High Voltage, Current Shunt Monitor AD8215 ±4000 V HBM ESD High common-mode voltage range −2 V to +65 V operating −3 V to +68 V survival Buffered output voltage Wide operating temperature range 8-Lead SOIC_N: −40°C to +125°C Excellent ac and dc performance 6 μV/°C typical offset drift −8 ppm/°C typical gain drift 120 dB typical CMRR at dc FUNCTIONAL BLOCK DIAGRAM IN+ IN– V+ A1 PROPRIETARY OFFSET CIRCUITRY OUT G = +20 AD8215 APPLICATIONS High-side current sensing Motor controls Transmission controls Engine management Suspension controls Vehicle dynamic controls DC-to-dc converters GND 07203-001 FEATURES Figure 1. GENERAL DESCRIPTION The AD8215 is a high voltage, precision current shunt monitor. It features a set gain of 20 V/V, with a maximum ±0.3% gain error over the entire temperature range. The buffered output voltage directly interfaces with any typical converter. Excellent commonmode rejection from −2 V to +65 V is independent of the 5 V supply. The AD8215 performs unidirectional current measurements across a shunt resistor in a variety of industrial and automotive applications, such as motor controls, solenoid controls, or battery management. Special circuitry is devoted to output linearity being maintained throughout the input differential voltage range of 0 mV to 250 mV, regardless of the common-mode voltage present. The AD8215 has an operating temperature range of −40°C to +125°C and is offered in a small 8-lead SOIC_N package. 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 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 ©2008 Analog Devices, Inc. All rights reserved. AD8215 TABLE OF CONTENTS Features .............................................................................................. 1 Theory of Operation ...................................................................... 10 Applications....................................................................................... 1 Application Notes ........................................................................... 11 Functional Block Diagram .............................................................. 1 Output Linearity......................................................................... 11 General Description ......................................................................... 1 Applications Information .............................................................. 12 Revision History ............................................................................... 2 High-Side Current Sensing with a Low-Side Switch ............. 12 Specifications..................................................................................... 3 High-Side Current Sensing ....................................................... 12 Absolute Maximum Ratings............................................................ 4 Low-Side Current Sensing ........................................................ 12 ESD Caution.................................................................................. 4 Outline Dimensions ....................................................................... 13 Pin Configuration and Function Descriptions............................. 5 Ordering Guide .......................................................................... 13 Typical Performance Characteristics ............................................. 6 REVISION HISTORY 1/08—Revision 0: Initial Version Rev. 0 | Page 2 of 16 AD8215 SPECIFICATIONS TOPR = −40°C to +125°C, TA = 25°C, VS = 5 V, RL = 25 kΩ (RL is the output load resistor), unless otherwise noted. Table 1. Parameter GAIN Initial Accuracy Accuracy Over Temperature Drift VOLTAGE OFFSET Offset Voltage, RTI Over Temperature, RTI Drift INPUT Input Impedance Differential Common Mode Common-Mode Input Voltage Range Differential Input Voltage Range Common-Mode Rejection Ratio Min Typ Max Unit Conditions −8 ±0.15 ±0.3 −15 V/V % % ppm/°C VO ≥ 0.1 V dc, TA TOPR TOPR +6 ±1 ±2.5 +18 mV mV μV/°C TA TOPR TOPR +65 kΩ MΩ kΩ V mV dB dB Common-mode voltage > 5 V Common-mode voltage < 5 V Common-mode continuous Differential input voltage TOPR, f = dc to 50 kHz, VCM > 5 V TOPR, f = dc to 40 kHz, VCM < 5 V 20 0 −15 5 5 3.5 −2 100 80 OUTPUT Output Voltage Range Low 250 120 90 0.03 TA TOPR TA TOPR 2 V V V V Ω 450 4.5 kHz V/μs TOPR TA 7 70 μV p-p nV/√Hz 0.10 Output Voltage Range High 4.95 4.90 Output Impedance DYNAMIC RESPONSE Small Signal −3 dB Bandwidth Slew Rate NOISE 0.1 Hz to 10 Hz, RTI Spectral Density, 1 kHz, RTI POWER SUPPLY Operating Range Quiescent Current Over Temperature Power Supply Rejection Ratio TEMPERATURE RANGE For Specified Performance 1 4.5 1.3 5.5 2.2 V mA dB +125 °C 75 −40 VCM > 5 V 1 , TOPR TOPR When the input common-mode voltage is less than 5 V, the supply current increases, which can be calculated by IS = −0.275 (VCM) + 2.5. Rev. 0 | Page 3 of 16 AD8215 ABSOLUTE MAXIMUM RATINGS Table 2. Parameter Supply Voltage Continuous Input Voltage Continuous Differential Input Voltage Reverse Supply Voltage Human Body Model (HBM) ESD Rating Charged Device Model (CDM) ESD Rating Operating Temperature Range Storage Temperature Range Output Short-Circuit Duration ESD CAUTION Rating 12.5 V −3 V to +68 V 0.5 V −0.3 V ±4000 V ±1000 V −40°C to +125°C −65°C to +150°C Indefinite 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. Rev. 0 | Page 4 of 16 AD8215 1 8 –IN 1 GND 2 AD8215 NC 3 6 55 07203-002 2 TOP VIEW NC 4 (Not to Scale) NC 6 V+ 5 OUT Figure 3. Pin Configuration Table 3. Pin Function Descriptions Mnemonic −IN GND NC OUT V+ +IN +IN 7 NC = NO CONNECT Figure 2. Metallization Diagram Pin No. 1 2 3, 4, 7 5 6 8 8 X −228 −273 N/A +265 +273 +229 Y +519 −251 N/A −466 −266 +519 Rev. 0 | Page 5 of 16 Description Inverting Input. Ground. No Connect. Buffered Output. Supply. Noninverting Input. 07203-003 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS AD8215 1.2 1.0 0.8 0.6 0.2 GAIN (dB) VOSI (mV) 0.4 0 –0.2 –0.4 –0.6 –0.8 –1.2 –40 –20 0 20 40 60 80 100 120 TEMPERATURE (°C) 07203-017 –1.0 100k 1M 10M FREQUENCY (Hz) Figure 4. Typical Offset Drift vs. Temperature Figure 7. Typical Small Signal Bandwidth (VOUT = 200 mV p-p) 140 10 9 130 TOTAL OUTPUT ERROR (%) COMMON-MODE VOLTAGE >5V 120 CMRR (dB) 40 35 30 25 20 15 10 5 0 –5 –10 –15 –20 –25 –30 –35 –40 10k 07203-018 TYPICAL PERFORMANCE CHARACTERISTICS 110 COMMON-MODE VOLTAGE <5V 100 90 80 8 7 6 5 4 3 2 70 1 1k 10k 100k 1M FREQUENCY (Hz) 0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 250 DIFFERENTIAL INPUT VOLTAGE (mV) Figure 5. Typical CMRR vs. Frequency Figure 8. Total Output Error vs. Differential Input Voltage 2500 –480 2000 –490 INPUT BIAS CURRENT (µA) 1000 500 0 –500 –1000 –500 –510 –520 –540 –550 –2000 –560 –20 0 20 40 60 80 100 TEMPERATURE (°C) 120 Figure 6. Typical Gain Error vs. Temperature VIN+ –530 –1500 07203-016 GAIN ERROR (ppm) 1500 –2500 –40 07203-022 100 VIN– –570 0 25 50 75 100 125 150 175 200 225 250 DIFFERENTIAL INPUT VOLTAGE (mV) Figure 9. Input Bias Current vs. Differential Input Voltage, VCM = 0 V Rev. 0 | Page 6 of 16 07203-007 10 07203-024 60 AD8215 120 100 100mV/DIV INPUT 1 90 IN+ 80 1V/DIV 70 OUTPUT IN– 2 60 07203-012 INPUT BIAS CURRENT (µA) 110 50 0 25 50 75 100 125 150 175 200 225 250 DIFFERENTIAL INPUT VOLTAGE (mV) TIME (400ns/DIV) 07203-006 40 Figure 13. Fall Time Figure 10. Input Bias Current vs. Differential Input Voltage, VCM = 5 V 0.8 0.4 100mV/DIV 1 –0.4 OUTPUT –0.8 –1.2 1V/DIV 2 –1.6 07203-015 INPUT BIAS CURRENT (mA) INPUT 0 –2.0 –4 –2 0 2 4 6 8 65 INPUT COMMON-MODE VOLTAGE (V) TIME (400ns/DIV) 07203-004 –2.4 Figure 14. Rise Time Figure 11. Input Bias Current vs. Input Common-Mode Voltage 4.0 200mV/DIV INPUT 3.0 1 2.5 2V/DIV 2.0 OUTPUT 1.5 1.0 –4 –2 0 2 4 6 8 INPUT COMMON-MODE VOLTAGE (V) 65 07203-013 2 TIME (1µs/DIV) 07203-005 SUPPLY CURRENT (mA) 3.5 Figure 15. Differential Overload Recovery (Falling) Figure 12. Supply Current vs. Common-Mode Voltage Rev. 0 | Page 7 of 16 AD8215 12 200mV/DIV 1 OUTPUT 2V/DIV 07203-014 2 11 10 9 8 7 6 5 –40 TIME (1µs/DIV) –20 0 20 40 60 80 100 120 07203-010 MAXIMUM OUTPUT SINK CURRENT (mA) INPUT 140 TEMPERATURE (°C) Figure 16. Differential Overload Recovery (Rising) Figure 19. Maximum Output Sink Current vs. Temperature 1 2V/DIV 2 07203-019 0.01%/DIV 9 8 7 6 5 4 –40 TIME (4µs/DIV) –20 0 20 40 60 80 100 120 07203-011 MAXIMUM OUTPUT SOURCE CURRENT (mA) 10 140 TEMPERATURE (°C) Figure 17. Settling Time (Falling) Figure 20. Maximum Output Source Current vs. Temperature 5.0 4.6 OUTPUT VOLTAGE RANGE (V) 2V/DIV 1 0.01%/DIV 07203-020 3.8 3.4 3.0 2.6 2.2 1.8 1.4 1.0 TIME (4µs/DIV) 0 1 2 3 4 5 6 7 8 OUTPUT SOURCE CURRENT (mA) Figure 18. Settling Time (Rising) Figure 21. Output Voltage Range vs. Output Source Current Rev. 0 | Page 8 of 16 9 07203-008 2 4.2 AD8215 2.0 2400 1800 1500 1.2 COUNT OUTPUT VOLTAGE RANGE (V) 2100 1.6 0.8 1200 900 600 0.4 1 2 3 4 5 6 7 8 9 10 11 12 OUTPUT SINK CURRENT (mA) 0 –16 –14 –6 –4 –2 0 15 20 1600 1400 1200 2500 1000 COUNT 2000 1500 800 600 1000 400 500 200 0 –2 –1 0 VOS (mV) 1 2 0 –20 07203-021 COUNT –8 Figure 24. Gain Drift Distribution +125°C +25°C –40°C 3000 –10 GAIN DRIFT (ppm/°C) Figure 22. Output Voltage Range from GND vs. Output Sink Current 3500 –12 07203-023 0 07203-009 0 07203-030 300 –15 –10 –5 0 5 OFFSET DRIFT (µV/°C) Figure 23. Offset Distribution Figure 25. Offset Drift Rev. 0 | Page 9 of 16 10 AD8215 THEORY OF OPERATION In typical applications, the AD8215 amplifies a small differential input voltage generated by the load current flowing through a shunt resistor. The AD8215 rejects high common-mode voltages (up to 65 V) and provides a ground-referenced, buffered output that interfaces with an analog-to-digital converter (ADC). Figure 26 shows a simplified schematic of the AD8215. ISHUNT RSHUNT A load current flowing through the external shunt resistor produces a voltage at the input terminals of the AD8215. The input terminals are connected to A1 by R and R1. The inverting terminal, which has very high input impedance, is held to (VCM) − (ISHUNT × RSHUNT) because negligible current flows through R. A1 forces the noninverting input to the same potential. Therefore, the current that flows through R1 is equal to IIN = (ISHUNT × RSHUNT)/R1 IIN R1 R This current (IIN) is converted back to a voltage via ROUT. The output buffer amplifier has a gain of 20 V/V and offers excellent accuracy as the internal gain setting resistors are precision trimmed to within 0.01% matching. The resulting output voltage is equal to V+ A1 PROPRIETARY OFFSET CIRCUITRY OUT = (ISHUNT × RSHUNT ) × 20 AD8215 GND 07203-025 G = +20 ROUT OUT = (ISHUNT × RSHUNT) × 20 Figure 26. Simplified Schematic Rev. 0 | Page 10 of 16 AD8215 APPLICATION NOTES OUTPUT LINEARITY In all current sensing applications, and especially in automotive and industrial environments where the common-mode voltage can vary significantly, it is important that the current sensor maintain the specified output linearity, regardless of the input differential or common-mode voltage. The AD8215 contains specific circuitry on the input stage, which ensures that even when the differential input voltage is very small and the common-mode voltage is also low (below the 5 V supply), the input-to-output linearity is maintained. Figure 27 shows the differential input voltage vs. the corresponding output voltage at different common modes. Regardless of the common mode, the AD8215 provides a correct output voltage when the differential input is at least 2 mV, which is due to the voltage range of the output amplifier that can go as low as 33 mV typical. The specified minimum output amplifier voltage is 100 mV to provide sufficient guardbands. The ability of the AD8215 to work with very small differential inputs, regardless of the common-mode voltage, allows for more dynamic range, accuracy, and flexibility in any current sensing application. 200 180 140 120 100 80 60 40 IDEAL VOUT (mV) VOUT (mV) @ VCM = 0V VOUT (mV) @ VCM = 65V 20 07203-026 OUTPUT VOLTAGE (mV) 160 0 0 1 2 3 4 5 6 7 8 9 10 DIFFERENTIAL INPUT VOLTAGE (mV) Figure 27. Gain Linearity Due to Differential and Common-Mode Voltage Rev. 0 | Page 11 of 16 AD8215 APPLICATIONS INFORMATION HIGH-SIDE CURRENT SENSING WITH A LOW-SIDE SWITCH OVERCURRENT DETECTION (<100ns) In such load control configurations, the PWM-controlled 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 28). An advantage of placing the shunt on the high side is that the entire current, including the recirculation current, can be measured because 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. 5 6 7 8 OUT GND NC –IN NC VREG +IN VS 4 3 2 1 AD8214 5V 5 6 7 8 OUT V+ NC IN+ AD8215 NC 4 SHUNT CLAMP DIODE NC GND IN– 3 2 5 1 INDUCTIVE LOAD BATTERY 5V BATTERY SWITCH 7 IN+ NC 6 5 07203-028 8 V+ OUT AD8215 SHUNT Figure 29. Battery-Referenced Shunt Resistor IN– GND NC NC 2 4 5 1 4 3 LOW-SIDE CURRENT SENSING SWITCH 07203-027 In systems where low-side current sensing is preferred, the AD8215 provides an integrated solution with great accuracy. Ground noise is rejected, CMRR is typically higher than 90 dB, and output linearity is not compromised, regardless of the input differential voltage. Figure 28. Low-Side Switch HIGH-SIDE CURRENT SENSING In this configuration, the shunt resistor is referenced to the battery. High voltage is present at the inputs of the current sense amplifier. In this mode, the recirculation current is again measured and shorts to ground can be detected. When the shunt is battery referenced, the AD8215 produces a linear ground-referenced analog output. An AD8214 can also be used to provide an overcurrent detection signal in as little as 100 ns (see Figure 29). This feature is useful in high current systems where fast shutdown in over-current conditions is essential. 5V 5 6 7 8 OUT V+ NC IN+ AD8215 NC 4 INDUCTIVE LOAD CLAMP DIODE SWITCH BATTERY NC GND IN– 3 2 1 5 SHUNT Figure 30. Ground-Referenced Shunt Resistor Rev. 0 | Page 12 of 16 07203-029 INDUCTIVE LOAD CLAMP DIODE AD8215 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 1 5 4 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) COPLANARITY 0.10 SEATING PLANE 6.20 (0.2441) 5.80 (0.2284) 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) 0.31 (0.0122) 0.50 (0.0196) 0.25 (0.0099) 45° 8° 0° 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) COMPLIANT TO JEDEC STANDARDS MS-012-A A 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. 012407-A 8 4.00 (0.1574) 3.80 (0.1497) Figure 31. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) ORDERING GUIDE Model AD8215YRZ 1 AD8215YRZ-RL1 AD8215YRZ-R71 1 Temperature Range −40°C to +125°C −40°C to +125°C −40°C to +125°C Package Description 8-Lead SOIC_N 8-Lead SOIC_N, 13” Tape and Reel 8-Lead SOIC_N, 7” Tape and Reel Z = RoHS Compliant Part. Rev. 0 | Page 13 of 16 Package Option R-8 R-8 R-8 AD8215 NOTES Rev. 0 | Page 14 of 16 AD8215 NOTES Rev. 0 | Page 15 of 16 AD8215 NOTES ©2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D07203-0-1/08(0) Rev. 0 | Page 16 of 16