LT1790 Micropower SOT-23 Low Dropout Reference Family FEATURES DESCRIPTION n The LT(R)1790 is a family of SOT-23 micropower low dropout series references that combine high accuracy and low drift with low power dissipation and small package size. These micropower references use curvature compensation to obtain a low temperature coefficient and trimmed precision thin-film resistors to achieve high output accuracy. In addition, each LT1790 is post-package trimmed to greatly reduce the temperature coefficient and increase the output accuracy. Output accuracy is further assured by excellent line and load regulation. Special care has been taken to minimize thermally induced hysteresis. n n n n n n n n n High Accuracy: A Grade--0.05% Max B Grade--0.1% Max Low Drift: A Grade--10ppm/C Max B Grade--25ppm/C Max Low Thermal Hysteresis 40ppm (Typical) -40C to 85C Low Supply Current: 60A Max Sinks and Sources Current Low Dropout Voltage Guaranteed Operational -40C to 125C Wide Supply Range to 18V Available Output Voltage Options: 1.25V, 2.048V, 2.5V, 3V, 3.3V, 4.096V and 5V Low Profile (1mm) ThinSOTTM Package APPLICATIONS n n n n n Handheld Instruments Negative Voltage References Industrial Control Systems Data Acquisition Systems Battery-Operated Equipment The LT1790s are ideally suited for battery-operated systems because of their small size, low supply current and reduced dropout voltage. These references provide supply current and power dissipation advantages over shunt references that must idle the entire load current to operate. Since the LT1790 can also sink current, it can operate as a micropower negative voltage reference with the same performance as a positive reference. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION Positive Connection for LT1790-2.5 Typical VOUT Distribution for LT1790-2.5 50 0.1F LT1790-2.5 1, 2 6 40 1F 1790 TA01 167 UNITS 45 VOUT = 2.5V NUMBER OF UNITS 2.6V VIN 18V 4 LT1790B LIMITS 35 LT1790A LIMITS 30 25 20 15 10 5 0 2.498 2.499 2.500 2.501 OUTPUT VOLTAGE (V) 2.502 1790 TA02 1790fb 1 LT1790 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) Input Voltage.............................................................20V Specified Temperature Range Commercial............................................. 0C to 70C Industrial .............................................- 40C to 85C Output Short-Circuit Duration .......................... Indefinite Operating Temperature Range (Note 2)..................................................-40C to 125C Storage Temperature Range (Note 3).................................................. -65C to 150C Lead Temperature (Soldering, 10 sec) .................. 300C TOP VIEW GND 1 6 VOUT GND 2 5 DNC* DNC* 3 4 VIN S6 PACKAGE 6-LEAD PLASTIC TSOT-23 TJMAX = 150C, JA = 230C/W *DNC: DO NOT CONNECT ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE LT1790ACS6-1.25#PBF LT1790ACS6-1.25#TRPBF LTXT 6-Lead Plastic TSOT-23 0C to 70C LT1790AIS6-1.25#PBF LT1790AIS6-1.25#TRPBF LTXT 6-Lead Plastic TSOT-23 -40C to 85C LT1790BCS6-1.25#PBF LT1790BCS6-1.25#TRPBF LTXT 6-Lead Plastic TSOT-23 0C to 70C LT1790BIS6-1.25#PBF LT1790BIS6-1.25#TRPBF LTXT 6-Lead Plastic TSOT-23 -40C to 85C LT1790ACS6-2.048#PBF LT1790ACS6-2.048#TRPBF LTXU 6-Lead Plastic TSOT-23 0C to 70C LT1790AIS6-2.048#PBF LT1790AIS6-2.048#TRPBF LTXU 6-Lead Plastic TSOT-23 -40C to 85C LT1790BCS6-2.048#PBF LT1790BCS6-2.048#TRPBF LTXU 6-Lead Plastic TSOT-23 0C to 70C LT1790BIS6-2.048#PBF LT1790BIS6-2.048#TRPBF LTXU 6-Lead Plastic TSOT-23 -40C to 85C LT1790ACS6-2.5#PBF LT1790ACS6-2.5#TRPBF LTPZ 6-Lead Plastic TSOT-23 0C to 70C LT1790AIS6-2.5#PBF LT1790AIS6-2.5#TRPBF LTPZ 6-Lead Plastic TSOT-23 -40C to 85C LT1790BCS6-2.5#PBF LT1790BCS6-2.5#TRPBF LTPZ 6-Lead Plastic TSOT-23 0C to 70C LT1790BIS6-2.5#PBF LT1790BIS6-2.5#TRPBF LTPZ 6-Lead Plastic TSOT-23 -40C to 85C LT1790ACS6-3#PBF LT1790ACS6-3#TRPBF LTQA 6-Lead Plastic TSOT-23 0C to 70C LT1790AIS6-3#PBF LT1790AIS6-3#TRPBF LTQA 6-Lead Plastic TSOT-23 -40C to 85C LT1790BCS6-3#PBF LT1790BCS6-3#TRPBF LTQA 6-Lead Plastic TSOT-23 0C to 70C LT1790BIS6-3#PBF LT1790BIS6-3#TRPBF LTQA 6-Lead Plastic TSOT-23 -40C to 85C LT1790ACS6-3.3#PBF LT1790ACS6-3.3#TRPBF LTXW 6-Lead Plastic TSOT-23 0C to 70C LT1790AIS6-3.3#PBF LT1790AIS6-3.3#TRPBF LTXW 6-Lead Plastic TSOT-23 -40C to 85C LT1790BCS6-3.3#PBF LT1790BCS6-3.3#TRPBF LTXW 6-Lead Plastic TSOT-23 0C to 70C LT1790BIS6-3.3#PBF LT1790BIS6-3.3#TRPBF LTXW 6-Lead Plastic TSOT-23 -40C to 85C LT1790ACS6-4.096#PBF LT1790ACS6-4.096#TRPBF LTQB 6-Lead Plastic TSOT-23 0C to 70C LT1790AIS6-4.096#PBF LT1790AIS6-4.096#TRPBF LTQB 6-Lead Plastic TSOT-23 -40C to 85C LT1790BCS6-4.096#PBF LT1790BCS6-4.096#TRPBF LTQB 6-Lead Plastic TSOT-23 0C to 70C LT1790BIS6-4.096#PBF LT1790BIS6-4.096#TRPBF LTQB 6-Lead Plastic TSOT-23 -40C to 85C LT1790ACS6-5#PBF LT1790ACS6-5#TRPBF LTQC 6-Lead Plastic TSOT-23 0C to 70C LT1790AIS6-5#PBF LT1790AIS6-5#TRPBF LTQC 6-Lead Plastic TSOT-23 -40C to 85C LT1790BCS6-5#PBF LT1790BCS6-5#TRPBF LTQC 6-Lead Plastic TSOT-23 0C to 70C LT1790BIS6-5#PBF LT1790BIS6-5#TRPBF LTQC 6-Lead Plastic TSOT-23 -40C to 85C 1790fb 2 LT1790 ORDER INFORMATION LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE LT1790ACS6-1.25 LT1790ACS6-1.25#TR LTXT 6-Lead Plastic TSOT-23 0C to 70C LT1790AIS6-1.25 LT1790AIS6-1.25#TR LTXT 6-Lead Plastic TSOT-23 -40C to 85C LT1790BCS6-1.25 LT1790BCS6-1.25#TR LTXT 6-Lead Plastic TSOT-23 0C to 70C LT1790BIS6-1.25 LT1790BIS6-1.25#TR LTXT 6-Lead Plastic TSOT-23 -40C to 85C LT1790ACS6-2.048 LT1790ACS6-2.048#TR LTXU 6-Lead Plastic TSOT-23 0C to 70C LT1790AIS6-2.048 LT1790AIS6-2.048#TR LTXU 6-Lead Plastic TSOT-23 -40C to 85C LT1790BCS6-2.048 LT1790BCS6-2.048#TR LTXU 6-Lead Plastic TSOT-23 0C to 70C LT1790BIS6-2.048 LT1790BIS6-2.048#TR LTXU 6-Lead Plastic TSOT-23 -40C to 85C LT1790ACS6-2.5 LT1790ACS6-2.5#TR LTPZ 6-Lead Plastic TSOT-23 0C to 70C LT1790AIS6-2.5 LT1790AIS6-2.5#TR LTPZ 6-Lead Plastic TSOT-23 -40C to 85C LT1790BCS6-2.5 LT1790BCS6-2.5#TR LTPZ 6-Lead Plastic TSOT-23 0C to 70C LT1790BIS6-2.5 LT1790BIS6-2.5#TR LTPZ 6-Lead Plastic TSOT-23 -40C to 85C LT1790ACS6-3 LT1790ACS6-3#TR LTQA 6-Lead Plastic TSOT-23 0C to 70C LT1790AIS6-3 LT1790AIS6-3#TR LTQA 6-Lead Plastic TSOT-23 -40C to 85C LT1790BCS6-3 LT1790BCS6-3#TR LTQA 6-Lead Plastic TSOT-23 0C to 70C LT1790BIS6-3 LT1790BIS6-3#TR LTQA 6-Lead Plastic TSOT-23 -40C to 85C LT1790ACS6-3.3 LT1790ACS6-3.3#TR LTXW 6-Lead Plastic TSOT-23 0C to 70C LT1790AIS6-3.3 LT1790AIS6-3.3#TR LTXW 6-Lead Plastic TSOT-23 -40C to 85C LT1790BCS6-3.3 LT1790BCS6-3.3#TR LTXW 6-Lead Plastic TSOT-23 0C to 70C LT1790BIS6-3.3 LT1790BIS6-3.3#TR LTXW 6-Lead Plastic TSOT-23 -40C to 85C LT1790ACS6-4.096 LT1790ACS6-4.096#TR LTQB 6-Lead Plastic TSOT-23 0C to 70C LT1790AIS6-4.096 LT1790AIS6-4.096#TR LTQB 6-Lead Plastic TSOT-23 -40C to 85C LT1790BCS6-4.096 LT1790BCS6-4.096#TR LTQB 6-Lead Plastic TSOT-23 0C to 70C LT1790BIS6-4.096 LT1790BIS6-4.096#TR LTQB 6-Lead Plastic TSOT-23 -40C to 85C LT1790ACS6-5 LT1790ACS6-5#TR LTQC 6-Lead Plastic TSOT-23 0C to 70C LT1790AIS6-5 LT1790AIS6-5#TR LTQC 6-Lead Plastic TSOT-23 -40C to 85C LT1790BCS6-5 LT1790BCS6-5#TR LTQC 6-Lead Plastic TSOT-23 0C to 70C LT1790BIS6-5 LT1790BIS6-5#TR LTQC 6-Lead Plastic TSOT-23 -40C to 85C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 1790fb 3 LT1790 AVAILABLE OPTIONS TEMPERATURE RANGE OUTPUT VOLTAGE INITIAL ACCURACY TEMPERATURE COEFFICIENT 0C TO 70C -40C TO 85C ORDER PART NUMBER ORDER PART NUMBER 1.250V 0.05% 0.1% 10ppm/C 25ppm/C LT1790ACS6-1.25 LT1790BCS6-1.25 LT1790AIS6-1.25 LT1790BIS6-1.25 2.048V 0.05% 0.1% 10ppm/C 25ppm/C LT1790ACS6-2.048 LT1790BCS6-2.048 LT1790AIS6-2.048 LT1790BIS6-2.048 2.500V 0.05% 0.1% 10ppm/C 25ppm/C LT1790ACS6-2.5 LT1790BCS6-2.5 LT1790AIS6-2.5 LT1790BIS6-2.5 3.000V 0.05% 0.1% 10ppm/C 25ppm/C LT1790ACS6-3 LT1790BCS6-3 LT1790AIS6-3 LT1790BIS6-3 3.300V 0.05% 0.1% 10ppm/C 25ppm/C LT1790ACS6-3.3 LT1790BCS6-3.3 LT1790AIS6-3.3 LT1790BIS6-3.3 4.096V 0.05% 0.1% 10ppm/C 25ppm/C LT1790ACS6-4.096 LT1790BCS6-4.096 LT1790AIS6-4.096 LT1790BIS6-4.096 5.000V 0.05% 0.1% 10ppm/C 25ppm/C LT1790ACS6-5 LT1790BCS6-5 LT1790AIS6-5 LT1790BIS6-5 1.25V ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25C. CL = 1F and VIN = 2.6V, unless otherwise noted. PARAMETER CONDITIONS Output Voltage (Notes 3, 4) Output Voltage Temperature Coefficient (Note 5) MIN TYP MAX LT1790A 1.24937 -0.05 1.25 1.25062 0.05 V % LT1790B 1.24875 -0.1 1.25 1.25125 0.1 V % LT1790AC l l 1.24850 -0.12 1.25 1.2515 0.12 V % LT1790AI l l 1.24781 -0.175 1.25 1.25219 0.175 V % LT1790BC l l 1.24656 -0.275 1.25 1.25344 0.275 V % LT1790BI l l 1.24484 -0.4125 1.25 1.25516 0.4125 V % 5 12 10 25 ppm/C ppm/C 50 170 220 ppm/V ppm/V 100 160 250 ppm/mA ppm/mA 120 180 250 ppm/mA ppm/mA 1.95 2.15 2.50 2.90 2.95 V V V V TMIN TA TMAX LT1790A LT1790B Line Regulation 2.6V VIN 18V Load Regulation (Note 6) IOUT Source = 5mA, VIN = 2.8V IOUT Sink = 1mA, VIN = 3.2V Minimum Operating Voltage (Note 7) UNITS VIN, VOUT = 0.1% IOUT = 0mA IOUT Source = 5mA IOUT Sink = 1mA l l l l l l l l 1790fb 4 LT1790 1.25V ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25C. CL = 1F and VIN = 2.6V, unless otherwise noted. PARAMETER CONDITIONS Supply Current No Load Minimum Operating Current-- Negative Output (See Figure 7) MIN TYP MAX 35 60 75 A A VOUT = - 1.25V, 0.1% 100 125 A Turn-On Time CLOAD = 1F 250 s Output Noise (Note 8) 0.1Hz f 10Hz 10Hz f 1kHz 10 14 VP-P VRMS 50 ppm/kHr 25 40 ppm ppm l Long-Term Drift of Output Voltage (Note 9) Hysteresis (Note 10) T = 0C to 70C T = -40C to 85C l l UNITS 2.048V ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25C. CL = 1F and VIN = 2.8V, unless otherwise noted. PARAMETER CONDITIONS Output Voltage (Notes 3, 4) Output Voltage Temperature Coefficient (Note 5) MIN TYP MAX LT1790A 2.04697 -0.05 2.048 2.04902 0.05 V % LT1790B 2.04595 -0.1 2.048 2.05005 0.1 V % LT1790AC l l 2.04554 -0.12 2.048 2.05046 0.12 V % LT1790AI l l 2.04442 -0.175 2.048 2.05158 0.175 V % LT1790BC l l 2.04237 -0.275 2.048 2.05363 0.275 V % LT1790BI l l 2.03955 -0.4125 2.048 2.05645 0.4125 V % 5 12 10 25 ppm/C ppm/C 50 170 220 ppm/V ppm/V 120 200 280 ppm/mA ppm/mA 130 260 450 ppm/mA ppm/mA 50 100 500 750 450 mV mV mV mV 35 60 75 A A 125 A TMIN TA TMAX LT1790A LT1790B Line Regulation 2.8V VIN 18V Load Regulation (Note 6) IOUT Source = 5mA IOUT Sink = 3mA Dropout Voltage (Note 7) UNITS VIN - VOUT, VOUT = 0.1% IOUT = 0mA IOUT Source = 5mA IOUT Sink = 3mA l l l l l l l l Supply Current No Load Minimum Operating Current-- Negative Output (See Figure 7) VOUT = - 2.048V, 0.1% 100 Turn-On Time CLOAD = 1F 350 l s 1790fb 5 LT1790 2.048V ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25C. CL = 1F and VIN = 2.8V, unless otherwise noted. PARAMETER CONDITIONS Output Noise (Note 8) 0.1Hz f 10Hz 10Hz f 1kHz MIN Long-Term Drift of Output Voltage (Note 9) Hysteresis (Note 10) T = 0C to 70C T = -40C to 85C l l TYP MAX UNITS 22 41 VP-P VRMS 50 ppm/kHr 25 40 ppm ppm 2.5V ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25C. CL = 1F and VIN = 3V, unless otherwise noted. PARAMETER CONDITIONS Output Voltage (Notes 3, 4) Output Voltage Temperature Coefficient (Note 5) MIN TYP MAX LT1790A 2.49875 -0.05 2.5 2.50125 0.05 V % LT1790B 2.4975 -0.1 2.5 2.5025 0.1 V % LT1790AC l l 2.4970 -0.12 2.5 2.5030 0.12 V % LT1790AI l l 2.49563 -0.175 2.5 2.50438 0.175 V % LT1790BC l l 2.49313 -0.275 2.5 2.50688 0.275 V % LT1790BI l l 2.48969 -0.4125 2.5 2.51031 0.4125 V % 5 12 10 25 ppm/C ppm/C 50 170 220 ppm/V ppm/V 80 160 250 ppm/mA ppm/mA 70 110 300 ppm/mA ppm/mA 50 100 120 450 250 mV mV mV mV 35 60 80 A A 125 A TMIN TA TMAX LT1790A LT1790B Line Regulation 3V VIN 18V Load Regulation (Note 6) IOUT Source = 5mA IOUT Sink = 3mA Dropout Voltage (Note 7) UNITS VIN - VOUT, VOUT = 0.1% IOUT = 0mA IOUT Source = 5mA IOUT Sink = 3mA l l l l l l l l Supply Current No Load Minimum Operating Current-- Negative Output (See Figure 7) VOUT = - 2.5V, 0.1% 100 Turn-On Time CLOAD = 1F 700 s Output Noise (Note 8) 0.1Hz f 10Hz 10Hz f 1kHz 32 48 VP-P VRMS 50 ppm/kHr 25 40 ppm ppm l Long-Term Drift of Output Voltage (Note 9) Hysteresis (Note 10) T = 0C to 70C T = -40C to 85C l l 1790fb 6 LT1790 3V ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25C. CL = 1F and VIN = 3.5V, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX Output Voltage (Notes 3, 4) LT1790A 2.9985 -0.05 3 3.0015 0.05 V % LT1790B 2.9970 -0.10 3 3.0030 0.10 V % Output Voltage Temperature Coefficient (Note 5) LT1790AC l l 2.99640 -0.12 3 3.00360 0.12 V % LT1790AI l l 2.99475 -0.175 3 3.00525 0.175 V % LT1790BC l l 2.99175 -0.275 3 3.00825 0.275 V % LT1790BI l l 2.98763 -0.4125 3 3.01238 0.4125 V % 5 12 10 25 ppm/C ppm/C 50 170 220 ppm/V ppm/V 80 160 250 ppm/mA ppm/mA 70 110 300 ppm/mA ppm/mA 50 100 120 450 250 mV mV mV mV 35 60 80 A A 125 A TMIN TA TMAX LT1790A LT1790B Line Regulation 3.5V VIN 18V Load Regulation (Note 6) IOUT Source = 5mA IOUT Sink = 3mA Dropout Voltage (Note 7) UNITS VIN - VOUT, VOUT = 0.1% IOUT = 0mA IOUT Source = 5mA IOUT Sink = 3mA l l l l l l l l Supply Current No Load Minimum Operating Current-- Negative Output (See Figure 7) VOUT = - 3V, 0.1% 100 Turn-On Time CLOAD = 1F 700 s Output Noise (Note 8) 0.1Hz f 10Hz 10Hz f 1kHz 50 56 VP-P VRMS 50 ppm/kHr 25 40 ppm ppm l Long-Term Drift of Output Voltage (Note 9) Hysteresis (Note 10) T = 0C to 70C T = -40C to 85C l l 1790fb 7 LT1790 3.3V ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25C. CL = 1F and VIN = 3.8V, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX Output Voltage (Notes 3, 4) LT1790A 3.29835 -0.05 3.3 3.30165 0.05 V % LT1790B 3.2967 -0.10 3.3 3.3033 0.10 V % Output Voltage Temperature Coefficient (Note 5) LT1790AC l l 3.29604 -0.120 3.3 3.30396 0.120 V % LT1790AI l l 3.29423 -0.175 3.3 3.30578 0.175 V % LT1790BC l l 3.29093 -0.275 3.3 3.30908 0.275 V % LT1790BI l l 3.28639 -0.4125 3.3 3.31361 0.4125 V % 5 12 10 25 ppm/C ppm/C 50 170 220 ppm/V ppm/V 80 160 250 ppm/mA ppm/mA 70 110 300 ppm/mA ppm/mA 50 100 120 450 250 mV mV mV mV 35 60 80 A A 125 A TMIN TA TMAX LT1790A LT1790B Line Regulation 3.8V VIN 18V Load Regulation (Note 6) IOUT Source = 5mA IOUT Sink = 3mA Dropout Voltage (Note 7) UNITS VIN - VOUT, VOUT = 0.1% IOUT = 0mA IOUT Source = 5mA IOUT Sink = 3mA l l l l l l l l Supply Current No Load Minimum Operating Current-- Negative Output (See Figure 7) VOUT = - 3.3V, 0.1% 100 Turn-On Time CLOAD = 1F 700 s Output Noise (Note 8) 0.1Hz f 10Hz 10Hz f 1kHz 50 67 VP-P VRMS 50 ppm/kHr 25 40 ppm ppm l Long-Term Drift of Output Voltage (Note 9) Hysteresis (Note 10) T = 0C to 70C T = -40C to 85C l l 1790fb 8 LT1790 4.096V ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25C. CL = 1F and VIN = 4.6V, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Output Voltage (Notes 3, 4) LT1790A 4.094 -0.05 4.096 4.098 0.05 V % LT1790B 4.092 -0.10 4.096 4.10 0.10 V % Output Voltage Temperature Coefficient (Note 5) LT1790AC l l 4.09108 -0.120 4.096 4.10092 0.120 V % LT1790AI l l 4.08883 -0.175 4.096 4.10317 0.175 V % LT1790BC l l 4.08474 -0.275 4.096 4.10726 0.275 V % LT1790BI l l 4.07910 -0.4125 4.096 4.11290 0.4125 V % 5 12 10 25 ppm/C ppm/C 50 170 220 ppm/V ppm/V 80 160 250 ppm/mA ppm/mA 70 110 300 ppm/mA ppm/mA 50 100 120 450 250 mV mV mV mV 35 60 80 A A 125 A TMIN TA TMAX LT1790A LT1790B Line Regulation 4.6V VIN 18V Load Regulation (Note 6) IOUT Source = 5mA IOUT Sink = 3mA Dropout Voltage (Note 7) VIN - VOUT, VOUT = 0.1% IOUT = 0mA IOUT Source = 5mA IOUT Sink = 3mA l l l l l l l l Supply Current No Load Minimum Operating Current-- Negative Output (See Figure 7) VOUT = - 4.096V, 0.1% 100 Turn-On Time CLOAD = 1F 700 s Output Noise (Note 8) 0.1Hz f 10Hz 10Hz f 1kHz 60 89 VP-P VRMS 50 ppm/kHr 25 40 ppm ppm l Long-Term Drift of Output Voltage (Note 9) Hysteresis (Note 10) T = 0C to 70C T = -40C to 85C l l 1790fb 9 LT1790 5V ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25C. CL = 1F and VIN = 5.5V, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX Output Voltage (Notes 3, 4) LT1790A 4.9975 -0.05 5 5.0025 0.05 V % LT1790B 4.995 -0.10 5 5.005 0.10 V % Output Voltage Temperature Coefficient (Note 5) LT1790AC l l 4.99400 -0.120 5 5.00600 0.120 V % LT1790AI l l 4.99125 -0.175 5 5.00875 0.175 V % LT1790BC l l 4.98625 -0.275 5 5.01375 0.275 V % LT1790BI l l 4.97938 -0.4125 5 5.02063 0.4125 V % 5 12 10 25 ppm/C ppm/C 50 170 220 ppm/V ppm/V 80 160 250 ppm/mA ppm/mA 70 110 300 ppm/mA ppm/mA 50 100 120 450 250 mV mV mV mV 35 60 80 A A 125 A TMIN TA TMAX LT1790A LT1790B Line Regulation 5.5V VIN 18V Load Regulation (Note 6) IOUT Source = 5mA IOUT Sink = 3mA Dropout Voltage (Note 7) UNITS VIN - VOUT, VOUT = 0.1% IOUT = 0mA IOUT Source = 5mA IOUT Sink = 3mA l l l l l l l l Supply Current No Load Minimum Operating Current-- Negative Output (See Figure 7) VOUT = - 5V, 0.1% 100 Turn-On Time CLOAD = 1F 700 s Output Noise (Note 8) 0.1Hz f 10Hz 10Hz f 1kHz 80 118 VP-P VRMS 50 ppm/kHr 25 40 ppm ppm l Long-Term Drift of Output Voltage (Note 9) Hysteresis (Note 10) T = 0C to 70C T = -40C to 85C Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT1790 is guaranteed functional over the operating temperature range of - 40C to 125C. The LT1790-1.25 at 125C is typically less than 2% above the nominal voltage. The other voltage options are typically less than 0.25% above their nominal voltage. Note 3: If the part is stored outside of the specified temperature range, the output voltage may shift due to hysteresis. l l Note 4: ESD (Electrostatic Discharge) sensitive device. Extensive use of ESD protection devices are used internal to the LT1790, however, high electrostatic discharge can damage or degrade the device. Use proper ESD handling precautions. Note 5: Temperature coefficient is measured by dividing the change in output voltage by the specified temperature range. Incremental slope is also measured at 25C. Note 6: Load regulation is measured on a pulse basis from no load to the specified load current. Output changes due to die temperature change must be taken into account separately. Note 7: Excludes load regulation errors. 1790fb 10 LT1790 ELECTRICAL CHARACTERISTICS Note 8: Peak-to-peak noise is measured with a single pole highpass filter at 0.1Hz and a 2-pole lowpass filter at 10Hz. The unit is enclosed in a still air environment to eliminate thermocouple effects on the leads. The test time is 10 seconds. Integrated RMS noise is measured from 10Hz to 1kHz with the HP3561A analyzer. Note 9: Long-term drift typically has a logarithmic characteristic and therefore changes after 1000 hours tend to be smaller than before that time. Long-term drift is affected by differential stress between the IC and the board material created during board assembly. See the Applications Information section. Note 10: Hysteresis in the output voltage is created by package stress that differs depending on whether the IC was previously at a higher or lower temperature. Output voltage is always measured at 25C, but the IC is cycled to 85C or -40C before a successive measurements. Hysteresis is roughly proportional to the square of the temperature change. Hysteresis is not a problem for operational temperature excursions where the instrument might be stored at high or low temperature. See the Applications Information section. 1.25V TYPICAL PERFORMANCE CHARACTERISTICS Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options, the curves can be estimated based on the 2.5V and 5V curves. Minimum Input-Output Voltage Differential (Sourcing) Output Voltage Temperature Drift 1.253 Minimum Input-Output Voltage Differential (Sinking) 1.0 10 FOUR TYPICAL PARTS 0.9 1.251 1.250 1.249 TA = 125C VOLTAGE DIFFERENTIAL (V) OUTPUT CURRENT (mA) OUTPUT VOLTAGE (V) 1.252 TA = -55C 1 TA = 25C 1.248 0.8 100A 0.7 5mA 1mA 0.6 0.5 0.4 0.3 0.2 0.1 1.247 -50 -30 -10 10 30 50 70 TEMPERATURE (C) 90 0.1 110 0 0.5 1 1.5 2 INPUT-OUTPUT VOLTAGE (V) 17901.25 G02 17091.25 G01 Load Regulation (Sourcing) -600 -800 -1000 TA = 25C TA = 125C -1200 -1400 -1600 -1800 -2000 0.1 100 1800 90 1600 80 1400 1200 1000 10 17901.25 G04 TA = -55C 800 600 400 200 1 OUTPUT CURRENT (mA) Supply Current vs Input Voltage 2000 SUPPLY CURRENT (A) TA = -55C -200 -400 17091.25 G03 Load Regulation (Sinking) OUTPUT VOLTAGE CHANGE (ppm) OUTPUT VOLTAGE CHANGE (ppm) 0 0 -50 -30 -10 10 30 50 70 90 110 130 TEMPERATURE (C) 2.5 0 0.1 TA = 125C TA = -55C TA = 25C 70 60 50 TA = 125C 40 30 20 TA = 25C 1 OUTPUT CURRENT (mA) 10 10 17901.25 G05 0 0 5 15 10 INPUT VOLTAGE (V) 20 17901.25 G06 1790fb 11 LT1790 1.25V TYPICAL PERFORMANCE CHARACTERISTICS Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options, the curves can be estimated based on the 2.5V and 5V curves. Power Supply Rejection Ratio vs Frequency Line Regulation 500 TA = 125C -10 100 1.265 1.260 1.255 TA = 25C 1.250 TA = -55C 1.245 1.240 1.235 1.230 1.225 4 2 0 -20 -30 -40 -50 -60 10 CL = 4.7F CL = 1F 1 -80 1k 10k 100k FREQUENCY (Hz) 1M 0 100 1k 10k FREQUENCY (Hz) 100k 17901.25 G09 17901.25 G08 17901.25. G07 Long-Term Drift (Data Points Reduced After 500 Hr) - 1.25V Characteristics 0.30 Output Noise 0.1Hz to 10Hz 140 LT1790S6-1.25V 120 2 TYPICAL PARTS SOLDERED TO PCB TA = 30C 100 R1 10k 3V 4 LT1790-1.25 CURRENT IN RL (mA) 1 0.20 0.15 6 2 80 VOUT RL 5k 1F 60 ppm 0.25 CL = 0.47F -70 -90 100 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) VIN = 3V OUTPUT NOISE (5V/DIV) OUTPUT VOLTAGE (V) 1.275 1.270 VIN = 3V 0 CL = 1F OUTPUT IMPEDANCE () POWER SUPPLY REJECTION RATIO (dB) 1.280 Output Impedance vs Frequency 10 1.285 -VEE 40 20 0.10 0 TA = 25C TA = 125C TA = -55C 0.05 -20 -40 0 -2.5 -2.0 -1.5 -1.0 -0.5 OUTPUT TO GROUND VOLTAGE (V) -60 0 200 0 600 400 HOURS 800 17091.25 G10 INTEGRATED NOISE (VRMS) NOISE VOLTAGE (V/Hz) 3.5 3.0 2.5 IO = 100A IO = 0A IO = 250A 1.5 1.0 0.5 IO = 1mA 0 10 2 3 4 5 6 TIME (SEC) 7 8 9 10 17901.25 G12 Integrated Noise 10Hz to 1kHz 4.0 2.0 1 100 CL = 1F 4.5 0 17901.25 G11 Output Voltage Noise Spectrum 5.0 1000 100 1k FREQUENCY (Hz) 10 1 10k 17901.25 G13 10 100 FREQUENCY (Hz) 1000 17901.25 G14 1790fb 12 LT1790 2.048V TYPICAL PERFORMANCE CHARACTERISTICS Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options, the curves can be estimated based on the 2.5V and 5V curves. Minimum Input-Output Voltage Minimum Input-Output Voltage Output Voltage Temperature Drift Differential (Sourcing) Differential (Sinking) 2.056 10 130 TA = 25C OUTPUT CURRENT (mA) OUTPUT VOLTAGE (V) 2.054 2.052 2.050 2.048 2.046 TA = 125C 110 VOLTAGE DIFFERENTIAL (mV) FOUR TYPICAL PARTS TA = -55C 1 2.044 0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 INPUT-OUTPUT VOLTAGE (V) 17902.048 G01 5mA 50 1mA 30 10 100A -10 Load Regulation (Sinking) -600 TA = 125C -800 -1000 -1200 -1400 -1600 80 1800 1 OUTPUT CURRENT (mA) 1400 1200 TA = -40C 1000 800 600 TA = 125C 400 1 OUTPUT CURRENT (mA) 20 2.050 TA = 25C TA = -55C 2.046 2.044 2.042 0 2 4 30 TA = 125C 20 10 0 10 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) 17902.048 G07 0 10 5 10 20 15 INPUT VOLTAGE (V) 17902.048 G06 Output Impedance vs Frequency 1000 CL = 1F 0 OUTPUT IMPEDANCE () POWER SUPPLY REJECTION RATIO (dB) 2.054 TA = 125C TA = 25C 40 Power Supply Rejection Ratio vs Frequency Line Regulation 2.048 50 17902.048 G05 17902.048 G04 2.052 60 TA = 25C 0 0.1 10 TA = -55C 70 1600 200 -1800 -2000 0.1 Supply Current vs Input Voltage SUPPLY CURRENT (A) OUTPUT VOLTAGE CHANGE (ppm) TA = 25C -400 17902.048 G03 2000 TA = -55C -200 -50 -50 -30 -10 10 30 50 70 90 110 130 TEMPERATURE (C) 0.7 17902.048 G02 Load Regulation (Sourcing) 0 OUTPUT VOLTAGE CHANGE (ppm) 70 -30 2.042 -50 -30 -10 10 30 50 70 90 110 130 TEMPERATURE (C) OUTPUT VOLTAGE (V) 90 -10 -20 -30 -40 -50 CL = 0.47F 100 10 CL = 4.7F CL = 1F -60 -70 -80 100 1k 10k 100k FREQUENCY (Hz) 1M 17902.048 G08 1 10k 100k 1M FREQUENCY (Hz) 10M 17902.048 G09 1790fb 13 LT1790 2.048V TYPICAL PERFORMANCE CHARACTERISTICS Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options, the curves can be estimated based on the 2.5V and 5V curves. - 2.048V Characteristics Long-Term Drift 0.30 100 TA = 30C 80 2 TYPICAL PARTS SOLDERED TO PCB R1 10k 3V 4 0.25 LT1790-2.048 CURRENT IN RL (mA) 1 0.20 40 VOUT RL 5k 1F 20 ppm 0.15 60 6 2 -VEE 0 -20 0.10 TA = 125C TA = 25C TA = -55C 0.05 -40 -60 -80 -100 0 -4 -3.5 -3 -2.5 -2 -1.5 -1 -0.5 OUTPUT TO GROUND VOLTAGE (V) 0 200 0 600 400 HOURS 17092.048 G10 800 1000 17902.048 G11 Output Voltage Noise Spectrum Output Noise 0.1Hz to 10Hz 10 CL = 1F NOISE VOLTAGE (V/Hz) OUTPUT NOISE (10V/DIV) 9 8 7 6 5 IO = 100A 4 IO = 0A 3 IO = 250A 2 1 IO = 1mA 0 0 1 2 3 4 5 6 TIME (SEC) 7 8 9 10 10 100 1k FREQUENCY (Hz) 10k 17902.048 G13 17902.048 G12 Integrated Noise 10Hz to 1kHz INTEGRATED NOISE (VRMS) 100 10 1 10 100 FREQUENCY (Hz) 1000 17902.048 G14 1790fb 14 LT1790 2.5 TYPICAL PERFORMANCE CHARACTERISTICS Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options, the curves can be estimated based on the 2.5V and 5V curves. Minimum Input-Output Voltage Differential (Sourcing) Output Voltage Temperature Drift 2.508 Minimum Input-Output Voltage Differential (Sinking) 90 10 FOUR TYPICAL PARTS 2.504 2.502 2.500 2.498 TA = -55C VOLTAGE DIFFERENTIAL (mV) OUTPUT CURRENT (mA) OUTPUT VOLTAGE (V) 2.506 TA = 125C TA = 25C 1 2.496 2.494 -50 -30 -10 10 30 50 70 90 110 130 TEMPERATURE (C) 0.3 0.4 0.5 0.1 0.2 INPUT-OUTPUT VOLTAGE (V) Load Regulation (Sourcing) TA = 125C -800 -1000 -1200 -1400 -1600 Supply Current vs Input Voltage 70 1400 1200 1000 800 TA = -55C 600 400 20 TA = 125C 20 10 1 OUTPUT CURRENT (mA) 0 10 2.505 TA = 25C 2.500 TA = -55C 2.490 2.489 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) 17902.5 G07 0 10 5 10 20 15 INPUT VOLTAGE (V) 17902.5 G06 Output Impedance vs Frequency 1000 CL = 1F CL = 0.47F 0 OUTPUT IMPEDANCE () POWER SUPPLY REJECTION RATIO (dB) 2.510 4 30 Power Supply Rejection Ratio vs Frequency 2.515 2 TA = 25C 40 17902.5 G05 Line Regulation 0 50 TA = 25C 17902.5 G04 2.495 60 TA = 125C 0 0.1 10 TA = 125C TA = -55C 1600 200 1 OUTPUT CURRENT (mA) -10 80 1800 -1800 -2000 0.1 1mA 5mA 17902.5 G03 SUPPLY CURRENT (A) OUTPUT VOLTAGE CHANGE (ppm) OUTPUT VOLTAGE CHANGE (ppm) TA = -55C -600 OUTPUT VOLTAGE (V) 0.6 2000 TA = 25C 100A 10 Load Regulation (Sinking) 0 -400 30 17902.5 G02 17902.5 G01 -200 50 -30 -50 -30 -10 10 30 50 70 90 110 130 TEMPERATURE (C) 0.1 0 70 -10 -20 -30 -40 -50 CL = 1F 100 CL = 4.7F 10 -60 -70 -80 100 1k 10k 100k FREQUENCY (Hz) 1M 17902.5 G08 1 100 1k 10k FREQUENCY (Hz) 100k 17902.5 G09 1790fb 15 LT1790 2.5V TYPICAL PERFORMANCE CHARACTERISTICS Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options, the curves can be estimated based on the 2.5V and 5V curves. Long-Term Drift - 2.5V Characteristics (Data Points Reduced After 500 Hr) 140 0.30 0.25 3V LT1790-2.5 100 6 1, 2 0.20 0.15 80 VOUT RL 5k 1F 60 ppm CURRENT IN RL (mA) TA = 30C 120 2 TYPICAL PARTS SOLDERED TO PCB R1 10k 4 -VEE 40 20 0.10 0 TA = 25C TA = 125C TA = -55C 0.05 -20 -40 0 -4.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 OUTPUT TO GROUND VOLTAGE (V) -60 0 200 0 600 400 HOURS 800 1000 17902.5 G11 17902.5 G10 Output Noise 0.1Hz to 10Hz Output Voltage Noise Spectrum NOISE VOLTAGE (V/Hz) OUTPUT NOISE (10V/DIV) 10 CL = 1F 8 IO = 0A 6 IO = 250A 4 IO = 1mA 2 0 1 2 3 4 5 6 TIME (SEC) 7 8 9 0 10 10 100 1k FREQUENCY (Hz) 10k 17902.5 G13 17902.5 G12 Integrated Noise 10Hz to 1kHz INTEGRATED NOISE (VRMS) 100 10 1 10 100 FREQUENCY (Hz) 1000 17902.5 G14 1790fb 16 LT1790 5V TYPICAL PERFORMANCE CHARACTERISTICS Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options, the curves can be estimated based on the 2.5V and 5V curves. Minimum Input-Output Voltage Differential (Sourcing) Output Voltage Temperature Drift 5.025 Minimum Input-Output Voltage Differential (Sinking) 90 10 FOUR TYPICAL PARTS 5.020 OUTPUT VOLTAGE (V) 5.015 5.010 5.005 5.000 4.995 VOLTAGE DIFFERENTIAL (mV) OUTPUT CURRENT (mA) 70 TA = -55C TA = 125C TA = 25C 1 50 100A 30 -10 0 0.1 0.2 0.3 0.4 0.5 INPUT-OUTPUT VOLTAGE (V) Load Regulation (Sourcing) Load Regulation (Sinking) TA = 25C -600 TA = 125C -800 -1000 -1200 -1400 -1600 1800 70 1400 1200 1000 TA = -40C 800 600 400 0 0.1 10 20 5.02 TA = 25C TA = -55C 4.96 4.94 4.92 2 4 20 10 1 OUTPUT CURRENT (mA) 0 10 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) 17905 G07 0 10 5 10 20 15 INPUT VOLTAGE (V) 17905 G06 Output Impedance vs Frequency 1000 CL = 1F 0 OUTPUT IMPEDANCE () POWER SUPPLY REJECTION RATIO (dB) TA = 125C TA = 125C 30 Power Supply Rejection Ratio vs Frequency 5.04 0 40 17905 G05 Line Regulation 4.98 TA = 25C 50 TA = 25C 17905 G04 5.00 60 TA = 125C 200 1 OUTPUT CURRENT (mA) TA = -55C 1600 -1800 -2000 0.1 Supply Current vs Input Voltage 80 SUPPLY CURRENT (A) OUTPUT VOLTAGE CHANGE (ppm) -400 17905 G03 2000 TA = -55C -200 0.6 17905 G02 17905 G01 0 -50 -50 -30 -10 10 30 50 70 90 110 130 TEMPERATURE (C) 0.1 4.985 -50 -30 -10 10 30 50 70 90 110 130 TEMPERATURE (C) OUTPUT VOLTAGE CHANGE (ppm) 5mA -30 4.990 OUTPUT VOLTAGE (V) 1mA 10 -10 -20 -30 -40 -50 CL = 0.47F 100 CL = 1F CL = 4.7F 10 -60 -70 -80 100 1k 10k 100k FREQUENCY (Hz) 1M 17905 G08 1 100 1k 10k FREQUENCY (Hz) 100k 17905 G09 1790fb 17 LT1790 5V TYPICAL PERFORMANCE CHARACTERISTICS Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options, the curves can be estimated based on the 2.5V and 5V curves. Long-Term Drift - 5V Characteristics 0.30 100 TA = 30C 80 2 TYPICAL PARTS SOLDERED TO PCB R1 10k 5.5V 4 0.25 LT1790-5 CURRENT IN RL (mA) 1 0.20 40 VOUT RL 5k 1F 20 ppm 0.15 60 6 2 -VEE 0 -20 0.10 -40 TA = 125C TA = 25C 0.05 TA = -55C 0 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 OUTPUT TO GROUND VOLTAGE (V) -60 -80 0 -100 200 0 600 400 HOURS 800 17905 G10 1000 17905 G11 Output Noise 0.1Hz to 10Hz Output Voltage Noise Spectrum NOISE VOLTAGE (V/Hz) OUTPUT NOISE (20V/DIV) 10 CL = 1F 8 IO = 0A 6 IO = 250A 4 IO = 1mA 2 0 1 2 3 4 5 6 TIME (SEC) 7 8 9 0 10 100 1k FREQUENCY (Hz) 10 10k 17905 G13 17905 G12 Integrated Noise 10Hz to 1kHz INTEGRATED NOISE (VRMS) 1000 100 10 1 10 100 FREQUENCY (Hz) 1000 17905 G14 1790fb 18 LT1790 APPLICATIONS INFORMATION Bypass and Load Capacitors The LT1790 voltage references should have an input bypass capacitor of 0.1F or larger, however the bypassing of other local devices may serve as the required component. These references also require an output capacitor for stability. The optimum output capacitance for most applications is 1F, although larger values work as well. This capacitor affects the turn-on and settling time for the output to reach its final value. All LT1790 voltages perform virtually the same, so the LT1790-2.5 is used as an example. Figure 1 shows the turn-on time for the LT1790-2.5 with a 1F input bypass and 1F load capacitor. Figure 2 shows the output response to a 0.5V transient on VIN with the same capacitors. The test circuit of Figure 3 is used to measure the stability of various load currents. With RL = 1k, the 1V step produces a current step of 1mA. Figure 4 shows the response to a 0.5mA load. 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. VIN VOUT 3V VIN VOUT 3V 2V 2V 1V 1V 0V 0V 1790 F01 1790 F02 Figure 2. Output Response to 0.5V Ripple on VIN Figure 1. Turn-On Characteristics of LT1790-2.5 4 VIN 3V CIN 0.1F LT1790-2.5 1k 6 CL 1F 1, 2 VGEN 1V 1790 F03 Figure 3. Response Time Test Circuit VGEN 3V 2V VOUT (AC COUPLED) VOUT (AC COUPLED) VGEN -2V -3V 1790 F04 Figure 4. LT1790-2.5 Sourcing and Sinking 0.5mA 1790 F05 Figure 5. LT1790-2.5 Sourcing 4mA to 5mA 1790fb 19 LT1790 APPLICATIONS INFORMATION Positive or Negative Operation Series operation is ideal for extending battery life. If an LT1790 is operated in series mode it does not require an external current setting resistor. The specifications guarantee that the LT1790 family operates to 18V. When the circuitry being regulated does not demand current, the series connected LT1790 consumes only a few hundred W, yet the same connection can sink or source 5mA of load current when demanded. A typical series connection is shown on the front page of this data sheet. The circuit in Figure 7 shows the connection for a - 2.5V reference, although any LT1790 voltage option can be configured this way to make a negative reference. The LT1790 can be used as very stable negative references, however, they require a positive voltage applied to Pin 4 to bias internal circuitry. This voltage must be current limited with R1 to keep the output PNP transistor from turning on and driving the grounded output. C1 provides stability during load transients. This connection maintains nearly the same accuracy and temperature coefficient of the positive connected LT1790. Long-Term Drift Long-term drift cannot be extrapolated from accelerated high temperature testing. This erroneous technique gives drift numbers that are widely optimistic. The only way long-term drift can be determined is to measure it over the time interval of interest. The LT1790S6 drift data was taken on over 100 parts that were soldered into PC boards similar to a real world application. The boards were then placed into a constant temperature oven with TA = 30C, their outputs scanned regularly and measured with an 8.5 digit DVM. Long-term drift curves are shown in the Typical Performance Characteristics section. VGEN 8V R1 10k 3V 4 6V 6 VOUT (AC COUPLED) 4V LT1790-2.5 C1 0.1F 1, 2 VOUT = -2.5V 2V 0V V - VOUT RL = EE 125A CL 1F VEE 1790 F07 1790 F06 Figure 6. LT1790-2.5 Sinking - 4mA to -5mA Figure 7. Using the LT1790-2.5 to Build a -2.5V Reference 1790fb 20 LT1790 APPLICATIONS INFORMATION Hysteresis Hysteresis data shown in Figures 8 and 9 represent the worst-case data taken on parts from 0C to 70C and from - 40C to 85C. Units were cycled several times over these temperature ranges and the largest change is shown. As expected, the parts cycled over the higher temperature range have higher hysteresis than those cycled over the lower range. In addition to thermal hysteresis, the thermal shock associated with high temperature soldering may cause the output to shift. For traditional PbSn solder temperatures, the output shift of the LT1790 is typically just 150ppm (0.015%). For lead-free solder, IR reflow temperatures are much higher, often 240C to 260C at the peak. As a result, the packaging materials have been optimized to reduce VOUT shift as possible during high temperature reflow. In addition, care should be taken when using lead-free solder to minimize the peak temperature and dwell time as much as is practical. A typical lead-free reflow profile is shown in Figure 10. LT1790 units were heated using a similar profile, with a peak temperature of 250C. These parts were run through the heating process 3 times to show the cumulative effect of these heat cycles. Figure 11 shows 300 380s DEGREES (C) NUMBER OF UNITS 25 20 TS(MAX) = 200C T = 190C 70C TO 25C tP 130s T = 150C 150 tL 130s RAMP TO 150C 0C TO 25C 15 RAMP DOWN TL = 217C 225 30 TP = 260 75 40s 120s 10 0 0 2 5 4 6 MINUTES 8 10 1790 F10 0 -60 -50 -40 -30 -20 -10 0 10 20 DISTRIBUTION (ppm) 30 40 50 Figure 10. Lead-Free Reflow Profile 60 1790 F08 Figure 8. Worst-Case 0C to 70C Hysteresis on 79 Units 9 8 50 7 NUMBER OF UNITS 45 NUMBER OF UNITS 40 35 30 25 80C TO 25C 6 5 4 3 2 20 -40C TO 25C 15 1 10 0 5 0 0 10 20 30 40 50 PPM -100 -80 -60 -40 -20 0 20 40 DISTRIBUTION (ppm) 60 80 100 1790 F09 1790 F11 Figure 11. 1X IR Reflow Peak Temperature = 250C, Delta Output Voltage (ppm) Figure 9. Worst-Case -40C to 85C Hysteresis on 80 Units 1790fb 21 LT1790 APPLICATIONS INFORMATION the shift after 1 cycle, while Figure 12 shows shift after 3 cycles. In the worst case, shifts are typically 150ppm, but may be as high as 290ppm. Shifts in output voltage are proportional to temperature and dwell time. In general, the output shift can be reduced or fully recovered by a long (12-24 hour) bake of the completed PC Board assembly at high temperature (100C to 150C) after soldering to remove mechanical stress that has been induced by thermal shock. Once the PC Boards have cooled to room temperature, they may continue to shift for up to 3 times the bake time. This should be taken into account before any calibration is performed. Assuming 80A max supply current for the LT1790, a 25A load, 120mV max dropout and a 4V to 30V input specification, the largest that R1 can be is (4V - 3.3V - 120mV)/(80A + 25A) = 5.5k. Furthermore, assuming 220mW of dissipation in the 18V SOT-23 Zener, this gives a max current of (220mW)/(18V) = 12.2mA. So the smallest that R1 should be is (30V - 18V)/12.2mA = 1k, rated at 150mW. With R1 = 1k, and assuming a 450mV worst-case dropout, the LT1790 can deliver a minimum current of (4V - 3.3V-450mV)/(1k) = 250A. In Figure 13, R1 and C1 provide filtering of the Zener noise when the Zener is in its noisy V-I knee. 3.5 There are other variations for higher voltage operation that use a pass transistor shown in Figures 14 and 15. These circuits allow the input voltage to be as high as 160V while maintaining low supply current. NUMBER OF UNITS 3.0 2.5 2.0 1.5 1.0 R1 330k VS 6V TO 160V R2 4.7k ON SEMI MMBT5551 0.5 0 BZX84C12 70 90 110 130 150 170 190 210 230 250 270 290 PPM C1 0.1F LT1790 VOUT C2 1F 1790 F12 Figure 12. 3X IR Reflow Peak Temperature = 250C, Delta Output Voltage (ppm) Higher Input Voltage 1790 F14 Figure 14. Extended Supply Range Reference The circuit in Figure 13 shows an easy way to increase the input voltage range of the LT1790. The Zener diode can be anywhere from 6V to 18V. For equal power sharing between R1 and the Zener (at 30V), the 18V option is better. The circuit can tolerate much higher voltages for short periods and is suitable for transient protection. ON SEMI MMBT5551 R1 330k C1 0.1F VS 6.5V TO 160V BAV99 4V TO 30V C2 1F VOUT LT1790-3.3 BZX84C18 C1 0.1F VOUT LT1790 R1 1790 F15 Figure 15. Extended Supply Range Reference 1F 1790 F13 Figure 13. Extended Supply Range Reference 1790fb 22 LT1790 APPLICATIONS INFORMATION More Output Current The circuit in Figure 16 is a compact, high output current, low dropout precision supply. The circuit uses the SOT-23 LT1782 and the ThinSOT LT1790. Resistive divider R1 and R2 set a voltage 22mV below VS. For under 1mA of output current, the LT1790 supplies the load. Above 1mA of load current, the (+) input of the LT1782 is pulled below the 22mV divider reference and the output FET turns on to supply the load current. Capacitor C1 stops oscillations in the transition region. The no load standing current is only 120A, yet the output can deliver over 300mA. Noise An estimate of the total integrated noise from 10Hz to 1kHz can be made by multiplying the flat band spot noise by BW. For example, from the Typical Performance curves, the LT1790-1.25 noise spectrum shows the average spot noise to be about 450nV/Hz. The square root of the VS 2.8V TO 3.3V NO LOAD SUPPLY CURRENT 120A R1 680 5% R3 22 5% bandwidth is 990 = 31.4. The total noise 10Hz to 1kHz noise is (450nV)(31.4) = 14.1V. This agrees well with the measured noise. This estimate may not be as good with higher voltage options, there are several reasons for this. Higher voltage options have higher noise and they have higher variability due to process variations. 10Hz to 1kHz noise may vary by 2dB on the LT1790-5 and 1dB on the LT1790-2.5. Measured noise may also vary because of peaking in the noise spectrum. This effect can be seen in the range of 1kHz to 10kHz with all voltage options sourcing different load currents. From the Typical Performance curves the 10Hz to 1kHz noise spectrum of the LT1790-5 is shown to be 3V/Hz at low frequency. The estimated noise is (3V)(31.4) = 93.4V. The actual integrated 10Hz to 1kHz noise measures 118.3V. The peaking shown causes this larger number. Peaking is a function of output capacitor as well as load current and process variations. R4 1k 5% + LT1782 - R2 100k 5% VISHAY SILICONIX Si3445DV C1 0.1F LT1790-2.5 C2 1F 17909 F16 VOUT = 2.5V ILOAD = 0mA to 300mA NOTE: NOT CURRENT LIMITED Figure 16. Compact, High Output Current, Low Dropout, Precision 2.5V Supply 1790fb 23 LT1790 SIMPLIFIED SCHEMATIC 4 VIN 6 VOUT 1, 2 GND 1790 SS 1790fb 24 LT1790 PACKAGE DESCRIPTION S6 Package 6-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1636) 0.62 MAX 2.90 BSC (NOTE 4) 0.95 REF 1.22 REF 3.85 MAX 2.62 REF 1.4 MIN 2.80 BSC 1.50 - 1.75 (NOTE 4) PIN ONE ID RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.30 - 0.45 6 PLCS (NOTE 3) 0.95 BSC 0.80 - 0.90 0.20 BSC 0.01 - 0.10 1.00 MAX DATUM `A' 0.30 - 0.50 REF 0.09 - 0.20 (NOTE 3) 1.90 BSC NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING 4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 5. MOLD FLASH SHALL NOT EXCEED 0.254mm 6. JEDEC PACKAGE REFERENCE IS MO-193 S6 TSOT-23 0302 REV B 1790fb Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 25 LT1790 TYPICAL APPLICATION - 2.5V Negative 50mA Series Reference No Load Supply Current ICC = 1.6mA IEE = 440A VCC = 5V 2k 4 LT1790-2.5 VZ = 5.1V 6 1, 2 5.1k -2.5V 50mA VEE = -5V MPS2907A 1F 1790 TA03 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1019 Precision Reference Low Noise Bandgap, 0.05%, 5ppm/C LTC(R)1798 Micropower Low Dropout Reference 0.15% Max, 6.5A Supply Current LT1460 Micropower Precision Series Reference Bandgap, 130A Supply Current, 10ppm/C, Available in SOT-23 LT1461 Micropower Precision Low Dropout Reference Bandgap 0.04%, 3ppm/C, 50A Max Supply Current 1790fb 26 Linear Technology Corporation LT 0609 REV B * PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com (c) LINEAR TECHNOLOGY CORPORATION 2000