DS4000 Просмотр технического описания (PDF) - Dallas Semiconductor -> Maxim Integrated

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DS4000

Digitally Controlled TCXO

Dallas Semiconductor -> Maxim Integrated 

DS4000 Digitally Controlled TCXO

DIGITAL TEMPERATURE SENSOR

The digital temperature sensor provides 10-bit temperature readings that indicate the temperature of the device.

Temperature readings are communicated from the DS4000 over a 2-wire serial interface. No additional

components are required. The DS4000 has an external address bit that allows a user to choose the slave address

from two possible values.

The factory-calibrated temperature sensor requires no external components. Upon power-up, the DS4000 starts

performing temperature conversions with a resolution of 10 bits (+0.25°C resolution). Following an 8-bit command

protocol, temperature data can be read over the 2-wire interface. The host can periodically read the value in the

temperature register, which contains the last completed conversion. As conversions are performed in the

background, reading the temperature register does not affect the conversion in progress.

READING TEMPERATURE

The DS4000 measures temperature through the use of an on-chip temperature-measurement technique with an

operation range from 0°C to +70°C (commercial) or -40°C to +85°C (industrial). The device performs continuous

conversions with the most recent result being stored in the temperature register. The digital temperature is

retrieved from the temperature register using the READ TEMPERATURE command, as described in detail in the

following paragraphs.

Table 2 shows the exact relationship of output data to measured temperature. The data is transmitted serially over

the 2-wire serial interface, MSB first. The MSB of the temperature register contains the “sign” (S) bit, denoting

whether the temperature is positive or negative. For Fahrenheit usage, a lookup table or conversion routine must

be used.

TEMPERATURE/DATA RELATIONSHIP (UNIT = °C)

MSB (64h)

BIT 7

BIT 6

S

26

BIT 5

25

BIT 4

24

BIT 3

23

BIT 2

22

BIT 1

21

BIT 0

20

LSB (65h)

BIT 7

BIT 6

2-1

2-2

BIT 5

0

BIT 4

0

BIT 3

0

BIT 2

0

BIT 1

0

BIT 0

0

Table 2. Temperature/Data Relationship

TEMPERATURE

(°C)

DIGITAL OUTPUT

(Binary)

DIGITALOUTPUT

(hex)

+85

0101 0101 0000 0000

5500h

+75

0100 1011 0000 0000

4B00h

+0.5

0000 0000 1000 0000

0080h

0

0000 0000 0000 0000

0000h

-0.5

1111 1111 1000 0000

FF80h

-20

1110 1100 0000 0000

EC00h

-40

1101 1000 0000 0000

D800h

Note: Internal power dissipation raises the temperature above the ambient. The delta between ambient and the die temperature depends on

power consumption, PC board layout, and airflow.

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