LM334M

LM134, LM234, LM334 www.ti.com SNVS746E – MARCH 2000 – REVISED MAY 2013 LM134/LM234/LM334 3-Terminal Adjustable Current Sources Check for Samples: LM134, LM234, LM334 FEATURES 1 • • • • • 2 • Operates From 1V to 40V 0.02%/V Current Regulation Programmable From 1μA to 10mA True 2-Terminal Operation Available as Fully Specified Temperature Sensor ±3% Initial Accuracy DESCRIPTION The LM134/LM234/LM334 are 3-terminal adjustable current sources featuring 10,000:1 range in operating current, excellent current regulation and a wide dynamic voltage range of 1V to 40V. Current is established with one external resistor and no other parts are required. Initial current accuracy is ±3%. The LM134/LM234/LM334 are true floating current sources with no separate power supply connections. In addition, reverse applied voltages of up to 20V will draw only a few dozen microamperes of current, allowing the devices to act as both a rectifier and current source in AC applications. The sense voltage used to establish operating current in the LM134 is 64mV at 25°C and is directly proportional to absolute temperature (°K). The simplest one external resistor connection, then, generates a current with ≈+0.33%/°C temperature dependence. Zero drift operation can be obtained by adding one extra resistor and a diode. Applications for the current sources include bias networks, surge protection, low power reference, ramp generation, LED driver, and temperature sensing. The LM234-3 and LM234-6 are specified as true temperature sensors with ensured initial accuracy of ±3°C and ±6°C, respectively. These devices are ideal in remote sense applications because series resistance in long wire runs does not affect accuracy. In addition, only 2 wires are required. The LM134 is specified over a temperature range of −55°C to +125°C, the LM234 from −25°C to +100°C and the LM334 from 0°C to +70°C. These devices are available in TO hermetic, TO-92 and SOIC-8 plastic packages. Connection Diagrams Figure 1. SOIC-8 Surface Mount Package (LM334M; LM334M/NOPB; LM334MX; LM334MX/NOPB) See Package Number D Figure 2. SOIC-8 Alternative Pinout Surface Mount Package (LM334SM; LM334SM/NOPB; LM334SMX; LM334SMX/NOPB) See Package Number D Figure 3. TO Metal Can Package (Bottom View) See Package Number NDV Figure 4. TO-92 Plastic Package (Bottom View) See Package Number LP 1 2 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2000–2013, Texas Instruments Incorporated LM134, LM234, LM334 SNVS746E – MARCH 2000 – REVISED MAY 2013 www.ti.com These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. Absolute Maximum Ratings (1) (2) V+ to V− Forward Voltage LM134/LM234/LM334 40V LM234-3/LM234-6 30V V+ to V− Reverse Voltage 20V − 5V Set Current 10 mA R Pin to V Voltage Power Dissipation ESD Susceptibility 400 mW (3) 2000V Operating Temperature Range (4) LM134 −55°C to +125°C LM234/LM234-3/LM234-6 −25°C to +100°C LM334 Soldering Information 0°C to +70°C TO-92 Package (10 sec.) 260°C TO Package (10 sec.) SOIC Package (1) (2) (3) (4) 300°C Vapor Phase (60 sec.) 215°C Infrared (15 sec.) 220°C “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not ensure specific performance limits. If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and specifications. Human body model, 100pF discharged through a 1.5kΩ resistor. For elevated temperature operation, TJ max is: LM134 150°C LM234 125°C LM334 100°C See Thermal Characteristics. Thermal Characteristics over operating free-air temperature range (unless otherwise noted) Thermal Resistance θja (Junction to Ambient) TO-92 TO SOIC-8 180°C/W (0.4″ leads) 440°C/W 165°C/W 32°C/W 80°C/W 160°C/W (0.125″ leads) θjc (Junction to Case) 2 Submit Documentation Feedback N/A Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 LM134, LM234, LM334 www.ti.com SNVS746E – MARCH 2000 – REVISED MAY 2013 Electrical Characteristics (1) Parameter Conditions Set Current Error, V+=2.5V (2) LM134/LM234 Min Typ 6 % 8 % 12 % 8 14 18 23 14 14 18 26 14 2 μA≤ISET≤100 μA 18 2μA ≤ ISET ≤ 100μA 0.8 0.8 V 100μA < ISET ≤ 1mA 0.9 0.9 V 1mA < ISET ≤ 5mA 1mA < ISET ≤ 5mA 23 18 1.0 26 1.0 V 1.5 ≤ V+ ≤ 5V 0.02 0.05 0.02 0.1 %/V 5V ≤ V+ ≤ 40V 0.01 0.03 0.01 0.05 %/V 1.5V ≤ V ≤ 5V 0.03 5V ≤ V ≤ 40V 25μA ≤ ISET ≤ 1mA 0.03 0.02 0.96T Effective Shunt Capacitance (3) Units 5 Average Change in Set Current 2μA ≤ ISET ≤ 1mA with Input Voltage (1) (2) Max 3 1mA ≤ ISET ≤ 5mA Temperature Dependence of Set Current (3) Typ 1mA < ISET ≤ 5mA 100μA ≤ ISET ≤ 1mA Minimum Operating Voltage Min 10μA ≤ ISET ≤ 1mA 2μA ≤ ISET < 10μA Ratio of Set Current to Bias Current LM334 Max T %/V 0.02 1.04T 0.96T 15 T %/V 1.04T 15 pF Unless otherwise specified, tests are performed at Tj = 25°C with pulse testing so that junction temperature does not change during test Set current is the current flowing into the V+ pin. For the Basic 2-Terminal Current Source circuit shown in Figure 13. ISET is determined by the following formula: ISET = 67.7 mV/RSET (@ 25°C). Set current error is expressed as a percent deviation from this amount. ISET increases at 0.336%/°C @ Tj = 25°C (227 μV/°C). 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). Electrical Characteristics (1) Parameter Set Current Error, V+=2.5V Conditions (2) LM234-3 Min Typ 100μA ≤ ISET ≤ 1mA LM234-6 Max Min Typ Max Units ±1 ±2 % ±3 ±6 °C TJ = 25° Equivalent Temperature Error Ratio of Set Current to Bias Current 100μA ≤ ISET ≤ 1mA Minimum Operating Voltage 100μA ISET ≤ 1mA Average Change in Set Current 100μA ≤ ISET ≤ 1mA with Input Voltage Temperature Dependence of Set Current (3) 100μA ≤ ISET ≤ 1mA 14 18 0.02 5V ≤ V+ ≤ 30V 0.98T 18 0.01 0.03 T 1.02T 15 26 0.9 0.05 0.02 0.97T V 0.01 %/V 0.01 0.05 %/V T 1.03T ±2 Effective Shunt Capacitance (3) 14 0.9 1.5 ≤ V+ ≤ 5V Equivalent Slope Error (1) (2) 26 ±3 15 % pF Unless otherwise specified, tests are performed at Tj = 25°C with pulse testing so that junction temperature does not change during test Set current is the current flowing into the V+ pin. For the Basic 2-Terminal Current Source circuit shown in Figure 13. ISET is determined by the following formula: ISET = 67.7 mV/RSET (@ 25°C). Set current error is expressed as a percent deviation from this amount. ISET increases at 0.336%/°C @ Tj = 25°C (227 μV/°C). 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). Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 Submit Documentation Feedback 3 LM134, LM234, LM334 SNVS746E – MARCH 2000 – REVISED MAY 2013 www.ti.com Typical Performance Characteristics 4 Output Impedance Maximum Slew Rate Linear Operation Figure 5. Figure 6. Start-Up Transient Response Figure 7. Figure 8. Voltage Across RSET (VR) Current Noise Figure 9. Figure 10. Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 LM134, LM234, LM334 www.ti.com SNVS746E – MARCH 2000 – REVISED MAY 2013 Typical Performance Characteristics (continued) Turn-On Voltage Ratio of ISET to IBIAS Figure 11. Figure 12. Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 Submit Documentation Feedback 5 LM134, LM234, LM334 SNVS746E – MARCH 2000 – REVISED MAY 2013 www.ti.com APPLICATION HINTS The LM134 has been designed for ease of application, but a general discussion of design features is presented here to familiarize the designer with device characteristics which may not be immediately obvious. These include the effects of slewing, power dissipation, capacitance, noise, and contact resistance. Calculating RSET The total current through the LM134 (ISET) is the sum of the current going through the SET resistor (IR) and the LM134's bias current (IBIAS), as shown in Figure 13. Figure 13. Basic Current Source A graph showing the ratio of these two currents is supplied under Ratio of ISET to IBIAS in Typical Performance Characteristics. The current flowing through RSET is determined by VR, which is approximately 214μV/°K (64 mV/298°K ∼ 214μV/°K). (1) Since (for a given set current) IBIAS is simply a percentage of ISET, the equation can be rewritten where • n is the ratio of ISET to IBIAS as specified in Electrical Characteristics and shown in the graph (2) Since n is typically 18 for 2μA ≤ ISET ≤ 1mA, the equation can be further simplified to (3) for most set currents. Slew Rate At slew rates above a given threshold (see curve), the LM134 may exhibit non-linear current shifts. The slewing rate at which this occurs is directly proportional to ISET. At ISET = 10μA, maximum dV/dt is 0.01V/μs; at ISET = 1mA, the limit is 1V/μs. Slew rates above the limit do not harm the LM134, or cause large currents to flow. Thermal Effects Internal heating can have a significant effect on current regulation for ISET greater than 100μA. For example, each 1V increase across the LM134 at ISET = 1 mA will increase junction temperature by ≈0.4°C in still air. Output current (ISET) has a temperature coefficient of ≈0.33%/°C, so the change in current due to temperature rise will be (0.4) (0.33) = 0.132%. This is a 10:1 degradation in regulation compared to true electrical effects. Thermal effects, therefore, must be taken into account when DC regulation is critical and ISET exceeds 100μA. Heat sinking of the TO package or the TO-92 leads can reduce this effect by more than 3:1. 6 Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 LM134, LM234, LM334 www.ti.com SNVS746E – MARCH 2000 – REVISED MAY 2013 Shunt Capacitance In certain applications, the 15 pF shunt capacitance of the LM134 may have to be reduced, either because of loading problems or because it limits the AC output impedance of the current source. This can be easily accomplished by buffering the LM134 with an FET as shown in the applications. This can reduce capacitance to less than 3 pF and improve regulation by at least an order of magnitude. DC characteristics (with the exception of minimum input voltage), are not affected. Noise Current noise generated by the LM134 is approximately 4 times the shot noise of a transistor. If the LM134 is used as an active load for a transistor amplifier, input referred noise will be increased by about 12dB. In many cases, this is acceptable and a single stage amplifier can be built with a voltage gain exceeding 2000. Lead Resistance The sense voltage which determines operating current of the LM134 is less than 100mV. At this level, thermocouple or lead resistance effects should be minimized by locating the current setting resistor physically close to the device. Sockets should be avoided if possible. It takes only 0.7Ω contact resistance to reduce output current by 1% at the 1 mA level. Sensing Temperature The LM134 makes an ideal remote temperature sensor because its current mode operation does not lose accuracy over long wire runs. Output current is directly proportional to absolute temperature in degrees Kelvin, according to the following formula: (4) Calibration of the LM134 is greatly simplified because of the fact that most of the initial inaccuracy is due to a gain term (slope error) and not an offset. This means that a calibration consisting of a gain adjustment only will trim both slope and zero at the same time. In addition, gain adjustment is a one point trim because the output of the LM134 extrapolates to zero at 0°K, independent of RSET or any initial inaccuracy. Figure 14. Gain Adjustment This property of the LM134 is illustrated in the accompanying graph. Line abc is the sensor current before trimming. Line a′b′c′ is the desired output. A gain trim done at T2 will move the output from b to b′ and will simultaneously correct the slope so that the output at T1 and T3 will be correct. This gain trim can be done on RSET or on the load resistor used to terminate the LM134. Slope error after trim will normally be less than ±1%. To maintain this accuracy, however, a low temperature coefficient resistor must be used for RSET. A 33 ppm/°C drift of RSET will give a 1% slope error because the resistor will normally see about the same temperature variations as the LM134. Separating RSET from the LM134 requires 3 wires and has lead resistance problems, so is not normally recommended. Metal film resistors with less than 20 ppm/°C drift are readily available. Wire wound resistors may also be used where best stability is required. Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 Submit Documentation Feedback 7 LM134, LM234, LM334 SNVS746E – MARCH 2000 – REVISED MAY 2013 www.ti.com Application as a Zero Temperature Coefficent Current Source Adding a diode and a resistor to the standard LM134 configuration can cancel the temperature-dependent characteristic of the LM134. The circuit shown in Figure 15 balances the positive tempco of the LM134 (about +0.23 mV/°C) with the negative tempco of a forward-biased silicon diode (about −2.5 mV/°C). Figure 15. Zero Tempco Current Source The set current (ISET) is the sum of I1 and I2, each contributing approximately 50% of the set current, and IBIAS. IBIAS is usually included in the I1 term by increasing the VR value used for calculations by 5.9%. (See CALCULATING RSET.) (5) 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 IBIAS component), and −2.5 mV/°C as the tempco of the diode (for best results, this value should be directly measured or obtained from the manufacturer of the diode). (6) (7) With the R1 to R2 ratio determined, values for R1 and R2 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 (VD) is 0.6V, the voltage across R1 is 67.7mV (64 mV + 5.9% to account for IBIAS), and R2/R1 = 10 (from the previous calculations). 8 Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 LM134, LM234, LM334 www.ti.com SNVS746E – MARCH 2000 – REVISED MAY 2013 (8) 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 ISET, however, the circuit should be built and tested over temperature. If the measured tempco of ISET is positive, R2 should be reduced. If the resulting tempco is negative, R2 should be increased. The recommended diode for use in this circuit is the 1N457 because its tempco is centered at 11 times the tempco of the LM134, allowing R2 = 10 R1. You can also use this circuit to create a current source 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 R1 and R2: (9) The values of R1 and R2 can be changed to standard 1% resistor values (R1 = 133Ω and R2 = 1.33kΩ) with less than a 0.75% error. If the forward voltage drop of the diode was 0.65V instead of the estimate of 0.6V (an error of 8%), the actual set current will be (10) an error of less than 5%. If the estimate for the tempco of the diode's forward voltage drop was off, the tempco cancellation is still reasonably effective. Assume the tempco of the diode is 2.6mV/°C instead of 2.5mV/°C (an error of 4%). The tempco of the circuit is now: (11) A 1mA LM134 current source with no temperature compensation would have a set resistor of 68Ω and a resulting tempco of (12) So even if the diode's tempco varies as much as ±4% from its estimated value, the circuit still eliminates 98% of the LM134's inherent tempco. Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 Submit Documentation Feedback 9 LM134, LM234, LM334 SNVS746E – MARCH 2000 – REVISED MAY 2013 www.ti.com Typical Applications *Select R3 = VREF/583μA. VREF may be any stable positive voltage ≥ 2V Trim R3 to calibrate Figure 16. Ground Referred Fahrenheit Thermometer Figure 17. Terminating Remote Sensor for Voltage Output *Output impedance of the LM134 at the “R” pin is approximately where R2 is the equivalent external resistance connected from the V− pin to ground. This negative resistance can be reduced by a factor of 5 or more by inserting an equivalent resistor R3 = (R2/16) in series with the output. Figure 18. Low Output Impedance Thermometer 10 Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 LM134, LM234, LM334 www.ti.com SNVS746E – MARCH 2000 – REVISED MAY 2013 Figure 19. Low Output Impedance Thermometer *Select R1 and C1 for optimum stability Figure 20. Higher Output Current Figure 21. Basic 2-Terminal Current Source Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 Submit Documentation Feedback 11 LM134, LM234, LM334 SNVS746E – MARCH 2000 – REVISED MAY 2013 www.ti.com Figure 22. Micropower Bias Figure 23. Low Input Voltage Reference Driver Figure 24. Ramp Generator 12 Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 LM134, LM234, LM334 www.ti.com SNVS746E – MARCH 2000 – REVISED MAY 2013 *Select ratio of R1 to R2 to obtain zero temperature drift Figure 25. 1.2V Reference Operates on 10 μA and 2V *Select ratio of R1 to R2 for zero temperature drift Figure 26. 1.2V Regulator with 1.8V Minimum Input Figure 27. Zener Biasing Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 Submit Documentation Feedback 13 LM134, LM234, LM334 SNVS746E – MARCH 2000 – REVISED MAY 2013 www.ti.com *For ±10% adjustment, select RSET10% high, and make R1 ≈ 3 RSET Figure 28. Alternate Trimming Technique Figure 29. Buffer for Photoconductive Cell *Select Q1 or Q2 to ensure at least 1V across the LM134. Vp (1 − ISET/IDSS) ≥ 1.2V. 14 Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 LM134, LM234, LM334 www.ti.com SNVS746E – MARCH 2000 – REVISED MAY 2013 Figure 30. FET Cascoding for Low Capacitance and/or Ultra High Output Impedance *ZOUT ≈ −16 • R1 (R1/VIN must not exceed ISET) Figure 31. Generating Negative Output Impedance *Use minimum value required to ensure stability of protected device. This minimizes inrush current to a direct short. Figure 32. In-Line Current Limiter Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 Submit Documentation Feedback 15 LM134, LM234, LM334 SNVS746E – MARCH 2000 – REVISED MAY 2013 www.ti.com Schematic Diagram 16 Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 LM134, LM234, LM334 www.ti.com SNVS746E – MARCH 2000 – REVISED MAY 2013 REVISION HISTORY Changes from Revision C (April 2013) to Revision D • Page Changed layout of National Data Sheet to TI format .......................................................................................................... 16 Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM134 LM234 LM334 Submit Documentation Feedback 17 PACKAGE OPTION ADDENDUM www.ti.com 7-Oct-2021 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) (6) LM134 MDC ACTIVE DIESALE Y 0 400 RoHS & Green Call TI Level-1-NA-UNLIM -40 to 85 LM134H ACTIVE TO NDV 3 1000 Non-RoHS & Non-Green Call TI Call TI -55 to 125 ( LM134H, LM134H) LM134H/NOPB ACTIVE TO NDV 3 1000 RoHS & Green Call TI Level-1-NA-UNLIM -55 to 125 ( LM134H, LM134H) LM234Z-3/NOPB ACTIVE TO-92 LP 3 1800 RoHS & Green Call TI N / A for Pkg Type -25 to 100 LM234 Z-3 LM234Z-6/NOPB ACTIVE TO-92 LP 3 1800 RoHS & Green Call TI N / A for Pkg Type -25 to 100 LM234 Z-6 LM334 MWC ACTIVE WAFERSALE YS 0 1 RoHS & Green Call TI Level-1-NA-UNLIM -40 to 85 LM334M NRND SOIC D 8 95 Non-RoHS & Green Call TI Level-1-235C-UNLIM 0 to 70 LM334 M LM334M/NOPB ACTIVE SOIC D 8 95 RoHS & Green SN Level-1-260C-UNLIM 0 to 70 LM334 M LM334MX/NOPB ACTIVE SOIC D 8 2500 RoHS & Green SN Level-1-260C-UNLIM 0 to 70 LM334 M LM334SM/NOPB ACTIVE SOIC D 8 95 RoHS & Green SN Level-1-260C-UNLIM 0 to 70 LM334 SM LM334SMX NRND SOIC D 8 2500 Non-RoHS & Green Call TI Level-1-235C-UNLIM 0 to 70 LM334 SM LM334SMX/NOPB ACTIVE SOIC D 8 2500 RoHS & Green SN Level-1-260C-UNLIM 0 to 70 LM334 SM LM334Z/LFT1 ACTIVE TO-92 LP 3 2000 RoHS & Green SN N / A for Pkg Type LM334Z/NOPB ACTIVE TO-92 LP 3 1800 RoHS & Green Call TI N / A for Pkg Type (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. Addendum-Page 1 LM334 Z 0 to 70 LM334 Z Samples PACKAGE OPTION ADDENDUM www.ti.com 7-Oct-2021 (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of