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LM134-LM234-LM334
Three terminal adjustable current sources
Features

Operates from 1V to 40V 0.02%/V current regulation Programmable from 1A to 10mA 3% initial accuracy Z TO-92 (Plastic package)
Description
The LM134/LM234/LM334 are 3-terminal adjustable current sources characterized by:

an operating current range of 10000: 1 an excellent current regulation a wide dynamic voltage range of 1V t 10V
D SO-8 (Plastic micropackage)
The current is determined by an external resistor without requiring other external components. Reverse voltages of up to 20V will only draw a current of several microamperes. This enables the circuit to operate as a rectifier and as a source of current in a.c. applications. For the LM134/LM234/LM334, the voltage on the control pin is 64mV at +25C and is directly proportional to the absolute temperature (K). The simplest external resistor connection generates a current with approximately 0.33%/C temperature dependence. Zero drift can be obtained by adding an additional resistor and a diode to the external circuit.
Pin connections TO-92 (Bottom view)
v+
2 ADJ 1
v3
SO-8 (Top view)
NC 8 NC 7 V6 NC 5
1 ADJ
2 NC
3 NC
4 V+
May 2007
Rev 3
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Schematic diagram
LM134-LM234-LM334
1
Schematic diagram
Figure 1. Schematic diagram
2
Absolute maximum ratings
Table 1.
Symbol
Absolute maximum ratings
Parameter Voltage V+ to VForward Reverse LM134 LM234 LM334 Unit
40 20 5 10 400 -65 to +150 -55 to +125 -25 to +100
30 20
V V mA mW C
VADJIset Ptot Tstg Toper
ADJ pin to V- voltage Set current Power dissipation Storage temperature range Operating free-air temperature range
0 to +70
C
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LM134-LM234-LM334
Electrical characteristics
3
Electrical characteristics
Tj = +25C with pulse testing so that junction temperature does not change during testing (unless otherwise specified)
Table 2.
Electrical characteristics
LM134 - LM234 Parameter Min. Typ. Max. Min. Typ. Max. LM334 Unit
Set current error (V+ = +2.5V) -(1) 10A Iset 1mA 1mA Iset 5mA 2A Iset 10A Ratio of set current to V- current 10A Iset 1mA 1mA Iset 5mA 2A Iset 10A Minimum operating voltage 2A Iset 100A 100A Iset 1mA 1mA Iset 5mA Average change in set current with input voltage 2A Iset 1mA +1.5V V+ +5V +5V V+ +40V 1mA Iset 5mA +1.5V V+ +5V +5V V+ +40V Temperature dependence of set current - (2) 25A Iset 1mA Effective shunt capacitance 0.96 T 14 18 14 14 0.8 0.9 1
3 5 8 23 14 18 14 14 0.8 0.9 1
6 8 12 26
%
V
0.02 0.01 0.03 0.02 T 15
0.05 0.03
0.02 0.01 0.03 0.02
0.1 0.05
%/V
1.04 T 0.96 T
T 15
1.04 T pF
1. The set current is the current flowing into the V+ pin. It is determined by the following formula: Iset = 67.7mV/Rset (Tj = +25C) The set current error is expressed as a percent deviation from this amount. 2. Iset is directly proportional to absolute temperature (K). Iset at any temperature can be calculated from Iset = Io (T/To) where Io is Iset measured at To (K).
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Electrical characteristics
LM134-LM234-LM334
Figure 2.
Output impedance
Figure 3.
Maximum slew rate for linear operation
Impedance (Ohm)
Frequency (Hz) Figure 4. Startup Figure 5.
Slew rate (V/s)
Iset (A) Transient response
Time (scale changes at each current level) Figure 6. Voltage across Rset
Time (scale changes at each current level) Figure 7. Current noise
Current (pA/ Hz)
Voltage (mV)
Temperature (C)
Frequency (Hz)
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LM134-LM234-LM334 Figure 8. Turn-on voltage Figure 9.
Electrical characteristics Ratio of Iset to V- current
Iset (mA)
V+ to V- voltage (V)
Ratio
Iset (mA)
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Application information
LM134-LM234-LM334
4
4.1
Application information
Slew rate
At slew rates above a threshold (see Figure 4 and Figure 5), the LM134, LM234, LM334 can have a non-linear current characteristic. The slew rate at which this takes place is directly proportional to Iset. At Iset = 10A, dv/dt max. = 0.01V/s ; at Iset = 1mA, dv/dt max. = 1V/s. Slew rates of more than 1V/s do not damage the circuit nor do they produce high currents.
4.2
Thermal effects
Internal heating can have a significant effect on current regulation for an Iset above 100A. For example, each increase of 1V in the voltage across the LM134 at Iset = 1mA will increase the junction temperature by 0.4C (in still air). The output current (Iset) has a temperature coefficient of about 0.33%/C. Thus the change in current due to the increase in temperature will be (0.4) (0.33) = 0.132%. This is a degradation of 10 : 1 in regulation versus the true electrical effects. Thermal effects should be taken into account when d.c. regulation is critical and Iset is higher than 100A.
4.3
Shunt capacitance
In certain applications, the 15pF value for the shunt capacitance should be reduced:

because of loading problems, because of limitation of output impedance of the current source in a.c. applications.
You can easily reduce the capacitance by adding a FET as shown in Typical applications on page 8. The value of this capacitance can be reduced by at least 3pF and regulation can be improved by an order of magnitude without any modifications of the d.c. characteristics (except for the minimum input voltage).
4.4
Noise
The current noise produced by LM134, LM234, and LM334 is about 4 times that of a transistor. If the LM134, LM234, LM334 is used as an active load for a transistor amplifier, the noise at the input will increase by about 12dB. In most cases this is acceptable, and a single amplifier can be built with a voltage gain higher than 2000.
4.5
Lead resistance
The sense voltage which determines the current of the LM134, LM234, LM334 is less than 100mV. At this level, the thermocouple effects and the connection resistance should be reduced by locating the current setting resistor close to the device. Do not use sockets for the ICs. A contact resistance of 0.7 is sufficient to decrease the output current by 1% at the 1mA level.
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LM134-LM234-LM334
Application information
4.6
Sensing temperature
The LM134, LM234, LM334 are excellent remote controlled temperature sensors because their operation as current sources preserves their accuracy even in the case of long connecting wires. The output current is directly proportional to the absolute temperature in Kelvin degrees according to the following equation.
( 227V/K) (T ) I set = ---------------------------------------R set
The calibration of the LM134, LM234, LM334 is simplified by the fact that most of the initial accuracy is due to gain limitation (slope error) and not an offset. Gain adjustment is a one point trim because the output of the device extrapolates to zero at 0K. Figure 10. Device calibration
This particularity of the LM134, LM234, LM334 is illustrated in the above diagram. Line abc represents the sensor current before adjustment and line a'b'c' represents the desired output. A gain adjustment provided at T2 will move the output from b to b' and will correct the slope at the same time so that the output at T1 and T3 will be correct. This gain adjustment can be carried out by means of Rset or the load resistor used in the circuit. After adjustment, the slope error should be less than 1%. A low temperature coefficient for Rset is necessary to keep this accuracy. A 33ppm/C temperature drift of Rset will give an error of 1% on the slope because the resistance follows the same temperature variations as the LM134, LM234, LM334. Three wires are required to isolate Rset from the LM134, LM234, LM334. Since this solution is not recommended, metal-film resistors with a drift of less than 20ppm/C are now available. Wirewound resistors can be used when very high stability is required.
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Application information
LM134-LM234-LM334
Typical applications
Figure 11. Basic 2-terminal current source Figure 12. Alternate trimming technique
Figure 13. Terminating remote sensor for voltage output
Figure 14. Zero temperature coefficient current source
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LM134-LM234-LM334
Application information
Figure 15. Low output impedance thermometer
Figure 16. Low output impedance thermometer
Figure 17. Micropower bias
Figure 18. Low input voltage reference driver
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Application information
LM134-LM234-LM334
Figure 19. In-line current limiter
Figure 20. Fet cascading for low capacitance
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LM134-LM234-LM334
Package information
5
Package information
In order to meet environmental requirements, STMicroelectronics offers these devices in ECOPACK(R) packages. These packages have a lead-free second level interconnect. The category of second level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an STMicroelectronics trademark. ECOPACK specifications are available at: www.st.com.
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Package information
LM134-LM234-LM334
5.1
SO-8 package mechanical data
Dimensions Ref. Min. A A1 A2 b c D H E1 e h L k ccc 0.25 0.40 1 0.10 1.25 0.28 0.17 4.80 5.80 3.80 4.90 6.00 3.90 1.27 0.50 1.27 8 0.10 0.010 0.016 1 0.48 0.23 5.00 6.20 4.00 Millimeters Typ. Max. 1.75 0.25 0.004 0.049 0.011 0.007 0.189 0.228 0.150 0.193 0.236 0.154 0.050 0.020 0.050 8 0.004 0.019 0.010 0.197 0.244 0.157 Min. Inches Typ. Max. 0.069 0.010
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LM134-LM234-LM334
Package information
5.2
TO-92 ammopack and tape & reel package mechanical data
A1 P P T H
d
A
H1
H0
H
I1
W0
D0 F1 F2 P2 P0
W2 W1 W
L1
Millimeters Dim. Min. AL A T d I1 P PO P2 F1/F2 h P W W0 W1 W2 H H0 H1 DO L1 3.8 4.0 15.5 16 2.5 11.7 12.4 5.95 2.4 -1 -1 17.5 5.7 8.5 12.7 12.7 6.35 2.5 0 0 18.0 6 9 13.7 13 6.75 2.8 1 1 19.0 6.3 9.75 0.5 20 16.5 25 4.2 11 0.150 0.610 0.45 0.098 0.461 0.488 0.234 0.094 -0.039 -0.039 0.689 0.224 0.335 Typ. Max. 5.0 5.0 4.0 Min.
Inches Typ. Max. 0.197 0.197 0.157 0.018
0.500 0.500 0.250 0.098 0 0 0.709 0.236 0.354
0.539 0.512 0.266 0.110 0.039 0.039 0.748 0.248 0.384 0.020 0.787
0.630
0.650 0.984
0.157
0.165 0.433
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Package information
LM134-LM234-LM334
5.3
TO-92 bulk package mechanical data
Millimeters Dim. Min. L B O1 C K O2 a 3.2 4.45 4.58 12.7 0.407 0.35 0.5 0.508 Typ. 1.27 3.7 5.00 5.03 4.2 5.2 5.33 0.126 0.1752 0.1803 0.5 0.016 0.0138 Max. Min.
Inches Typ. 0.05 0.1457 0.1969 0.198 0.1654 0.2047 0.2098 Max.
0.0197
0.02
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LM134-LM234-LM334
Ordering information
6
Ordering information
Table 3. Order codes
Temperature range -55C to +125C Package SO-8 Packing Tube or Tape & reel Bulk or Tape & reel or Ammopack Tube or Tape & reel Bulk or Tape & reel or Ammopack Tube or Tape & reel Bulk or Tape & reel or Ammopack Tube or Tape & reel Bulk or Tape & reel or Ammopack Marking LM134
Part number LM134D/DT
LM134Z/ZT/AP
-55C to +125C
TO-92
LM134
LM234D/DT
-25C to +100C
SO-8
LM234
LM234Z/ZT/AP
-24C to +100C
TO-92
LM234
LM334D/DT
-0C to +70C
SO-8
LM334
LM334Z/ZT/AP
-0C to +70C
TO-92
LM334
LM334AD/ADT
-0C to +70C
SO-8
LM334A
LM334AZ/AZT/AAP
-0C to +70C
TO-92
LM334A
7
Revision history
Date 2-May-2003 28-Oct-2005 Revision 1 2 Initial release. Internal revision. Corrected error in pinout diagram for TO-92 package on cover page (it is a bottom view, not a top view). Updated Section 5: Package information and expanded Table 3: Order codes. Changes
29-May-2007
3
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LM134-LM234-LM334
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