ANALOG DEVICES AD8293G80

Low Cost, Zero-Drift In-Amp with Filter and Fixed Gain AD8293G80/AD8293G160 FEATURES FUNCTIONAL BLOCK DIAGRAM Small package: 8-lead SOT-23 7 5 6 Reduced component count +V FILT OUT S Incorporates gain resistors and filter resistors R2 Low offset voltage: 20 μV maximum +IN 8 Low offset drift: 0.3 μV/°C maximum R3 5kΩ R1 Low gain drift: 25 ppm/°C maximum 4 IN-AMP 4kΩ ADC OUT OUTPUT TO ADC High CMR: 140 dB typical WITH ANTIALIASING –IN 1 FILTER Low noise: 0.7 μV p-p from 0.01 Hz to 10 Hz GND REF AD8293Gxx Single-supply operation: 1.8 V to 5.5 V 2 3 Rail-to-rail output Figure 1. Available in 2 fixed-gain models +5V APPLICATIONS C2 0.1µF Current sensing 7 5 6 +V FILT OUT S Strain gauges LOAD R2 Laser diode control loops +IN 8 R3 Portable medical instruments 5kΩ R1 I R 4 ADC IN-AMP SHUNT 4kΩ ADC OUT Thermocouple amplifiers C3 –IN REF 1 +3.3V 1.8V 0.1µF 10µF DC-DC GND REF AD8293Gxx 2 3 Figure 2. Measuring Current Using the AD8293G80/AD8293G160 Table 1. AD8293Gxx Models and Gains Model Gain AD8293G80 80 AD8293G160 160 GENERAL DESCRIPTION The AD8293G80/AD8293G160 are small, low cost, precision Precision instrumentation, position and pressure sensors, instrumentation amplifiers that have low noise and rail-to-rail medical instrumentation, and strain gauge amplifiers benefit outputs. They are available in two fixed-gain models: 80 and 160. from the low noise, low input bias current, and high common- They incorporate the gain setting resistors and filter resistors, mode rejection. The small footprint and low cost are ideal for reducing the number of ancillary components. For example, high volume applications. only two external capacitors are needed to implement a 2-pole The small package and low power consumption allow the maxi- filter. The AD8293G80/AD8293G160 also feature low offset mum channel density and the minimum board size required for voltage, offset drift, and gain drift coupled with high common- portable systems. Designed for ease of use, these instrumentation mode rejection. They are capable of operating on a supply of amplifiers, unlike more traditional ones, have a buffered reference, 1.8 V to 5.5 V. eliminating the need for an additional op amp to set the reference With a low offset voltage of 20 μV (AD8293G160B), an offset voltage to midsupply. voltage drift of 0.3 μV/°C, and a voltage noise of only 0.7 μV p-p The AD8293G80/AD8293G160 are specified over the industrial (0.01 Hz to 10 Hz), the AD8293G80/AD8293G160 are ideal temperature range from −40°C to +85°C. The AD8293G80/ for applications where error sources cannot be tolerated. AD8293G160 are available in a halogen-free, Pb-free, 8-lead SOT-23. Rev. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 www.analog.com license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Fax: 781.461.3113 ©2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 07451-001 07451-002 AD8293G80/AD8293G160 TABLE OF CONTENTS Features .............................................................................................. 1  Theory of Operation ...................................................................... 10  Applications ....................................................................................... 1  High PSR and CMR ................................................................... 10  Functional Block Diagram .............................................................. 1  1/f Noise Correction .................................................................. 10  General Description ......................................................................... 1  Applications Information .............................................................. 11  Revision History ............................................................................... 2  Overview ..................................................................................... 11  Specif ica t ions ..................................................................................... 3  Reference Connection ............................................................... 11  Electrical Characteristics ............................................................. 3  Output Filtering .......................................................................... 11  Absolute Maximum Ratings ............................................................ 5  Clock Feedthrough ..................................................................... 12  Thermal Resistance ...................................................................... 5  Power Supply Bypassing ............................................................ 12  ESD Caution .................................................................................. 5  Input Overvoltage Protection ................................................... 12  Pin Configuration and Function Descriptions ............................. 6  Outline Dimensions ....................................................................... 13  Typical Performance Characteristics ............................................. 7  Ordering Guide .......................................................................... 13  REVISION HISTORY 8/08—Revision 0: Initial Version Rev. 0 | Page 2 of 16 AD8293G80/AD8293G160 SPECIFICATIONS ELECTRICAL CHARACTERISTICS V = 5.0 V, V = −0 V, V = 3.3 V, V = V − V , T = 25°C, tested at ADC OUT, unless otherwise noted. Temperature CC CM REF IN INP INN A specifications guaranteed by characterization. Table 2. A Grade AD8293G80A AD8293G160A Parameter Symbol Conditions Min Typ Max Min Typ Max Unit COMMON-MODE REJECTION CMR V = 0 V to 3.3 V, 94 140 94 140 dB CM −40°C ≤ TA ≤ +85°C NOISE PERFORMANCE Voltage Noise e f = 0.01 Hz to 10 Hz 0.7 0.7 μV p-p n p-p Voltage Noise Density en f = 1 kHz 35 35 nV/√Hz INPUT CHARACTERISTICS Input Offset Voltage V 9 50 9 50 μV OS vs. Temperature ΔVOS/ΔT −40°C ≤ TA ≤ +85°C 0.02 0.3 0.02 0.3 μV/°C Input Bias Current IB −40°C ≤ TA ≤ +85°C 0.4 2 0.4 2 nA Input Offset Current IOS 4 4 nA Input Operating Impedance Differential 50||1 50||1 MΩ||pF Common Mode 10||10 10||10 GΩ||pF Input Voltage Range 0 VCC − 1.7 0 VCC − 1.7 V DYNAMIC RESPONSE 1 Small Signal Bandwidth BW Filter limited 500 500 Hz Slew Rate SR Filter limited Filter limited 2 Settling Time ts 0.1% 500 Hz filter, VO = 2 V step 1.9 1.9 ms 0.01% 2.4 2.4 ms Internal Clock Frequency 60 60 kHz GAIN 80 160 Gain Error V = 0.075 V to 4.925 V 0.3 1 0.3 1 % O Gain Drift −40°C ≤ T ≤ +85°C 5 25 5 25 ppm/°C A Nonlinearity VO = 0.075 V to 4.925 V 0.003 0.03 0.003 0.03 % FS OUTPUT CHARACTERISTICS Output Voltage High V V OH VCC − VCC − 0.075 0.075 Output Voltage Low VOL 0.075 0.075 V Short-Circuit Current I ±35 ±35 mA SC REFERENCE CHARACTERISTICS VREF Range 0.8 VCC − 0.8 0.8 VCC − 0.8 V REF Pin Current I 0.01 1 0.01 1 nA REF POWER SUPPLY Operating Range 1.8 5.5 1.8 5.5 V Power Supply Rejection PSR V = 1.8 V to 5.5 V, V = 0 V 94 120 94 120 dB CC CM Supply Current I I = 0 mA, V = 0 V 1.0 1.3 1.0 1.3 mA SY O IN −40°C ≤ T ≤ +85°C 1.5 1.5 mA A TEMPERATURE RANGE Specified Range −40 +85 −40 +85 °C 1 Higher bandwidths result in higher noise. 2 Settling time is determined by filter setting. Rev. 0 | Page 3 of 16 AD8293G80/AD8293G160 V = 2.7 V to 5.0 V, V = −0 V, V = V /2, V = V − V , T = 25°C, tested at OUT with 10 kΩ load and ADC OUT, unless CC CM REF CC IN INP INN A otherwise noted. Temperature specifications guaranteed by characterization. Table 3. B Grade (Tested and Guaranteed over a Wider Supply Range to More Stringent Specifications Than the A Grade) AD8293G80B AD8293G160B Parameter Symbol Conditions Min Typ Max Min Typ Max Unit COMMON-MODE REJECTION CMR V = 5 V, V = 0 V to 3.3 V; 110 140 110 140 dB CC CM ≤ +85°C −40°C ≤ TA VCC = 2.7 V, VCM = 0 V to 1 V; 106 140 106 140 dB −40°C ≤ TA ≤ +85°C NOISE PERFORMANCE Voltage Noise en p-p f = 0.01 Hz to 10 Hz 0.7 0.7 μV p-p Voltage Noise Density en f = 1 kHz 35 35 nV/√Hz INPUT CHARACTERISTICS Input Offset Voltage VOS 5 30 3 20 μV vs. Temperature ΔVOS/ΔT −40°C ≤ TA ≤ +85°C, VCC = 5 V 0.02 0.3 0.02 0.3 μV/°C vs. Temperature ΔV /ΔT −40°C ≤ T ≤ +85°C, V = 2.7 V 0.01 0.5 0.01 0.5 μV/°C OS A CC Input Bias Current I −40°C ≤ T ≤ +85°C 0.4 2 0.4 2 nA B A Input Offset Current I 4 4 nA OS Input Operating Impedance Differential 50||1 50||1 MΩ||pF Common Mode 10||10 10||10 GΩ||pF Input Voltage Range 0 V − 1.7 0 V − 1.7 V CC CC DYNAMIC RESPONSE 1 Small Signal Bandwidth BW Filter limited; measured at 500 500 Hz ADC OUT Slew Rate SR Filter limited Filter limited 2 Settling Time ts 0.1% 500 Hz filter, VO = 2 V step; 1.9 1.9 ms measured at ADC OUT 0.01% 2.4 2.4 ms Internal Clock Frequency 60 60 kHz GAIN 80 160 Gain Error V = 0.075 V to 4.925 V 0.3 0.5 0.3 0.5 % O Gain Drift −40°C ≤ T ≤ +85°C 5 25 5 25 ppm/°C A Nonlinearity VO = 0.075 V to 4.925 V 0.003 0.009 0.003 0.009 % FS OUTPUT CHARACTERISTICS Output Voltage High V V − V − V OH CC CC 0.075 0.075 Output Voltage Low VOL 0.075 0.075 V Short-Circuit Current ISC VCC = 5 V ±35 ±35 mA V = 2.7 V ±25 ±25 mA CC REFERENCE CHARACTERISTICS VREF Range 0.8 VCC − 0.8 0.8 VCC − 0.8 V REF Pin Current I 0.01 1 0.01 1 nA REF POWER SUPPLY Operating Range 1.8 5.5 1.8 5.5 V Power Supply Rejection PSR V = 1.8 V to 5.5 V, V = 0 V 100 120 100 120 dB CC CM Supply Current I I = 0 mA, V = 0 V 1.0 1.3 1.0 1.3 mA SY O IN −40°C ≤ T ≤ +85°C 1.5 1.5 mA A TEMPERATURE RANGE Specified Range −40 +85 −40 +85 °C 1 Higher bandwidths result in higher noise. 2 Settling time is determined by filter setting. Rev. 0 | Page 4 of 16 AD8293G80/AD8293G160 ABSOLUTE MAXIMUM RATINGS Stresses above those listed under Absolute Maximum Ratings Table 4. may cause permanent damage to the device. This is a stress Parameter Rating rating only; functional operation of the device at these or any Supply Voltage 6 V other conditions above those indicated in the operational Input Voltage +V SUPPLY section of this specification is not implied. Exposure to absolute 1 Differential Input Voltage ±VSUPPLY maximum rating conditions for extended periods may affect Output Short-Circuit Duration to GND Indefinite device reliability. Storage Temperature Range (RJ Package) −65°C to +150°C Operating Temperature Range −40°C to +85°C THERMAL RESISTANCE Junction Temperature Range (RJ Package) −65°C to +150°C θ is specified for the worst-case conditions, that is, a device JA Lead Temperature (Soldering, 10 sec) 300°C soldered in a circuit board for surface-mount packages. 1 Differential input voltage is limited to ±5.0 V, the supply voltage, or Table 5. whichever is less. 1 Package Type θ θ Unit JA JC 8-Lead SOT-23 (RJ) 211.5 91.99 °C/W 1 θ is specified for the nominal conditions, that is, θ is specified for the JA JA device soldered on a circuit board. ESD CAUTION Rev. 0 | Page 5 of 16 AD8293G80/AD8293G160 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS AD8293Gxx –IN 1 8 +IN 7 +V GND 2 S 3 6 REF OUT 4 5 ADC OUT FILT TOP VIEW (Not to Scale) Figure 3. Pin Configuration Table 6. Pin Function Descriptions Pin No. Mnemonic Description 1 −IN Inverting Input Terminal (True Differential Input) 2 GND Ground 3 REF Reference Voltage Terminal (Drive This Terminal to Level-Shift the Output) 4 ADC OUT Output with Series 5 kΩ Resistor for Use with an Antialiasing Filter 5 FILT Place a capacitor across FILT and OUT to limit the amount of switching noise at the output (see Applications Information) 6 OUT Output Terminal Without Integrated Filter 7 +VS Positive Power Supply Terminal 8 +IN Noninverting Input Terminal (True Differential Input) Rev. 0 | Page 6 of 16 07451-003 AD8293G80/AD8293G160 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VCC = 5 V, and VREF = VCC/2; G = 80, C2 = 1300 pF, and C3 = 39 nF; G = 160, C2 = 680 pF, and C3 = 39 nF, unless otherwise specified. 60 60 V = 2.7V, 5V V = 2.7V, 5V CC CC FILTER = 500Hz FILTER = 10kHz G = 160 40 40 G = 160 20 G = 80 G = 80 20 0 0 –20 –40 –20 10 100 1k 10k 100k 10 100 1k 10k 100k FREQUENCY (Hz) FREQUENCY (Hz) Figure 4. Gain vs. Frequency Figure 7. Gain vs. Frequency 180 180 V = 2.7V, 5V V = 2.7V, 5V CC CC GAIN = 80, 160 GAIN = 80, 160 160 160 FILTER = 500Hz FILTER = 10kHz 140 140 120 120 100 100 80 80 60 60 40 40 20 20 10 100 1k 10k 100k 10 100 1k 10k 100k FREQUENCY (Hz) FREQUENCY (Hz) Figure 5. Common-Mode Rejection (CMR) vs. Frequency Figure 8. Common-Mode Rejection (CMR) vs. Frequency 4 4 (0.02V, 3V) (4.98V, 3V) (0.02V, 3.3V) (4.98V, 3.3V) V = 5V, V = V /2 3 3 CC REF CC V = 5V, V = V /2 CC REF CC 2 2 (0.02V, 1V) (0.02V, 1V) (2.68V, 1V) (2.68V, 1V) 1 1 V = 2.7V, CC V = V /2 REF CC V = 2.7V, CC V = V /2 (2.68V, 0V) REF CC (2.68V, 0V) 0 0 (0.02V, 0V) (4.98V, 0V) (0.02V, 0V) (4.98V, 0V) –1 –1 –1 01 234 5 6 –1 01 234 5 6 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) Figure 9. Input Common-Mode Voltage Range vs. Output Voltage, G = 160 Figure 6. Input Common-Mode Voltage Range vs. Output Voltage, G = 80 Rev. 0 | Page 7 of 16 CMR (dB) INPUT COMMON-MODE VOLTAGE (V) GAIN (dB) 07451-018 07451-004 07451-005 CMR (dB) INPUT COMMON-MODE VOLTAGE (V) GAIN (dB) 07451-019 07451-007 07451-008 AD8293G80/AD8293G160 10 10 POWER SUPPLY ON POWER SUPPLY ON 5 4μV OFFSET 5 0 4μV OFFSET 0 –5 GAIN = 160 –10 –5 GAIN = 160 GAIN = 80 –15 GAIN = 80 –10 –20 V = 2.7V CC V = 2.7V CC V = 5V CC V = 5V CC –25 –15 –0.2 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 –0.05 0 0.05 0.10 0.15 0.20 TIME (ms) TIME (ms) Figure 10. Input Offset Voltage vs. Turn-On Time, Filter = 500 Hz Figure 13. Input Offset Voltage vs. Turn-On Time, Filter = 10 kHz 1000 100 GAIN = 160 GAIN = 80 10 1 0.01 0.1 1 10 100 1k 10k 100k TIME (10s/DIV) FREQUENCY (Hz) Figure 14. 0.01 Hz to 10 Hz Voltage Noise Figure 11. Voltage Noise Density 160 0.30 V = 2.7V, 5V CC G = 80, 160 0.25 140 GAIN = 160 0.20 120 0.15 10kHz FILTER 100 0.10 GAIN = 80 0.05 80 0 60 –0.05 500Hz FILTER 40 –0.10 500Hz FILTER 10kHz FILTER 20 –0.15 10 100 1k 10k 100k 1ms/DIV FREQUENCY (Hz) Figure 15. Small Signal Step Response Figure 12. Power Supply Rejection (PSR) vs. Frequency Rev. 0 | Page 8 of 16 INPUT OFFSET VOLTAGE (5mV/DIV) PSR (dB) NOISE (nV/ Hz) 07451-009 07451-024 07451-010 INPUT OFFSET VOLTAGE (5mV/DIV) 50mV/DIV VOLTAGE NOISE (200nV/DIV) 07451-025 07451-011 07451-012 AD8293G80/AD8293G160 V = 2.7V V = 5V CC CC G = 80, 160 G = 80, 160 10kHz FILTER 10kHz FILTER 500Hz FILTER 500Hz FILTER 1ms/DIV 1ms/DIV Figure 16. Large Signal Step Response Figure 17. Large Signal Step Response Rev. 0 | Page 9 of 16 500mV/DIV 07451-013 1V/DIV 07451-017 AD8293G80/AD8293G160 THEORY OF OPERATION The AD8293G80/AD8293G160 are precision current-mode HIGH PSR AND CMR correction instrumentation amplifiers capable of single-supply Common-mode rejection and power supply rejection indicate operation. The current-mode correction topology results in the amount that the offset voltage of an amplifier changes when excellent accuracy. Figure 18 shows a simplified diagram its common-mode input voltage or power supply voltage changes. illustrating the basic operation of the AD8293G80/AD8293G160 The autocorrection architecture of the AD8293G80/AD8293G160 (without correction). The circuit consists of a voltage-to-current continuously corrects for offset errors, including those induced amplifier (M1 to M6), followed by a current-to-voltage amplifier by changes in input or supply voltage, resulting in exceptional (R2 and A1). Application of a differential input voltage forces a rejection performance. The continuous autocorrection provides current through External Resistor R1, resulting in conversion of great CMR and PSR performances over the entire operating the input voltage to a signal current. Transistor M3 to Transistor temperature range (−40°C to +85°C). M6 transfer twice this signal current to the inverting input of The parasitic resistance in series with R2 does not degrade CMR, the op amp A1. Amplifier A1 and External Resistor R2 form but causes a small gain error and a very small offset error. a current-to-voltage converter to produce a rail-to-rail output Therefore, an external buffer amplifier is not required to drive voltage at V . OUT VREF to maintain excellent CMR performance. This helps reduce Op amp A1 is a high precision auto-zero amplifier. This amplifier system costs over conventional instrumentation amplifiers. preserves the performance of the autocorrecting, current-mode 1/f NOISE CORRECTION amplifier topology while offering the user a true voltage-in, voltage-out instrumentation amplifier. Offset errors are corrected Flicker noise, also known as 1/f noise, is noise inherent in the internally. physics of semiconductor devices and decreases 10 dB per decade. The 1/f corner frequency of an amplifier is the frequency at which An external reference voltage is applied to the noninverting the flicker noise is equal to the broadband noise of the amplifier. At input of A1 to set the output reference level. External Capacitor lower frequencies, flicker noise dominates, causing large errors C2 is used to filter out correction noise. in low frequency or dc applications. Flicker noise is seen effectively as a slowly varying offset error, which is reduced by the autocorrection topology of the AD8293G80/AD8293G160. This allows the AD8293G80/ AD8293G160 to have lower noise near dc than standard low noise instrumentation amplifiers. V CC C2 2R2 M5 M6 II R2 V – V V = V + INP INN OUT REF R1 R1 I – I R1 2I R1 I – I R1 R3 I + I R1 (V – V ) INP INN I = C3 R1 A1 R1 V BIAS V REF V V INP INN M3 M4 M1 M2 2I 2I EXTERNAL Figure 18. Simplified Schematic Rev. 0 | Page 10 of 16 07451-020 AD8293G80/AD8293G160 APPLICATIONS INFORMATION +5V OVERVIEW C2 The AD8293G80/AD8293G160 reduce board area by integrating 0.1µF OUTPUT filter components, such as Resistors R1, R2, and R3, as shown in 7 5 6 Figure 19. Two outputs are available to the user: OUT (Pin 6) and +V FILT OUT S ADC OUT (Pin 4). The difference between the two is the inclusion R2 +IN of a series 5 kΩ resistor at ADC OUT. With the addition of an 8 R3 external capacitor, C3, ADC OUT forms a second filter, comprising 5kΩ R1 4 IN-AMP 4kΩ of the 5 kΩ resistor and C3, which can be used as an ADC anti- ADC OUT –IN aliasing filter. In contrast, OUT is the direct output of the instru- 1 mentation amplifier. When using the antialiasing filter, there is AD8293Gxx GND REF slightly less switching ripple at ADC OUT than when obtaining 2 3 the signal directly from OUT. 0.1µF 1µF VOLTAGE +5V REFERENCE C2 680pF 0.1µF 0.1µF 7 5 6 Figure 20. Operating on a Single Supply Using an External Voltage Reference +V FILT OUT S (The Output Can Be Used Without an Antialiasing Filter if the Signal Bandwidth Is <10 Hz) R2 +IN 320kΩ OUTPUT TO ADC 8 WITH ANTIALIASING R3 OUTPUT FILTERING FILTER 5kΩ R1 IN-AMP 4 4kΩ ADC OUT C3 The output of the AD8293G80/AD8293G160 can be filtered to –IN 39nF 1 reduce switching ripple. Two filters can be used in conjunction to set the filter frequency. In the example that follows, two 700 Hz AD8293G160 GND REF 2 3 +5V filters are used in conjunction to form a 500 Hz (recommended) bandwidth. Because the filter resistors are integrated in the 100kΩ 100kΩ 0.1µF AD8293G80/AD8293G160, only external capacitors are needed to set the filter frequencies. Figure 19. AD8293G160 with Antialiasing Filter and Level-Shifted Output The primary filter is needed to limit the amount of switching (Using the Resistor Divider at the REF Pin, the Output Is Biased at 2.5 V) noise at the output. Regardless of the output that is being used, REFERENCE CONNECTION OUT or ADC OUT, the primary filter comprising R2 and C2 Unlike traditional 3-op-amp instrumentation amplifiers, parasitic must be implemented. The R2 value depends on the model; Table 7 resistance in series with REF (Pin 3) does not degrade CMR shows the R2 value for each model. performance. The AD8293G80/AD8293G160 can attain extremely Table 7. Internal R2 Values high CMR performance without the use of an external buffer Model R2 (kΩ) amplifier to drive the REF pin, which is required by industry- AD8293G80 160 standard instrumentation amplifiers. Reducing the need for AD8293G160 320 buffer amplifiers to drive the REF pin helps to save valuable printed circuit board (PCB) space and minimizes system costs. The following equation results in the C2 value needed to set a For optimal performance in single-supply applications, REF 700 Hz primary filter. For a gain of 160, substitute R2 with should be set with a low noise precision voltage reference, such 320 kΩ; for a gain of 80, substitute R2 with 160 kΩ. as the ADR44x (see Figure 20). However, for a lower system cost, the reference voltage can be set with a simple resistor voltage C2 = 1/(700 × 2 × π × R2) divider between the supply and GND (see Figure 19). This Adding an external capacitor, C3, and measuring the output from configuration results in degraded output offset performance if ADC OUT further reduces the correction ripple. The internal the resistors deviate from their ideal values. In dual-supply 5 kΩ resistor, labeled R3 in Figure 18, forms a low-pass filter applications, VREF can simply be connected to GND. with C3. This low-pass filter is the secondary filter. Set to The REF pin current is approximately 10 pA, and as a result, an 700 Hz, the secondary filter equation for C3 is as follows: external buffer is not required. C3 = 1/(700 × 2 × π × 5 kΩ) Rev. 0 | Page 11 of 16 07451-021 07451-022 AD8293G80/AD8293G160 The addition of another single pole of 700 Hz on the output POWER SUPPLY BYPASSING (from the secondary filter in Figure 18) is required for bandwidths The AD8293G80/AD8293G160 use internally generated clock greater than 10 Hz. These two filters, together, produce an overall signals to perform autocorrection. As a result, proper bypassing bandwidth of 500 Hz. The internal resistors, R2 and R3, have an is necessary to achieve optimum performance. Inadequate or absolute tolerance of 20%. Table 8 lists the standard capacitors improper bypassing of the supply lines can lead to excessive needed to create a filter with an overall bandwidth of 500 Hz. noise and offset voltage. Table 8. Standard Capacitors Used to Form a Filter with an A 0.1 μF surface-mount capacitor should be connected between Overall Bandwidth of 500 Hz the supply lines. This capacitor is necessary to minimize ripple Model C2 (pF) C3 (nF) from the correction clocks inside the IC. For dual-supply operation, a 0.1 μF (ceramic) surface-mount capacitor should be connected AD8293G80 1300 39 from each supply pin to GND. AD8293G160 680 39 For single-supply operation, a 0.1 μF surface-mount capacitor For applications with low bandwidths (<10 Hz), only the primary should be connected from the supply line to GND. filter is required. In such an event, the high frequency noise All bypass capacitors should be positioned as close to the DUT from the auto-zero amplifier (output amplifier) is not filtered supply pins as possible, especially the bypass capacitor between before the following stage. the supplies. Placement of the bypass capacitor on the back of CLOCK FEEDTHROUGH the board directly under the DUT is preferred. The AD8293G80/AD8293G160 use two synchronized clocks INPUT OVERVOLTAGE PROTECTION to perform the autocorrection. The input voltage-to-current All terminals of the AD8293G80/AD8293G160 are protected amplifiers are corrected at 60 kHz. against ESD. In the case of a dc overload voltage beyond either Trace amounts of these clock frequencies can be observed at supply, a large current would flow directly through the ESD the OUT pin. The amount of visible correction feedthrough protection diodes. If such a condition can occur, an external resistor is dependent on the values of the filters set by R2/C2. Use should be used in series with the inputs to limit current for voltages ADC OUT to create a filter using R3/C3 to further reduce beyond the supply rails. The AD8293G80/AD8293G160 can safely correction feedthrough as described in the Output Filtering handle 5 mA of continuous current, resulting in an external section. resistor selection of REXT = (VIN − VS)/5 mA +5V C2 1.3nF 0.1µF 7 5 6 +V FILT OUT S LOAD R2 +IN 160kΩ 8 R3 5kΩ R1 I R 4 ADC IN-AMP SHUNT 4kΩ ADC OUT C3 39nF –IN REF 1 +3.3V 1.8V GND REF AD8293G80 DC-DC 0.1µF 10µF 2 3 Figure 21. Measuring Current Through a Shunt Resistor (Filter Is Set to 500 Hz) Rev. 0 | Page 12 of 16 07451-023 AD8293G80/AD8293G160 OUTLINE DIMENSIONS 2.90 BSC 8 7 6 5 1.60 BSC 2.80 BSC 13 2 4 PIN 1 INDICATOR 0.65 BSC 1.95 1.30 BSC 1.15 0.90 1.45 MAX 0.22 0.08 0.60 8° 0.38 0.45 0.15 MAX 4° SEATING 0.30 0.22 0° PLANE COMPLIANT TO JEDEC STANDARDS MO-178-BA Figure 22. 8-Lead Small Outline Transistor Package [SOT-23] (RJ-8) Dimensions shown in millimeters ORDERING GUIDE Model Gain Temperature Range Package Description Package Option Branding 1 AD8293G80ARJZ-R2 80 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1H 1 AD8293G80ARJZ-R7 80 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1H 1 AD8293G80ARJZ-RL 80 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1H 1 AD8293G80BRJZ-R2 80 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1N 1 AD8293G80BRJZ-R7 80 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1N 1 AD8293G80BRJZ-RL 80 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1N 1 AD8293G160ARJZ-R2 160 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y11 1 AD8293G160ARJZ-R7 160 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y11 1 AD8293G160ARJZ-RL 160 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y11 1 AD8293G160BRJZ-R2 160 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1K 1 AD8293G160BRJZ-R7 160 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1K 1 AD8293G160BRJZ-RL 160 −40°C to +85°C 8-Lead SOT-23 RJ-8 Y1K 1 Z = RoHS Compliant Part. Rev. 0 | Page 13 of 16 AD8293G80/AD8293G160 NOTES Rev. 0 | Page 14 of 16 AD8293G80/AD8293G160 NOTES Rev. 0 | Page 15 of 16 AD8293G80/AD8293G160 NOTES ©2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D07451-0-8/08(0) Rev. 0 | Page 16 of 16