High Voltage Current Shunt Monitor AD8211 ±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 5-lead SOT: −40°C to +125°C Excellent ac and dc performance 5 μV/°C typical offset drift −13 ppm/°C typical gain drift 120 dB typical CMRR at dc FUNCTIONAL BLOCK DIAGRAM VIN+ VIN– V+ A1 PROPRIETARY OFFSET CIRCUITRY OUT G = +20 AD8211 APPLICATIONS High-side current sensing Motor controls Transmission controls Engine management Suspension controls Vehicle dynamic controls DC-to-dc converters GND 06824-001 FEATURES Figure 1. GENERAL DESCRIPTION The AD8211 is a high voltage, precision current shunt amplifier. It features a set gain of 20 V/V, with a typical ±0.5% 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 AD8211 performs unidirectional current measurements across a shunt resistor in a variety of industrial and automotive applications, such as motor control, solenoid control, 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 AD8211 has an operating temperature range of −40°C to +125°C and is offered in a small 5-lead SOT 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 ©2007 Analog Devices, Inc. All rights reserved. AD8211 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 Sense 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 7/07—Revision 0: Initial Version Rev. 0 | Page 2 of 16 AD8211 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 Gain vs. Temperature VOLTAGE OFFSET Offset Voltage (RTI) Over Temperature (RTI) Offset Drift INPUT Input Impedance Differential Common Mode Common-Mode Input Voltage Range Differential Input Voltage Range Common-Mode Rejection OUTPUT Output Voltage Range Low Output Voltage Range High 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 Min Typ Max Unit Conditions V/V % % ppm/°C VO ≥ 0.1 V dc TOPR TOPR 1 mV mV μV/°C 25°C TOPR TOPR 2 +65 kΩ MΩ kΩ V mV dB dB Common-mode voltage > 5 V Common-mode voltage < 5 V Common-mode continuous Differential input voltage TA, f = dc, VCM > 5 V, see Figure 5 TA, f = dc, VCM < 5 V, see Figure 5 4.9 V V Ω 20 ±0.25 ±0.35 −13 ±1 ±2.2 5 5 5 3.5 −2 100 80 0.1 250 120 90 0.05 4.95 2 500 4.5 kHz V/μs 7 70 μV p-p nV/√Hz 4.5 1.2 5.5 2.0 V mA dB +125 °C 76 −40 1 VCM > 5 V 3 , see Figure 12 The mean of the gain drift distribution is typically −13 ppm/°C, with a σ = 3 ppm/°C. The mean of the offset drift distribution is typically +5 μV/°C, with a σ = 3 μV/°C. 3 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. 2 Rev. 0 | Page 3 of 16 AD8211 ABSOLUTE MAXIMUM RATINGS Table 2. Parameter Supply Voltage Continuous Input Voltage Reverse Supply Voltage HBM (Human Body Model) ESD Rating CDM (Charged Device Model) ESD Rating Operating Temperature Range Storage Temperature Range Output Short-Circuit Duration Rating 12.5 V −3 V to +68 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. ESD CAUTION Rev. 0 | Page 4 of 16 AD8211 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS OUT 1 5 V+ 4 VIN– AD8211 2 GND 2 5 VIN+ 3 TOP VIEW (Not to Scale) NC = NO CONNECT 3 4 06824-030 Figure 3. Pin Configuration Figure 2. Metallization Diagram Table 3. Pin Function Descriptions Pin No. 1 2 3 4 5 Mnemonic OUT GND VIN+ VIN− V+ X −277 −140 −228 +229 +264 Y +466 +466 −519 −519 +466 Description Buffered Output. Ground. Noninverting Input. Inverting Input. Supply. Rev. 0 | Page 5 of 16 06824-002 1 AD8211 TYPICAL PERFORMANCE CHARACTERISTICS 1.2 40 35 1.0 30 0.8 25 20 15 GAIN (dB) 0.2 0 –0.2 10 5 0 –5 –0.4 –10 –15 –0.6 –20 –0.8 –25 –30 06824-112 VOSI (mV) 0.4 –1.0 –1.2 –40 –20 0 20 40 60 80 100 06824-107 0.6 –35 –40 10k 120 100k TEMPERATURE (°C) Figure 4. Typical Offset vs. Temperature 10M 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) 1M FREQUENCY (Hz) 110 100 COMMON-MODE VOLTAGE < 5V 90 80 8 7 6 5 4 3 06824-114 60 10 100 1k 10k 100k 06824-118 2 70 1 0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 250 1M FREQUNCY (Hz) DIFFERENTIAL INPUT VOLTAGE (mV) Figure 5. Typical CMRR vs. Frequency Figure 8. Total Output Error vs. Differential Input Voltage 2500 –510 2000 –515 –520 500 0 –500 –1000 –1500 –530 –535 VIN+ –540 –545 –550 –555 –560 –2000 –2500 –40 –525 –20 0 20 40 60 80 100 VIN– 06824-103 INPUT BIAS CURRENT (µA) 1000 06824-113 GAIN ERROR (PPM) 1500 –565 –570 0 120 TEMPERATURE (°C) 25 50 75 100 125 150 175 200 225 DIFFERENTIAL INPUT VOLTAGE (mV) Figure 6. Typical Gain Error vs. Temperature Figure 9. Input Bias Current vs. Differential Input Voltage, VCM = 0 V Rev. 0 | Page 6 of 16 250 AD8211 110 100mV/DIV 90 INPUT VIN+ 80 1V/DIV 70 VIN– 60 OUTPUT 06824-104 50 40 0 25 50 75 100 125 150 175 200 225 06824-110 INPUT BIAS CURRENT (µA) 100 250 TIME (500ns/DIV) DIFFERENTIAL INPUT VOLTAGE (mV) Figure 10. Input Bias Current vs. Differential Input Voltage, VCM = 5 V Figure 13. Fall Time 0.8 INPUT 0 100mV/DIV –0.4 OUTPUT –0.8 1V/DIV –1.2 –1.6 –2.4 –5 06824-102 –2.0 0 5 10 15 20 25 30 35 40 45 50 55 60 06824-111 INPUT BIAS CURRENT (mA) 0.4 65 TIME (500ns/DIV) INPUT COMMON-MODE VOLTAGE (V) Figure 11. Input Bias Current vs. Input Common-Mode Voltage Figure 14. Rise Time 4.0 200mV/DIV 3.0 INPUT 2.5 2V/DIV 2.0 1.5 OUTPUT –2 0 2 4 6 8 06824-109 1.0 –4 06824-101 SUPPLY CURRENT (mA) 3.5 65 TIME (1µs/DIV) COMMON-MODE VOLTAGE (V) Figure 12. Supply Current vs. Common-Mode Voltage Figure 15. Differential Overload Recovery (Falling) Rev. 0 | Page 7 of 16 AD8211 INPUT 200mV/DIV OUTPUT 06824-108 2V/DIV 11.5 11.0 10.5 10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 06824-106 MAXIMUM OUTPUT SINK CURRENT (mA) 12.0 5.5 5.0 –40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 TIME (1µs/DIV) TEMPERATURE (°C) Figure 16. Differential Overload Recovery (Rising) Figure 19. Maximum Output Sink Current vs. Temperature 2V/DIV 06824-120 0.01/DIV 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 –40 TIME 5µs/DIV) 06824-105 MAXIMUM OUTPUT SOURCE CURRENT (mA) 9.0 –20 0 20 40 60 80 100 120 140 TEMPERATURE (°C) Figure 20. Maximum Output Source Current vs. Temperature Figure 17. Settling Time (Falling) 5.0 2V/DIV 06824-119 0.01/DIV 4.2 3.8 3.4 3.0 2.6 2.2 1.8 06824-117 OUTPUT VOLTAGE RANGE (V) 4.6 1.4 1.0 TIME 5µs/DIV) 0 1 2 3 4 5 6 7 8 OUTPUT SOURCE CURRENT (mA) Figure 21. Output Voltage Range vs. Output Source Current Figure 18. Settling Time (Rising) Rev. 0 | Page 8 of 16 9 AD8211 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 06824-116 OUTPUT VOLTAGE RANGE FROM GND (V) 2.0 0.2 0 0 1 2 3 4 5 6 7 8 9 10 11 12 OUTPUT SINK CURRENT (mA) Figure 22. Output Voltage Range from GND vs. Output Sink Current Rev. 0 | Page 9 of 16 AD8211 THEORY OF OPERATION In typical applications, the AD8211 amplifies a small differential input voltage generated by the load current flowing through a shunt resistor. The AD8211 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 23 shows a simplified schematic of the AD8211. ISHUNT (VCM) − (ISHUNT × RSHUNT) because negligible current flows through Resistor R. Amplifier A1 forces the noninverting input to the same potential. Therefore, the current that flows through Resistor R1, is equal to RSHUNT IIN A load current flowing through the external shunt resistor produces a voltage at the input terminals of the AD8211. The input terminals are connected to Amplifier A1 by Resistor R and Resistor R1. The inverting terminal, which has very high input impedance is held to R R1 IIN = (ISHUNT × RSHUNT)/R1 V+ A1 PROPRIETARY OFFSET CIRCUITRY 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 Q1 VOUT = (ISHUNT × RSHUNT) × 20 VOUT = (ISHUNT × RSHUNT ) × 20 AD8211 GND 06824-022 G = +20 ROUT Figure 23. Simplified Schematic Rev. 0 | Page 10 of 16 AD8211 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 AD8211 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 24 shows the input differential voltage vs. the corresponding output voltage at different common modes. Regardless of the common mode, the AD8211 provides a correct output voltage when the input differential 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 AD8211 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 06824-115 OUTPUT VOLTAGE (mV) 160 0 0 1 2 3 4 5 6 7 8 9 10 DIFFERENTIAL INPUT VOLTAGE (mV) Figure 24. Gain Linearity Due to Differential and Common-Mode Voltage Rev. 0 | Page 11 of 16 AD8211 APPLICATIONS INFORMATION OVERCURRENT DETECTION (<100ns) HIGH-SIDE CURRENT SENSE WITH A LOW-SIDE SWITCH 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 25). 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. OUT GND VIN+ AD8211 VIN– 4 5 5 4 8 –IN NC VREG +IN VS 4 3 2 1 AD8214 1 3 2 1 3 OUT GND VIN+ AD8211 SHUNT CLAMP DIODE VIN– V+ 4 5 5 4 INDUCTIVE LOAD BATTERY 5V SWITCH INDUCTIVE LOAD CLAMP DIODE SHUNT V+ 7 NC 06824-025 1 3 6 GND Figure 26. Battery-Referenced Shunt Resistor BATTERY LOW-SIDE CURRENT SENSING SWITCH 5V In systems where low-side current sensing is preferred, the AD8211 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 25. 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 AD8211 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. This feature is useful in high current systems where fast shutdown in overcurrent conditions is essential. 1 3 2 1 3 OUT GND VIN+ AD8211 SWITCH V+ VIN– 4 5 5 4 5V INDUCTIVE LOAD CLAMP DIODE SHUNT Figure 27. Ground-Referenced Shunt Resistor Rev. 0 | Page 12 of 16 BATTERY 06824-026 2 06824-024 1 3 5 OUT AD8211 OUTLINE DIMENSIONS 2.90 BSC 5 4 2.80 BSC 1.60 BSC 1 2 3 PIN 1 0.95 BSC 1.90 BSC 1.30 1.15 0.90 1.45 MAX 0.15 MAX 0.50 0.30 0.22 0.08 SEATING PLANE 10° 5° 0° 0.60 0.45 0.30 COMPLIANT TO JEDEC STANDARDS MO-178-A A Figure 28. 5-Lead Small Outline Transistor Package [SOT-23] (RJ-5) Dimensions shown in millimeters ORDERING GUIDE Model AD8211YRJZ-R2 1 AD8211YRJZ-RL1 AD8211YRJZ-RL71 1 Temperature Range −40°C to +125°C −40°C to +125°C −40°C to +125°C Package Description 5-Lead SOT-23 5-Lead SOT-23 5-Lead SOT-23 Z = RoHS Compliant Part. Rev. 0 | Page 13 of 16 Package Option RJ-5 RJ-5 RJ-5 Branding Y02 Y02 Y02 AD8211 NOTES Rev. 0 | Page 14 of 16 AD8211 NOTES Rev. 0 | Page 15 of 16 AD8211 NOTES ©2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D06824-0-7/07(0) Rev. 0 | Page 16 of 16