TMP35GT9 查看數據表（PDF） - Analog Devices

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TMP35GT9

Low Voltage Temperature Sensors

Analog Devices 

TMP35/TMP36/TMP37

3V 6

2

REF193

R21

+

1µF

4

+VS

R11

TMP3x

VOUT

GND

P11

20mA

ADJUST

R31

P21

4mA

ADJUST

2– 7

OP193

3

+

4

D1

R41

0.1µF

6

R6

100kΩ

R5

100kΩ

Q1

2N1711

VLOOP

9V TO 18V

VOUT

RL

250Ω

NOTE:

1 SEE TEXT FOR VALUES.

D1: HP5082-2810

R7

100Ω

IL

Figure 33. Temperature to 4–20 mA Loop Transmitter

TEMPERATURE-TO-FREQUENCY CONVERTER

Another common method of transmitting analog information

from a remote location is to convert a voltage to an equivalent

value in the frequency domain. This is readily done with any of

the low cost, monolithic voltage-to-frequency converters (VFCs)

available. These VFCs feature a robust, open-collector output

transistor for easy interfacing to digital circuitry. The digital

signal produced by the VFC is less susceptible to contamination

from external noise sources and line voltage drops because the

only important information is the frequency of the digital sig-

nal. When the conversions between temperature and frequency

are done accurately, the temperature data from the sensors can

be reliably transmitted.

The circuit in Figure 34 illustrates a method by which the

outputs of these temperature sensors can be converted to a

frequency using the AD654. The output signal of the AD654 is

a square wave that is proportional to the dc input voltage across

Pin 4 and Pin 3. The transfer equation of the circuit is given by

f OUT

=

⎜⎜⎝⎛

VTPM − VOFFSET

10 × (RT × CT )

⎟⎟⎠⎞

10µF/0.1µF

5V

0.1µF

+VS

TMP3x VOUT 4

3

GND

R1

CT1

86

7

1

AD654

5

2

RPU

5kΩ

fOUT

5V

P2

100kΩ

RT1

P1

ROFF1

470Ω

NB: ATTA (MIN), fOUT = 0Hz

fOUT

OFFSET

NOTE:

1RT AND CT – SEE TABLE

ROFF2

10Ω

SENSOR

TMP35

TMP36

TMP37

RT (R1 + P1)

11.8kΩ + 500Ω

16.2kΩ + 500Ω

18.2kΩ + 1kΩ

CT

1.7nF

1.8nF

2.1nF

Figure 34. Temperature-to-Frequency Converter

Rev. F | Page 16 of 20

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