LM134-LM234-LM334 Three terminal adjustable current sources Features ■ Operates from 1V to 40V ■ 0.02%/V current regulation ■ Programmable from 1µA 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. Pin connections 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. TO-92 (Bottom view) For the LM134/LM234/LM334, the voltage on the control pin is 64mV at +25°C 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. May 2007 v+ 2 v- ADJ 1 3 SO-8 (Top view) Rev 3 NC 8 NC 7 V6 NC 5 1 ADJ 2 NC 3 NC 4 V+ 1/16 www.st.com 16 Schematic diagram 1 Schematic diagram Figure 1. 2 LM134-LM234-LM334 Schematic diagram Absolute maximum ratings Table 1. Absolute maximum ratings Symbol Parameter LM134 Voltage V+ to VForward Reverse VADJ- 2/16 LM234 40 20 LM334 Unit 30 20 V ADJ pin to V- voltage 5 V Iset Set current 10 mA Ptot Power dissipation 400 mW Tstg Storage temperature range -65 to +150 °C Toper Operating free-air temperature range -55 to +125 -25 to +100 0 to +70 °C LM134-LM234-LM334 3 Electrical characteristics Electrical characteristics Tj = +25°C with pulse testing so that junction temperature does not change during testing (unless otherwise specified) Table 2. Electrical characteristics LM134 - LM234 LM334 Parameter Unit Min. Typ. Set current error (V+ = +2.5V) -(1) 10µA ≤ Iset ≤ 1mA 1mA ≤ Iset ≤ 5mA 2µA ≤ Iset ≤ 10µA Ratio of set current to V- current 10µA ≤ Iset ≤ 1mA 1mA ≤ Iset ≤ 5mA 2µA ≤ Iset ≤ 10µA 14 Typ. 18 14 14 23 0.02 0.01 14 T 18 14 14 0.05 0.03 0.02 0.01 % 26 0.8 0.9 1 0.03 0.02 0.96 T Max. 6 8 12 0.8 0.9 1 Average change in set current with input voltage 2µA ≤ Iset ≤ 1mA +1.5V ≤ V+ ≤ +5V +5V ≤ V+ ≤ +40V 1mA ≤ Iset ≤ 5mA +1.5V ≤ V+ ≤ +5V +5V ≤ V+ ≤ +40V Effective shunt capacitance Min. 3 5 8 Minimum operating voltage 2µA ≤ Iset ≤ 100µA 100µA ≤ Iset ≤ 1mA 1mA ≤ Iset ≤ 5mA Temperature dependence of set current - (2) 25µA ≤ Iset ≤ 1mA Max. V 0.1 0.05 %/V 0.03 0.02 1.04 T 0.96 T 15 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 = +25°C) 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). 3/16 Electrical characteristics Output impedance Figure 3. Frequency (Hz) Figure 4. Startup Iset (µA) Figure 5. Time (scale changes at each current level) Transient response Time (scale changes at each current level) Figure 7. Current noise Current (pA/√Hz) Voltage across Rset Voltage (mV) Figure 6. Temperature (°C) 4/16 Maximum slew rate for linear operation Slew rate (V/µs) Impedance (Ohm) Figure 2. LM134-LM234-LM334 Frequency (Hz) LM134-LM234-LM334 Turn-on voltage Figure 9. Ratio of Iset to V- current Ratio Iset (mA) Figure 8. Electrical characteristics V+ to V- voltage (V) Iset (mA) 5/16 Application information 4 Application information 4.1 Slew rate LM134-LM234-LM334 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 = 10µA, dv/dt max. = 0.01V/µs ; at Iset = 1mA, dv/dt max. = 1V/µs. Slew rates of more than 1V/µs 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 100µA. For example, each increase of 1V in the voltage across the LM134 at Iset = 1mA will increase the junction temperature by ≈ 0.4°C (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 100µA. 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 0.7Ω is sufficient to decrease the output current by 1% at the 1mA level. 6/16 LM134-LM234-LM334 4.6 Application information 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. ( 227µV/°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 0°K. 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. 7/16 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 8/16 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 9/16 Application information Figure 19. In-line current limiter 10/16 LM134-LM234-LM334 Figure 20. Fet cascading for low capacitance LM134-LM234-LM334 5 Package information Package information In order to meet environmental requirements, STMicroelectronics offers these devices in ECOPACK® 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. 11/16 Package information 5.1 LM134-LM234-LM334 SO-8 package mechanical data Dimensions Ref. Millimeters Min. Typ. A Max. Min. Typ. 1.75 0.25 Max. 0.069 A1 0.10 A2 1.25 b 0.28 0.48 0.011 0.019 c 0.17 0.23 0.007 0.010 D 4.80 4.90 5.00 0.189 0.193 0.197 H 5.80 6.00 6.20 0.228 0.236 0.244 E1 3.80 3.90 4.00 0.150 0.154 0.157 e 0.004 0.010 0.049 1.27 0.050 h 0.25 0.50 0.010 0.020 L 0.40 1.27 0.016 0.050 k 1° 8° 1° 8° ccc 12/16 Inches 0.10 0.004 LM134-LM234-LM334 TO-92 ammopack and tape & reel package mechanical data A1 P T P A H W2 W0 W L1 W1 H0 H I1 d H1 5.2 Package information D0 F1 F2 P2 P0 Millimeters Inches Dim. Min. Typ. Max. Min. Typ. Max. AL 5.0 0.197 A 5.0 0.197 T 4.0 0.157 d 0.45 0.018 I1 2.5 0.098 P 11.7 12.7 13.7 0.461 0.500 0.539 PO 12.4 12.7 13 0.488 0.500 0.512 P2 5.95 6.35 6.75 0.234 0.250 0.266 F1/F2 2.4 2.5 2.8 0.094 0.098 0.110 Δh -1 0 1 -0.039 0 0.039 ΔP -1 0 1 -0.039 0 0.039 W 17.5 18.0 19.0 0.689 0.709 0.748 W0 5.7 6 6.3 0.224 0.236 0.248 W1 8.5 9 9.75 0.335 0.354 0.384 W2 0.5 0.020 H 20 0.787 H0 15.5 16 H1 DO L1 16.5 0.610 0.630 25 3.8 4.0 4.2 11 0.650 0.984 0.150 0.157 0.165 0.433 13/16 Package information 5.3 LM134-LM234-LM334 TO-92 bulk package mechanical data Millimeters Inches Dim. Min. L 14/16 Typ. Max. Min. 1.27 Typ. Max. 0.05 B 3.2 3.7 4.2 0.126 0.1457 0.1654 O1 4.45 5.00 5.2 0.1752 0.1969 0.2047 C 4.58 5.03 5.33 0.1803 0.198 0.2098 K 12.7 O2 0.407 0.0197 0.02 a 0.35 0.5 0.5 0.508 0.016 0.0138 LM134-LM234-LM334 6 Ordering information Ordering information Table 3. Order codes Temperature range Package Packing Marking LM134D/DT -55°C to +125°C SO-8 Tube or Tape & reel LM134 LM134Z/ZT/AP -55°C to +125°C TO-92 Bulk or Tape & reel or Ammopack LM134 LM234D/DT -25°C to +100°C SO-8 Tube or Tape & reel LM234 LM234Z/ZT/AP -24°C to +100°C TO-92 Bulk or Tape & reel or Ammopack LM234 LM334D/DT -0°C to +70°C SO-8 Tube or Tape & reel LM334 LM334Z/ZT/AP -0°C to +70°C TO-92 Bulk or Tape & reel or Ammopack LM334 LM334AD/ADT -0°C to +70°C SO-8 Tube or Tape & reel LM334A LM334AZ/AZT/AAP -0°C to +70°C TO-92 Bulk or Tape & reel or Ammopack LM334A Part number 7 Revision history Date Revision 2-May-2003 1 Initial release. 28-Oct-2005 2 Internal revision. 3 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. 29-May-2007 Changes 15/16 LM134-LM234-LM334 Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no liability whatsoever relating to the choice, selection or use of the ST products and services described herein. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. 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