LT1790 Micropower SOT-23 Low Dropout Reference Family FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION

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1 FEATURES n High Accuracy: A Grade.5 Max B Grade. Max n Low Drift: A Grade / C Max B Grade / C Max n Low Therma Hysteresis 4 (Typica) 4 C to 85 C n Low Suppy Current: 6 Max n Sinks and Sources Current n Low Dropout otage n Guaranteed Operationa 4 C to C n Wide Suppy Range to 8 n Avaiabe Output otage Options:., 2.48, 2.5, 3, 3.3, 4.96 and 5 n Low Profi e (mm) ThinSOT Package APPLICATIONS n Handhed Instruments n Negative otage References n Industria Contro Systems n Data Acquisition Systems n Battery-Operated Equipment DESCRIPTION LT79 Micropower SOT-23 Low Dropout Reference Famiy The LT 79 is a famiy of SOT-23 micropower ow dropout series references that combine high accuracy and ow drift with ow power dissipation and sma package size. These micropower references use curvature compensation to obtain a ow temperature coefficient and trimmed precision thin-fim resistors to achieve high output accuracy. In addition, each LT79 is post-package trimmed to greaty reduce the temperature coefficient and increase the output accuracy. Output accuracy is further assured by exceent ine and oad reguation. Specia care has been taken to minimize thermay induced hysteresis. The LT79s are ideay suited for battery-operated systems because of their sma size, ow suppy current and reduced dropout votage. These references provide suppy current and power dissipation advantages over shunt references that must ide the entire oad current to operate. Since the LT79 can aso sink current, it can operate as a micropower negative votage reference with the same performance as a positive reference. L, LT, LTC, LTM, Linear Technoogy and the Linear ogo are registered trademarks of Linear Technoogy Corporation. ThinSOT is a trademark of Linear Technoogy Corporation. A other trademarks are the property of their respective owners. TYPICAL APPLICATION Positive Connection for LT Typica OUT Distribution for LT IN 8.μF 4 LT79-2.5, 2 6 OUT = 2.5 μf 79 TA NUMBER OF UNITS UNITS LT79B LIMITS LT79A LIMITS OUTPUT OLTAGE () 79 TA2 79fb

2 LT79 ABSOLUTE MAXIMUM RATINGS (Note ) Input otage...2 Specifi ed Temperature Range Commercia... C to 7 C Industria... 4 C to 85 C Output Short-Circuit Duration... Indefinite Operating Temperature Range (Note 2)... 4 C to C Storage Temperature Range (Note 3) C to 5 C Lead Temperature (Sodering, sec)... 3 C PIN CONFIGURATION GND GND 2 DNC* 3 TOP IEW S6 PACKAGE 6-LEAD PLASTIC TSOT-23 6 OUT 5 DNC* 4 IN T JMAX = 5 C, θ JA = 23 C/W *DNC: DO NOT CONNECT ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE LT79ACS6-.#PBF LT79ACS6-.#TRPBF LTXT 6-Lead Pastic TSOT-23 C to 7 C LT79AIS6-.#PBF LT79AIS6-.#TRPBF LTXT 6-Lead Pastic TSOT-23 4 C to 85 C LT79BCS6-.#PBF LT79BCS6-.#TRPBF LTXT 6-Lead Pastic TSOT-23 C to 7 C LT79BIS6-.#PBF LT79BIS6-.#TRPBF LTXT 6-Lead Pastic TSOT-23 4 C to 85 C LT79ACS6-2.48#PBF LT79ACS6-2.48#TRPBF LTXU 6-Lead Pastic TSOT-23 C to 7 C LT79AIS6-2.48#PBF LT79AIS6-2.48#TRPBF LTXU 6-Lead Pastic TSOT-23 4 C to 85 C LT79BCS6-2.48#PBF LT79BCS6-2.48#TRPBF LTXU 6-Lead Pastic TSOT-23 C to 7 C LT79BIS6-2.48#PBF LT79BIS6-2.48#TRPBF LTXU 6-Lead Pastic TSOT-23 4 C to 85 C LT79ACS6-2.5#PBF LT79ACS6-2.5#TRPBF LTPZ 6-Lead Pastic TSOT-23 C to 7 C LT79AIS6-2.5#PBF LT79AIS6-2.5#TRPBF LTPZ 6-Lead Pastic TSOT-23 4 C to 85 C LT79BCS6-2.5#PBF LT79BCS6-2.5#TRPBF LTPZ 6-Lead Pastic TSOT-23 C to 7 C LT79BIS6-2.5#PBF LT79BIS6-2.5#TRPBF LTPZ 6-Lead Pastic TSOT-23 4 C to 85 C LT79ACS6-3#PBF LT79ACS6-3#TRPBF LTQA 6-Lead Pastic TSOT-23 C to 7 C LT79AIS6-3#PBF LT79AIS6-3#TRPBF LTQA 6-Lead Pastic TSOT-23 4 C to 85 C LT79BCS6-3#PBF LT79BCS6-3#TRPBF LTQA 6-Lead Pastic TSOT-23 C to 7 C LT79BIS6-3#PBF LT79BIS6-3#TRPBF LTQA 6-Lead Pastic TSOT-23 4 C to 85 C LT79ACS6-3.3#PBF LT79ACS6-3.3#TRPBF LTXW 6-Lead Pastic TSOT-23 C to 7 C LT79AIS6-3.3#PBF LT79AIS6-3.3#TRPBF LTXW 6-Lead Pastic TSOT-23 4 C to 85 C LT79BCS6-3.3#PBF LT79BCS6-3.3#TRPBF LTXW 6-Lead Pastic TSOT-23 C to 7 C LT79BIS6-3.3#PBF LT79BIS6-3.3#TRPBF LTXW 6-Lead Pastic TSOT-23 4 C to 85 C LT79ACS6-4.96#PBF LT79ACS6-4.96#TRPBF LTQB 6-Lead Pastic TSOT-23 C to 7 C LT79AIS6-4.96#PBF LT79AIS6-4.96#TRPBF LTQB 6-Lead Pastic TSOT-23 4 C to 85 C LT79BCS6-4.96#PBF LT79BCS6-4.96#TRPBF LTQB 6-Lead Pastic TSOT-23 C to 7 C LT79BIS6-4.96#PBF LT79BIS6-4.96#TRPBF LTQB 6-Lead Pastic TSOT-23 4 C to 85 C LT79ACS6-5#PBF LT79ACS6-5#TRPBF LTQC 6-Lead Pastic TSOT-23 C to 7 C LT79AIS6-5#PBF LT79AIS6-5#TRPBF LTQC 6-Lead Pastic TSOT-23 4 C to 85 C LT79BCS6-5#PBF LT79BCS6-5#TRPBF LTQC 6-Lead Pastic TSOT-23 C to 7 C LT79BIS6-5#PBF LT79BIS6-5#TRPBF LTQC 6-Lead Pastic TSOT-23 4 C to 85 C 2 79fb

3 LT79 ORDER INFORMATION LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE LT79ACS6-. LT79ACS6-.#TR LTXT 6-Lead Pastic TSOT-23 C to 7 C LT79AIS6-. LT79AIS6-.#TR LTXT 6-Lead Pastic TSOT-23 4 C to 85 C LT79BCS6-. LT79BCS6-.#TR LTXT 6-Lead Pastic TSOT-23 C to 7 C LT79BIS6-. LT79BIS6-.#TR LTXT 6-Lead Pastic TSOT-23 4 C to 85 C LT79ACS LT79ACS6-2.48#TR LTXU 6-Lead Pastic TSOT-23 C to 7 C LT79AIS LT79AIS6-2.48#TR LTXU 6-Lead Pastic TSOT-23 4 C to 85 C LT79BCS LT79BCS6-2.48#TR LTXU 6-Lead Pastic TSOT-23 C to 7 C LT79BIS LT79BIS6-2.48#TR LTXU 6-Lead Pastic TSOT-23 4 C to 85 C LT79ACS6-2.5 LT79ACS6-2.5#TR LTPZ 6-Lead Pastic TSOT-23 C to 7 C LT79AIS6-2.5 LT79AIS6-2.5#TR LTPZ 6-Lead Pastic TSOT-23 4 C to 85 C LT79BCS6-2.5 LT79BCS6-2.5#TR LTPZ 6-Lead Pastic TSOT-23 C to 7 C LT79BIS6-2.5 LT79BIS6-2.5#TR LTPZ 6-Lead Pastic TSOT-23 4 C to 85 C LT79ACS6-3 LT79ACS6-3#TR LTQA 6-Lead Pastic TSOT-23 C to 7 C LT79AIS6-3 LT79AIS6-3#TR LTQA 6-Lead Pastic TSOT-23 4 C to 85 C LT79BCS6-3 LT79BCS6-3#TR LTQA 6-Lead Pastic TSOT-23 C to 7 C LT79BIS6-3 LT79BIS6-3#TR LTQA 6-Lead Pastic TSOT-23 4 C to 85 C LT79ACS6-3.3 LT79ACS6-3.3#TR LTXW 6-Lead Pastic TSOT-23 C to 7 C LT79AIS6-3.3 LT79AIS6-3.3#TR LTXW 6-Lead Pastic TSOT-23 4 C to 85 C LT79BCS6-3.3 LT79BCS6-3.3#TR LTXW 6-Lead Pastic TSOT-23 C to 7 C LT79BIS6-3.3 LT79BIS6-3.3#TR LTXW 6-Lead Pastic TSOT-23 4 C to 85 C LT79ACS LT79ACS6-4.96#TR LTQB 6-Lead Pastic TSOT-23 C to 7 C LT79AIS LT79AIS6-4.96#TR LTQB 6-Lead Pastic TSOT-23 4 C to 85 C LT79BCS LT79BCS6-4.96#TR LTQB 6-Lead Pastic TSOT-23 C to 7 C LT79BIS LT79BIS6-4.96#TR LTQB 6-Lead Pastic TSOT-23 4 C to 85 C LT79ACS6-5 LT79ACS6-5#TR LTQC 6-Lead Pastic TSOT-23 C to 7 C LT79AIS6-5 LT79AIS6-5#TR LTQC 6-Lead Pastic TSOT-23 4 C to 85 C LT79BCS6-5 LT79BCS6-5#TR LTQC 6-Lead Pastic TSOT-23 C to 7 C LT79BIS6-5 LT79BIS6-5#TR LTQC 6-Lead Pastic TSOT-23 4 C to 85 C Consut LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a abe on the shipping container. For more information on ead free part marking, go to: For more information on tape and ree specifi cations, go to: 79fb 3

4 LT79 AAILABLE OPTIONS OUTPUT OLTAGE INITIAL ACCURACY TEMPERATURE COEFFICIENT / C / C / C / C / C / C / C / C / C / C / C / C / C / C TEMPERATURE RANGE C TO 7 C 4 C TO 85 C ORDER PART NUMBER ORDER PART NUMBER LT79ACS6-. LT79BCS6-. LT79ACS LT79BCS LT79ACS6-2.5 LT79BCS6-2.5 LT79ACS6-3 LT79BCS6-3 LT79ACS6-3.3 LT79BCS6-3.3 LT79ACS LT79BCS LT79ACS6-5 LT79BCS6-5 LT79AIS6-. LT79BIS6-. LT79AIS LT79BIS LT79AIS6-2.5 LT79BIS6-2.5 LT79AIS6-3 LT79BIS6-3 LT79AIS6-3.3 LT79BIS6-3.3 LT79AIS LT79BIS LT79AIS6-5 LT79BIS6-5. ELECTRICAL CHARACTERISTICS The denotes the specifi cations which appy over the specifi ed temperature range, otherwise specifi cations are at. C L = μf and IN = 2.6, uness otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Output otage (Notes 3, 4) LT79A LT79B Output otage Temperature Coeffi cient (Note 5) Line Reguation LT79AC LT79AI LT79BC LT79BI T MIN T A T MAX LT79A LT79B 2.6 IN 8 Load Reguation (Note 6) I OUT Source = 5mA, IN = 2.8 I OUT Sink = ma, IN = 3.2 Minimum Operating otage (Note 7) IN, Δ OUT =. I OUT = ma I OUT Source = 5mA I OUT Sink = ma / C / C / / 4 79fb

5 LT79. ELECTRICAL CHARACTERISTICS The denotes the specifi cations which appy over the specifi ed temperature range, otherwise specifi cations are at. C L = μf and IN = 2.6, uness otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Suppy Current No Load Minimum Operating Current OUT =., ±. Negative Output (See Figure 7) Turn-On Time C LOAD = μf μs Output Noise (Note 8).Hz f Hz Hz f khz 4 μ P-P μ RMS Long-Term Drift of Output otage (Note 9) 5 / khr Hysteresis (Note ) ΔT = C to 7 C ΔT = 4 C to 85 C ELECTRICAL CHARACTERISTICS The denotes the specifi cations which appy over the specifi ed temperature range, otherwise specifi cations are at. C L = μf and IN = 2.8, uness otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Output otage (Notes 3, 4) LT79A LT79B Output otage Temperature Coeffi cient (Note 5) Line Reguation Load Reguation (Note 6) LT79AC LT79AI LT79BC LT79BI T MIN T A T MAX LT79A LT79B 2.8 IN 8 I OUT Source = 5mA I OUT Sink = 3mA Dropout otage (Note 7) IN OUT, Δ OUT =. I OUT = ma Suppy Current I OUT Source = 5mA I OUT Sink = 3mA No Load / C / C / / Minimum Operating Current OUT = 2.48,. Negative Output (See Figure 7) Turn-On Time C LOAD = μf 35 μs m m m m 79fb 5

6 LT ELECTRICAL CHARACTERISTICS The denotes the specifi cations which appy over the specifi ed temperature range, otherwise specifi cations are at. C L = μf and IN = 2.8, uness otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Output Noise (Note 8).Hz f Hz Hz f khz 22 4 μ P-P μ RMS Long-Term Drift of Output otage (Note 9) 5 / khr Hysteresis (Note ) ΔT = C to 7 C ΔT = 4 C to 85 C ELECTRICAL CHARACTERISTICS The denotes the specifi cations which appy over the specifi ed temperature range, otherwise specifi cations are at. C L = μf and IN = 3, uness otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Output otage (Notes 3, 4) LT79A LT79B Output otage Temperature Coeffi cient (Note 5) Line Reguation Load Reguation (Note 6) LT79AC LT79AI LT79BC LT79BI T MIN T A T MAX LT79A LT79B 3 IN 8 I OUT Source = 5mA I OUT Sink = 3mA Dropout otage (Note 7) IN OUT, Δ OUT =. I OUT = ma Suppy Current I OUT Source = 5mA I OUT Sink = 3mA No Load / C / C / / Minimum Operating Current OUT = 2.5,. Negative Output (See Figure 7) Turn-On Time C LOAD = μf 7 μs Output Noise (Note 8).Hz f Hz Hz f khz Long-Term Drift of Output otage (Note 9) 5 / khr Hysteresis (Note ) ΔT = C to 7 C ΔT = 4 C to 85 C m m m m μ P-P μ RMS 6 79fb

7 LT79 3 ELECTRICAL CHARACTERISTICS The denotes the specifi cations which appy over the specifi ed temperature range, otherwise specifi cations are at. C L = μf and IN = 3.5, uness otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Output otage (Notes 3, 4) LT79A LT79B Output otage Temperature Coeffi cient (Note 5) Line Reguation Load Reguation (Note 6) LT79AC LT79AI LT79BC LT79BI T MIN T A T MAX LT79A LT79B 3.5 IN 8 I OUT Source = 5mA I OUT Sink = 3mA Dropout otage (Note 7) IN OUT, Δ OUT =. I OUT = ma Suppy Current I OUT Source = 5mA I OUT Sink = 3mA No Load / C / C / / Minimum Operating Current OUT = 3,. Negative Output (See Figure 7) Turn-On Time C LOAD = μf 7 μs Output Noise (Note 8).Hz f Hz Hz f khz Long-Term Drift of Output otage (Note 9) 5 / khr Hysteresis (Note ) ΔT = C to 7 C ΔT = 4 C to 85 C m m m m μ P-P μ RMS 79fb 7

8 LT ELECTRICAL CHARACTERISTICS The denotes the specifi cations which appy over the specifi ed temperature range, otherwise specifi cations are at. C L = μf and IN = 3.8, uness otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Output otage (Notes 3, 4) LT79A LT79B Output otage Temperature Coeffi cient (Note 5) Line Reguation Load Reguation (Note 6) LT79AC LT79AI LT79BC LT79BI T MIN T A T MAX LT79A LT79B 3.8 IN 8 I OUT Source = 5mA I OUT Sink = 3mA Dropout otage (Note 7) IN OUT, Δ OUT =. I OUT = ma Suppy Current I OUT Source = 5mA I OUT Sink = 3mA No Load / C / C / / Minimum Operating Current OUT = 3.3,. Negative Output (See Figure 7) Turn-On Time C LOAD = μf 7 μs Output Noise (Note 8).Hz f Hz Hz f khz Long-Term Drift of Output otage (Note 9) 5 / khr Hysteresis (Note ) ΔT = C to 7 C ΔT = 4 C to 85 C m m m m μ P-P μ RMS 8 79fb

9 LT ELECTRICAL CHARACTERISTICS The denotes the specifi cations which appy over the specifi ed temperature range, otherwise specifi cations are at. C L = μf and IN = 4.6, uness otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Output otage (Notes 3, 4) LT79A LT79B Output otage Temperature Coeffi cient (Note 5) Line Reguation Load Reguation (Note 6) LT79AC LT79AI LT79BC LT79BI T MIN T A T MAX LT79A LT79B 4.6 IN 8 I OUT Source = 5mA I OUT Sink = 3mA Dropout otage (Note 7) IN OUT, Δ OUT =. I OUT = ma Suppy Current I OUT Source = 5mA I OUT Sink = 3mA No Load / C / C / / Minimum Operating Current OUT = 4.96,. Negative Output (See Figure 7) Turn-On Time C LOAD = μf 7 μs Output Noise (Note 8).Hz f Hz Hz f khz Long-Term Drift of Output otage (Note 9) 5 / khr Hysteresis (Note ) ΔT = C to 7 C ΔT = 4 C to 85 C m m m m μ P-P μ RMS 79fb 9

10 LT79 5 ELECTRICAL CHARACTERISTICS The denotes the specifi cations which appy over the specifi ed temperature range, otherwise specifi cations are at. C L = μf and IN = 5.5, uness otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Output otage (Notes 3, 4) LT79A LT79B Output otage Temperature Coeffi cient (Note 5) Line Reguation Load Reguation (Note 6) LT79AC LT79AI LT79BC LT79BI T MIN T A T MAX LT79A LT79B 5.5 IN 8 I OUT Source = 5mA I OUT Sink = 3mA Dropout otage (Note 7) IN OUT, Δ OUT =. I OUT = ma Suppy Current I OUT Source = 5mA I OUT Sink = 3mA No Load / C / C / / Minimum Operating Current OUT = 5,. Negative Output (See Figure 7) Turn-On Time C LOAD = μf 7 μs Output Noise (Note 8).Hz f Hz Hz f khz Long-Term Drift of Output otage (Note 9) 5 / khr Hysteresis (Note ) ΔT = C to 7 C ΔT = 4 C to 85 C m m m m μ P-P μ RMS Note : Stresses beyond those isted under Absoute Maximum Ratings may cause permanent damage to the device. Exposure to any Absoute Maximum Rating condition for extended periods may affect device reiabiity and ifetime. Note 2: The LT79 is guaranteed functiona over the operating temperature range of 4 C to C. The LT79-. at C is typicay ess than 2 above the nomina votage. The other votage options are typicay ess than. above their nomina votage. Note 3: If the part is stored outside of the specifi ed temperature range, the output votage may shift due to hysteresis. Note 4: ESD (Eectrostatic Discharge) sensitive device. Extensive use of ESD protection devices are used interna to the LT79, however, high eectrostatic discharge can damage or degrade the device. Use proper ESD handing precautions. Note 5: Temperature coeffi cient is measured by dividing the change in output votage by the specifi ed temperature range. Incrementa sope is aso measured at C. Note 6: Load reguation is measured on a puse basis from no oad to the specifi ed oad current. Output changes due to die temperature change must be taken into account separatey. Note 7: Excudes oad reguation errors. 79fb

11 ELECTRICAL CHARACTERISTICS Note 8: Peak-to-peak noise is measured with a singe poe highpass fi ter at.hz and a 2-poe owpass fi ter at Hz. The unit is encosed in a sti air environment to eiminate thermocoupe effects on the eads. The test time is seconds. Integrated RMS noise is measured from Hz to khz with the HP356A anayzer. Note 9: Long-term drift typicay has a ogarithmic characteristic and therefore changes after hours tend to be smaer than before that time. Long-term drift is affected by differentia stress between the IC and the board materia created during board assemby. See the Appications Information section. LT79 Note : Hysteresis in the output votage is created by package stress that differs depending on whether the IC was previousy at a higher or ower temperature. Output votage is aways measured at C, but the IC is cyced to 85 C or 4 C before a successive measurements. Hysteresis is roughy proportiona to the square of the temperature change. Hysteresis is not a probem for operationa temperature excursions where the instrument might be stored at high or ow temperature. See the Appications Information section.. TYPICAL PERFORMANCE CHARACTERISTICS Each of the votage options have simiar performance curves. For the 3, 3.3 and the 4.96 options, the curves can be estimated based on the 2.5 and 5 curves. OUTPUT OLTAGE () Output otage Temperature Drift FOUR TYPICAL PARTS OUTPUT CURRENT (ma) Minimum Input-Output otage Differentia (Sourcing) OLTAGE DIFFERENTIAL () Minimum Input-Output otage Differentia (Sinking) ma 5mA TEMPERATURE ( C) INPUT-OUTPUT OLTAGE () TEMPERATURE ( C) 79. G 79. G2 79. G3 OUTPUT OLTAGE CHANGE () Load Reguation (Sourcing) OUTPUT CURRENT (ma) 79. G4 OUTPUT OLTAGE CHANGE () Load Reguation (Sinking) OUTPUT CURRENT (ma) 79. G5 SUPPLY CURRENT () Suppy Current vs Input otage INPUT OLTAGE () 79. G6 79fb

12 LT79. TYPICAL PERFORMANCE CHARACTERISTICS Each of the votage options have simiar performance curves. For the 3, 3.3 and the 4.96 options, the curves can be estimated based on the 2.5 and 5 curves. OUTPUT OLTAGE () Line Reguation INPUT OLTAGE () 79.. G7 POWER SUPPLY REJECTION RATIO (db) Power Suppy Rejection Ratio vs Frequency IN = 3 C L = μf 9 k k k M 79. G8 OUTPUT IMPEDANCE (Ω) 5 IN = 3 Output Impedance vs Frequency C L = 4.7μF C L = μf C L =.47μF k k k 79. G9 CURRENT IN R L (ma) Characteristics 4 LT EE R L 5k R k 3 μf OUT Long-Term Drift (Data Points Reduced After 5 Hr) LT79S6-. 2 TYPICAL PARTS SOLDERED TO PCB T A = 3 C OUTPUT NOISE (5μ/DI) Output Noise.Hz to Hz OUTPUT TO GROUND OLTAGE () HOURS TIME (SEC) 79. G 79. G 79. G2 NOISE OLTAGE (μ/ Hz) Output otage Noise Spectrum 5. C L = μf I O = 2. I O =.5 I O =..5 I O = ma k k 79. G3 INTEGRATED NOISE (μ RMS ) Integrated Noise Hz to khz 79. G4 2 79fb

13 2.48 TYPICAL PERFORMANCE CHARACTERISTICS Each of the votage options have simiar performance curves. For the 3, 3.3 and the 4.96 options, the curves can be estimated based on the 2.5 and 5 curves. OUTPUT OLTAGE () Output otage Temperature Drift FOUR TYPICAL PARTS TEMPERATURE ( C) OUTPUT CURRENT (ma) Minimum Input-Output otage Differentia (Sourcing) INPUT-OUTPUT OLTAGE () OLTAGE DIFFERENTIAL (m) LT79 Minimum Input-Output otage Differentia (Sinking) ma 5mA TEMPERATURE ( C) G G G3 OUTPUT OLTAGE CHANGE () Load Reguation (Sourcing) OUTPUT OLTAGE CHANGE () Load Reguation (Sinking) T A = 4 C SUPPLY CURRENT () Suppy Current vs Input otage OUTPUT CURRENT (ma). OUTPUT CURRENT (ma) 5 5 INPUT OLTAGE () G G G6 OUTPUT OLTAGE () Line Reguation POWER SUPPLY REJECTION RATIO (db) Power Suppy Rejection Ratio vs Frequency C L = μf OUTPUT IMPEDANCE (Ω) Output Impedance vs Frequency C L = 4.7μF C L = μf C L =.47μF INPUT OLTAGE () 2 8 k k k M k k M M G G G9 79fb 3

14 LT TYPICAL PERFORMANCE CHARACTERISTICS Each of the votage options have simiar performance curves. For the 3, 3.3 and the 4.96 options, the curves can be estimated based on the 2.5 and 5 curves. CURRENT IN R L (ma) Characteristics 4 LT EE R L 5k R k 3 μf OUT OUTPUT TO GROUND OLTAGE () G Long-Term Drift T A = 3 C 2 TYPICAL PARTS SOLDERED TO PCB HOURS G OUTPUT NOISE (μ/di) Output Noise.Hz to Hz TIME (SEC) G2 NOISE OLTAGE (μ/ Hz) Output otage Noise Spectrum C L = μf I O = 4 I O = 3 I O = 2 I O = ma k k G3 Integrated Noise Hz to khz INTEGRATED NOISE (μ RMS ) G4 4 79fb

15 2.5 TYPICAL PERFORMANCE CHARACTERISTICS Each of the votage options have simiar performance curves. For the 3, 3.3 and the 4.96 options, the curves can be estimated based on the 2.5 and 5 curves. OUTPUT OLTAGE () Output otage Temperature Drift FOUR TYPICAL PARTS OUTPUT CURRENT (ma) Minimum Input-Output otage Differentia (Sourcing) OLTAGE DIFFERENTIAL (m) LT79 Minimum Input-Output otage Differentia (Sinking) ma 5mA TEMPERATURE ( C) INPUT-OUTPUT OLTAGE () TEMPERATURE ( C) G G G3 Load Reguation (Sourcing) 2 Load Reguation (Sinking) 8 Suppy Current vs Input otage OUTPUT OLTAGE CHANGE () OUTPUT CURRENT (ma) OUTPUT OLTAGE CHANGE () OUTPUT CURRENT (ma) SUPPLY CURRENT () INPUT OLTAGE () G G G6 OUTPUT OLTAGE () Line Reguation INPUT OLTAGE () G7 POWER SUPPLY REJECTION RATIO (db) Power Suppy Rejection Ratio vs Frequency C L = μf 8 k k k M G8 OUTPUT IMPEDANCE (Ω) Output Impedance vs Frequency C L = 4.7μF C L =.47μF C L = μf k k k G9 79fb 5

16 LT TYPICAL PERFORMANCE CHARACTERISTICS Each of the votage options have simiar performance curves. For the 3, 3.3 and the 4.96 options, the curves can be estimated based on the 2.5 and 5 curves. CURRENT IN R L (ma) Characteristics EE R L 5k OUT OUTPUT TO GROUND OLTAGE () 4 LT79-2.5, 2 R k 6 μf Long-Term Drift (Data Points Reduced After 5 Hr) T A = 3 C 2 TYPICAL PARTS SOLDERED TO PCB HOURS G G Output Noise.Hz to Hz Output otage Noise Spectrum C L = μf OUTPUT NOISE (μ/di) NOISE OLTAGE (μ/ Hz) I O = I O = I O = ma TIME (SEC) G2 k k G3 Integrated Noise Hz to khz INTEGRATED NOISE (μrms) G4 6 79fb

17 5 TYPICAL PERFORMANCE CHARACTERISTICS Each of the votage options have simiar performance curves. For the 3, 3.3 and the 4.96 options, the curves can be estimated based on the 2.5 and 5 curves. OUTPUT OLTAGE () Output otage Temperature Drift FOUR TYPICAL PARTS OUTPUT CURRENT (ma) Minimum Input-Output otage Differentia (Sourcing) OLTAGE DIFFERENTIAL (m) LT79 Minimum Input-Output otage Differentia (Sinking) 5mA ma TEMPERATURE ( C) INPUT-OUTPUT OLTAGE () TEMPERATURE ( C) 795 G 795 G2 795 G3 OUTPUT OLTAGE CHANGE () Load Reguation (Sourcing) OUTPUT CURRENT (ma) OUTPUT OLTAGE CHANGE () Load Reguation (Sinking) T A = 4 C OUTPUT CURRENT (ma) SUPPLY CURRENT () Suppy Current vs Input otage INPUT OLTAGE () G4 795 G5 795 G6 OUTPUT OLTAGE () Line Reguation POWER SUPPLY REJECTION RATIO (db) Power Suppy Rejection Ratio vs Frequency C L = μf OUTPUT IMPEDANCE (Ω) Output Impedance vs Frequency C L = 4.7μF C L =.47μF C L = μf INPUT OLTAGE () 2 8 k k k M k k k 795 G7 795 G8 795 G9 79fb 7

18 LT79 5 TYPICAL PERFORMANCE CHARACTERISTICS Each of the votage options have simiar performance curves. For the 3, 3.3 and the 4.96 options, the curves can be estimated based on the 2.5 and 5 curves. CURRENT IN R L (ma) Characteristics Long-Term Drift 4 LT EE R L 5k R k 6 μf 5.5 OUT OUTPUT TO GROUND OLTAGE () T A = 3 C 2 TYPICAL PARTS SOLDERED TO PCB HOURS 795 G 795 G Output Noise.Hz to Hz Output otage Noise Spectrum C L = μf OUTPUT NOISE (2μ/DI) NOISE OLTAGE (μ/ Hz) I O = I O = I O = ma TIME (SEC) k k 795 G2 795 G3 Integrated Noise Hz to khz INTEGRATED NOISE (μ RMS ) 795 G4 8 79fb

19 APPLICATIONS INFORMATION Bypass and Load Capacitors The LT79 votage references shoud have an input bypass capacitor of.μf or arger, however the bypassing of other oca devices may serve as the required component. These references aso require an output capacitor for stabiity. The optimum output capacitance for most appications is μf, athough arger vaues work as we. This capacitor affects the turn-on and setting time for the output to reach its fi na vaue. A LT79 votages perform virtuay the same, so the LT is used as an exampe. LT79 Figure shows the turn-on time for the LT with a μf input bypass and μf oad capacitor. Figure 2 shows the output response to a.5 transient on IN with the same capacitors. The test circuit of Figure 3 is used to measure the stabiity of various oad currents. With R L = k, the step produces a current step of ma. Figure 4 shows the response to a ±.5mA oad. Figure 5 is the output response to a sourcing step from 4mA to 5mA, and Figure 6 is the output response of a sinking step from 4mA to 5mA. 3 2 IN OUT 3 2 IN OUT 79 F 79 F2 Figure. Turn-On Characteristics of LT Figure 2. Output Response to.5 Rippe on IN IN 3 4 C IN.μF LT79-2.5, 2 6 C L μf k GEN 79 F3 Figure 3. Response Time Test Circuit GEN 3 2 OUT (AC COUPLED) OUT (AC COUPLED) GEN F4 79 F5 Figure 4. LT Sourcing and Sinking.5mA Figure 5. LT Sourcing 4mA to 5mA 79fb 9

20 LT79 APPLICATIONS INFORMATION Positive or Negative Operation Series operation is idea for extending battery ife. If an LT79 is operated in series mode it does not require an externa current setting resistor. The specifi cations guarantee that the LT79 famiy operates to 8. When the circuitry being reguated does not demand current, the series connected LT79 consumes ony a few hundred μw, yet the same connection can sink or source 5mA of oad current when demanded. A typica series connection is shown on the front page of this data sheet. The circuit in Figure 7 shows the connection for a 2.5 reference, athough any LT79 votage option can be confi gured this way to make a negative reference. The LT79 can be used as very stabe negative references, however, they require a positive votage appied to Pin 4 to bias interna circuitry. This votage must be current imited with R to keep the output PNP transistor from turning on and driving the grounded output. C provides stabiity during oad transients. This connection maintains neary the same accuracy and temperature coeffi cient of the positive connected LT79. Long-Term Drift Long-term drift cannot be extrapoated from acceerated high temperature testing. This erroneous technique gives drift numbers that are widey optimistic. The ony way ong-term drift can be determined is to measure it over the time interva of interest. The LT79S6 drift data was taken on over parts that were sodered into PC boards simiar to a rea word appication. The boards were then paced into a constant temperature oven with T A = 3 C, their outputs scanned reguary and measured with an 8.5 digit DM. Long-term drift curves are shown in the Typica Performance Characteristics section. GEN R k 3 4 OUT (AC COUPLED) 6 LT79-2.5, 2 C.μF OUT = R L = EE OUT C L μf 79 F6 EE 79 F7 Figure 6. LT Sinking 4mA to 5mA Figure 7. Using the LT to Buid a 2.5 Reference 2 79fb

21 LT79 APPLICATIONS INFORMATION Hysteresis Hysteresis data shown in Figures 8 and 9 represent the worst-case data taken on parts from C to 7 C and from 4 C to 85 C. Units were cyced severa times over these temperature ranges and the argest change is shown. As expected, the parts cyced over the higher temperature range have higher hysteresis than those cyced over the ower range. In addition to therma hysteresis, the therma shock associated with high temperature sodering may cause the output to shift. For traditiona PbSn soder temperatures, the output shift of the LT79 is typicay just 5 (.5). NUMBER OF UNITS C TO C C TO C For ead-free soder, IR refow temperatures are much higher, often 24 C to 26 C at the peak. As a resut, the packaging materias have been optimized to reduce OUT shift as possibe during high temperature refow. In addition, care shoud be taken when using ead-free soder to minimize the peak temperature and dwe time as much as is practica. A typica ead-free refow profie is shown in Figure. LT79 units were heated using a simiar profie, with a peak temperature of C. These parts were run through the heating process 3 times to show the cumuative effect of these heat cyces. Figure shows DEGREES (C) s T S(MAX) = 2 C T = 9 C T = 5 C RAMP TO 5 C T L = 27 C 2s T P = 26 t P 3s t L 3s 4s RAMP DOWN MINUTES DISTRIBUTION () 79 F Figure. Lead-Free Ref ow Profi e NUMBER OF UNITS 79 F8 Figure 8. Worst-Case C to 7 C Hysteresis on 79 Units C TO C 2 4 C TO C DISTRIBUTION () 79 F9 Figure 9. Worst-Case 4 C to 85 C Hysteresis on 8 Units NUMBER OF UNITS PPM 79 F Figure. X IR Ref ow Peak Temperature = C, Deta Output otage () 79fb 2

22 LT79 APPLICATIONS INFORMATION the shift after cyce, whie Figure 2 shows shift after 3 cyces. In the worst case, shifts are typicay 5, but may be as high as 29. Shifts in output votage are proportiona to temperature and dwe time. In genera, the output shift can be reduced or fuy recovered by a ong (2-24 hour) bake of the competed PC Board assemby at high temperature ( C to 5C ) after sodering to remove mechanica stress that has been induced by therma shock. Once the PC Boards have cooed to room temperature, they may continue to shift for up to 3 times the bake time. This shoud be taken into account before any caibration is performed. NUMBER OF UNITS PPM 79 F2 Figure 2. 3X IR Ref ow Peak Temperature = C, Deta Output otage () Higher Input otage Assuming 8 max suppy current for the LT79, a oad, 2m max dropout and a 4 to 3 input specification, the argest that R can be is ( m)/(8 + ) = 5.5k. Furthermore, assuming 22mW of dissipation in the 8 SOT-23 Zener, this gives a max current of (22mW)/(8) = 2.2mA. So the smaest that R shoud be is (3 8)/2.2mA = k, rated at 5mW. With R = k, and assuming a 45m worst-case dropout, the LT79 can deiver a minimum current of ( m)/(k) =. In Figure 3, R and C provide fitering of the Zener noise when the Zener is in its noisy -I knee. There are other variations for higher votage operation that use a pass transistor shown in Figures 4 and 5. These circuits aow the input votage to be as high as 6 whie maintaining ow suppy current. R 33k BZX84C2 R2 4.7k C.μF LT79 ON SEMI MMBT555 S 6 TO 6 C2 μf 79 F4 Figure 4. Extended Suppy Range Reference OUT The circuit in Figure 3 shows an easy way to increase the input votage range of the LT79. The Zener diode can be anywhere from 6 to 8. For equa power sharing between R and the Zener (at 3), the 8 option is better. The circuit can toerate much higher votages for short periods and is suitabe for transient protection. ON SEMI MMBT555 R 33k C.μF S 6.5 TO 6 BA99 4 TO 3 R LT79 C2 μf OUT LT OUT 79 F5 BZX84C8 C.μF μf Figure 5. Extended Suppy Range Reference 79 F3 Figure 3. Extended Suppy Range Reference 22 79fb

23 APPLICATIONS INFORMATION More Output Current The circuit in Figure 6 is a compact, high output current, ow dropout precision suppy. The circuit uses the SOT-23 LT782 and the ThinSOT LT79. Resistive divider R and R2 set a votage 22m beow S. For under ma of output current, the LT79 suppies the oad. Above ma of oad current, the (+) input of the LT782 is pued beow the 22m divider reference and the output FET turns on to suppy the oad current. Capacitor C stops osciations in the transition region. The no oad standing current is ony 2, yet the output can deiver over 3mA. Noise An estimate of the tota integrated noise from Hz to khz can be made by mutipying the fat band spot noise by BW. For exampe, from the Typica Performance curves, the LT79-. noise spectrum shows the average spot noise to be about 45n/ Hz. The square root of the LT79 bandwidth is 99 = 3.4. The tota noise Hz to khz noise is (45n)(3.4) = 4.μ. This agrees we with the measured noise. This estimate may not be as good with higher votage options, there are severa reasons for this. Higher votage options have higher noise and they have higher variabiity due to process variations. Hz to khz noise may vary by 2dB on the LT79-5 and db on the LT Measured noise may aso vary because of peaking in the noise spectrum. This effect can be seen in the range of khz to khz with a votage options sourcing different oad currents. From the Typica Performance curves the Hz to khz noise spectrum of the LT79-5 is shown to be 3μ/ Hz at ow frequency. The estimated noise is (3μ)(3.4) = 93.4μ. The actua integrated Hz to khz noise measures 8.3μ. The peaking shown causes this arger number. Peaking is a function of output capacitor as we as oad current and process variations. S 2.8 TO 3.3 NO LOAD SUPPLY CURRENT 2 R 68Ω 5 R2 k 5 R3 22Ω 5 LT C2 μf LT782 C.μF R4 k F6 NOTE: NOT CURRENT LIMITED ISHAY SILICONIX Si3445D OUT = 2.5 I LOAD = ma to 3mA Figure 6. Compact, High Output Current, Low Dropout, Precision 2.5 Suppy 79fb 23

24 LT79 SIMPLIFIED SCHEMATIC 4 IN 6 OUT, 2 GND 79 SS 24 79fb

25 PACKAGE DESCRIPTION S6 Package 6-Lead Pastic TSOT-23 (Reference LTC DWG # ) LT79.62 MAX.95 REF 2.9 BSC (NOTE 4).22 REF 3.85 MAX 2.62 REF.4 MIN 2.8 BSC.5.75 (NOTE 4) PIN ONE ID RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR.95 BSC PLCS (NOTE 3) BSC DATUM A. MAX REF.9.2 (NOTE 3) NOTE:. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIE OF PLATING 4. DIMENSIONS ARE EXCLUSIE OF MOLD FLASH AND METAL BURR 5. MOLD FLASH SHALL NOT EXCEED.4mm 6. JEDEC PACKAGE REFERENCE IS MO-93.9 BSC S6 TSOT RE B Information furnished by Linear Technoogy Corporation is beieved to be accurate and reiabe. However, no responsibiity is assumed for its use. Linear Technoogy Corporation makes no representation that the interconnection of its circuits as described herein wi not infringe on existing patent rights. 79fb

26 LT79 TYPICAL APPLICATION 2.5 Negative 5mA Series Reference No Load Suppy Current I CC =.6mA I EE = 44 CC = 5 2k 4 LT k Z = 5., 2 EE = 5 MPS297A μf 2.5 5mA 79 TA3 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT9 Precision Reference Low Noise Bandgap,.5, 5/ C LTC 798 Micropower Low Dropout Reference.5 Max, 6.5 Suppy Current LT46 Micropower Precision Series Reference Bandgap, 3 Suppy Current, / C, Avaiabe in SOT-23 LT46 Micropower Precision Low Dropout Reference Bandgap.4, 3/ C, 5 Max Suppy Current 26 LT 69 RE B PRINTED IN USA Linear Technoogy Corporation 63 McCarthy Bvd., Mipitas, CA (48) FAX: (48) LINEAR TECHNOLOGY CORPORATION 2 79fb