2 is set to a logic ‘1’. Any write opera-

tion to these bit locations will have no affect on the

operation of the TC72.

4.2

Temperature Register

The Temperature register is a read-only register and

contains a 10-bit two’s complement representation of

the temperature measurement. Bit 0 through Bit 5 of

the LSB Temperature register are always set to a logic

‘0’.

At Power-On Reset (POR) or a Brown-Out Reset

(BOR) low voltage occurrence, the temperature regis-

ter is reset to all zeroes, which corresponds to a tem-

perature value of 0°C. A VDD power supply less than

1.6V is considered a reset event and will reset the

Temperature register to the power-up state.

4.3

Manufacturer ID Register

The Manufacturer Identification (ID) register is a read-

only register used to identify the temperature sensor as

a Microchip component.

TABLE 4-2:

CONTROL REGISTER TEMPERATURE CONVERSION MODE SELECTION

Read

Address

Write

Address

Bit

Value on

POR/BOR

Control

00hex

80hex

One-Shot

(OS)

Shutdown

(SHDN)

05hex

LSB Temperature

01hex

N/A

00hex

MSB Temperature

02hex

N/A

T5 T4 T3

00hex

Manufacturer ID

03hex

N/A

54hex

Operational Mode

One-Shot (OS) Bit 4

Shutdown (SHDN) Bit 0

Continuous Temperature Conversion

Shutdown

Continuous Temperature Conversion

(One-Shot Command is ignored if SHDN = ‘0’)

One-Shot

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