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| (R) EL8170, EL8173 Data Sheet March 9, 2006 FN7490.1 Micropower, Single Supply, Rail-to-Rail Input-Output Instrumentation Amplifiers The EL8170 and EL8173 are micropower instrumentation amplifiers optimized for operation at 2.9V to 5V single supplies. Inputs and outputs can operate rail-to-rail. As with all instrumentation amplifiers, a pair of inputs provide very high common-mode rejection and are completely independent from a pair of feedback terminals. The feedback terminals allow zero input to be translated to any output offset, including ground. A feedback divider controls the overall gain of the amplifier. The EL8170 is compensated for a gain of 100 or more, and the EL8173 is compensated for a gain of 10 or more. The EL8170 and EL8173 have bipolar input devices for best offset and 1/f noise performance. The amplifiers can be operated from one lithium cell or two Ni-Cd batteries. The EL8170 and EL8173 input range includes ground to slightly above positive rail. The output stage swings to ground and positive supply - no pull-up or pull-down resistors are needed. Features * 78A maximum supply current * Maximum offset voltage - 250V (EL8170) - 1000V (EL8173) * 500pA input bias current * 2V/C offset voltage drift * 396kHz -3dB bandwidth (G = 10) * 192kHz -3dB bandwidth (G = 100) * 0.5V/s slew rate * Single supply operation - Input voltage range is rail-to-rail - Output swings rail-to-rail * Output sources and sinks 29mA load current * 0.2% gain error * Pb-free plus anneal available (RoHS compliant) Pinout EL8170, EL8173 (8 LD SO) TOP VIEW ENABLE 1 IN- 2 IN+ 3 VS- 4 + + - Applications * Battery- or solar-powered systems * Strain gauges * Current monitors 8 FB+ 7 VS+ 6 OUT 5 FB- * Thermocouple amplifiers 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright (c) Intersil Americas Inc. 2006. All Rights Reserved. All other trademarks mentioned are the property of their respective owners. EL8170, EL8173 Ordering Information PART NUMBER EL8170IS EL8170IS-T7 EL8170IS-T13 EL8170ISZ (See Note) EL8170ISZ-T7 (See Note) EL8170ISZ-T13 (See Note) PART MARKING 8170IS 8170IS 8170IS 8170ISZ 8170ISZ 8170ISZ TAPE & REEL 7" 13" 7" 13" PACKAGE 8 Ld SO 8 Ld SO 8 Ld SO 8 Ld SO (Pb-free) 8 Ld SO (Pb-free) 8 Ld SO (Pb-free) PKG. DWG. # MDP0027 MDP0027 MDP0027 MDP0027 MDP0027 MDP0027 PART NUMBER EL8173IS EL8173IS-T7 EL8173IS-T13 EL8173ISZ (See Note) EL8173ISZ-T7 (See Note) EL8173ISZ-T13 (See Note) PART MARKING 8173IS 8173IS 8173IS 8173ISZ 8173ISZ 8173ISZ TAPE & REEL 7" 13" 7" 13" PACKAGE 8 Ld SO 8 Ld SO 8 Ld SO 8 Ld SO (Pb-free) 8 Ld SO (Pb-free) 8 Ld SO (Pb-free) PKG. DWG. # MDP0027 MDP0027 MDP0027 MDP0027 MDP0027 MDP0027 NOTE: Intersil Pb-free plus anneal products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate termination finish, which are RoHS compliant and compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020. Pin Description EL8170/EL8173 1 PIN NAME ENABLE PIN FUNCTION Active Low. When pulled up above 2V, the in-amp conserves 3A disabled supply current and the output is in a high impedance state. An internal pull down defines the ENABLE low when left floating. Inverting (IN-) and non-inverting (IN+) high impedance input terminals. 2 3 4 5 8 ININ+ VSFBFB+ Negative supply terminal. High impedance feedback terminals. The feedback terminals have a very similar equivalent circuit as the input terminals. They also have an Input Bias Compensation/Cancelling Circuit. The negative feedback (FB-) pin connects to an external resistive network to set the gain of the in-amp. The positive feedback (FB+) can be used to shift the DC level of the output or as an output offset. Positive supply terminal. Output Voltage. 7 6 VS+ VOUT 2 FN7490.1 March 9, 2006 EL8170, EL8173 Absolute Maximum Ratings (TA = 25C) Supply Voltage, VS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5V Differential Input Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5mA Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5V VEN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - 0.5V, VS+ + 0.5V ESD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3kV Output Short-Circuit Duration . . . . . . . . . . . . . . . . . . . . . . .Indefinite Ambient Operating Temperature . . . . . . . . . . . . . . . .-40C to +85C Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . .-65C to +150C CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. IMPORTANT NOTE: All parameters having Min/Max specifications are guaranteed. Typical values are for information purposes only. Unless otherwise noted, all tests are at the specified temperature and are pulsed tests, therefore: TJ = TC = TA Electrical Specifications PARAMETER VOS VS+ = +5V, VS- = GND, VCM = 1/2VS+, TA = 25C, unless otherwise specified. CONDITIONS EL8170 EL8173 MIN TYP 100 400 2 0.5 0.5 EL8170 EL8173 f = 0.1Hz to 10Hz 2 10 fo = 1kHz 50 200 0.1 8 14 0 80 80 VS = 2.9V to 5V 80 70 RL = 100k to 2.5V -1.5 -0.8 0 108 104 104 90 +0.3 +0.2 4 0.13 4.990 4.75 0.3 4.996 4.88 0.5 0.7 +1.5 +0.8 10 0.25 5 2 2 MAX 250 1000 UNIT V V V/C nA nA VP-P VP-P nV/Hz nV/Hz pA/Hz M M V dB dB dB dB % % mV V V V V/s DESCRIPTION Input Offset Voltage TCVOS Input Offset Voltage Temperature Coefficient Input Offset Current between IN+, and IN- and between FB+ and FBInput Bias Current (IN+, IN-, FB+, and FB- terminals) Input Noise Voltage Temperature = -40C to 85C IOS IB eN Input Noise Voltage Density EL8170 EL8173 iN RIN Input Noise Current Density Input Resistance fo = 1kHz EL8170 EL8173 VIN CMRR Input Voltage Range Common Mode Rejection Ratio Guaranteed by CMRR test EL8170 EL8173 VCM = 0V to +5V PSRR Power Supply Rejection Ratio EL8170 EL8173 EG Gain Error EL8170 EL8173 VOUT Maximum Voltage Swing Output low, 100k to 2.5V Output low, 1k to 2.5V Output high, 100k to 2.5V Output high, 1k to GND SR Slew Rate RL = 1k to GND 3 FN7490.1 March 9, 2006 EL8170, EL8173 Electrical Specifications PARAMETER -3dB BW -3dB Bandwidth VS+ = +5V, VS- = GND, VCM = 1/2VS+, TA = 25C, unless otherwise specified. (Continued) CONDITIONS EL8170 Gain = 100V/V Gain = 200 Gain = 500 Gain = 1000 EL8173 Gain = 10 Gain = 20 Gain = 50 Gain = 100 IS,EN IS,DIS VENH VENL VS IO Supply Current, Enabled Supply Current, Disabled Enable Pin for Shut-down Enable Pin for Power-on Minimum Supply Voltage Output Current into 10 to VS/2 VS = 5V VS = 2.9V 18 4 2.2 29 7.5 EN = VS+ 40 1.5 2 0.8 2.4 MIN TYP 192 93 30 13 396 221 69 30 60 2.9 78 5 MAX UNIT kHz kHz kHz kHz kHz kHz kHz kHz A A V V V mA mA DESCRIPTION Typical Performance Curves 65 60 55 50 GAIN (dB) 45 40 35 30 25 20 1 G=500 G=200 G=100 G=50 G=1000 45 40 35 30 GAIN (dB) 25 20 15 10 VS=5V 5 100 1k 10k 100k 1M 0 1 VS=5V 10 100 1k 10k 100k 1M G=5 G=50 G=20 G=10 G=100 10 FREQUENCY (Hz) FREQUENCY (Hz) FIGURE 1. EL8170 FREQUENCY RESPONSE vs CLOSED LOOP GAIN FIGURE 2. EL8173 FREQUENCY RESPONSE vs CLOSED LOOP GAIN 4 FN7490.1 March 9, 2006 EL8170, EL8173 Typical Performance Curves (Continued) 45 40 35 30 GAIN (dB) 25 20 AV=100 15 R =10k L 10 CL=10pF RF/RG=99.02 5 RF=221k RG=2.23k 0 100 1k VS=3.3V VS=2.9V MAGNITUDE (dB) VS=5V 20 VS=3.3V 15 VS=2.9V 25 VS=5V 10k 100k 1M 10 A =10 V RL=10k CL=10pF 5 R /R =9.08 FG RF=178k RG=19.6k 0 100 1k 10k FREQUENCY (Hz) 100k 1M FREQUENCY (Hz) FIGURE 3. EL8170 FREQUENCY RESPONSE vs SUPPLY VOLTAGE FIGURE 4. EL8173 FREQUENCY RESPONSE vs SUPPLY VOLTAGE 50 30 25 CL=470pF CL=820pF GAIN (dB) CL=47pF 20 CL=27pF 15 AV=10 10 V =5V S RL=10k RF/RG=9.08 5 RF=178k RG=19.6k 0 100 1k CL=2.7pF CL=100pF 45 GAIN (dB) 40 CL=220pF 35 A =100 V VS=5V RL=10k 30 R /R =99.02 FG RF=221k RG=2.23k 25 100 1k CL=56pF 10k 100k 1M 10k FREQUENCY (Hz) 100k 1M FREQUENCY (Hz) FIGURE 5. EL8170 FREQUENCY RESPONSE vs CLOAD FIGURE 6. EL8173 FREQUENCY RESPONSE vs CLOAD AVERAGE INPUT BIAS CURRENT (pA) 1000 VS=3.3V 500 VS=5.0V AVERAGE INPUT BIAS CURRENT (pA) 1500 2000 1500 1000 VS=5.0V 0 VS=2.9V 500 VS=2.9V VS=3.3V -500 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 COMMON-MODE INPUT VOLTAGE (V) 0 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 COMMON-MODE INPUT VOLTAGE (V) FIGURE 7. EL8170 AVERAGE INPUT BIAS CURRENT vs COMMON-MODE INPUT VOLTAGE @ 25C FIGURE 8. EL8173 AVERAGE INPUT BIAS CURRENT vs COMMON-MODE INPUT VOLTAGE @ 25C 5 FN7490.1 March 9, 2006 EL8170, EL8173 Typical Performance Curves (Continued) INPUT OFFSET CURRENT (pA) INPUT OFFSET CURRENT (pA) 100 100 VS=2.9V -100 VS=3.3V VS=5.0V VS=2.9V -100 VS=3.3V VS=5.0V -300 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 COMMON-MODE INPUT VOLTAGE (V) -300 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 COMMON-MODE INPUT VOLTAGE (V) FIGURE 9. EL8170 INPUT OFFSET CURRENT vs COMMONMODE INPUT VOLTAGE @ 25C FIGURE 10. EL8173 INPUT OFFSET CURRENT vs COMMONMODE INPUT VOLTAGE @ 25C AVERAGE INPUT BIAS CURRENT (pA) 1500 AVERAGE INPUT BIAS CURRENT (pA) 1000 500 VS=5V 85C 2000 1500 25C 85C -45C 0 -500 1000 -45C 25C 500 0 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 COMMON-MODE INPUT VOLTAGE (V) 0 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 COMMON-MODE INPUT VOLTAGE (V) FIGURE 11. EL8170 AVERAGE INPUT BIAS CURRENT vs COMMON-MODE INPUT VOLTAGE @ VS = 5V, TEMPERATURE = -45C, 25C, AND 85C FIGURE 12. EL8173 AVERAGE INPUT BIAS CURRENT vs COMMON-MODE INPUT VOLTAGE @ VS = 5V, TEMPERATURE = -45C, 25C, AND 85C AVERAGE INPUT BIAS CURRENT (pA) AVERAGE INPUT BIAS CURRENT (pA) 1500 VS=3.3V 1000 500 0 -500 -1000 -0.5 85C 25C 2000 1500 25C 1000 -45C 500 85C -45C 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 COMMON-MODE INPUT VOLTAGE (V) COMMON-MODE INPUT VOLTAGE (V) FIGURE 13. EL8170 AVERAGE INPUT BIAS CURRENT vs COMMON MODE INPUT VOLTAGE @ VS = 3.3V, TEMPERATURE = -45C, 25C, AND 85C FIGURE 14. EL8173 AVERAGE INPUT BIAS CURRENT vs COMMON MODE INPUT VOLTAGE @ VS = 3.3V, TEMPERATURE = -45C, 25C, AND 85C 6 FN7490.1 March 9, 2006 EL8170, EL8173 Typical Performance Curves (Continued) AVERAGE INPUT BIAS CURRENT (pA) 1500 VS=2.9V 1000 500 0 -500 -1000 -0.5 85C 25C AVERAGE INPUT BIAS CURRENT (pA) 2000 1500 25C 1000 -45C 500 85C -45C 0 0.5 1.0 1.5 2.0 2.5 3.0 0 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 COMMON-MODE INPUT VOLTAGE (V) COMMON-MODE INPUT VOLTAGE (V) FIGURE 15. EL8170 AVERAGE INPUT BIAS CURRENTS vs COMMON-MODE INPUT VOLTAGE @ VS = 2.9V, TEMPERATURE = -45C, 25C, AND 85C FIGURE 16. EL8173 AVERAGE INPUT BIAS CURRENTS vs COMMON-MODE INPUT VOLTAGE @ VS = 2.9V, TEMPERATURE = -45C, 25C, AND 85C 250 INPUT OFFSET VOLTAGE (V) 200 150 100 50 0 -0.5 0 VS=5V INPUT OFFSET VOLTAGE (V) 25C 0 25C -200 VS=5V -400 VS=3.3V -600 -800 -1000 -0.5 0 VS=2.9V VS=3.3V VS=2.9V 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 COMMON-MODE INPUT VOLTAGE (V) 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 COMMON-MODE INPUT VOLTAGE (V) FIGURE 17. EL8170 INPUT OFFSET VOLTAGE vs COMMONMODE INPUT VOLTAGE @ VS = 5V, 3.3V AND 2.9V AND TEMPERATURE = 25C FIGURE 18. EL8173 INPUT OFFSET VOLTAGE vs COMMONMODE INPUT VOLTAGE @ VS = 5V, 3.3V, AND 2.9V AND TEMPERATURE = 25C 250 INPUT OFFSET VOLTAGE (V) 200 150 100 50 0 -0.5 0 25C 85C INPUT OFFSET VOLTAGE (V) 0 -200 -400 -600 -800 -1000 -0.5 0 25C -45C 85C -45C 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 COMMON-MODE INPUT VOLTAGE (V) 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 COMMON-MODE INPUT VOLTAGE (V) FIGURE 19. EL8170 INPUT OFFSET VOLTAGE vs COMMONMODE INPUT VOLTAGE @ VS = 5.0V, TEMPERATURE = -45C, 25C, AND 85C FIGURE 20. EL8173 INPUT OFFSET VOLTAGE vs COMMONMODE INPUT VOLTAGE @ VS = 5.0V, TEMPERATURE = -45C, 25C, AND 85C 7 FN7490.1 March 9, 2006 EL8170, EL8173 Typical Performance Curves (Continued) 250 INPUT OFFSET VOLTAGE (V) INPUT OFFSET VOLTAGE (V) 200 150 100 50 -45C 0 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 25C 85C 0 -200 -400 25C -600 -800 -1000 -0.5 -45C 85C 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 COMMON-MODE INPUT VOLTAGE (V) COMMON-MODE INPUT VOLTAGE (V) FIGURE 21. EL8170 INPUT OFFSET VOLTAGE vs COMMONMODE INPUT VOLTAGE @ VS = 3.3V, TEMPERATURE = -45C, 25C, AND 85C FIGURE 22. EL8173 INPUT OFFSET VOLTAGE vs COMMONMODE INPUT VOLTAGE @ VS = 3.3V, TEMPERATURE = -45C, 25C, AND 85C 450 INPUT OFFSET VOLTAGE (V) INPUT OFFSET VOLTAGE (V) 300 200 100 0 -100 -0.5 25C 0 -200 -400 25C -600 -800 -1000 -0.5 -45C 85C 85C -45C 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 COMMON-MODE INPUT VOLTAGE (V) COMMON-MODE INPUT VOLTAGE (V) FIGURE 23. EL8170 INPUT OFFSET VOLTAGE vs COMMONMODE INPUT VOLTAGE @ VS = 2.9V, TEMPERATURE = -45C, 25C, AND 85C FIGURE 24. EL8173 INPUT OFFSET VOLTAGE vs COMMONMODE INPUT VOLTAGE @ VS = 3.3V, TEMPERATURE = - 45C, 25C, AND 85C 500 INPUT OFFSET VOLTAGE (uV) 1500 INPUT OFFSET VOLTAGE (uV) 1000 500 0 -500 -1000 -1500 12 samples Vs=5V Average = 1.8uV/C 250 0 -250 -500 12 samples Vs=5V Average = 2uV/C -750 -50 -25 0 25 50 75 TEMPERATURE (degrees C) TEMPERATURE (C) 100 125 -50 -25 0 25 50 75 TEMPERATURE (degrees C) TEMPERATURE (C) 100 125 FIGURE 25. EL8170 INPUT OFFSET VOLTAGE vs TEMPERATURE @ VS = 5.0V FIGURE 26. EL8173 INPUT OFFSET VOLTAGE vs TEMPERATURE @ VS = 5.0V 8 FN7490.1 March 9, 2006 EL8170, EL8173 Typical Performance Curves (Continued) 500 1500 INPUT OFFSET VOLTAGE (uV) 1000 500 0 -500 INPUT OFFSET VOLTAGE (uV) 12 samples Vs=2.9V Average = 1.38uV/C 250 0 -250 12 samples Vs=2.9V Average = 2.2uV/C -500 -1000 -1500 -750 -50 -25 0 25 50 75 100 125 TEMPERATURE (degrees C) TEMPERATURE (C) -50 -25 0 25 50 75 TEMPERATURE (degrees C) TEMPERATURE (C) 100 125 FIGURE 27. EL8170 INPUT OFFSET VOLTAGE vs TEMPERATURE @ VS = 2.9V FIGURE 28. EL8173 INPUT OFFSET VOLTAGE vs TEMPERATURE @ VS = 2.9V 120 110 100 CMRR (dB) 90 80 70 60 50 40 1 10 100 1k 10k 100k 1M GAIN=100 GAIN=1000 CMRR (dB) 120 110 100 90 80 70 60 50 40 1 10 100 1k GAIN=10 10k 100k 1M GAIN=100 GAIN=1000 FREQUENCY (Hz) FREQUENCY (Hz) FIGURE 29. EL8170 CMRR vs FREQUENCY FIGURE 30. EL8173 CMRR vs FREQUENCY 120 110 100 PSRR (dB) PSRR (dB) 90 80 70 60 50 40 1 10 100 1k 10k 100k 1M PSRRPSRR+ 100 90 80 70 60 50 40 30 20 1 10 100 1k 10k 100k 1M PSRRPSRR+ FREQUENCY (Hz) FREQUENCY (Hz) FIGURE 31. EL8170 PSRR vs FREQUENCY FIGURE 32. EL8173 PSRR vs FREQUENCY 9 FN7490.1 March 9, 2006 EL8170, EL8173 Typical Performance Curves (Continued) 100 INPUT VOLTAGE NOISE (nV/Hz) INPUT VOLTAGE NOISE (nV/Hz) 1k eN @ 1kHz = 50nV/Hz 10 10 100 FREQUENCY (Hz) 1k 10k eN @ 1kHz = 200nV/Hz 100 10 100 FREQUENCY (Hz) 1k 10k FIGURE 33. EL8170 VOLTAGE NOISE DENSITY FIGURE 34. EL8173 VOLTAGE NOISE DENSITY 1 CURRENT NOISE (pA/Hz) 0.1 0.01 10 iN @ 1kHz = 0.1pA/Hz 100 FREQUENCY (Hz) 1k 10k FIGURE 35. EL8170 AND EL8173 CURRENT NOISE DENSITY 1V/DIV 1s/DIV 5V/DIV 1s/DIV FIGURE 36. EL8170 0.1Hz TO 10Hz INPUT VOLTAGE NOISE (GAIN = 100) FIGURE 37. EL8173 0.1Hz TO 10Hz INPUT VOLTAGE NOISE (GAIN = 10) 10 FN7490.1 March 9, 2006 EL8170, EL8173 Typical Performance Curves (Continued) 70 60 SUPPLY CURRENT (A) 50 40 30 20 10 0 2 2.5 3 3.5 4 4.5 5 5.5 SUPPLY VOLTAGE (V) FIGURE 38. EL8170 AND EL8173 SUPPLY CURRENT vs SUPPLY VOLTAGE 1.4 POWER DISSIPATION (W) 1.2 JEDEC JESD51-7 HIGH EFFECTIVE THERMAL CONDUCTIVITY TEST BOARD 1 0.9 POWER DISSIPATION (W) 0.8 JEDEC JESD51-3 LOW EFFECTIVE THERMAL CONDUCTIVITY TEST BOARD 1 909mW 0.8 0.6 0.4 0.2 0 0 25 50 75 85 100 125 150 SO 11 8 0 C/ W 0.7 625mW 0.6 0.5 0.4 0.3 0.2 0.1 0 0 25 50 75 85 100 125 150 JA JA = =1 60 SO 8 C /W AMBIENT TEMPERATURE (C) AMBIENT TEMPERATURE (C) FIGURE 39. PACKAGE POWER DISSIPATION vs AMBIENT TEMPERATURE FIGURE 40. PACKAGE POWER DISSIPATION vs AMBIENT TEMPERATURE Description of Operation and Applications Information Product Description The EL8170 and EL8173 are micropower instrumentation amplifiers (in-amps) which deliver rail-to-rail input amplification and rail-to-rail output swing on a single 2.9V to 5V supply. The EL8170 and EL8173 also deliver excellent DC and AC specifications while consuming only 60A typical supply current. Because the EL8170 and EL8173 provide an independent pair of feedback terminals to set the gain and to adjust output level, these in-amps achieve high commonmode rejection ratio regardless of the tolerance of the gain setting resistors. The EL8173 is internally compensated for a minimum closed loop gain of 10 or greater, well suited for moderate to high gains. For higher gains, the EL8170 is internally compensated for a minimum gain of 100. An ENABLE pin is used to reduce power consumption, typically 2.9A, while the instrumentation amplifier is disabled. Input Protection All input and feedback terminals of the EL8170 and EL8173 have internal ESD protection diodes to both positive and negative supply rails, limiting the input voltage to within one diode drop beyond the supply rails. The EL8170 has additional back-to-back diodes across the input terminals and also across the feedback terminals. If overdriving the inputs is necessary, the external input current must never exceed 5mA. On the other hand, the EL8173 has no clamps to limit the differential voltage on the input terminals allowing 11 FN7490.1 March 9, 2006 EL8170, EL8173 higher differential input voltages at lower gain applications. It is recommended however, that the input terminals of the EL8173 is not overdriven beyond 1V to avoid offset drift. An external series resistor may be used as an external protection to limit excessive external voltage and current from damaging the inputs. function can be derived. The gain of the EL8170 and EL8173 is set by two external resistors, the feedback resistor RF, and the gain resistor RG. 2.9V to 5V 7 VIN/2 3 IN+ 2 IN8 FB+ 5 FB+ + 4 1 VS+ EN 6 EN_BAR Input Stage and Input Voltage Range The input terminals (IN+ and IN-) of the EL8170 and EL8173 are single differential pair bipolar PNP devices aided by an Input Range Enhancement Circuit to increase the headroom of operation of the common-mode input voltage. The feedback terminals (FB+ and FB-) also have a similar topology. As a result, the input common-mode voltage range of both the EL8170 and EL8173 is rail-to-rail. These in-amps are able to handle input voltages that are at or slightly beyond the supply and ground making these in-amps well suited for single 5V or 3.3V low voltage supply systems. There is no need then to move the common-mode input of the in-amps to achieve symmetrical input voltage. VIN/2 EL8170/3 VS- VOUT VCM RG RF FIGURE 41. GAIN IS SET BY TWO EXTERNAL RESISTORS, RF AND RG RF VOUT = 1 + ------- VIN R G Input Bias Cancellation/Compensation Inside the EL8170 and EL8173 is an Input Bias Cancellation/Compensation Circuit for both the input and feedback terminals (IN+, IN-, FB+ and FB-), achieving a low input bias current all throughout the input common-mode range and the operating temperature range. While the PNP bipolar input stages are biased with an adequate amount of biasing current for speed and increased noise performance, the Input Bias Cancellation/Compensation Circuit sinks most of the base current of the input transistor leaving a small portion as input bias current, typically 500pA. In addition, the Input Bias Cancellation/Compensation Circuit maintains a smooth and flat behavior of input bias current over the common mode range and over the operating temperature range. The Input Bias Cancellation/Compensation Circuit operates from input voltages of 10mV above the negative supply to input voltages slightly above the positive supply. See Average Input Bias Current vs Common-Mode Input Voltage in the performance curves section. In Figure 41, the FB+ pin and one end of resistor RG are connected to GND. With this configuration, the above gain equation is only true for a positive swing in VIN; negative input swings will be ignored and the output will be at ground. Reference Connection Unlike a three-op amp instrumentation amplifier, a finite series resistance seen at the REF terminal does not degrade the EL8170 and EL8173's high CMRR performance eliminating the need for an additional external buffer amplifier. Figure 42 uses the FB+ pin to provide a high impedance REF terminal. 2.9V to 5V 7 VIN/2 3 IN+ 2 IN8 FB+ 5 FB+ + 4 1 VS+ EN 6 VOUT EN_BAR Output Stage and Output Voltage Range A pair of complementary MOSFET devices drives the output VOUT to within a few millivolts of the supply rails. At a 100k load, the PMOS sources current and pulls the output up to 4mV below the positive supply, while the NMOS sinks current and pulls the output down to 4mV above the negative supply, or ground in the case of a single supply operation. The current sinking and sourcing capability of the EL8170 and EL8173 are internally limited to 29mA. VIN/2 2.9V to 5V VCM REF R2 RG R1 EL8170/3 VS- RF Gain Setting VIN, the potential difference across IN+ and IN-, is replicated (less the input offset voltage) across FB+ and FB-. The obsession of the EL8170 and EL8173 in-amp is to maintain the differential voltage across FB+ and FB- equal to IN+ and IN-; (FB+ - FB-) = (IN+ - IN-). Consequently, the transfer 12 FIGURE 42. GAIN SETTING AND REFERENCE CONNECTION . RF RF VOUT = 1 + ------- ( VIN ) + 1 + ------- ( VREF ) R G R G FN7490.1 March 9, 2006 EL8170, EL8173 The FB+ pin is used as a REF terminal to center or to adjust the output. Because the FB+ pin is a high impedance input, an economical resistor divider can be used to set the voltage at the REF terminal without degrading or affecting the CMRR performance. Any voltage applied to the REF terminal will shift VOUT by VREF times the closed loop gain, which is set by resistors RF and RG. See Figure 42. The FB+ pin can also be connected to the other end of resistor, RG. See Figure 43. Keeping the basic concept that the EL8170 and EL8173 in-amps maintain constant differential voltage across the input terminals and feedback terminals (IN+ - IN- = FB+ - FB-), the transfer function of Figure 43 can be derived. 2.9V to 5V 7 VIN/2 3 IN+ 2 IN8 FB+ 5 FB+ + 4 1 VS+ EN 6 of the EL8170 and EL8173 and does not include the gain error contributed by the resistors. There is an additional gain error due to the tolerance of the resistors used. The resulting non-ideal transfer function effectively becomes: RF VOUT = 1 + ------- x [ 1 - ( E RG + E RF + E G ) ] x VIN R G Where: ERG = Tolerance of RG ERF = Tolerance of RF EG = Gain Error of the EL8170 or EL8173 EN_BAR The term [1 - (ERG +ERF +EG)] is the deviation from the theoretical gain. Thus, (ERG +ERF +EG) is the total gain error. For example, if 1% resistors are used for the EL8170, the total gain error would be: = ( E RG + E RF + E G ( typical ) ) VIN/2 EL8170/3 VS- VOUT = ( 0.01 + 0.01 + 0.003 ) = 2.3% VCM Disable/Power-Down The EL8170 and EL8173 can be powered down reducing the supply current to typically 2.9A. When disabled, the output is in a high impedance state. The active low ENABLE bar pin has an internal pull down and hence can be left floating and the in-amp enabled by default. When the ENABLE bar is connected to an external logic, the in-amp will power down when ENABLE bar is pulled above 2V, and will power on when ENABLE bar is pulled below 0.8V. VREF RG RF FIGURE 43. REFERENCE CONNECTIONWITH AN AVAILABLE VREF RF VOUT = 1 + ------- ( VIN ) + ( VREF ) R G A finite resistance RS in series with the VREF source, adds an output offset of VIN*(RS/RG). As the series resistance Rs approaches zero, the gain equation is simplified to the above equation for Figure 43. VOUT is simply shifted by an amount VREF. External Resistor Mismatches Because of the independent pair of feedback terminals provided by the EL8170 and EL8173, the CMRR is not degraded by any resistor mismatches. Hence, unlike a three op amp and especially a two op amp in-amp, the EL8170 and EL8173 reduce the cost of external components by allowing the use of 1% or more tolerance resistors without sacrificing CMRR performance. The EL8170 and EL8173 CMRR will be 108dB regardless of the tolerance of the resistors used. Gain Error and Accuracy The EL8173 has a Gain Error, EG, of 0.2% typical. The EL8170 has an EG of 0.3% typical. The gain error indicated in the electrical specifications table is the inherent gain error 13 FN7490.1 March 9, 2006 EL8170, EL8173 Package Outline Drawing NOTE: The package drawing shown here may not be the latest version. To check the latest revision, please refer to the Intersil website at http://www.intersil.com/design/packages/index.asp All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems. Intersil Corporation's quality certifications can be viewed at www.intersil.com/design/quality Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries. For information regarding Intersil Corporation and its products, see www.intersil.com 14 FN7490.1 March 9, 2006 |
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