LM134 Series
U
W U U
APPLICATIO S I FOR ATIO
If higher accuracy is required, a two point calibration
techniquecanbeused.InFigure4,separatezeroandslope
trims are provided. Residual nonlinearity is now the limi-
tation on accuracy. Nonlinearity of the LM134 in a 100°C
span is typically less than 0.5°C. This particular method of
trimming has the advantage that the slope trim does not
interact with the zero trim. Trim procedure is to adjust for
zero output with TSENSOR = 0°C, then trim slope for proper
output at some convenient second temperature. No fur-
ther trimming is required.
The two trims shown in Figure 3 are still intended to be a
“one point” temperature calibration, where the zero and
theslopearetrimmedatasingletemperature. TheLT1009
referenceisadjustedtogive2.700Vatnode“a”atTSENSOR
= 25°C. The 1k trimmer then adjusts the output for 0.25V,
completing the calibration. If the calibration is to be done
at a temperature other than 25°C , trim the LT1009 for
2.7025—(1µA)[TSENSOR (°C)](100Ω) at node “a”, then
adjust the 1k trimmer for proper output.
V
≥ 4V
S
+
+
V
≥ 5V
V
LM134-3
R
+
V
LM134-3
R
R
OUTPUT
SET
–
226Ω
10mV/°C
V
9.53k
OUTPUT
226Ω*
–
1%
10mV/°C
V
332k
1%
11k*
1%
1k
SLOPE
ADJ
50k
SLOPE
TRIM
500k
*LOW TC, STABLE RESISTOR
LT1009
ZERO
TRIM
10k
15k
LT1009
100Ω
“a”
10k
–15V
134 F04
134 F03
10k
ZERO
ADJ
–15V
Figure 4. Centigrade Temperature Sensor with 2 Point Trim
Figure 3. Centigrade Temperature Sensor
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TYPICAL APPLICATIO S
Basic 2-Terminal
Zero Temperature
Coefficient Current Source
Low Output Impedance
Thermometer (Kelvin Output)
Current Source
V
IN
V
IN
V
IN
≥ 4.8V
+
I
+
–
+
+
V
V
V
R3*
600Ω
R
R
R
V
= 10mV/°K
≤ 100Ω
I
OUT
OUT
SET
Z
R1
230Ω
1%
R
SET
–
–
V
LM334
LM334
LM334
V
V
R
SET
R2
10k
1%
C1
0.1µF
D1
1N457
R1*
≈10 R
134 TA02
SET
–V
IN
134 TA03
–V
IN
134 TA04
*SELECT RATIO OF R1 TO R
TO
SET
+
*OUTPUT IMPEDANCE OF THE LM134 AT THE “R” PIN IS
OBTAIN ZERO DRIFT. I ≈2 I
.
SET
–R
O
APPROXIMATELY
Ω, WHERE R IS THE EQUIVALENT
O
16
–
EXTERNAL RESISTANCE CONNECTED TO THE V PIN. THIS
NEGATIVE RESISTANCE CAN BE REDUCED BY A FACTOR OF
5 OR MORE BY INSERTING AN EQUIVALENT RESISTOR IN
SERIES WITH THE OUTPUT.
7
Linear [ Linear ]
