TL431 Programmable Precision Reference T he TL431 integrated circuits are three-terminal programmable shunt regulator diodes. These monolithic IC voltage references operate as a low temperature coefficient zener which is programmable from Vref to 36 volts with two external resistors. This device exhibits a wide operating current range of 1.0 to 100 mA with a typical dynamic impedance of 0.22Ω. The characteristics of these references make them excellent replacements for zener diodes in many applications such as digital voltmeters, power supplies, and op amp circuitry. The 2.5 volt reference makes it convenient to obtain a stable reference from 5.0 volt logic supplies, and since the TL431 operates as a shunt regulator, it can be used as either a positive or negative voltage reference FEATURE 1. Programmable Output Voltage to 36 Volts 2. Low Dynamic Output Impedance,0.22Ω Typical 3. Sink Current Capability of 1.0 to 100mA 4. Equivalent Full-Range Temperature Coefficient of 50ppm/℃ Typical REFERENCE ANODE CATHODE 5. Temperature Compensated for Operation over Full Rated Operating Temperature Range TO-92 TOP VIEW 6. Low Output Noise Voltage ANODE REF CATHODE SOT-23 TOP VIEW REF ANODE CATHODE SOT-89 TOP VIEW 1 1 8 8 REF CATHODE NC NC ANODE ANODE NC ANODE ANODE ANODE NC NC CATHODE REF NC NC SOP-8 TOP VIEW DIP-8 TOP VIEW 1 2001-05-A TL431 Programmable Precision Reference BLOCK DIAGRAM Cathode (K) Cathode (K) 800 800 Ref erence (R) 20pF Ref erence (R) Anode (A) SYMBOL 150 3.28K 4.0K 10K 2.4K Cathode(K) 7.2K 20pF + Ref erence(R) 1.0K 2.5Vref 800 Anode(A) Representative Block Diagram Anode (A) ABSOLUTE MAXIMUM RATINGS (Full operating ambient temperature range applies, unless otherwise noted) Rating Symbol Value Unit VKA 37 V Cathode Current Range, Continuous IK -100 to +150 mA Reference Input Current Range, Continuous Iref -0.05 to +10 mA Operating Junction Temperature TJ 150 ℃ Cathode To Anode Voltage Operating Ambient Temperature Range TL431CT/CP/CD/CH/CLT1 TA -20 ~ +85 ℃ Storage temperature Range Tstg -65 to +150 ℃ PD 0.70 W Total Power Dissipation @TA=25℃ Derate above 25℃ Ambient Temperature T,D Suffix Package P Suffix Package 1.10 H Suffix Package 1.0 LT1 Suffix Package 0.28 2 2001-05-A TL431 Programmable Precision Reference Total Power Dissipation @TC=25℃ Derate above 25℃ Case Temperature T,D Suffix Package W 1.5 PD P Suffix Package 3.0 H Suffix Package LT1 Suffix Package THERMAL CHARACTERISTICS Characteristics Symbol T,D P H LT1 Suffix Suffix Suffix Suffix Unit Thermal Resistance, Junction to Ambient RθJA 178 114 110 575 ℃/W Thermal Resistance, Junction to Case RθJC 83 41 8 150 ℃/W RECOMMENDED OPERATING CONDITIONS Condition/Value Cathode to Anode Voltage Cathode Current Symbol Min Max Unit VKA Vref 36 V IK 1.0 100 mA ELECTRICAL CHARACTERISTICS(Ambient temperature at 25℃ unless otherwise noted) Characteristic Symbol TL431 Min Typ Max Unit Reference Input Voltage (Fig 1) VKA=Vref , IK=10mA TA=+25℃ Tolerance 0.5% Vref 2.483 1% 2.470 2% 2.445 2.507 2.495 2.520 2.55 2.453 -- 2.537 ΔVref -- 3.0 17 ∆Vref ∆VKA -- -1.4 -2.7 -- -1.0 -2.0 TA=Tlow to Thigh (Note 1) V Reference Input Voltage Deviation Over Temperature Range (Fig 1, Note 1,2) mV VKA=Vref . IK=10mA Ratio of Change in Reference Input Voltage To Change in Cathode to Anode Voltage IK=10mA (Figure 2), ΔVKA=10V to Vref ΔVKA=36V to 10V 3 mV/V 2001-05-A TL431 Programmable Precision Reference Reference Input Current (Figure 2) IK=10mA, R1=10k, R2=∞ Iref TA=+25℃ µA -- 1.8 4.0 -- -- 5.2 ΔIref -- 0.4 1.2 µA Imin -- 0.5 1.0 mA Ioff -- 260 1000 nA |ZKA| -- 0.22 0.5 Ω TA=Tlow to Thigh (Note 1) Reference Input Current Deviation Over Temperature Range (Figure 2, Note 1) IK=10mA, R1=10k, R2=∞ Minimum Cathode Current for Regulation VKA=Vref (Figure 1) Off-State Cathode Current (Figure 3) VKA=36V, Vref =0V Dynamic Impedance (Figure 1, Note 3) VKA=Vref, ΔIK=1.0mA to 100mA, f< 1.0kHz 1 Tlow=0℃, Thigh=+70℃ 2 The deviation parameter ΔVref is defined as the differences between the maximum and minimum values obtained over the full operating ambient temperature range the applies. The average temperature coefficient of the reference input voltage, αVref, is defined as: ∆Vref × 106 ppm Vref @ 25°C ∆Vref × 10 6 αVref = = ∆TA(Vref @ 25°C ) °C ∆TA αVref can be positive or negative depending on whether Vref Min of Vref Max occurs at the lower ambient temperature. (Refer to Figure 6) Example: ΔVref =8.0mV and slope is positive, Vref @25℃=2.495V, ΔTA=70℃ αVref = 0.008 × 106 =45.8 ppm/℃ 70(2.495) 4 2001-05-A TL431 Programmable Precision Reference 3 The dynamic impedance ZKA is defined as: | ZKA | = ∆VKA ∆IK When the device is programmed with two external resistors, R1 and r2, (refer to Figure 2) the total dynamic impedance of the circuit is defined as: | ZKA’| ≈ | ZKA | (1+ R1 ) R2 5 2001-05-A TL431 Programmable Precision Reference TEST CIRCUITS R1 )+ Iref‧R1 R2 Fig 2.Test Circuit for VKA>Vref VKA = Vref (1+ Fig 1.Test Circuit for VKA=Vref Fig 3.Test Circuit for Ioff APPLICATION EXAMPLE Fig 4.Test circuit for curves A of stability boundary conditions Fig 6.Shunt regulator Fig 5.Test circuit for curves B.C and D of stability boundary conditions Fig 7.High current shunt regulator 6 2001-05-A TL431 Programmable Precision Reference Fig 8. Output control of a threeTerminal fixed regulator Fig 9. Series pass regulator Fig 10 .Constant current source Fig 11 .Constant current sink Fig 12 .Triac crowbar Fig 13.SCR crowbar 7 2001-05-A TL431 Programmable Precision Reference Fig 14.Voltage monitor Fig 15 . Single-supply comparator with temperature-compensated threshold Fig 16 .Simple 400mW phone amplifier Fig 17.Liner ohmmeter 8 2001-05-A TL431 Programmable Precision Reference Test Line Regulation Load Regulation Output Ripple Output Ripple Efficiency Conditions Vin=10V to 20V,Io=1.0A Vin=15V ,Io=0A to 1.0A Vin=10V ,Io=1.0A Vin=20V,Io=1.0A Vin=15V,Io=1.0A Results 53mV (1.1%) 25mV (0.5%) 50mVPP P.A.R.D 100mVPP P.A.R.D 82% Fig 18.High efficiency step-down switching converter 9 2001-05-A TL431 Programmable Precision Reference ELECTRICAL CHARACTERISTICS CURVES Fig 19.Cathode current versus cathode voltage Fig 20.Cathode current versus cathode voltage Fig 21.Reference input voltage versus ambient temperature Fig 22.Reference input current versus ambient temperature Fig 23.Change in reference input voltage versus Fig 24. Off state cathode current versus Cathode voltage ambient temperature 10 2001-05-A TL431 Programmable Precision Reference Fig 25. Dynamic impedance versus frequency Fig 26.Dynamic impedance versus ambient temperature Fig 27. Open loop voltage gain versus frequency Fig 28. Spectral noise density Fig 29. Pulse response Fig 30. Stability boundary conditions 11 2001-05-A TL431 Programmable Precision Reference ORDER INFORMATION DEVICE TL431BCT 0.5% TL431ACT 1% TL431CT 2% TL431BCP 0.5% TL431ACP 1% TL431CP 2% TL431BCD 0.5% TL431ACD 1% TL431CD 2% TL431BCLT1 0.5% TL431ACLT1 1% TL431CLT1 2% TL431BCH 0.5% TL431ACH 1% TL431CH 2% TEMPERATURE RANGE -20~+85℃ -20~+85℃ -20~+85℃ -20~+85℃ -20~+85℃ -20~+85℃ -20~+85℃ -20~+85℃ -20~+85℃ -20~+85℃ -20~+85℃ -20~+85℃ -20~+85℃ -20~+85℃ -20~+85℃ 12 PACKAGE TO-92 TO-92 TO-92 DIP-8 DIP-8 DIP-8 SOP-8 SOP-8 SOP-8 SOT-23 SOT-23 SOT-23 SOT-89 SOT-89 SOT-89 2001-05-A