LINEAR TECHNOLOGY - LT1678/LT1679 handbook
Contents
1. 16789 G29 100 Vs 15V n Ay 5 TA 25 C m 80 Vin R 1k pe v 4 5 60 0 01 OF 0 01 0F z m FULL SCALE FULL SCALE 5 3 5 ES 40 d 2 2 20 0 196 0 1 1 FFULL SCALE FULL SCALE 0 0 10 20 10 8 6 4 2 0 2 4 6 8 10 0 1 1 10 100 OUTPUT STEP V FREQUENCY MHz 16789 G23 16789 G24 Output Voltage Swing vs Gain Phase Shift vs Frequency Load Current 50 V 100 s 0 L nu 01 RE ins are CM 10 80 T 1250 40 10pF 125 N L p gt 0 2 A i Z a 5 08 TA 25 C 830 605 oar T co mod d lt o m Ty 125 C ui 20 2 06 A s 8 05 C S 10 04 Ty 25 C a 03 0 0 DA 0 2 55 C 10 i 20 Vs 0 0 1 1 100 10 8 6 4 2 0 2 4 6 8 10 FREQUENCY MHz OUTPUT CURRENT mA 16789 G26 16789 G27 Total Harmonic Distortion and Total Harmo2. 16 Vs 15V 14 lou OV _ 12 10 s Z 8 6 2 4 p 2 0 2 4 6 50 25 0 25 50 75 100 125 TEMPERATURE C 16789 606 Offset Voltage Shift vs Common Mode 5 500 4 400 3 Vos IS REFERRED TO 300 2 Vom OV 200 9 c 1 100 1 5 0 0 n gt 1 100 amp 2 200 Vs 1 5V TO 151 Ed 4 TA 25 C 400 5 TYPICAL PARTS 5 500 10 V 10 20 0 8 0 4 V 04 Vcu V V Vem V V 16789 G09 Vos vs Temperature of Representive Units 200 Vs 5V OV Vom 0V 100 on bun 5 0 T ii 2 100 TRI 5 N NIS gt 200 N N 00 55 35 15 5 TEMPERATURE C 25 45 65 85 105 125 16789 G12 sn16789 16789fs M L11678 LT1679 TYPICAL PERFORMANCE CHARACTERISTICS Common Mode Range vs Common Mode Rejection Ratio 16789 G19
3. Temperature Supply Current vs Supply Voltage vs Frequency 2 Vg 2 5V 15V SU m 0 o Vs 15V 4 400 5 25 3 300 g 59 e Vom 0V o Lr 2 205 gp z B 1 100 7 2 e s g Ta 125 C 5 0 0 8 amp 25 B gt oc E 108 8 TA 25 C e 2 20 E 2 200 5 3 z o M gt Ta 55 C 5 amp 15 4 400 E 8 500 1 0 10 V 10 20 0 8 0 4 V 04 5 10 15 20 10k 100k 1M 10M Vem Vg V Vem Ve V SUPPLY VOLTAGE V FREQUENCY Hz 16789 G09 16789 014 16789 615 Power Supply Rejection Ratio vs Frequency Voltage Gain vs Supply Voltage Overshoot vs Capacitive Load 160 10 60 2 2 299 10k 440 TA 25 C 10k 50 1 5 100 5 g NEGATIVE SUPPLY m 80 1 9 30 3 5 RISING EDGE 60 E POSITIVE SUPPLY 8 o 20 40 B n mc i FALLING EDGE 5 20 RL TO GND Vom Vo Vs 2 0 0 1 0 0 001 001 01 1 10 100 1000 0 10 20 30 10 100 1000 FREQUENCY kHz SUPPLY VOLTAGE V CAPACITIVE LOAD pF 16789 G16 16789 G17 16789 618 Phase Margin Gain Bandwidth Product and Slew Rate vs Large Signal Small Signal Temperature Transient Response Transient Response 90 o n Vs 15V z 80 C 15pF jg PHASE MARGIN Ay 1 2 50 g7 Rr Rg 1k 2 10 lt 60 30 c 2 50 25 7o ov GAIN BANDWIDTH PRODUCT 2 40 20 5 5 8 152 0 ee AOV 50mV 10 u
4. 5016789 1678915 2 AL WIE LT1678 LT1679 ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range otherwise specifications are at Ta 25 C Vs 3V Vem Vo 1 7V Vg 5V Vem Vo 2 5V unless otherwise noted SYMBOL PARAMETER CONDITIONS Note 6 MIN TYP MAX UNITS los Input Offset Current Note 11 4 25 nA 0 C lt TA lt 70 C 5 35 40 C lt TA lt 85 C 8 55 Vs 5V Vom Vs 0 1V 6 30 nA Vs 5V Vom Vs 0 3V 0 C lt TA lt 70 C e 10 40 nA Vs 5V Vom Vs 0 3V 40 C lt Ty lt 85 C e 15 65 nA Vs 5V Vom 0 1V 0 1 1 6 Vs 5V Vom OV 0 C lt Ta lt 70 C 0 1 2 0 Vs 5V Vom OV 40 lt Ta 85 C 0 15 24 uA en Input Noise Voltage 0 1Hz to 10Hz Note 7 90 nVp p Vom Vs 180 nVp p Vom OV 1600 nVp p Input Noise Voltage Density Note 8 fo 10Hz 4 4 nV VHz Vom Vs fo 10Hz 6 6 nV VHz Vom OV fo 10Hz 19 nV VHz fo 1kHz 3 9 5 5 nV VHz Vom Vs fo 1kHz 5 3 Vom OV fo 1kHz 9 nV VHz in Input Noise Current Density fo 10Hz 1 0 pA VHz fo 1kHz 0 3 pA VHz Input Voltage Range 0 1 Vs 0 1V V e 0 Vs 0 3V V Rin Input Resistance Common Mode 2 GQ Cin Input Capacitance 42 pF CMRR Common Mode Rejection Ratio Vs 5V Vom 1 9V to 3 9V 98 120 dB Vs 5V Vom 1 9V to 3 9V e 92 120 dB
5. FEATURES m Rail to Rail Input and Output 100 Tested Low Voltage Noise 3 9nV VHz Typ at 1kHz 5 5nV vHz Max at 1kHz Single Supply Operation from 2 7V to 36V Offset Voltage 100uV Max Low Input Bias Current 20nA Max High Avot 3V uV Min 10k High CMRR 100dB Min High PSRR 106dB Min Gain Bandwidth Product 20MHz Operating Temperature Range 40 C to 85 C Matching Specifications No Phase Inversion 8 Lead 50 and 14 Lead 50 Packages APPLICATIONS Strain Gauge Amplifiers Portable Microphones Battery Powered Rail to Rail Instrumentation Low Noise Signal Processing Microvolt Accuracy Threshold Detection Infrared Detectors D LT1678 L1 1679 TECHNOLOGY Dual Quad Low Noise Rail to Rail Precision Op Amps DESCRIPTION The LT 1678 LT1679 are dual quad rail to rail op amps offering both low noise and precision 3 9nV VHz wideband noise 1 f corner frequency of 4Hz and 90nV peak to peak 0 1Hz to 10Hz noise are combined with outstanding precision 100uV maximum offset voltage greater than 100dB common mode and power supply rejection and 20MHz gain bandwidth product The LT1678 LT1679 bring precision as well as low noise to single supply applications as low as 3V The input range exceeds the power supply by 100mV with no phase inversion while the output can swing to within 170mV of either rail The LT1678 LT1679 are offered in the 50 8 and 50 14 packages A full set of matching specifications are al
6. 2 lt En e gt co a 25 50 75 100 125 TEMPERATURE C 16789 604 Input Bias Current vs Temperature 1400 Vom 14V i808 CURRENT OUT OF DUT 1000 800 2 ce 600 5 400 z 200 0 50 25 0 25 50 75 100 125 TEMPERATURE C 16789 G07 Current Noise vs Frequency Vg 2151 Ta 25 C g lt amp Vem OV 1 A D Vem 14 5V 2 om 14 0 1 0 01 0 1 1 FREQUENCY kHz Input Bias Current Over the Common Mode Range 10 16789 G05 INPUT BIAS CURRENT nA INPUT BIAS CUR 0 16 12 8 c Vem 15 2 4 0 4 8 12 COMMON MODE INPUT VOLTAGE V Distribution of Input Offset 16789 608 Warm Up Drift vs Time Voltage Drift 50 8 0 gt ro zu Vg 5V OV ys N Ta 40 C TO 85 C 25 111 PARTS 2 LOTS CE 50 PACKAGE EJ a S 6 Ex gt D 15 S 4 lu 9 10 tu a 57 5 0 0 0 1 2 3 4 3 0 2 0 10 0 10 20 30 TIME min INPUT OFFSET VOLTAGE DRIFT uV C 16789 G10 16789 G11 OFFSET VOLTAGE mV Input Bias Current vs Temperature
7. 5V and Vs 151 tests Note 13 Guaranteed by correlation to slew rate at Vs 15V GBW at Vs 3V and Vs 15V tests Note 14 ACMRR and APSRR are defined as follows 1 CMRR and PSRR are measured in uV V on the individual amplifiers 2 The difference is calculated between the matching sides in uV V 3 The result is converted to dB Note 15 Matching parameters are the difference between amplifiers A and B on the LT1678 and between amplifiers A and D and B and C in the LT1679 Note 16 Input range guaranteed by the common mode rejection ratio test TYPICAL PERFORMANCE CHARACTERISTICS Voltage Noise vs Frequency 100 EVs 15V C Ta 25 C Vs 5V OV 0 1Hz to 10Hz Voltage Noise 0 01Hz to 1Hz Voltage Noise Vs 5V OV NOISE VOLTAGE nV VHz 5 VOLTAGE NOISE 50nV DIV VOLTAGE NOISE 50nV DIV 0 1 1 10 100 1000 0 2 FREQUENCY Hz 16789 G01 6 8 10 0 20 40 60 80 100 TIME sec 16789 G02 16789 G03 5 16789 1678915 7 LT1678 LT 1679 TYPICAL PERFORMANCE CHARACTERISTICS Voltage Noise vs Temperature gt gt 10Hz I a a 5 1kHz
8. B emitterfollowers for theoutput stage Theoutput NPN transistor 029 sinks the current necessary to move the outputin the negative direc tion The change in Q29 s base emitter voltage is reflected directly to the gain node collectors of Q20 and Q16 For large sinking currents the delta Var of 029 can dominate the gain Figure 7 shows the change in input voltage for a change in output voltage for different load resistors con nected between the supplies The gain is much higher for output voltages above ground Q28 sources current since the change in base emitter voltage of Q28 is attenuated by the gain in the PNP portion of the output stage Therefore for positive output swings output sourcing current there is hardly any change in input voltage for any load resistance Highest gain and best linearity are achieved when the output is sourcing current which is the case in single supply op eration when the load is ground referenced Figure 8 shows gains for both sinking and sourcing load currents for a worst case load of 6000 VOLTAGE GAIN SINGLE SUPPLY Vs 5V 6002 MEASURED ON TEKTRONIX 577 CURVE TRACER INPUT VOLTAGE 10uV DIV 0 1 2 3 4 5 OUTPUT VOLTAGE V 16789 08 Figure 8 Voltage Gain Single Supply 5 16789 1678915 AL MVR 13 LT1678 LT 1679 SIMPLIFIED SCHEMATIC SS 68 91 SA M0138 A0 lt vri SA M0738 AL 0 lt DA yriog SA M0734 A20 gt DA vigo al SA M0738 AZ0 gt WIA 11
9. C aes 16781 50 Tymax 150 C 0j4 160 C W Consult LTC Marketing for parts specified with wider operating temperature ranges ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range otherwise specifications are at TA 25 C Vs 3V Vem Vo 1 7V Vs 5V Vem Vo 2 5V unless otherwise noted SYMBOL PARAMETER CONDITIONS Note 6 MIN TYP MAX UNITS Vos Input Offset Voltage Note 11 35 100 uV 0 C lt Ta lt 70 C 55 270 uV 40 C lt TA lt 85 C 75 350 uV Vs 5V 0 1V 150 550 uV Vs 5V Vom Vs 0 3V 0 C lt Ta lt 70 C e 180 750 uV Vs 5V Vom Vg 0 3V 40 lt Ty lt 85 C e 200 1000 uV Vs 5V Vom 0 1V 1 5 30 mV Vs 5V Vem OV 0 C lt TA lt 70 C e 1 8 45 mV Vs 5V Vom OV 40 lt lt 85 C 2 0 50 AVos Average Input Offset Drift Note 10 0 40 3 uV C ATemp lp Input Bias Current Note 11 2 20 nA 0 C lt TA lt 70 C 3 35 40 C lt TA lt 85 C e 7 50 Vs 5V Vom Vs 0 1V 0 19 0 40 Vs 5V Vom Vs 0 3V 0 C lt TA lt 70 C 0 19 0 60 uA Vs 5V Vom Vs 0 3V 40 lt Ta lt 85 C e 0 25 0 75 uA Vs 5V Vom 0 1V 5 0 41 Vs 5V Vom 0 C lt Ta lt 70 C e 84 0 45 uA Vs 5V Vom OV 40 lt Ta 85 C e 10 0 47
10. 0 100 SOURCE RESISTANCE kQ 16789 F06 Figure 6 Total Noise vs Source Resistance 5 16789 1678915 12 LI MYR LT1678 LT1679 APPLICATIONS INFORMATION Rail to Rail Input The input common mode range for the LT1678 LT1679 can exceed the supplies by at least 100mV As the common mode voltage approaches the positive rail Vs 0 7V the tail current for the input pair Q1 Q2 is reduced which prevents the input pair from saturating refer to the Simplified Schematic The voltage drop across the load resistors Rc Rea is reduced to less than 200mV degrading the slew rate bandwidth voltage noise offset voltage and input bias current the cancella tion is shut off When the input common mode range goes below 1 5V above the negative rail the NPN input pair Q1 Q2 shuts off and the PNP input pair Q8 Q9 turns on The offset voltage input bias current voltage noise and bandwidth are also degraded The graph of Offset Voltage Shift vs Common Mode shows where the knees occur by display ing the change in offset voltage The change over points aretemperature dependent see the graph Common Mode Range vs Temperature INPUT VOLTAGE 50uV DIV 15 10 0 5 10 15 OUTPUT VOLTAGE V 16789 F07 Figure 7 Voltage Gain Split Supply Rail to Rail Output The rail to rail output swing is achieved by using transis tor collectors 028 Q29 referring to the Simplified Sche matic instead of customary class A
11. 00 21 SA 3A08V A6 1 gt 002 SA 3A08V ASL lt DA 91 yI 5 16789 1678915 AL MYR 14 LT1678 LT 1679 PACKAGE DESCRIPTION 8 Package 8 Lead Plastic Small Outline Narrow 150 Inch Reference LTC DWG 05 08 1610 045 005 4 801 5 004 050 BSC gt y NOTE 3 8 7 6 5 MIN 160 005 des 228 244 m 781 6197 8 810 3 988 NOTE 3 Logo 130 005 gt Y RECOMMENDED SOLDER PAD LAYOUT 010 020 45 lt 053 069 0 254 0 508 4 22 008 010 004 010 em E Yn Er TES t_ t 014 019 21 050 0 355 0 483 1 270 1 DIMENSIONS IN _ Be MILLIMETERS 2 DRAWING NOT TO SCALE 3 THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 006 0 15mm 5 Package 14 Lead Plastic Small Outline Narrow 150 Inch Reference LTC DWG 05 08 1610 337 344 E 045 005 8 560 8 738 050 BSC gt Y NOTE 3 14 12 11 10 9 8 an 160 005 228 244 150 157 4 5 791 6 197 3 810 3 988 NOTE 3 2 030 005 gt lt RECOMMENDED SOLDER PAD LAYO
12. 6 4SR 0 500ns SR Aye 1 5us DIV 1 0 5us DIV D Vs 15V Vs 151 a 2 4 15 55 35 15 5 25 45 65 85 105 125 TOREM hd TEMPERATURE sn16789 1678915 9 LT1678 LT 1679 TYPICAL PERFORMANCE CHARACTERISTICS Vs 215V 5k Ay 1 5k 5 25 C WN J Vour 44 2 gt gt 00950 N 0 01 OF E FULL SCALE FULL SCALE 9 l E 2 a n 0 196 OF 1 FULL SCALE 4 FULL SCALE se 0 10 8 6 4 2 0 2 4 6 8 10 OUTPUT STEP V 16789 G22 Gain Phase Shift vs Frequency 50 100 Vs 15V Vom 14 7V 40 Cj 10pF 180 m RM PHASE 55 amp 30 25 C 1605 4 eo TA 125 C S 20 40 N J Ty 55 C 5 3 10 o 208 9 Ta 125 C GAIN Aj e AH 25 Ww 0 10 s 20 0 1 1 10 100 FREQUENCY MHz 16789 G25 Closed Loop Output Impedance vs Frequency 100 _ Vs 15V 58 e _ 10 1 E Ay 100 a t5 z a 5 0 1 n a 0 01 0 001 10 100 1k 10k 100k 1 FREQUENCY Hz Settling Time vs Output Step Inverting 16789 G28 Settling Time vs Output Step Noninverting Gain Phase Shift vs Frequency
13. PSRR Power Supply Rejection Ratio Vs 2 7V to 36V Vom Vo 1 7V 100 125 dB Vs 3 1V to 36V Vom Vo 1 7V e 98 120 dB AVoL Large Signal Voltage Gain Vs 3V 10k Vo 2 5V to 0 7V 0 6 3 V uV 0 3 2 V uV Vs Ry 2k Vo 22V to 0 7V 0 5 3 V uV 0 C lt TA lt 70 0 4 0 9 V uV 40 6 lt T4 lt 85 C 0 4 0 8 V uV Vs 3V Ry 6002 Vo 2 2V to 0 7V 0 20 0 43 V uV 0 C lt TA lt 70 C e 015 0 40 V uV 40 6 lt Ty lt 85 C e 010 0 35 V uV Vs 5V Ry 10k Vo 4 5V to 0 7V 1 3 8 V uV 0 C lt TA lt 70 C 0 6 2 V uV 40 lt T4 lt 85 C 0 3 2 V uV Vs 5V Ry 2k Vo 4 2V to 0 7V 0 7 3 5 V uV 0 C lt Ta lt 70 C e 0 6 3 2 V uV 40 6 lt Ty lt 85 C e 0 5 3 0 V uV Vs 5V 6000 Vo 4 2V to 0 7V 0 6 3 0 V uV 0 C Ta lt 70 C 0 5 2 8 V uV 40 C lt Ty lt 85 C 0 4 2 5 V uV VoL Output Voltage Swing Low Note 11 Above GND 0 1mA 80 170 mV 0 C lt TA lt 70 C 125 200 40 6 lt TA lt 85 C 130 250 mV 5 16789 1678915 AL MVR 2 LT1678 LT 1679 ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range otherwise specifications are at T 25 C Vs 3V Vem Vg 1 7V Vg 5V Vem Vo 2 5V unless otherwise noted SYMBOL PARAMETER CONDITIONS Note 6 MIN TYP MAX UNITS VoL Output Voltage Sw
14. UT y 1 2 3 4 5 6 7 6294 ES x45 gt lt 053 069 4 1 346 1 752 004 010 008 010 0 203 0 254 0 8 TYP 0 101 0 254 Y E t 014 50 Nu 018 050 e 1 270 NOTE s pag 514 0502 1 DIMENSIONS MILLIMETERS 2 DRAWING NOT TO SCALE 3 THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 006 0 15mm sn16789 16789fs Information furnished by Linear Technology Corporation is believed to be accurate and reliable 1 D TAR However no responsibility is assumed for its use Linear Technology Corporation makes no represen n ECHNOLOGY tationthatthe interconnection of its circuits as described herein will not infringe on existing patent rights LT1678 LT 1679 TYPICAL APPLICATION Bridge Reversal Eliminates 1 f Noise and Offset Drift of a Low Noise Non autozeroed Bipolar Amplifier Circuit Gives 14nV Noise Level or 19 Effective Bits Over a 10mV Span 1k LT1461 5 LTC2440 SILICONIX 2 519801 2 1 92 05 16789 TA02 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1028 LT1128 Ultralow Noise Precision Op Amps Lowest Noise 0 85nV VHz LT1115 Ultralow Noise Low distortion Audio Op Amp 0 002 THD Max Noise 1 2nV VHz LT1124 LT1125 Dual Quad Low Noise High Speed Precision Op Amps Similar
15. ection Match Vs 5V Vom 1 9V to 3 9V 94 110 dB Notes 11 14 15 88 110 dB APSRR Power Supply Rejection Match Vs 2 7V to 36V Vou Vo 1 7V 96 120 dB Notes 11 14 15 Vs 3 1V to 36V Voy Vo 1 7V 94 120 dB 5 16789 1678915 TECHNOLOGY L11678 LT1679 ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range otherwise specifications are at Ta 25 C Vs 15V Vem Vo OV unless otherwise noted SYMBOL PARAMETER CONDITIONS Note 6 MIN TYP MAX UNITS Vos Input Offset Voltage 20 150 uV 0 C lt TA lt 70 C 30 350 uV 40 6 lt TA lt 85 C e 45 420 uV AVos Average Input Offset Drift Note 10 e 0 40 3 uV C ATemp lp Input Bias Current 2 20 0 C lt TA lt 70 C 3 35 nA 40 6 lt TA lt 85 C 7 50 los Input Offset Current 3 25 nA 0 C lt TA lt 70 C 5 35 40 C lt TA lt 85 C 8 55 en Input Noise Voltage 0 1Hz to 10Hz Note 7 90 nVp p Vom 15V 180 nVp p Vom 15V 1600 nVp p Input Noise Voltage Density fo 10Hz 4 4 nV VHz Vom 15V fo 10Hz 6 6 nV VHz Vom 15 fo 10Hz 19 nV VHz fo 1kHz 3 9 5 5 nV VHz Vom 15V fo 1kHz 5 3 nV VHz Vom 15 fo 1kHz 9 nV VHz in Input Noise Current Density fo 10Hz 12 pA VHz fo 1kHz 0 3 pA VHz Vom Input Voltage Range Note 16 e 13 3 14 V RiN Input Resistance Co
16. ing Low Note 11 Above GND Isink 2 5mA 170 250 mV 0 C TA lt 70 C 195 320 mV 40 C lt TA lt 85 C 205 350 mV Above GND Isink 10mA 370 600 mV 0 C lt TA lt 70 C 440 720 mV 40 C lt TA lt 85 C 465 770 mV VoH Output Voltage Swing High Note 11 Below Vs Isource 0 1mA 75 150 mV 0 C lt TA lt 70 C 85 200 mV 40 C lt TA lt 85 C 93 250 mV Below Vs 1 2 5mA 110 250 mV 0 C lt Ta lt 70 C 195 350 mV 40 6 lt TA lt 85 C 205 375 mV Below Vs IsouRcE 10mA 170 400 mV 0 C lt TA lt 70 C 200 500 mV 40 C lt TA lt 85 C 230 550 mV Output Short Circuit Current Note 3 Vs 3V 15 22 mA 13 19 mA Vs 5V 18 29 mA 14 25 mA SR Slew Rate Note 13 Ay 2 1 10k 4 6 V us Ri 10k 0 C lt TA lt 70 C 3 5 5 8 V us 10k 40 C lt Ty lt 85 C 3 5 5 V us GBW Gain Bandwidth Product Note 11 fo 100kHz 13 20 MHz fo 100kHz 12 5 19 MHz ts Settling Time 2V Step 0 1 Ay 1 1 4 us 2V Step 0 01 Ay 1 2 4 uS Ro Open Loop Output Resistance lout 0 100 Q Closed Loop Output Resistance Ay 100 f 10kHz 1 Q Is Supply Current per Amplifier Note 12 2 3 4 mA 2 5 3 8 mA AVos Offset Voltage Match 35 150 wW Notes 11 15 0 C lt Ta lt 70 55 400 uV 40 C lt Ty lt 85 C 75 525 AIB Noninverting Bias Current Match 2 30 nA Notes 11 15 0 C lt TA lt 70 C 3 55 40 C lt T4 lt 85 C 7 75 Common Mode Rej
17. look as shown in the pulsed operation diagram Figure 2 During the fast feedthrough like portion of the output the input protection diodes effectively short the output to the input and a current limited only by the output short circuit protection will be drawn by the signal generator With Rr 5000 the output is capable of handling the current requirements lj 20mA at 10V and the amplifier stays in its active mode and a smooth transition will occur As with all operational amplifiers when Re gt 2k a pole will be created with Rp and the amplifier s input capacitance creating additional phase shift and reducing the phase margin A small capacitor 20pF to 50pF in parallel with Re will eliminate this problem Rr SS 6V us OUTPUT ali LT1678 16789 F02 Figure 2 Pulsed Operation Noise Testing The 0 1Hz to 10Hz peak to peak noise of the LT1678 LT1679 are measured in the test circuit shown Figure 3 The frequency response of this noise tester Figure 4 indicates that the 0 1Hz corner is defined by only one zero The test time to measure 0 1Hz to 10Hz noise should not exceed ten seconds as this time limit acts as an additional Zero to eliminate noise contributions from the frequency band below 0 1Hz Measuring the typical 90nV peak to peak noise perfor mance of the LT1678 LT1679 requires special test pre cautions The device should be warmed up for at least five minutes As the op amp warms up its
18. low Isounce 10mA 200 450 mV 0 C lt TA lt 70 C 250 500 mV 40 C lt TA lt 85 C 250 550 mV Output Short Circuit Current Note 3 20 35 mA 15 28 mA SR Slew Rate Rq 10k Note 9 4 6 V us 10k Note 9 0 C lt Ta lt 70 C 3 5 5 8 V us 10k Note 9 40 C lt lt 85 C 3 5 5 V us GBW Gain Bandwidth Product fo 100kHz 13 20 MHz fo 100kHz 12 5 19 MHz THD Total Harmonic Distortion Ry 2k Ay 1 fp 1kHz Vo 20Vp p 0 00025 ts Settling Time 10V Step 0 1 Ay 1 2 7 us 10V Step 0 01 Ay 1 3 9 us Ro Open Loop Output Resistance lout 0 100 Q Closed Loop Output Resistance Ay 100 f 10kHz 1 Q Is Supply Current per Amplifier 2 5 3 5 mA 3 45 mA Channel Separation f 10Hz Vo 10V 10k 132 dB AVos Offset Voltage Match 5 225 WV Note 15 0 C lt Ta lt 70 C 30 525 uV 40 C lt T4 lt 85 C 45 630 uV AIB Noninverting Bias Current Match 2 30 nA Note 15 0 C lt TA lt 70 C 3 55 nA 40 C lt Ty lt 85 C 7 75 nA ACMRR Common Mode Rejection Match Vom 13 3V to 14V 96 120 dB Notes 14 15 92 115 dB APSRR Power Supply Rejection Match Vs 1 7V to 18V 100 123 dB Notes 14 15 96 120 dB 5 16789 1678915 TECHNOLOGY LT1678 LT 1679 ELECTRICAL CHARACTERISTICS Note 1 Absolute Maximum Ratings are those values beyond which the life of the device may be impaired Note 2 The inputs are protected by back to back diodes Current limiting resistors are not u
19. mmon Mode 2 GQ Cin Input Capacitance 4 2 pF CMRR Common Mode Rejection Ratio Vom 13 3 to 14V 100 130 dB e 96 124 dB PSRR Power Supply Rejection Ratio Vs 1 7V to 18V 106 130 dB e 100 125 dB Avot Large Signal Voltage Gain 10k Vg 14V 3 7 V uV 0 C lt TA lt 70 C 2 6 V uV 40 C lt TA lt 85 C e 1 4 V uV R 2k 13 5V 0 8 1 7 V uV 0 C TA lt 70 C 0 5 14 V uV 40 C lt TA lt 85 C 0 4 11 V uV sn16789 16789fs LT1678 LT 1679 ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range otherwise specifications are at T 25 C Vg 15V Vem Vo OV unless otherwise noted SYMBOL PARAMETER CONDITIONS Note 6 MIN TYP MAX UNITS VoL Output Voltage Swing Low Above Vg Isink 0 1mA 110 200 mV 0 C lt TA lt 70 C 125 230 mV 40 C lt TA lt 85 C 130 260 mV Above Vs Isink 2 5mA 170 280 mV 0 C lt TA lt 70 C 195 350 mV 40 C lt TA lt 85 C 205 380 mV Above Vs 10mA 370 600 mV 0 C lt TA lt 70 C 440 700 mV 40 C lt Ty lt 85 C 450 750 mV Output Voltage Swing High Below Isource 0 1mA 80 150 mV 0 C lt TA lt 70 C 90 200 mV 40 C lt TA lt 85 C 100 250 mV Below Isource 2 5mA 110 200 0 C lt Ta lt 70 C 120 300 mV 40 C lt TA lt 85 C 120 350 mV Be
20. nic Distortion and Noise vs Frequency for Noise vs Frequency for Noninverting Gain Noninverting Gain 0 1 Z OK T5pF 01 Vs 15V EVs 15V Vo 20Vp p Vo 20Vp p Ay 1 10 100 Ay 1 10 100 MEASUREMENT BANDWIDTH MEASUREMENT BANDWIDTH 0 01 f 10Hz TO 80kHz 0 01 k 10Hz TO 80kHz E Ay 100 E Ay 100 e ea e 0 001 2 0 001 L Ay 10 E Ev 10 Ay 1 Ay 1 0 0001 0 0001 20 100 1k 10k 50 20 100 1k 10k 50k FREQUENCY Hz FREQUENCY Hz 16789 G30 5 16789 1678915 LY LT1678 LT 1679 APPLICATIONS INFORMATION Rail to Rail Operation To take full advantage of an input range that can exceed the supply the LT1678 LT1679 are designed to eliminate phase reversal Referring to the photographs shown in Figure 1 the LT1678 LT1679 are operating in the fol lower mode Ay 1 at a single 3V supply The output of the LT1678 LT1679 clips cleanly and recovers with no phase reversal This has the benefit of preventing lock up in servo systems and minimizing distortion components Input 0 5V to 3 5V INPUT VOLTAGE V 16789 F01a 50us DIV LT1678 Output OUTPUT VOLTAGE V 16789 FO1b 50us DIV Figure 1 Voltage Follower with Input Exceeding the Supply Voltage Vs 3V Unity Gain Buffer Application When Re 100Q and the input is driven with a fast large signal pulse gt 1V the output waveform will
21. offset voltage changes typically 3uV due to its chip temperature increasing 10 C to 20 C from the moment the power supplies are turned on In theten second measurement interval these temperature induced effects can easily exceed tens of nanovolts m For similar reasons the device must be well shielded from air currents to eliminate the possibility of thermoelectric effects in excess of a few nanovolts which would invalidate the measurements 5 16789 1678915 Lee 11 LT1678 LT 1679 APPLICATIONS INFORMATION 0 1uF VOLTAGE GAIN 50 000 DEVICE UNDER TEST NOTE ALL CAPACITOR VALUES ARE FOR NONPOLARIZED CAPACITORS ONLY Figure 3 0 1Hz to 10Hz Noise Test Circuit 3 Sudden motion in the vicinity of the device can also feedthrough to increase the observed noise Current noise is measured in the circuit shown in Figure 5 and calculated by the following formula 1 0 101 B 101 16789 05 Figure 5 LT1678 LT1679 achieve their low noise part by operating the input stage at 100uA versus the typical 10uA of most other op amps Voltage noise is inversely propor tional while current noise is directly proportional to the square root of the input stage current Therefore the LT1678 LT1679 s current noise will be relatively high At low frequencies the low 1 f current noise corner fre quency 200Hz minimizes current noise to some extent In most
22. practical applications however current noise will not limit system performance This is illustrated in the Total Noise vs Source Resistance plot Figure 6 where 77 GAIN dB 0 01 0 1 1 10 100 FREQUENCY Hz 16789 F03 16789 F04 Figure 4 0 1Hz to 10Hz Peak to Peak Noise Tester Frequency Response Total Noise amp voltage noise resistor noise current noise Rg Three regions can be identified as a function of source resistance i Rs 4009 Voltage noise dominates ii 4000 Rg 50k at 1kHz Resistor Noise 4000 Rs 8k at 10Hz j Dominates iii Rg gt 50k at 1kHz Current Noise Rs gt 8kat 10Hz Dominates Clearly the LT1678 LT1679 should not be used in region iii where total system noise is at least six times higher than the voltage noise of the op amp i e the low voltage noise specification is completely wasted In this region the LT1113 or LT1169 are better choices 1000 R Vs 15V m Ta 25 C 2 gt 100 SOURCE RESISTANCE 2R E AT 1kHz e h A ul AT 10Hz 2 10 lt RESISTOR OISE ONLY 1 0 1 1 1
23. sed in order to achieve low noise If differential input voltage exceeds 1 4V the input current should be limited to 25mA If the common mode range exceeds either rail the input current should be limited to 10mA Note 3 A heat sink may be required to keep the junction temperature below absolute maximum Note 4 The LT1678C LT1679C and LT16781 LT1679I are guaranteed functional over the Operating Temperature Range of 40 C to 85 C Note 5 The LT1678C LT1679C are guaranteed to meet specified performance from 0 C to 70 C The LT1678C LT1679C are designed characterized and expected to meet specified performance from 40 C to 85 C but is not tested QA sampled at these temperatures The LT16781 1716791 are guaranteed to meet specified performance from 40 C to 85 C Note 6 Typical parameters are defined as the 60 yield of parameter distributions of individual amplifier i e out of 100 LT1678 LT1679s typically 60 op amps will be better than the indicated specification Note 7 See the test circuit and frequency response curve for 0 1Hz to10Hz tester in the Applications Information section Note 8 Noise is 100 tested at 15V supplies Note 9 Slew rate is measured in Ay 1 input signal is 10V output measured at 5V Note 10 This parameter is not 100 tested Note 11 Vs 5V limits are guaranteed by correlation to Vs 3V and Vs 15V tests Note 12 Vs 3V limits are guaranteed by correlation to Vs
24. so provided facilitating their use in matching dependent appli cations such as a two op amp instrumentation amplifier design The LT1678 LT1679 are specified for supply volt ages of 15V single 5V as well as single 3V For a single amplifier with similiar performance see the LT1677 data sheet 47 LTC and LT are registered trademarks of Linear Technology Corporation TYPICAL APPLICATION Instrumentation Amplifier with Shield Driver GAIN 1000 0 1Hz to 10Hz Voltage Noise Vg 2 5V VOLTAGE NOISE 50nV DIV 4 6 TIME sec 5 16789 16789fs 1 LT1678 LT 1679 ABSOLUTE MAXIMUM RATINGS Note 1 supply 18V Lead Temperature Soldering 10 sec 300 C Input Voltages Note 2 0 3V Beyond Either Rail Operating Temperature Range Differential Input Current Note 2 25mA OCE D 40 0 to 85 C Output Short Circuit Duration Note 3 Indefinite Specified Temperature Range Storage Temperature Range 65 C to 150 C eee ee 40 to 85 C PACKAGE ORDER INFORMATION ORDER PART TOP VIEW ORDER PART TOP VIEW NUMBER m NUMBER 116780658 IN A IN D LT1679CS 171678158 1167915 INB INC S8 PART MARKING NE INC LEAD PASNE so 1678 OUT B OUT
25. to LT1007 LT1126 LT1127 Dual Quad Decompensated Low Noise High Speed Precision Op Amps Similar to LT1037 LT1226 Low Noise Very High Speed Op Amp 1GHz 2 6nV VHz Gain of 25 Stable LT1498 LT1499 10MHz 5V us Dual Quad Rail to Rail Input and Output Op Amps Precision C Load Stable LT1677 Single Version of LT1678 LT1679 Rail to Rail 3 2nV VHz LT1792 Low Noise Precision JFET Input Op Amp 4 2nV VHz 10fA VHz LT1793 Low Noise Picoampere Bias Current Op Amp 6nV VHz 1fA VHz 10pA LT1806 Low Noise 325MHz Rail to Rail Input and Output Op Amp 3 5nV VHz LT1881 LT1882 Dual Quad Rail to Rail Output Picoamp Input Precision Op Amps Ci oap to 1000pF Ig 200pA LT1884 LT1885 Dual Quad Rail to Rail Output Picoamp Input Precision Op Amps 2 2MHz Bandwidth 1 2V us SR C Load is a trademark of Linear Technology Corporation 5 16789 1678915 LT TP 0104 1K PRINTED IN USA Linear Technology Corporation 1630 McCarthy Blvd Milpitas CA 95035 7417 408 432 1900 FAX 408 434 0507 www linear com TECHNOLOGY LINEAR TECHNOLOGY CORPORATION 2003
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LINEAR TECHNOLOGY LT1678/LT1679 handbook lt1679cs#pbf ltc1693-1