LM334Z National Semiconductor, LM334Z Datasheet - Page 7
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LM334Z
Manufacturer Part Number
LM334Z
Description
IC, ADJ CURRENT SOURCE 40V, 10mA, TO92-3
Manufacturer
National Semiconductor
Datasheet
1.LM334SM.pdf
(14 pages)
Specifications of LM334Z
Forward Current If
10mA
Forward Voltage
40V
Power Dissipation Pd
400mW
Current Regulator Case Style
TO-92
No. Of Pins
3
Supply Voltage Range
1V To 40V
Sensor Case Style
TO-92
Accuracy %
3%
Current Rating
1 To 10A
Rohs Compliant
No
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LM334Z
Manufacturer:
NS/国半
Quantity:
20 000
Part Number:
LM334Z#PBF
Manufacturer:
LINEAR/凌特
Quantity:
20 000
Part Number:
LM334Z#TRPBF
Manufacturer:
LINEAR/凌特
Quantity:
20 000
Part Number:
LM334Z/NOPB
Manufacturer:
TI/德州仪器
Quantity:
20 000
Application Hints
The set current (I
uting approximately 50% of the set current, and I
usually included in the I
used for calculations by 5.9%. (See CALCULATING R
The first step is to minimize the tempco of the circuit, using
the following equations. An example is given using a value of
+227µV/˚C as the tempco of the LM134 (which includes the
I
diode (for best results, this value should be directly mea-
sured or obtained from the manufacturer of the diode).
With the R
should be determined to give the desired set current. The
formula for calculating the set current at T = 25˚C is shown
below, followed by an example that assumes the forward
voltage drop across the diode (V
across R
and R
BIAS
component), and −2.5 mV/˚C as the tempco of the
2
/R
1
1
is 67.7mV (64 mV + 5.9% to account for I
1
= 10 (from the previous calculations).
to R
SET
2
ratio determined, values for R
) is the sum of I
1
term by increasing the V
(Continued)
D
) is 0.6V, the voltage
1
and I
FIGURE 3. Zero Tempco Current Source
2
, each contrib-
BIAS
1
. I
R
and R
BIAS
value
BIAS
SET
is
.)
),
2
7
This circuit will eliminate most of the LM134’s temperature
coefficient, and it does a good job even if the estimates of the
diode’s characteristics are not accurate (as the following
example will show). For lowest tempco with a specific diode
at the desired I
tested over temperature. If the measured tempco of I
positive, R
negative, R
for use in this circuit is the 1N457 because its tempco is
centered at 11 times the tempco of the LM134, allowing R
10 R
with non-zero tempcos by setting the tempco component of
the tempco equation to the desired value instead of 0.
EXAMPLE: A 1mA, Zero-Tempco Current Source
First, solve for R
The values of R
resistor values (R
a 0.75% error.
1
. You can also use this circuit to create a current source
00569728
2
2
should be reduced. If the resulting tempco is
should be increased. The recommended diode
SET
1
1
1
and R
and R
, however, the circuit should be built and
= 133Ω and R
2
2
:
can be changed to standard 1%
2
= 1.33kΩ) with less than
www.national.com
SET
2
is
=