INA INA282-Q1 28x www.ti.com SBOS554 – MARCH 2012 High-Accuracy, Wide Common-Mode Range, Bi-Directional CURRENT SHUNT MONITOR Zerø-Drift Series Check for Samples: INA282-Q1 FEATURES DESCRIPTION • • The INA282-Q1 is a voltage output current shunt monitor that can sense drops across shunts at common-mode voltages from –14V to +80V, independent of the supply voltage. The low offset of the Zerø-Drift architecture enables current sensing with maximum drops across the shunt as low as 10mV full-scale. 1 2 • • • • • • Qualified for Automotive Applications AEC-Q100 Qualified With the Following Results – Device Temperature Grade 1: –40°C to +125°C Ambient Operating Temperature Range – Device HBM ESD Classification Level H2 – Device CDM ESD Classification Level C3B Wide Common-Mode Range: –14V to 80V Offset Voltage: ±20 μV CMRR: 140 dB Accuracy: – ±1.4% Gain Error (Max) – 0.3μV/°C Offset Drift – 0.005%/°C Gain Drift (Max) Available Gains: – 50V/V: INA282 – 100V/V: INA286 – 200V/V: INA283 – 500V/V: INA284 – 1000V/V: INA285 Quiescent Current: 900 μA (Max) This current shunt monitor operates from a single +2.7V to +18V supply, drawing a maximum of 900μA of supply current. It is specified over the extended operating temperature range of –40°C to +125°C, and offered in an SOIC-8 package. Supply -14V to +80V Load +2.7V to +18V +IN 1 V+ -IN Æ2 Æ2 Æ2 Æ2 1 Æ1 APPLICATIONS • • • • Telecom Equipment Automotive Power Management Solar Inverters Æ1 OUT ZerÆDrift GAIN PRODUCT 50V/V 100V/V 200V/V 500V/V 1000V/V INA282 INA286 INA283 INA284 INA285 33.3kW 33.3kW Output REF2 REF1 GND 1 2 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2012, Texas Instruments Incorporated INA282-Q1 SBOS554 – MARCH 2012 www.ti.com This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. PACKAGE/ORDERING INFORMATION (1) PRODUCT INA282AQDRQ1 INA282AQDRDN (1) GAIN PACKAGE PACKAGE DESIGNATOR 50V/V SOIC-8 D PACKAGE MARKING 282Q1 282DN For the most current package and ordering information, see the Package Option Addendum located at the end of this data sheet, or see the device product folder at www.ti.com. ABSOLUTE MAXIMUM RATINGS (1) Over operating free-air temperature range, unless otherwise noted. VALUE MIN MAX Supply voltage Analog inputs, V+IN, V–IN (2) Differential (V+IN) – (V–IN) (3) Common-Mode Ref1, Ref2, Out (1) (2) (3) V –5 5 V 80 V GND–0.3 (V+) + 0.3 V 5 mA –65 150 °C Junction temperature ESD ratings 18 –14 Input current into any pin Storage temperature UNIT Human Body Model (HBM) AEC-Q100 Classification Level H2 Charged-Device Model (CDM) AEC-Q100 Classification Level C3B 150 °C 2 kV 750 V Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those specified is not implied. V+IN and V–IN are the voltages at the +IN and –IN pins, respectively. Input voltages must not exceed common-mode rating. THERMAL INFORMATION THERMAL METRIC (1) INA282-Q1 D (8-PINS) θJA Junction-to-ambient thermal resistance 134.9 θJCtop Junction-to-case (top) thermal resistance 72.9 θJB Junction-to-board thermal resistance 61.3 ψJT Junction-to-top characterization parameter 18.9 ψJB Junction-to-board characterization parameter 54.3 θJCbot Junction-to-case (bottom) thermal resistance n/a (1) 2 UNITS °C/W For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 INA282-Q1 www.ti.com SBOS554 – MARCH 2012 ELECTRICAL CHARACTERISTICS Boldface limits apply over the specified temperature range, TA = –40°C to 125°C. At TA = +25°C, V+ = 5V, V+IN = 12V, VREF1 = VREF2 = 2.048V referenced to GND, and VSENSE = V+IN – V–IN, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNIT INPUT Offset Voltage, RTI (1) VOS vs Temperature dVOS/dT vs Power Supply PSRR Common-Mode Input Range Common-Mode Rejection Input Bias Current per Pin (2) Input Offset Current VSENSE = 0mV VS = +2.7V to +18V, VSENSE = 0mV VCM CMRR ±20 ±70 μV ±0.3 ±1.5 μV/°C V+IN = –14V to +80V, VSENSE = 0mV μV/V 3 –14 120 80 V 140 dB IB VSENSE = 0mV 25 μA IOS VSENSE = 0mV 1 μA 6 kΩ Differential Input Impedance REFERENCE INPUTS Reference Input Gain 1 Reference Input Voltage Range (3) 0 Divider Accuracy (4) Reference Voltage Rejection Ratio VREF1 = VREF2 = 40mV to 9V, V+ = 18V vs Temperature V ±0.2 ±0.5 % ±25 ±75 μV/V μV/V/°C 0.055 GND + 0.5V ≤ VOUT ≤ (V+) – 0.5V; VREF1 = VREF2 = (V+)/2 for all devices GAIN (5) Gain V/V VGND + 9 G V+ = +5V 50 Gain Error vs Temperature V/V ±0.4 ±1.4 % 0.0008 0.005 %/°C OUTPUT Nonlinearity Error ±0.01 Output Impedance 1.5 Ω 1 nF Maximum Capacitive Load No sustained oscillation VOLTAGE OUTPUT (6) % RL = 10kΩ to GND Swing to V+ Power-Supply Rail V+ = 5V Swing to GND (V+)–0.17 (V+)–0.4 V GND+0.015 GND+0.04 V FREQUENCY RESPONSE Effective Bandwidth (7) BW 10 kHz 110 nV/√Hz NOISE, RTI (1) Voltage Noise Density 1kHz POWER SUPPLY Specified Voltage Range Quiescent Current VS +2.7 IQ 600 +18 V 900 μA +125 °C TEMPERATURE RANGE Specified Range (1) (2) (3) (4) (5) (6) (7) –40 RTI = referred-to-input. See typical characteristic graph Figure 20 . The average of the voltage on pins REF1 and REF2 must be between VGND and the lesser of (VGND+9V) and V+. Reference divider accuracy specifies the match between the reference divider resistors using the configuration in Figure 37. See typical characteristic graph Figure 25. See typical characteristic graphs Figure 29 through Figure 31. See typical characteristic graph Figure 15 and the Effective Bandwidth section in the Applications Information. Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 3 INA282-Q1 SBOS554 – MARCH 2012 www.ti.com PIN CONFIGURATION D PACKAGE SOIC-8 (TOP VIEW) -IN 1 8 +IN GND 2 7 REF1 REF2 3 6 V+ (1) 4 5 OUT NC (1) NC: This pin is not internally connected. The NC pin should either be left floating or connected to GND. PIN DESCRIPTIONS SOIC-8 PIN NO. 4 NAME DESCRIPTION 1 –IN 2 GND Connection to negative side of shunt resistor. Ground 3 REF2 Reference voltage connection - See application section for connection options. 4 NC 5 OUT This pin is not internally connected. The NC pin should either be left floating or connected to GND. Output voltage 6 V+ Power supply 7 REF1 8 +IN Reference voltage connection - See application section for connection options. Connection to positive side of shunt resistor. Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 INA282-Q1 www.ti.com SBOS554 – MARCH 2012 TYPICAL CHARACTERISTICS At TA = +25°C, V+ = 5V, V+IN = 12V, VREF1 = VREF2 = 2.048V referenced to GND, and VSENSE = V+IN – V–IN, unless otherwise noted. START-UP TRANSIENT RESPONSE START-UP TRANSIENT RESPONSE VREF = GND, VDRIVE = 0.125V, RLOAD = 10kW, CLOAD = 10pF CLOAD = 10pF VREF = GND VDRIVE = 0.125V RLOAD = 10kW 5V/div V+ V+ 25ms/div 250ms/div Figure 1. Figure 2. 12V COMMON-MODE STEP RESPONSE 12V COMMON-MODE STEP RESPONSE 500mV/div 500mV/div 5V/div VOUT 500mV/div 500mV/div VOUT VOUT VOUT 5V/div VCM 2.5ms/div 2.5ms/div Figure 3. Figure 4. 12V COMMON-MODE STEP RESPONSE 12V COMMON-MODE STEP RESPONSE 500mV/div 500mV/div 5V/div VCM VOUT VOUT 5V/div 5V/div VCM VCM 2.5ms/div 2.5ms/div Figure 5. Figure 6. Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 5 INA282-Q1 SBOS554 – MARCH 2012 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, V+ = 5V, V+IN = 12V, VREF1 = VREF2 = 2.048V referenced to GND, and VSENSE = V+IN – V–IN, unless otherwise noted. VOUT VCM 10V/div 500mV/div VOUT 10V/div 50V COMMON-MODE STEP RESPONSE 500mV/div 50V COMMON-MODE STEP RESPONSE VCM 5ms/div 100mV STEP RESPONSE 500mV STEP RESPONSE 20mV/div 100mV/div Figure 8. 10ms/div 10ms/div Figure 9. Figure 10. 4V STEP RESPONSE 17V STEP RESPONSE 5V/div 1V/div 6 5ms/div Figure 7. 25ms/div 25ms/div Figure 11. Figure 12. Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 INA282-Q1 www.ti.com SBOS554 – MARCH 2012 TYPICAL CHARACTERISTICS (continued) At TA = +25°C, V+ = 5V, V+IN = 12V, VREF1 = VREF2 = 2.048V referenced to GND, and VSENSE = V+IN – V–IN, unless otherwise noted. INA282 PSRR (RTI) vs FREQUENCY INPUT OVERLOAD 120 Power-Supply Rejection Ratio (dB) Input Drive (1V to 0V) 1V/div VOUT (5V to midsupply) 110 100 90 80 70 60 50 40 30 20 25ms/div 100 1k 10k 100k 1M Frequency (Hz) Figure 13. Figure 14. GAIN vs FREQUENCY INA284 COMMON-MODE REJECTION RATIO (RTI) 150 Common-Mode Rejectio Ratio (dB) 60 50 Gain (dB) 40 30 20 10 INA282 (50V/V) INA285 (1kV/V) INA284 (500V/V) INA283 (200V/V) INA286 (100V/V) 0 -10 140 130 120 110 100 90 80 70 -20 10 100 1k 10k 100k 1 1M 10 1k 10k Figure 15. Figure 16. INA282 COMMON-MODE SLEW RATE INDUCED OFFSET INA286 OUTPUT IMPEDANCE vs FREQUENCY 0.1 100k 1k 0.01 100 0.001 ROUT (W) VOS, Referred-to-Input (V) 100 Frequency (Hz) Frequency (Hz) 0.0001 10 1 0.00001 0.000001 0.1 1k 10k 100k 1M 10 100 1k 10k 100k 1M Frequency (Hz) VCM Slew Rate (V/sec) Figure 17. Figure 18. Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 7 INA282-Q1 SBOS554 – MARCH 2012 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, V+ = 5V, V+IN = 12V, VREF1 = VREF2 = 2.048V referenced to GND, and VSENSE = V+IN – V–IN, unless otherwise noted. INA282 TYPICAL NONLINEARITY vs OUTPUT VOLTAGE INA283 +IN BIAS CURRENT vs COMMON-MODE VOLTAGE 30 0.06 VSENSE = -50mV to +50mV 20 +IN Bias Current (mA) Nonlinearity (%) 0.04 0.02 0 V+ = 18V -0.02 V+ = 3.5V -0.04 V+ = 18V 0 -10 -20 -30 -40 -0.06 0 3 6 9 12 15 -20 -10 18 0 10 800 800 Quiescent Current (mA) Quiescent Current (mA) 60 QUIESCENT CURRENT vs SUPPLY VOLTAGE V+ = 18V 700 650 V+ = 5V 550 500 70 80 700 600 500 400 300 200 100 V+ = 2.7V 0 400 0 -20 20 40 60 80 4 2 6 8 Common-Mode Voltage (V) 10 12 14 16 18 Supply Voltage (V) Figure 21. Figure 22. COMMON-MODE REJECTION RATIO vs TEMPERATURE QUIESCENT CURRENT vs TEMPERATURE 170 980 160 880 V+ = 12V 150 Quiescent Current (mA) Common-Mode Rejection Ratio (dB) 50 INA283 QUIESCENT CURRENT vs COMMON-MODE VOLTAGE 900 450 40 Figure 20. 850 600 30 Figure 19. 900 750 20 Common-Mode Voltage (V) VOUT (V) 140 130 120 V+ = 5V 110 100 90 V+ = 18V 780 V+ = 5V 680 580 480 380 V+ = 2.7V 280 180 80 80 -75 -50 -25 0 25 50 75 100 125 150 -75 Temperature (°C) -50 -25 0 25 50 75 100 125 150 Temperature (°C) Figure 23. 8 V+ = 5V V+ = 2.7V 10 Figure 24. Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 INA282-Q1 www.ti.com SBOS554 – MARCH 2012 TYPICAL CHARACTERISTICS (continued) At TA = +25°C, V+ = 5V, V+IN = 12V, VREF1 = VREF2 = 2.048V referenced to GND, and VSENSE = V+IN – V–IN, unless otherwise noted. +IN BIAS CURRENT vs TEMPERATURE GAIN vs TEMPERATURE 0 1.0 0.8 -5 0.4 +IN Bias Current (mA) Deviation in Gain (%) 0.6 V+ = 5V 0.2 0 -0.2 V+ = 12V -0.4 -0.6 -10 V+ = 2.7V -15 -20 V+ = 5V -25 V+ = 18V -30 -0.8 -35 -1.0 -40 VCM = 0V -75 -50 -25 0 25 75 50 100 125 150 -75 -50 0 -25 25 50 75 100 125 150 Temperature (°C) Temperature (°C) Figure 25. Figure 26. INA282 VOLTAGE NOISE vs FREQUENCY Voltage Noise, RTO (mV/ÖHz) 6.0 0.12 5.5 0.11 5.0 0.10 4.5 0.09 4.0 0.08 3.5 0.07 3.0 100 Time (1s/div) 1k Voltage Noise, RTI (mV/ÖHz) Voltage Noise, RTI (200nV/div) INA282 0.1Hz TO 10Hz VOLTAGE NOISE, RTI 0.06 100k 10k Frequency (Hz) Figure 27. Figure 28. INA284 SWING TO RAIL WITH SHORT-CIRCUIT CURRENT Source 2.7V ISC = 3.4mA VOUT, Sinking (V) 14 12 -2 700 -4 -6 Source 18V ISC = 5.8mA 10 800 Sink 18V ISC = 8.6mA -8 8 -10 6 -12 Sink 2.7V ISC = 6.2mA 4 -14 Sink 5V ISC = 8.2mA 2 0 0 1 2 3 4 5 6 7 8 9 10 -16 -18 VDROP from Rail, Sourcing (V) Source 5V ISC = 5.2mA 16 INA283 SWING TO RAIL vs OUTPUT CURRENT 0 Swing to Rail (mV) 18 +25°C +85°C +125°C 600 500 400 -40°C 300 200 2.7V Swing 5V Swing 100 0 0 IOUT (mA) 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 IOUT, Sourcing (mA) Figure 29. Figure 30. Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 9 INA282-Q1 SBOS554 – MARCH 2012 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, V+ = 5V, V+IN = 12V, VREF1 = VREF2 = 2.048V referenced to GND, and VSENSE = V+IN – V–IN, unless otherwise noted. INA283 SWING TO GROUND vs OUTPUT CURRENT 400 Swing to Ground (mV) 350 300 250 +125°C 200 150 100 2.7V Swing 5V Swing 18V Swing +85°C 50 +25°C 0 0 0.5 -40°C 1.0 1.5 2.0 2.5 IOUT, Sinking (mA) Figure 31. 10 Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 INA282-Q1 www.ti.com SBOS554 – MARCH 2012 APPLICATIONS INFORMATION GENERAL INFORMATION The INA282-Q1 voltage output current shunt monitor features a common-mode range that extends 14V below the negative supply rail, as well as up to 80V, which allows use for either low-side or high-side current sensing. BASIC CONNECTIONS Figure 32 shows the basic connection of an INA282-Q1. The input pins, +IN and –IN, should be connected as closely as possible to the shunt resistor to minimize any resistance in series with the shunt resistance. Supply -14V to +80V Load +2.7V to +18V +IN 1 V+ -IN Æ2 Æ2 Æ2 Æ1 Æ2 1 Æ1 OUT ZerÆDrift GAIN PRODUCT 50V/V 100V/V 200V/V 500V/V 1000V/V INA282 INA286 INA283 INA284 INA285 33.3kW 33.3kW Output REF2 REF1 GND Figure 32. Typical Application Power-supply bypass capacitors are required for stability. Applications with noisy or high-impedance power supplies may require additional decoupling capacitors to reject power-supply noise. Connect bypass capacitors close to the device pins. POWER SUPPLY The INA282-Q1 can make accurate measurements well outside of its own power-supply voltage, V+, because its inputs (+IN and –IN) may operate anywhere between –14V and +80V independent of V+. For example, the V+ power supply can be 5V while the common-mode voltage being monitored by the shunt may be as high as +80V. Of course, the output voltage range of the INA282-Q1 is constrained by the supply voltage that powers it on V+. Note that when the power to the INA282-Q1 is off (that is, no voltage is supplied to the V+ pin), the input pins (+IN and –IN) are high impedance with respect to ground and typically leak less than ±1μA over the full commonmode range of –14V to +80V Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 11 INA282-Q1 SBOS554 – MARCH 2012 www.ti.com SELECTING RS The Zerø-Drift architecture of the INA282-Q1 enables use with full-scale range shunt voltages as low as 10mV. EFFECTIVE BANDWIDTH The extremely high dc CMRR of the INA282-Q1 results from the switched capacitor input structure. Because of this architecture, the INA28x exhibits discrete time system behaviors as illustrated in the gain versus frequency graph of Figure 16 and the step response curves of Figure 3 through Figure 10. The response to a step input depends somewhat on the phase of the internal INA28x clock when the input step occurs. It is possible to overload the input amplifier with a rapid change in input common-mode voltage (see Figure 17). Errors as a result of common-mode voltage steps and/or overload situations typically disappear within 15μs after the disturbance is removed. TRANSIENT PROTECTION The –14V to +80V common-mode range of the INA282-Q1 is ideal for withstanding automotive fault conditions that range from 12V battery reversal up to +80V transients; no additional protective components are needed up to those levels. In the event that the INA282-Q1 is exposed to transients on the inputs in excess of its ratings, then external transient absorption with semiconductor transient absorbers (Zener or Transzorbs) will be necessary. Use of MOVs or VDRs is not recommended except when they are used in addition to a semiconductor transient absorber. Select the transient absorber such that it cannot allow the INA282-Q1 to be exposed to transients greater than 80V (that is, allow for transient absorber tolerance, as well as additional voltage as a result of transient absorber dynamic impedance). Despite the use of internal zener-type electrostatic discharge (ESD) protection, the INA282-Q1 does not lend itself to using external resistors in series with the inputs without degrading gain accuracy. SHUTDOWN While the INA282-Q1 does not provide a shutdown pin, the quiescent current of 600μA enables it to be powered from the output of a logic gate. Take the gate low to shut down the INA282-Q1. 12 Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 INA282-Q1 www.ti.com SBOS554 – MARCH 2012 REFERENCE PIN CONNECTION OPTIONS Figure 33 illustrates a test circuit for reference divider accuracy. The output of the INA282-Q1 can be connected for unidirectional or bidirectional operation. Note that neither the REF1 pin nor the REF2 pin may be connected to any voltage source lower than GND or higher than V+, and that the effective reference voltage (REF1 + REF2)/2 must be 9V or less. This parameter means that the V+ reference output connection shown in Figure 35 is not allowed for V+ greater than 9V. However, the split-supply reference connection shown in Figure 37 is allowed for all values of V+ up to 18V. V+ +IN Æ1 V+ -IN Æ2 Æ2 Æ2 Æ1 Æ2 See Note (1) Æ1 Æ1 OUT ZerÆDrift GAIN PRODUCT 50V/V 100V/V 200V/V 500V/V 1000V/V INA282 INA286 INA283 INA284 INA285 33.3kW 33.3kW REF2 REF1 GND (1) Reference divider accuracy is determined by measuring the output with the reference voltage applied to alternate reference resistors, and calculating a result such that the amplifier offset is cancelled in the final measurement. Figure 33. Test Circuit for Reference Divider Accuracy Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 13 INA282-Q1 SBOS554 – MARCH 2012 www.ti.com UNIDIRECTIONAL OPERATION Unidirectional operation allows the INA282-Q1 to measure currents through a resistive shunt in one direction. In the case of unidirectional operation, the output could be set at the negative rail (near ground, and the most common connection) or at the positive rail (near V+) when the differential input is 0V. The output moves to the opposite rail when a correct polarity differential input voltage is applied. The required polarity of the differential input depends on the output voltage setting. If the output is set at the positive rail, the input polarity must be negative to move the output down. If the output is set at ground, the polarity is positive to move the output up. The following sections describe how to configure the output for unidirectional operation. Ground Referenced Output When using the INA282-Q1 in this mode, both reference inputs are connected to ground; this configuration takes the output to the negative rail when there is 0V differential at the input (as Figure 34 shows). Supply -14V to +80V Load V+ +IN Æ1 V+ -IN Æ2 Æ2 Æ2 Æ1 Æ2 Æ1 Æ1 OUT ZerÆDrift GAIN PRODUCT 50V/V 100V/V 200V/V 500V/V 1000V/V INA282 INA286 INA283 INA284 INA285 33.3kW 33.3kW Output REF2 REF1 GND Figure 34. Ground Referenced Output 14 Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 INA282-Q1 www.ti.com SBOS554 – MARCH 2012 V+ Referenced Output This mode is set when both reference pins are connected to the positive supply. It is typically used when a diagnostic scheme requires detection of the amplifier and the wiring before power is applied to the load (as shown in Figure 35). ISENSE Supply -14V to +80V Load V+ +IN Æ1 V+ -IN Æ2 Æ2 Æ2 Æ1 Æ2 Æ1 Æ1 OUT ZerÆDrift GAIN PRODUCT 50V/V 100V/V 200V/V 500V/V 1000V/V INA282 INA286 INA283 INA284 INA285 33.3kW 33.3kW Output REF2 REF1 GND Figure 35. V+ Referenced Output Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 15 INA282-Q1 SBOS554 – MARCH 2012 www.ti.com BIDIRECTIONAL OPERATION Bidirectional operation allows the INA282-Q1 to measure currents through a resistive shunt in two directions. In this case, the output can be set anywhere within the limits of what the reference inputs allow (that is, between 0V to 9V, but never to exceed the supply voltage). Typically, it is set at half-scale for equal range in both directions. In some cases, however, it is set at a voltage other than half-scale when the bidirectional current is nonsymmetrical. The quiescent output voltage is set by applying voltage(s) to the reference inputs. REF1 and REF2 are connected to internal resistors that connect to an internal offset node. There is no operational difference between the pins. External Reference Output Connecting both pins together and to a reference produces an output at the reference voltage when there is no differential input; this configuration is illustrated in Figure 36. The output moves down from the reference voltage when the input is negative relative to the –IN pin and up when the input is positive relative to the –IN pin. Note that this technique is the most accurate way to bias the output to a precise voltage. Supply -14V to +80V Load V+ +IN Æ1 V+ -IN Æ2 Æ2 Æ2 Æ1 Æ2 Æ1 Æ1 OUT ZerÆDrift GAIN PRODUCT 50V/V 100V/V 200V/V 500V/V 1000V/V INA282 INA286 INA283 INA284 INA285 33.3kW 33.3kW REF2 Output REF3020 2.048V Reference REF1 GND Figure 36. External Reference Output 16 Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 INA282-Q1 www.ti.com SBOS554 – MARCH 2012 Splitting the Supply By connecting one reference pin to V+ and the other to the ground pin, the output is set at half of the supply when there is no differential input, as shown in Figure 37. This method creates a midscale offset that is ratiometric to the supply voltage; thus, if the supply increases or decreases, the output remains at half the supply. Supply -14V to +80V Load V+ +IN Æ1 V+ -IN Æ2 Æ2 Æ2 Æ1 Æ2 Æ1 Æ1 OUT ZerÆDrift GAIN PRODUCT 50V/V 100V/V 200V/V 500V/V 1000V/V INA282 INA286 INA283 INA284 INA285 33.3kW 33.3kW Output REF2 REF1 GND Figure 37. Split-Supply Output Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 17 INA282-Q1 SBOS554 – MARCH 2012 www.ti.com Splitting an External Reference In this case, an external reference is divided by 2 with an accuracy of approximately 0.5% by connecting one REF pin to ground and the other REF pin to the reference (as Figure 38 illustrates). Supply -14V to +80V Load V+ +IN Æ1 V+ -IN Æ2 Æ2 Æ2 Æ1 Æ2 Æ1 Æ1 OUT ZerÆDrift GAIN PRODUCT 50V/V 100V/V 200V/V 500V/V 1000V/V INA282 INA286 INA283 INA284 INA285 33.3kW 33.3kW REF2 Output REF02 5V Reference REF1 GND Figure 38. Split Reference Output 18 Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 INA282-Q1 www.ti.com SBOS554 – MARCH 2012 EXTENDED NEGATIVE COMMON-MODE RANGE Using a negative power supply can extend the common-mode range 14V more negative than the supply used. For instance, a –10V supply allows up to –24V negative common-mode. Remember to keep the total voltage between the GND pin and V+ pin to less than 18V. The positive common-mode decreases by the same amount. The reference input simplifies this type of operation because the output quiescent bias point is always based on the reference connections. Figure 39 shows a circuit configuration for common-mode ranges from –24V to +70V. Supply -24V to +70V Load V+ = 5V +IN 1 -IN Æ2 V+ Æ2 Æ2 Æ1 Æ2 Æ1 Æ1 OUT ZerÆDrift PRODUCT GAIN INA282 INA283 INA284 INA285 INA286 50V/V 200V/V 500V/V 1000V/V 100V/V 33.3kW 33.3kW REF2 REF1 See Note (1) GND Connect to -10V (1) Connect the REF pins as desired; however, they cannot exceed 9V above the GND pin voltage. Figure 39. Circuit Configuration for Common-Mode Ranges from –24V to +70V CALCULATING TOTAL ERROR The electrical specifications for the INA282-286 family of devices include the typical individual errors terms such as gain error, offset error, and nonlinearity error. Total error including all of these individual error components is not specified in the Electrical Characteristics table. In order to accurately calculate the error that can be expected from the device, we must first know the operating conditions to which the device is subjected. Some current shunt monitors specify a total error in the product data sheet. However, this total error term is accurate under only one particular set of operating conditions. Specifying the total error at this one point has little practical value because any deviation from these specific operating conditions no longer yields the same total error value. This section discusses the individual error sources, with information on how to apply them in order to calculate the total error value for the device under any normal operating conditions. The typical error sources that have the largest impact on the total error of the device are input offset voltage, common-mode voltage rejection, gain error and nonlinearity error. For the INA282-286, an additional error source referred to as Reference Common-Mode Rejection is also included in the total error value. Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 19 INA282-Q1 SBOS554 – MARCH 2012 www.ti.com The nonlinearity error of the INA282-286 is relatively low compared to the gain error specification, which results in a gain error that can be expected to be relatively constant throughout the linear input range of the device. While the gain error remains constant across the linear input range of the device, the error associated with the input offset voltage does not. As the differential input voltage developed across a shunt resistor at the input of the INA282-286 decreases, the inherent input offset voltage of the device becomes a larger percentage of the measured input signal resulting in an increase in error in the measurement. This varying error is present among all current shunt monitors, given the input offset voltage ratio to the voltage being sensed by the device. The relatively low input offset voltages present in the INA282-286 devices limit the amount of contribution the offset voltage has on the total error term. The term Reference Common-Mode Rejection refers to the amount of error induced by applying a reference voltage to the INA282-286 device that deviates from the inherent bias voltage present at the output of the first stage of the device. The output of the switched-capacitor network and first-stage amplifier has an inherent bias voltage of approximately 2.048V. Applying a reference voltage of 2.048V to the INA282-286 reference pins results in no additional error term contribution. Applying a voltage to the reference pins that differs from 2.048V creates a voltage potential in the internal difference amplifier, resulting in additional current flowing through the resistor network. As a result of resistor tolerances, this additional current flow causes additional error at the output because of resistor mismatches. Additionally, as a result of resistor tolerances, this additional current flow causes additional error at the output based on the common-mode rejection ratio of the output stage amplifier. This error term is referred back to the input of the device as additional input offset voltage. Increasing the difference between the 2.048V internal bias and the external reference voltage results in a higher input offset voltage. Also, as the error at the output is referred back to the input, there is a larger impact on the input-referred offset, VOS, for the lower-gain versions of the device. Two examples are provided that detail how different operating conditions can affect the total error calculations. Typical and maximum calculations are shown as well to provide the user more information on how much error variance could be present from device to device. Example 1 INA282; VS = 5V; VCM = 12V; VREF = 2.048V; VSENSE = 10mV Table 1. Example 1 TERM SYMBOL EQUATION TYPICAL VALUE MAXIMUM VALUE Initial Input Offset Voltage VOS — 20μV 70μV Added Input Offset Voltage Because of Common-Mode Voltage VOS_CM 0μV 0μV Added Input Offset Voltage Because of Reference Voltage VOS_REF 0μV 0μV Total Input Offset Voltage VOS_Total (VOS)2 + (VOS_CM)2 + (VOS_REF)2 20μV 70μV Error from Input Offset Voltage Error_VOS VOS_Total VSENSE ´ 100 0.20% 0.70% 10 ( 20 ( 20 1 CMRR_dB ´ (VCM - 12V) RCMR ´ (2.048V - VREF) Gain Error Error_Gain — 0.40% 1.40% Nonlinearity Error Error_Lin — 0.01% 0.01% Total Error — (Error_VOS)2 + (Error_Gain)2 + (Error_Lin)2 0.45% 1.56% Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 INA282-Q1 www.ti.com SBOS554 – MARCH 2012 Example 2 INA286; VS = 5V; VCM = 24V; VREF = 0V; VSENSE = 10mV Table 2. Example 2 TERM SYMBOL EQUATION TYPICAL VALUE MAXIMUM VALUE Initial Input Offset Voltage VOS — 20μV 70μV Added Input Offset Voltage Because of Common-Mode Voltage VOS_CM 1.2μV 12μV Added Input Offset Voltage Because of Reference Voltage VOS_REF 34.8μV 92.2μV Total Input Offset Voltage VOS_Total (VOS)2 + (VOS_CM)2 + (VOS_REF)2 40.2μV 116.4μV Error from Input Offset Voltage Error_VOS VOS_Total VSENSE ´ 100 0.40% 1.16% Gain Error Error_Gain — 0.40% 1.40% Nonlinearity Error Error_Lin 0.01% 0.01% 0.57% 1.82% 1 Total Error 20 ( 10 ( CMRR_dB ´ (VCM - 12V) RCMR ´ (2.048V - VREF) — 2 2 (Error_VOS) + (Error_Gain) + (Error_Lin) — 2 SUMMING CURRENTS AND PARALLELING The outputs of multiple INA282-Q1devices are easily summed by connecting the output of one INA282-Q1 device to the reference input of a second INA282-Q1 device. Summing beyond two devices is possible by repeating this connection, and is shown for three devices in Figure 40. The reference input of the first INA282-Q1 device sets the output quiescent level for all the devices in the string. First Circuit Æ1 Second Circuit VIN+ VIN- Æ2 Æ2 Æ1 Æ2 Æ1 Æ2 Æ1 VIN+ VIN- Æ2 Æ2 Third Circuit Æ1 Æ2 Æ1 Æ2 Æ1 VIN+ VIN- Æ2 Æ2 Æ1 Æ2 Æ2 Æ1 Æ1 Output Output Output Summed Output VREF GND GND V+ GND V+ V+ NOTE: The voltage applied to the reference inputs cannot exceed 9V. Figure 40. Summing the Outputs of Multiple INA282-Q1 Devices Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 21 INA282-Q1 SBOS554 – MARCH 2012 www.ti.com CURRENT DIFFERENCING Occasionally, the need arises to confirm that the current into a load is identical to the current out of a load, usually as part of diagnostic testing or fault detection. This situation requires precision current differencing, which is the same as summing except that the two amplifiers have the inputs connected opposite of each other. Under normal operating conditions, the final output is very close to the reference value and proportional to any current difference. Figure 41 is an example of the connections required for current differencing. First Circuit Second Circuit Supply Æ1 Load VIN+ VIN- Æ2 Æ2 Æ1 Æ2 Æ1 Æ2 Æ1 VIN+ VIN- Æ2 Æ2 Æ1 Æ2 Æ2 Æ1 Æ1 Æ1 Output Output Difference Output VREF GND GND V+ V+ NOTE: This example is identical to the current summing example, except that the two shunt inputs are reversed in polarity, this current differencing circuit is useful in detecting when current into and out of a load do not match. Figure 41. Current Differencing Using an INA282-Q1 Device 22 Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 INA282-Q1 www.ti.com SBOS554 – MARCH 2012 COMMON-MODE DYNAMICS AND CURRENT DIFFERENCING Current sensing is frequently used on totem-pole output stages, such as those of bridge-type motor drives. We can sense current in one of three locations on a totem-pole output: on the ground side (low-side sensing); on the power-supply side (high-side sensing); or on the output (phase sensing). Only the output line reports the exact load current. Obviously, the ground and supply-side sensing report only the current in the individual respective phases. Figure 42 depicts these various methods on a three-phase motor driver. Motor High Side Current Sense High Side Current Sense Phase Current Sense Low Side Current Sense Low Side Current Sense High Side Current Sense Phase Current Sense Phase Current Sense Low Side Current Sense NOTE: Motor drive current sensing can be done on the low side, phase side, or high side. Only the phase output gives complete information regarding current in the motor, but is subject to common-mode transients that even the best amplifiers do not reject completely. Figure 42. Motor Drive Current Sensing However, sensing on the output is subject to large common-mode voltage steps that result in feedthrough in even the best amplifiers. The ground and supply-side sensing configurations are free of this problem, thanks to the static common-mode environments. Sensing either ground or supply alone only provides partial information regarding motor current, but sense them individually and sum them and we have the same information provided by phase sensing, with an added advantage of not being subject to transient common-mode artifacts. See Figure 43 for an illustration of two INA282-Q1 devices connected in this manner. Technically, this configuration is current differencing, though, because we want the upper sense to report a positive-going excursion in the overall output, and the negative sense to report a negative-going excursion. Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 23 INA282-Q1 SBOS554 – MARCH 2012 www.ti.com Æ2 +2.7V to +18V Æ2 Æ2 Æ1 VIN+ Æ1 Æ1 VIN- Æ2 Æ1 Motor Supply (< 80V) Q1 D1 MOSFET Drive Circuits VREF Output +2.7V to +18V Æ2 Æ2 Æ1 VIN+ Æ1 Æ1 VIN- Æ2 Æ1 Q2 Æ2 D2 NOTE: By sensing totem-pole current on both the positive and negative rail and summing, dynamic common-mode issues can be avoided entirely. Note that IC2 is connected with inverting inputs because it should report current with an opposite polarity to that of IC1. Figure 43. Sensing and Summing Totem Pole Current 24 Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Product Folder Link(s): INA282-Q1 PACKAGE OPTION ADDENDUM www.ti.com 2-Apr-2012 PACKAGING INFORMATION Orderable Device INA282AQDRQ1 Status (1) Package Type Package Drawing ACTIVE SOIC D Pins Package Qty 8 2500 Eco Plan (2) Green (RoHS & no Sb/Br) Lead/ Ball Finish MSL Peak Temp (3) Samples (Requires Login) CU NIPDAU Level-2-260C-1 YEAR (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. 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OTHER QUALIFIED VERSIONS OF INA282-Q1 : • Catalog: INA282 NOTE: Qualified Version Definitions: • Catalog - TI's standard catalog product Addendum-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 2-Apr-2012 TAPE AND REEL INFORMATION *All dimensions are nominal Device INA282AQDRQ1 Package Package Pins Type Drawing SOIC D 8 SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 2500 330.0 12.4 Pack Materials-Page 1 6.4 B0 (mm) K0 (mm) P1 (mm) 5.2 2.1 8.0 W Pin1 (mm) Quadrant 12.0 Q1 PACKAGE MATERIALS INFORMATION www.ti.com 2-Apr-2012 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) INA282AQDRQ1 SOIC D 8 2500 346.0 346.0 29.0 Pack Materials-Page 2 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. 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