LM134/LM234/LM334 3-Terminal Adjustable …

1 LM134/LM234/LM3343- terminal Adjustable current SourcesGeneral DescriptionThe LM134/LM234/LM334 are 3-Terminal Adjustable currentsources featuring 10,000:1 range in operating current , excel-lent current regulation and a wide dynamic voltage range of1V to 40V. current is established with one external resistorand no other parts are required. Initial current accuracy is 3%. The LM134/LM234/LM334 are true floating currentsources with no separate power supply connections. In addi-tion, reverse applied voltages of up to 20V will draw only afew dozen microamperes of current , allowing the devices toact as both a rectifier and current source in AC sense voltage used to establish operating current in theLM134 is 64mV at 25 C and is directly proportional to abso-lute temperature ( K).

2 The simplest one external resistorconnection, then, generates a current with + C tem-perature dependence. Zero drift operation can be obtainedby adding one extra resistor and a for the current sources include bias networks,surge protection, low power reference, ramp generation,LED driver, and temperature sensing. The LM234-3 andLM234-6 are specified as true temperature sensors withguaranteed initial accuracy of 3 C and 6 C, devices are ideal in remote sense applications be-cause series resistance in long wire runs does not affect ac-curacy.

3 In addition, only 2 wires are LM134 is guaranteed over a temperature range of 55 C to +125 C, the LM234 from 25 C to +100 C and theLM334 from 0 C to +70 C. These devices are available inTO-46 hermetic, TO-92 and SO-8 plastic from 1V to current regulationnProgrammable from 1 A to 10mAnTrue 2- terminal operationnAvailable as fully specified temperature sensorn 3% initial accuracyConnection DiagramsSO-8 Surface Mount PackageDS005697-24 Order Number LM334M orLM334 MXSee NS Package Number M08 ASO-8 Alternative PinoutSurface Mount PackageDS005697-25 Order Number LM334SM orLM334 SMXSee NS Package Number M08 ATO-46 Metal Can PackageDS005697-12V Pin is electrically connected to ViewOrder Number LM134H.

4 LM234H or LM334 HSee NS PackageNumber H03 HTO-92 Plastic PackageDS005697-10 Bottom ViewOrder Number LM334Z, LM234Z-3 or LM234Z-6 See NS Package Number Z03 AMarch 2000LM134/LM234/LM334 3-Terminal Adjustable current Sources 2000 National Semiconductor Maximum Ratings(Note 1)If Military/Aerospace specified devices are required,please contact the National Semiconductor Sales Office/Distributors for availability and +to V Forward VoltageLM134/LM234/LM33440 VLM234-3/LM234-630VV+to V Reverse Voltage20VR Pin to V Voltage5 VSet Current10 mAPower Dissipation400 mWESD Susceptibility (Note 6)2000 VOperating Temperature Range (Note 5)LM134 55 C to +125 CLM234/LM234-3/LM234-6 25 C to +100 CLM3340 C to +70 CSoldering InformationTO-92 Package (10 sec.)

5 260 CTO-46 Package (10 sec.)300 CSO PackageVapor Phase (60 sec.)215 CInfrared (15 sec.)220 CSee AN-450 Surface Mounting Methods and Their Effect onProduct Reliability (Appendix D) for other methods of sol-dering surface mount Characteristics(Note 2)ParameterConditionsLM134/LM234LM334 UnitsMinTypMaxMinTypMaxSet current Error, V+= ,10 A ISET 1mA36%(Note 3)1mA<ISET 5mA58%2 A ISET<10 A812%Ratio of Set current to100 A ISET 1mA141823141826 Bias Current1mA ISET 5mA14142 A ISET 100 A18231826 Minimum Operating Voltage2 A ISET 100 A<ISET <ISET Change in Set Current2 A ISET 1mAwith Input V+ V+ <ISET V V Dependence of25 A ISET current (Note 4)Effective Shunt Capacitance1515pFNote 1.

6 Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the deviceisfunctional, but do not guarantee specific performance 2:Unless otherwise specified, tests are performed at Tj= 25 C with pulse testing so that junction temperature does not change during testNote 3:Set current is the current flowing into the V+pin. For the Basic 2- terminal current Source circuit shown on the first page of this data sheet. ISETis determinedby the following formula: ISET= mV/RSET(@25 C).

7 Set current error is expressed as a percent deviation from this amount. ISET increases at C@Tj= 25 C (227 V/ C).Note 4:ISETis directly proportional to absolute temperature ( K). ISETat any temperature can be calculated from: ISET=Io(T/To) where Iois ISET measured at To( K).Note 5:For elevated temperature operation, TJmax is:LM134150 CLM234125 CLM334100 CThermal ResistanceTO-92TO-46SO-8 ja(Junction to Ambient)180 C/W ( " leads)440 C/W165 C/W160 C/W ( " leads) jc(Junction to Case)N/A32 C/W80 C/WNote 6.

8 Human body model, 100pF discharged through a Characteristics(Note 2)ParameterConditionsLM234-3LM234-6 UnitsMinTypMaxMinTypMaxSet current Error, V+= ,100 A ISET 1mA 1 2%(Note 3)TJ= 25 Equivalent Temperature Error 3 6 CRatio of Set current to100 A ISET 1mA141826141826 Bias CurrentMinimum Operating Voltage100 A ISET Change in Set Current100 A ISET 1mAwith Input V+ V+ Dependence of100 A ISET current (Note 4) andEquivalent Slope Error 2 3%Effective Shunt Capacitance1515pFLM134/LM234 Performance CharacteristicsOutput ImpedanceDS005697-30 Maximum Slew RateLinear OperationDS005697-31 Start-UpDS005697-32 Transient ResponseDS005697-33 Voltage Across RSET(VR)DS005697-34 current NoiseDS005697-35LM134/LM234 Performance Characteristics(Continued)

9 Application HintsThe LM134 has been designed for ease of application, but ageneral discussion of design features is presented here tofamiliarize the designer with device characteristics whichmay not be immediately obvious. These include the effectsof slewing, power dissipation, capacitance, noise, and con-tact RSETThe total current through the LM134 (ISET) is the sum of thecurrent going through the SET resistor (IR) and the LM134 sbias current (IBIAS), as shown inFigure graph showing the ratio of these two currents is suppliedunderRatio of ISETto IBIASin the Typical PerformanceCharacteristics section.

10 The current flowing through RSET isdetermined by VR, which is approximately 214 V/ K (64 mV/298 K 214 V/ K).Since (for a given set current ) IBIASis simply a percentage ofISET, the equation can be rewrittenwhere n is the ratio of ISETto IBIASas specified in the Elec-trical Characteristics Section and shown in the graph. Sincen is typically 18 for 2 A ISET 1mA, the equation can befurther simplified tofor most set RATEAt slew rates above a given threshold (see curve), theLM134 may exhibit non-linear current shifts.