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參數(shù)資料
| 型號： | TMP3567 |
| 元件分類： | TVS-瞬態(tài)抑制二極管 |
| 英文描述： | Transient Voltage Suppressor Diodes |
| 文件頁數(shù)： | 11/16頁 |
| 文件大小： | 476K |
| 代理商： | TMP3567 |
REV. C
TMP35/TMP36/TMP37
–11–
A Temperature to 4–20 mA Loop Transmitter
In many process control applications, 2-wire transmitters are
used to convey analog signals through noisy ambient environ-
ments. These current transmitters use a “zero-scale” signal
current of 4 mA that can be used to power the transmitter’s
signal conditioning circuitry. The “full-scale” output signal in
these transmitters is 20 mA.
A circuit that transmits temperature information in this fashion
is illustrated in Figure 10. Using a TMP3x as the temperature
sensor, the output current is linearly proportional to the tem-
perature of the medium. The entire circuit operates from the
3 V output of the REF193. The REF193 requires no external
trimming for two reasons: (1) the REF193’s tight initial output
voltage tolerance and (2) the low supply current of TMP3x, the
OP193 and the REF193. The entire circuit consumes less than
3 mA from a total budget of 4 mA. The OP193 regulates the
output current to satisfy the current summation at the noninverting
node of the OP193. A generalized expression for the KCL
equation at the OP193’s Pin 3 is given by:
I
OUT
=
1
R
7
×
TMP
3
x
×
R
3
R
1
+
V
REF
×
R
3
R
2
For each of the three temperature sensors, the table below illus-
trates the values for each of the components, P1, P2, and R1–R4:
Table II. Circuit Element Values for Loop Transmitter
Sensor
R1( )
P1( )
R2( )
P2( ) R3( )
R4( )
TMP35
TMP36
TMP37
97.6 k
97.6 k
97.6 k
5 k
5 k
5 k
1.58 M
931 k
10.5 k
100 k
50 k
500
140 k
97.6 k
84.5 k
56.2 k
47 k
8.45 k
Illustrated in Figure 9 is a way to convert the output voltage of a
TMP3x sensor into a current to be transmitted down a long
twisted-pair shielded cable to a ground referenced receiver. The
temperature sensors do not possess the capability of high output
current operation; thus, a garden variety PNP transistor is used
to boost the output current drive of the circuit. As shown in the
table, the values of R2 and R3 were chosen to produce an arbi-
trary full-scale output current of 2 mA. Lower values for the
full-scale current are not recommended. The minimum-scale
output current produced by the circuit could be contaminated
by nearby ambient magnetic fields operating in the vicinity of
the circuit/cable pair. Because of the use of an external transis-
tor, the minimum recommended operating voltage for this
circuit is 5 V. Note, to minimize the effects of EMI (or RFI),
both the circuit’s and the temperature sensor’s supply pins are
bypassed with good quality, ceramic capacitors.
TWISTED PAIR
BELDEN TYPE 9502
OR EQUIVALENT
TMP3x
R2
R1
4.7k
V
OUT
0.1 F
2N2907
0.01 F
GND
V
S
5V
R3
V
OUT
SENSOR
TMP35
TMP36
TMP37
R2
634
887
1k
R3
634
887
1k
Figure 9. A Remote, 2-Wire Boosted Output Current Tem-
perature Sensor
V
OUT
V
S
TMP35
0.1 F
GND
OP193
0.1 F
R1
*
24.9k
R4
4.99k
R5
*
1.21M
TYPE K
THERMO-
COUPLE
CU
CU
R2
*
102
V
0V – 2.5V
R6
100k
5%
R3
10M
5%
3.3V < V
S
< 5.5V
COLD
JUNCTION
CHROMEL
ALUMEL
ISOTHERMAL
BLOCK
NOTE:
ALL RESISTORS 1%
UNLESS OTHERWISE NOTED
0 C T 250 C
7
6
4
3
2
P1
50k
Figure 8. A Single-Supply, Type K Thermocouple Signal Conditioning Circuit with Cold-Junction Compensation
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TMP35FS | 制造商:Analog Devices 功能描述:Temp Sensor Analog(Voltage) Serial (2-Wire) 8-Pin SOIC N 制造商:Rochester Electronics LLC 功能描述:3V TEMPERATURE SENSOR - Bulk |
| TMP35FS-REEL | 制造商:Analog Devices 功能描述:Temp Sensor Analog Serial (2-Wire) 8-Pin SOIC N T/R 制造商:Rochester Electronics LLC 功能描述:3V TEMPERATURE SENSOR TAPE & REEL - Tape and Reel |
| TMP35FSZ | 制造商:Analog Devices 功能描述:Temperature Sensor IC |
| TMP35FSZ-REEL | 制造商:Analog Devices 功能描述:TEMP SENSOR ANLG SERL 8SOIC N - Tape and Reel |
| TMP35FT9 | 制造商:Rochester Electronics LLC 功能描述:3V TEMPERATURE SENSOR - Bulk 制造商:Analog Devices 功能描述: |
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