High Voltage Current Shunt Monitor AD8212 Preliminary Technical Data FEATURES FUNCTIONAL BLOCK DIAGRAM VPLUS IS – RS +IN –IN LOAD AD8212 OFFSET APPLICATIONS High-side current sensing Motor controls Battery monitoring Hybrid vehicle control Diesel injection controls Vehicle dynamic controls Dc-to-dc converters + 99kΩ IOUT ALPHA COM BIAS RBIAS ROUT 05492-001 High common-mode voltage range 7 V to +65 V operating (no outside pass transistor) 7 V to >500 V survival (with outside pass transistor) Adjustable gain Bidirectional current measurement Wide operating temperature range Die: −40°C to +150°C 8-lead SOIC: −40°C to +125°C Available in SOIC and die form Figure 1. GENERAL DESCRIPTION The AD8212 is a self-biased current sense amplifier for level shifting and amplifying small differential voltages in the presence of common mode voltages exceeding 500 V1. The AD8212 offers excellent accuracy and programmable gain which can be set with a single resistor, making it ideal to use in industrial, automotive , and consumer applications. The AD8212 is offered in die and packaged form. The operating temperature range for the die is 25°C higher (up to 150°C) than that of the packaged part to enable the user to apply the AD8212 in high temperature applications. Excellent AC and DC performance over temperature keep errors in the measurement loop to a minimum. Offset drift is typically below 5 uV/ °C, and the gain drift is typically below 50 ppm/°C. 1 Depending upon Vce breakdown voltage of pass transistor 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: 781.461.3113 ©2006 Analog Devices, Inc. All rights reserved. AD8212 Preliminary Technical Data TABLE OF CONTENTS Features .............................................................................................. 1 Theory of Operation .........................................................................5 Applications....................................................................................... 1 Modes of Operation ..........................................................................6 Functional Block Diagram .............................................................. 1 Low Voltage Unidirectional Operation ......................................6 General Description ......................................................................... 1 Low Voltage BIidirectional Operation .......................................6 Specifications..................................................................................... 3 High Voltage Unidirectional Operation.....................................6 Absolute Maximum Ratings............................................................ 4 High Voltage Bidirectional Operation........................................6 ESD Caution.................................................................................. 4 Outline Dimensions ..........................................................................7 Pin Configuration......................................................................... 4 Rev. PrA | Page 2 of 8 Preliminary Technical Data AD8212 SPECIFICATIONS TA = Operating temperature range. Table 1. Parameter GAIN Initial Accuracy Accuracy Over Temperature Gain vs. Temperature VOLTAGE OFFSET Offset Voltage (RTI) Over Temperature (RTI) Offset Drift INPUT Input Impedance Differential Input Voltage Range Differential Input Range3 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 AD8212 SOIC1 Min Typ Max Min 1 1 ±0.5 100 ±1 ±1.5 AD8212 DIE2 Typ Max ±0.5 50 5 100 ±1.5 ±2.5 V/V % % ppm/°C 25°C, VO ≥ 0.1 V dc Specified temperature range ±2 ±4 mV mV μV/°C 5 2 2 65 >500 7 7 100 90 0.05 Conditions 50 ±1 ±2 7 7 Unit 65 >500 100 90 VPLUS − 5 V 0.05 VPLUS − 5 V kΩ V V mV dB No outside pass transistor With outside pass transistor Differential 25°C, f = dc to 20 kHz4 V RL = 25 kΩ 500 3 500 3 kHz V/μs TBD TBD TBD TBD μV p-p μV/√Hz 1 TMIN to TMAX = −40°C to +125°C. TMIN to TMAX = −40°C to +150°C. Input voltage range = ±75 mV with half-scale offset. 4 Source imbalance <2 Ω. 2 3 Rev. PrA | Page 3 of 8 25°C Specified temperature range AD8212 Preliminary Technical Data ABSOLUTE MAXIMUM RATINGS 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. Table 2. Parameter Continuous Input Voltage Transient Input Voltage Operating Temperature Range Storage Temperature Range Rating 7V to +65 V (No Pass Transistor) 72 V −40°C to +125°C −65°C to +150°C ESD CAUTION PIN CONFIGURATION VPLUS 1 COM 2 AD8212 8 VSENSE 7 OFFSET 6 ALPHA TOP VIEW NC 4 (Not to Scale) 5 IOUT NC = NO CONNECT Figure 2. Pin Configuration Rev. PrA | Page 4 of 8 05492-002 BIAS 3 Preliminary Technical Data AD82122 THEORY OF OPERATION The AD8212 is a self-biased, high common mode current sense amplifier. VPLUS IS VPLUS RS +IN between the Vplus and COM. Therefore, the device always sees 5 V across, no matter what the common mode voltage. The AD8212 can operate with voltages of up to 500V with the use of an external pass transistor. IS –IN RS LOAD RG1 +IN –IN LOAD AD8212 OFFSET AD8212 99kΩ OFFSET Q1 99kΩ VOUT BIAS ALPHA ROUT BIAS COM Figure 3. Typical Connection Diagram Iout = (Is * Rs) / (RG1) Vshunt = (Is * Rs) VOUT RBIAS Figure 4. At these high voltages a proper Rbias (depended upon the application) is necessary to regulate the device by pulling enough current through it to keep it to keep it going. Vout = (Is * Rs * Rout) / RG1 Table 3 lists the Rout values and the resulting gain for the AD8212. Ibias = (Vsupply –5V)/ Rbias The current necessary must be at least 90uA and can be as high as 1mA. The formula above can be used to easily calculate the external Rbias to deliver the proper current. Table 3. Rout (Ω) 1k 2k 5k 10k 20k 50k 100k ALPHA ROUT The current (IS) is drawn for the supply through the shunt resistor (RS). This produces a small voltage (Vshunt) across the inputs of the device, and in turn current flows across RG1 (1000 Ω) into the collector of Q1. This current (IOUT) is converted into a voltage through the use of an outside resistor (ROUT). RG1 = 1000Ω IOUT 05492-003 COM Q1 05492-004 IOUT Gain (V/V) 1 2 5 10 20 50 100 The Offset pin can be tied to COM for bidirectional current measurements. The Offset voltage can be calculated by: Voffset = (5 * 10^-5) * Rout With the device operating in the manner shown above the common mode voltage range is 7V to 65V. The 7V is necessary for the device to operate because of an internal regulator that turns on at that voltage. This internal regulator allows the AD8212 to be self biased, meaning that the AD8212 hangs from the common mode voltage, and no additional supply is necessary. This internal regulator also maintains 5 V at all times Between Vplus and COM there is 5V. When Offset is tied to Com we have a resistor divider of 1K and 99K and 5V. Therefore the current flowing to the Q1 collector is 0.5V/1kΩ=(5*10^-5). This current multiplied with Rout produces the offset voltage. A high voltage PNP transistor is necessary for using the AD8212 at high voltages. The only limitation on what Common Mode Voltage range, is the breakdown voltage of the pass transistor. Rev. PrA | Page 5 of 8 Preliminary Technical Data AD82122 MODES OF OPERATION The output of the AD8212 can be adjusted for unidirectional or bidirectional operation. HIGH VOLTAGE UNIDIRECTIONAL OPERATION VPLUS IS LOW VOLTAGE UNIDIRECTIONAL OPERATION RS Unidirectional operation allows the AD8212 to measure currents through a resistive shunt in one direction. The offset pin is not used and the Bias pin is directly connected to GND. COM VSENSE BIAS 4 NC 3 BIAS 4 NC IOUT 5 ROUT Figure 7. High Voltage Unidirectional Operation OFFSET 7 HIGH VOLTAGE BIDIRECTIONAL OPERATION ALPHA 6 VPLUS ROUT IS 05492-005 IOUT 5 RS LOAD Figure 5. Low Voltage Unidirectional Operation LOW VOLTAGE BIIDIRECTIONAL OPERATION 1 VPLUS 2 COM VSENSE 8 OFFSET 7 AD8212 By tying pin 7 (Offset) to COM the AD8212 can measure currents in both directions at the input. VPLUS ALPHA 6 8 AD8212 3 OFFSET 7 RBIAS LOAD 2 COM 8 3 BIAS 4 NC IS ALPHA 6 IOUT 5 ROUT RBIAS RS LOAD 1 VPLUS 2 COM VSENSE Figure 8.. High Voltage Unidirectional Operation 8 OFFSET 7 AD8212 BIAS 4 NC ALPHA 6 IOUT 5 ROUT 05492-006 3 05492-007 RS VPLUS 2 VSENSE AD8212 IS 1 VPLUS Figure 6. Low Voltage Bidirectional Operation Rev. PrA | Page 6 of 8 05492-008 VPLUS LOAD 1 Preliminary Technical Data AD82122 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 8 4.00 (0.1574) 3.80 (0.1497) 1 5 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 6.20 (0.2440) 4 5.80 (0.2284) 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) COPLANARITY SEATING 0.31 (0.0122) 0.10 PLANE 0.50 (0.0196) × 45° 0.25 (0.0099) 8° 0.25 (0.0098) 0° 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067) COMPLIANT TO JEDEC STANDARDS MS-012-AA 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 9. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches Rev. PrA | Page 7 of 8 AD8212 Preliminary Technical Data NOTES ©2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 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