AD8202_05 AD | Alldatasheet
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Rev. D | Page 2 of 20 TABLE OF CONTENTS High Line Current Sensing with LPF and Gain Adjustment 16
REVISION HISTORY
11/05—Rev. C to Rev. D 2/05—Rev. B to Rev. C 1/05—Rev. A to Rev. B 11/04—Rev. 0 to Rev. A 7/04—Revision 0: Initial Version
Rev. D | Page 3 of 20 SPECIFICATIONS SINGLE SUPPLY TA = operating temperature range, VS = 5 V , unless otherwise noted. Table 1. AD8202 SOIC AD8202 MSOP AD8202 Die Parameter Conditions Min Typ Max Min Typ Max Min Typ Max Unit S Y S T E M G A I N Initial 20 20 20 V/V vs. Temperature 1 20 1 25 1 30 ppm/°C V O L T A G E O F F S E T Input Offset (RTI) VCM = 0.15 V; 25°C −1 +1 −2 +2 −1 +1 mV vs. Temperature −40°C to +125°C −10 +0.3 +10 −20 +2 +20 −10 +0.3 +10 μV/°C I N P U T I n p u t I m p e d a n c e Differential 260 325 390 260 325 390 260 325 390 kΩ Common Mode 135 170 205 135 170 205 135 170 205 kΩ CMV Continuous −8 +28 −8 +28 −8 +28 V CMRR1 VCM = −8 V to +28 V f = dc 82 82 82 dB f = 1 kHz 82 82 82 dB f = 10 kHz2 80 80 80 dB PREAMPLIFIER Gain 10 10 10 V/V Output Resistance 97 100 103 97 100 103 97 100 103 kΩ OUTPUT BUFFER Gain 2 2 2 V/V Input Bias Current 40 40 40 nA Output Resistance 2 2 2 Ω D Y N A M I C R E S P O N S E System Bandwidth VIN = 0.1 V p-p; VOUT = 2.0 V p-p 30 50 30 50 30 50 kHz Slew Rate VIN = 0.2 V dc; VOUT = 4 V step 0.28 0.28 0.28 V/μs N O I S E
0.1 Hz to 10 Hz 10 10 10 μV p-p
Spectral Density, 1 kHz (RTI) 275 275 275 nV/√Hz POWER SUPPLY Operating Range 3.5 12 3.5 12 3.5 12 V Quiescent Current vs. Temperature PSRR VS = 3.5 V to 12 V 75 83 75 83 75 83 dB T E M P E R A T U R E R A N G E For Specified Performance −40 +125 −40 +125 −40 +150 °C 1 Source imbalance <2 Ω. 2 The AD8202 preamplifier exceeds 80 dB CMRR at 10 kHz. However, because the signal is available only by way of a 100 kΩ resistor, even the small amount of pin-to- pin capacitance between Pin 1, Pin 8 and Pin 3, Pin 4 might couple an input common-mode signal larger than the greatly attenuated preamplifier output. The effect of pin-to-pin coupling can be neglected in all applications by using filter capacitors at Node 3.
Rev. D | Page 4 of 20 ABSOLUTE MAXIMUM RATINGS Table 2. Parameter Rating Supply Voltage 12.5 V Transient Input Voltage (400 ms) 44 V Continuous Input Voltage (Common Mode) 35 V Reversed Supply Voltage Protection 0.3 V Operating Temperature Range Die −40°C to +150°C SOIC −40°C to +125°C MSOP −40°C to +125°C Storage Temperature −65°C to +150°C Output Short-Circuit Duration Indefinite Lead Temperature Range (Soldering, 10 sec) 300°C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ESD CAUTION ESD (electrostatic discharge) sensitive device. Electros tatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge wi thout detection. Although this product features proprietary ESD protection circuitry, permanent dama ge may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD pr ecautions are recommended to avoid performance degradation or loss of functionality.
Figure 4. Pin Configuration Table 3. Pin Function Descriptions
7 NC NA NA
Figure 5. Metallization Photograph
in Figure 40. Like-named resistors have equal values. The preamp uses a dynamic bridge (subtractor) circuit. (that is, 0), the two attenuators form a balanced-bridge network. A1, and thus its output, is 0. rejection approaches this ideal state. input until it matches the voltage at its noninverting input. input levels exceed the supply or fall below common (ground). tial inputs. The resistor ratios establish the preamp gain at 10. offset voltage and noise with respect to Pin 1 and Pin 8. Figure 40. Simplified Schematic voltages more negative than the power supply. ratio-trimmed for high accuracy. A2, implemented with carefully matched feedback resistors (RF). the resistance are correspondingly small. current increases (see Figure 41 for more information).
Figure 41. A2 Input Bias Current vs. Input Voltage and Temperature. The Shaded Area is the Bias Current from +125°C to −40°C.
- Amplifier A1 output saturation potential can drop as low as 20 mV at its output.
- A2 typical input bias current of 40 nA multiplied by the 100 kΩ preamplifier output resistor produces 40 nA × 100 kΩ = 4 mV at the A2 input
- Total voltage at the A2 input equals the output saturation voltage of A1 combined with the voltage error generated by the input bias current 20 mV + 4 mV = 24 mV
- The total error at the input of A2, 24 mV, multiplied by the buffer gain generates a resulting error of 48 mV at the output of the buffer. This is AD8202 system output low saturation potential.
- The high output voltage range of the AD8202 is specified as 4.8 V. Therefore, assuming a typical A2 input bias current, the output voltage range for the AD8202 is 48 mV to 4.8 V. For an example of the effect of changes in A2 input bias current vs. applied input potentials, see Figure 41. The change in bias current causes a change in error voltage at the input of the buffer amplifier. This results in a change in overall error potential at the output of the buffer amplifier.
Rev. D | Page 14 of 20
APPLICATIONS
The AD8202 difference amplifier is intended for applications that require extracting a small differential signal in the presence of large common-mode voltages. The differential input resistance is nominally 325 kΩ, and the device can tolerate common-mode voltages higher than the supply voltage and lower than ground. The open collector output stage sources current to within 20 mV of ground and to within 200 mV of VS. CURRENT SENSING High Line, High Current Sensing Basic automotive applications using the large common-mode range are shown in Figure 2 and Figure 3. The capability of the device to operate as an amplifier in primary battery supply circuits is shown in Figure 2; Figure 3 illustrates the ability of the device to withstand voltages below system ground. Low Current Sensing The AD8202 is also used in low current sensing applications, such as the 4 to 20 mA current loop shown in Figure 42. In such applications, the relatively large shunt resistor can degrade the common-mode rejection. Adding a resistor of equal value on the low impedance side of the input corrects for this error. OUTPUT 10Ω 10Ω NC = NO CONNECT GND NC –IN +IN +VS OUT AD8202 04981-015 Figure 42. 4 to 20 mA Current Loop Receiver lowered, raised, or finely calibrated.
2 GAIN =
Figure 43. Adjusting for Gains Less than 20 to the imbalance in source resistances at the input to the buffer. use in high gain, dc-coupled applications. Figure 44. Adjusting for Gains > 20
Figure 52. 8-Lead Standard Small Outline Package [SOIC_N]
0.65 BSC
1.10 MAX
Figure 53. 8-Lead Mini Small Outline Package [MSOP]
Rev. D | Page 18 of 20 NOTES
Rev. D | Page 19 of 20 NOTES
Rev. D | Page 20 of 20 NOTES © 2005 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D04981-0-11/05(D)