TC74A0-5.0VCT Просмотр технического описания (PDF) - Microchip Technology

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TC74A0-5.0VCT

Tiny Serial Digital Thermal Sensor

Microchip Technology 

4.0 REGISTER SET AND

PROGRAMMER’S MODEL

TABLE 4-1:

COMMAND BYTE

DESCRIPTION

(SMBUS READ_BYTE AND

WRITE_BYTE)

COMMAND CODE

FUNCTION

RTR

RWCR

00h Read Temperature (TEMP)

01h Read/Write Configuration

(CONFIG)

TABLE 4-2:

CONFIGURATION REGISTER

(CONFIG); 8 BITS, READ/

WRITE)

BIT POR FUNCTION TYPE OPERATION

D[7]

0

STANDBY Read/ 1 = standby,

Switch

Write 0 = normal

D[6]

0 Data Ready* Read 1 = ready

Only 0 = not ready

D[5]-D[0] 0

Reserved -

N/A

N/A

Always returns

zero when read

*Note: DATA_RDY bit RESET at power-up and SHDN

enable.

FIGURE 4-1:

DATA_RDY, SHDN

OPERATION LOGIC

DIAGRAM

VDD

DATA_RDY

SHDN

tconv

tconv

4.1 Temperature Register (TEMP),

8 Bits, READ ONLY

The binary value (2’s complement format) in this regis-

ter represents temperature of the onboard sensor

following a conversion cycle. The registers are

automatically updated in an alternating manner.

TC74

TABLE 4-3: TEMPERATURE REGISTER

(TEMP)

D[7] D[6] D[5] D[4] D[3] D[2] D[1] D[0]

MSB X

X

X X X X LSB

In the temperature data registers, each unit value repre-

sents one degree (Celsius). The value is in 2’s

complement binary format such that a reading of 0000

0000b corresponds to 0°C. Examples of this tempera-

ture to binary value relationship are shown in Table 4-4.

TABLE 4-4:

ACTUAL

TEMP.

+130.00°C

+127.00°C

+126.50°C

+25.25°C

+0.50°C

+0.25°C

0.00°C

-0.25°C

-0.50°C

-0.75°C

-1.00°C

-25.00°C

-25.25°C

-54.75°C

-55.00°C

-65.00°C

TEMPERATURE TO DIGITAL

VALUE CONVERSION (TEMP)

REGISTERED

TEMP.

BINARY

HEX

+127°C

+127°C

+127°C

+25°C

+1°C

0°C

0°C

0°C

0°C

-1°C

-1°C

-25°C

-25°C

-55°C

-55°C

-65°C

0111 1111

0111 1111

0111 1111

0001 1001

0000 0001

0000 0000

0000 0000

0000 0000

0000 0000

1111 1111

1111 1111

1110 0111

1110 0110

1100 1001

1100 1001

1011 1111

4.2 Register Set Summary

The TC74 register set is summarized in Table 4-5. All

registers are 8 bits wide.

TABLE 4-5: TC74 REGISTER SET

SUMMARY

NAME DESCRIPTION POR State READ WRITE

TEMP Internal Sensor 0000 0000b* 

Temp. (2’s

Complement)

CONFIG

CONFIG

0000 0000b 



Register

*Note: The TEMP resigister will be immediately updated by

the A/D converter after the DATA_RDY Bit goes High.

© 2002 Microchip Technology Inc.

DS21462B-page 9

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