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| Preliminary Technical Data FEATURES High common-mode voltage range -2 V to +65 V operating -5 V to +68 V survival Gain = 20 Wide operating temperature range Die: -40C to +150C 8-lead SOIC: -40C to +125C Adjustable offset Available in SOIC and die form Vsupply High-Side Bi-directional Current Shunt Monitor AD8210 FUNCTIONAL BLOCK DIAGRAM + Is Rs + IN -IN Vs + V+ AD8210 V Ref 1 LOAD EXCELLENT AC AND DC PERFORMANCE 5 V/C offset drift 30 ppm/C gain drift 80 dB CMRR dc to 10 kHz G=20 VOUT V Ref 2 GND APPLICATIONS 42V DC/DC Converter Current Sensing High Side Current Sensing Motor controls Transmission controls Diesel injection controls Engine management Suspension controls Vehicle dynamic controls Figure 1: Typical Operating Circuit GENERAL DESCRIPTION The AD8210 is a high-side, single-supply, bi-directional current shunt monitor featuring a wide input common mode voltage range of -2V to 65V, high bandwidth, set gain of 20, and a typical supply voltage of 5V. The AD8210 is offered in die and packaged form. The operating temperature range for the die is 25C higher (up to 150C) than that of the packaged part to enable the user to apply the AD8210 in high temperature applications. Excellent AC and DC performance over temperature keeps errors in the measurement loop to a minimum. Offset drift is typically below 5uV/ C, and the Gain drift is typically below 30ppm/C. Bi-directional current measurement is achieved by offsetting the output between 0.05V and 4.8V with a 5V supply. With the VREF 2 pin connected to the V+ pin, and VREF1 pin connected to GND pin, the output is set at half scale. Attaching both VREF pins to GND causes the output to be unipolar, starting near ground. Attaching both VREF pins to V+ cause the output to be Rev. PrA 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 rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.326.8703 (c) 2004 Analog Devices, Inc. All rights reserved. AD8210 unipolar starting near V+. Other offsets can be obtained by applying an external voltage to VREF1 and VREF2 pins. Preliminary Technical Data Specifications TA= Operating Temperature Range, Vs=5V, unless otherwise noted Parameter GAIN Gain Accuracy Accuracy Over Temperature Gain vs. Temperature VOLTAGE OFFSET Offset Voltage (RTI) Over Temperature (RTI) Offset Drift INPUT Input Impedance Differential Common Mode Common Mode Input Voltage Range Input Voltage Range Input Voltage Range Common-Mode Rejection Common-Mode Rejection OUTPUT Output Voltage Range DYNAMIC RESPONSE Small Signal -3 dB Bandwidth Slew Rate NOISE 0.1 Hz to 10 Hz, RTI Spectral Density, 1 kHz, RTI OFFSET ADJUSTMENT Offset Adjustment Range POWER SUPPLY Operating Range Quiescent Current Over Temp Power Supply Rejection Ratio Temperature Range For Specified Performance Conditions AD8210 SOIC Min Typ Max 20 0.5 30 AD8210 DIE Min Typ Max 20 0.5 50 Unit V/V % % ppm/C mV mV V/C VO 0.1V DC Specified Temperature Range 1 1.5 1.5 2.5 25C Specified Temperature Range 5 1 2 10 2 4 V common mode > 5V V common mode < 5V Common-Mode, Continuous Differential, Uni-directional Differential f =1 kHz f =10 kHz1 2 5 3.5 -2 250 125 80 80 0.05 400 3 TBD TBD 4.8 80 0.05 65 -2 2 5 3.5 65 250 125 k M k V mV mV dB dB V kHz V/s V p-p V/Hz 4.8 400 3 TBD TBD VS = 5 V For Specified Performance VO = 0.1 V dc 0.05 4.5 0.5 80 4.8 5.5 1.5 0.05 4.5 0.5 80 4.8 5.5 1.5 V V mA dB C Operating Temperature Range -40 +125 -40C +150 Rev. PrA | Page 2 of 8 Preliminary Technical Data ABSOLUTE MAXIMUM RATINGS Table 1. Parameter Supply Voltage Continuous Input Voltage Transient Input Voltage Reverse Supply Voltage Negative Common Mode Range Operating Temperature Range Storage Temperature Lead Temperature Range Rating 12.5 V 65V 72V -0.3 V -2.3V -40C to +125C -65 to +150C 300C AD8210 Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only and 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. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. Rev. PrA | Page 3 of 8 AD8210 OUTPUT OFFSET ADJUSTMENT The output of the AD8210 can be adjusted for unidirectional or bidirectional operation. Preliminary Technical Data V+ REFERENCED OUTPUT This mode is set when both reference pins are tied to the positive supply. It is typically used when the diagnostic scheme requires detection of the amplifier and the wiring before power is applied to the load (see Figure 3). Rs +IN -IN UNIDIRECTIONAL OPERATION Unidirectional operation allows the AD8210 to measure currents through a resistive shunt in one direction. The basic modes for unidirectional operation are ground referenced output mode and V+ referenced output mode. In the case of unidirectional operation, the output could be set at the negative rail (near ground) or at the positive rail (near V+) when the differential input is 0 V. The output moves to the opposite rail when a correct polarity differential input voltage is applied. In this case, full scale is approximately 250 mV. 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 needs to be negative to move the output down. If the output is set at ground, the polarity is positive to move the output up. Vs AD8210 V Ref 1 G=20 V Out V Ref 2 GND GROUND REFERENCED OUTPUT When using the AD8210 in this mode, both reference inputs are tied to ground, which causes the output to sit at the negative rail when there are zero differential volts at the input (see Figure 2). Rs +IN -IN Vs Figure 3. V+ Referenced Output Table 3. V+ = 5 V VIN (Referred to -IN) 0V 250 mV VO 4.8 V 0.05 V BIDIRECTIONAL OPERATION AD8210 V Ref 1 V Out G=20 Bidirectional operation allows the AD8210 to measure currents through a resistive shunt in two directions. In this case, the output is set anywhere within the output range. 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. Table 4. V+ = 5 V, VO = 2.5 with VIN = 0 V V Ref 2 GND Figure 2. Ground Referenced Output Table 2. V+ = 5 V VIN (Referred to -IN) 0V 250 mV VO 0.05 V 4.8 V VIN (Referred to -IN) +100 mV -100 mV VO 4.5 V 0.5 V Adjusting the output is accomplished by applying voltage(s) to the reference inputs. VREF1 and VREF2 are tied to internal resistors that connect to an internal offset node. There is no operational difference between the pins Rev. PrA | Page 4 of 8 Preliminary Technical Data EXTERNAL REFERENCE OUTPUT Tying both pins together and to a reference produces an output at the reference voltage when there is no differential input (see Figure 4). 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. Rs +IN -IN Vs AD8210 SPLITTING THE SUPPLY By tying 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 (see Figure 6). The benefit is that no external reference is required to offset the output for bidirectional current measurement. This creates a midscale offset that is ratiometric to the supply, which means that if the supply increases or decreases, the output remains at half the supply. For example, if the supply is 5.0 V, the output is at half scale or 2.5 V. If the supply increases by 10% (to 5.5 V), the output goes to 2.75 V. Rs +IN -IN Vs AD8210 VRef 1 G=20 2.5V V Out VRef 2 GND AD8210 V Ref 1 Figure 4. External Reference Output V Out G=20 SPLITTING AN EXTERNAL REFERENCE In this case, an external reference is divided by 2 with an accuracy of approximately 0.5% by connecting one VREF pin to ground and the other VREF pin to the reference (see Figure 17). Rs +IN -IN Vs V Ref 2 GND Figure 6: Split Supply AD8210 5V VRef 1 G=20 V Out VRef 2 GND Figure 5: Split External Reference Rev. PrA | Page 5 of 8 AD8210 APPLICATIONS A typical application for the AD8210 is high-side measurement of a current through a solenoid for PWM control of the solenoid opening. Typical applications include hydraulic transmission control and diesel injection control. Two typical circuit configurations are used for this type of application. Preliminary Technical Data When using a high-side switch, the battery voltage is connected to the load when the switch is closed, causing the commonmode voltage to increase to the battery voltage. In this case, when the switch is opened, the voltage reversal across the inductive load causes the common-mode voltage to be held one diode drop below ground by the clamp diode. HIGH-SIDE CURRENT SENSE WITH A LOW-SIDE SWITCH In this case, the PWM control switch is ground referenced. An inductive load (solenoid) is tied to a power supply. A resistive shunt is placed between the switch and the load (see Figure 7). An advantage of placing the shunt on the high side is that the entire current, including the re-circulation current, can be measured since the shunt remains in the loop when the switch is off. In addition, diagnostics can be enhanced because shorts to ground can be detected with the shunt on the high side. In this circuit configuration, when the switch is closed, the common-mode voltage moves down to near the negative rail. When the switch is opened, the voltage reversal across the inductive load causes the common-mode voltage to be held one diode drop above the battery by the clamp diode. 5V 42V BATTERY SWITCH +IN VREF1 +VS SHUNT -IN CLAMP DIODE INDUCTIVE LOAD NC = NO CONNECT OUT AD8210 GND VREF2 NC Figure 8. High-Side Switch CLAMP DIODE 42V BATTERY SHUNT INDUCTIVE LOAD +IN VREF1 +VS OUT AD8210 -IN GND VREF2 NC Another typical application for the AD8210 is as part of the control loop in H-bridge motor control. In this case, the AD8210 is placed in the middle of the H-bridge (see Figure 9) so that it can accurately measure current in both directions by using the shunt available at the motor. This is a better solution than a ground referenced op amp because ground is not typically a stable reference voltage in this type of application. This instability in the ground reference causes the measurements that could be made with a simple ground referenced op amp to be inaccurate. The AD8210 measures current in both directions as the H-bridge switches and the motor changes direction. The output of the AD8206 is configured in an external reference bidirectional mode, see the Output Offset Adjustment section. SWITCH NC = NO CONNECT 04953-019 Figure 7. Low-Side Switch 5V CONTROLLER HIGH-SIDE CURRENT SENSE WITH A HIGH-SIDE SWITCH This configuration minimizes the possibility of unexpected solenoid activation and excessive corrosion (see Figure 8). In this case, both the switch and the shunt are on the high side. When the switch is off, this removes the battery from the load, which prevents damage from potential shorts to ground, while still allowing the recirculation current to be measured and providing for diagnostics. Removing the power supply from the load for the majority of the time minimizes the corrosive effects that could be caused by the differential voltage between the load and ground. MOTOR +IN VREF1 +VS OUT AD8210 SHUNT -IN GND VREF2 NC 5V 2.5V NC = NO CONNECT Figure 9. Motor Control Application Rev. PrA | Page 6 of 8 Preliminary Technical Data OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 8 5 4 AD8210 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 1.75 (0.0688) 1.35 (0.0532) 0.50 (0.0196) x 45 0.25 (0.0099) 0.51 (0.0201) COPLANARITY SEATING 0.31 (0.0122) 0.10 PLANE 8 0.25 (0.0098) 0 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067) COMPLIANT TO JEDEC STANDARDS MS-012AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN Figure 10. 8-Lead Standard Small Outline Package [SOIC] Narrow Body (R-8) Dimensions shown in millimeters and (inches) Rev. PrA | Page 7 of 8 PR05147-0-9/04(PrA) 4.00 (0.1574) 3.80 (0.1497) 1 6.20 (0.2440) 5.80 (0.2284) |
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