ANALOG DEVICES AD8219

Zero Drift, Unidirectional Current Shunt Monitor AD8219 FEATURES FUNCTIONAL BLOCK DIAGRAM V S High common-mode voltage range R4 4 V to 80 V operating −0.3 V to +85 V survival LDO R1 Buffered output voltage –IN OUT Gain = 60 V/V +IN R2 Wide operating temperature range: −40°C to +125°C R3 Excellent ac and dc performance AD8219 ±100 nV/°C typical offset drift GND ±50 µV typical offset Figure 1. ±5 ppm/°C typical gain drift 110 dB typical CMRR at dc APPLICATIONS High-side current sensing 48 V telecom Power management Base stations Unidirectional motor control Precision high voltage current sources GENERAL DESCRIPTION The AD8219 is a high voltage, high resolution, current shunt The AD8219 offers breakthrough performance throughout amplifier. It features a set gain of 60 V/V, with a maximum the −40°C to +125°C temperature range. It features a zero ±0.3% gain error over the entire temperature range. The drift core, which leads to a typical offset drift of ±100 nV/°C buffered output voltage directly interfaces with any typical throughout the operating temperature and common-mode converter. The AD8219 offers excellent input common-mode voltage range. Special attention is devoted to output linearity rejection from 4 V to 80 V. The AD8219 performs unidirectional being maintained throughout the input differential voltage range, current measurements across a shunt resistor in a variety of regardless of the common-mode voltage present, while the industrial and telecom applications including motor control, typical input offset voltage is ±50 μV. power management, and base station power amplifier bias The AD8219 is offered in a 8-lead MSOP package. control. Rev. A 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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 www.analog.com license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Fax: 781.461.3113 ©2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 09415-001 AD8219 TABLE OF CONTENTS Features .............................................................................................. 1  Amplifier Core............................................................................ 10  Applications....................................................................................... 1  Supply Connections ................................................................... 10  Functional Block Diagram .............................................................. 1  Output Clamping ....................................................................... 10  General Description ......................................................................... 1  Output Linearity......................................................................... 10  Revision History ............................................................................... 2  Applications Information .............................................................. 11  Specifications..................................................................................... 3  High-Side Current Sensing ....................................................... 11  Absolute Maximum Ratings............................................................ 4  Motor Control Current Sensing ............................................... 11  ESD Caution.................................................................................. 4  Outline Dimensions....................................................................... 12  Pin Configuration and Function Descriptions............................. 5  Ordering Guide .......................................................................... 12  Typical Performance Characteristics ............................................. 6  Theory of Operation ...................................................................... 10  REVISION HISTORY 2/11—Rev. 0 to Rev. A Changes to Features Section............................................................ 1 Changes to Amplifier Core Section ............................................. 10 Moved Output Linearity Section into Theory of Operation Section.............................................................................................. 10 1/11—Revision 0: Initial Version Rev. A | Page 2 of 12 AD8219 SPECIFICATIONS TOPR = −40°C to +125°C, TA = 25°C, RL = 25 kΩ, input common-mode voltage (VCM) = 4 V (RL is the output load resistor), unless otherwise noted. Table 1. Parameter Min Typ Max Unit Test Conditions/Comments GAIN Initial 60 V/V Accuracy ±0.1 % VO ≥ 0.1 V dc, TA Accuracy over Temperature ±0.3 % TOPR Gain vs. Temperature ±5 ppm/°C T OPR VOLTAGE OFFSET 1 Offset Voltage (RTI) ±200 μV 25°C 1 Over Temperature (RTI) ±300 μV T OPR Offset Drift ±100 nV/°C T OPR INPUT 2 Bias Current 130 μA T , input common mode = 4 V, V = 4 V A S 220 μA T OPR Common-Mode Input Voltage Range 4 80 V Common-mode continuous 3 Differential Input Voltage Range 0 83 mV Differential input voltage Common-Mode Rejection (CMRR) 94 110 dB TOPR OUTPUT 4 Output Voltage Range Low 0.01 V TA 4 Output Voltage Range High VS − 0.1 V TA Output Impedance 2 Ω DYNAMIC RESPONSE Small Signal −3 dB Bandwidth 500 kHz Slew Rate 1 V/μs NOISE 1 0.1 Hz to 10 Hz, (RTI) 2.3 μV p-p 1 Spectral Density, 1 kHz, (RTI) 110 nV/√Hz POWER SUPPLY V input range Operating Range 4 80 V S 5 Quiescent Current Over Temperature 800 μA T Power Supply Rejection Ratio (PSRR) 100 110 dB OPR TEMPERATURE RANGE For Specified Performance −40 +125 °C 1 RTI = referred to input. 2 Refer to Figure 8 for further information on the input bias current. This current varies based on the input common-mode voltage. Additionally, the input bias current flowing to the +IN pin is also the supply current to the internal LDO. 3 The differential input voltage is specified as 83 mV maximum because the output is internally clamped to 5.6 V. See the Output Clamping section. 4 See Figure 19 and Figure 20 for further information on the output range of the AD8219 with various loads. The AD8219 output clamps to a maximum voltage of 5.6 V when the voltage at Pin +IN is greater than 5.6 V. When the voltage at +IN is less than 5.6 V, the output reaches a maximum value of (VS − 100 mV). 5 V (Pin 2) can be connected to a separate supply ranging from 4 V to 80 V, or it can be connected to the positive input pin (+IN) of the AD8219. In this mode, the S current drawn varies with increasing voltage. See Figure 9. Rev. A | Page 3 of 12 AD8219 ABSOLUTE MAXIMUM RATINGS Table 2. Stresses above those listed under Absolute Maximum Ratings Parameter Rating may cause permanent damage to the device. This is a stress Maximum Input Voltage ( +IN, −IN to GND) −0.3 V to +85 V rating only; functional operation of the device at these or any Differential Input Voltage (+IN to –IN) ±5 V other conditions above those indicated in the operational Human Body Model (HBM) ESD Rating ±1000 V section of this specification is not implied. Exposure to absolute Operating Temperature Range (TOPR) −40°C to +125°C maximum rating conditions for extended periods may affect Storage Temperature Range −65°C to +150°C device reliability. Output Short-Circuit Duration Indefinite ESD CAUTION Rev. A | Page 4 of 12 AD8219 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS +IN 1 8 –IN AD8219 V 2 7 NC S TOP VIEW NC 3 6 NC (Not to Scale) GND 4 5 OUT NC = NO CONNECT. DO NOT CONNECT TO THIS PIN. Figure 2. Pin Configuration Table 3. Pin Function Descriptions Pin No. Mnemonic Description 1 +IN Noninverting Input. 2 V Supply Pin. Bypass with a standard 0.1 μF capacitor. S 3 NC Do Not Connect to This Pin. 4 GND Ground. 5 OUT Output. 6 NC Do Not Connect to This Pin. 7 NC Do Not Connect to This Pin. 8 −IN Inverting Input. Rev. A | Page 5 of 12 09415-002 AD8219 TYPICAL PERFORMANCE CHARACTERISTICS 40 –19.0 –19.5 30 –20.0 20 –20.5 10 –21.0 –21.5 0 –22.0 –10 –22.5 –20 –23.0 –30 –23.5 –24.0 –40 –40 –20 0 20 40 60 80 100 120 140 1k 10k 100k 1M 10M TEMPERATURE (°C) FREQUENCY (Hz) Figure 3. Typical Input Offset vs. Temperature Figure 6. Typical Small Signal Bandwidth (V = 200 mV p-p) OUT 120 7 6 110 5 100 4 90 3 2 80 1 70 0 60 –1 50 –2 100 1k 10k 100k 1M 01 1 2 3 4 5 6 7 8 90 FREQUENCY (Hz) DIFFERENTIAL INPUT VOLTAGE (mV) Figure 4. Typical CMRR vs. Frequency Figure 7. Typical Output Error vs. Differential Input Voltage 0 300 –50 250 –100 +IN –150 200 –200 –250 150 –300 100 –350 –400 50 –450 –IN –500 0 –40 –20 0 20 40 60 80 100 120 140 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 TEMPERATURE (°C) INPUT COMMON-MODE VOLTAGE (V) Figure 5. Typical Gain Error vs. Temperature Figure 8. Input Bias Current vs. Input Common-Mode Voltage (Differential Input Voltage = 5 mV) (V = 5 V) S Rev. A | Page 6 of 12 V (µV) CMRR (dB) GAIN ERROR (ppm) OS 09415-120 09415-121 09415-104 TYPICAL OUTPUT ERROR (%) MAGNITUDE (dB) INPUT BIAS CURRENT (µA) 09415-128 09415-101 09415-105 AD8219 550 500 V = 5V CM 450 INPUT 50mV/DIV V = 80V CM 400 350 OUTPUT 2V/DIV 300 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 SUPPLY VOLTAGE (V) 5µs/DIV Figure 9. Typical Supply Current vs. Supply Voltage (V Connected to +IN) Figure 12. Rise Time (Differential Input = 50 mV) S 550 500 INPUT 450 5mV/DIV 400 350 OUTPUT 200mV/DIV 300 250 200 –40 –20 0 20 40 60 80 100 120 140 TEMPERATURE (°C) 1µs/DIV Figure 10. Typical Supply Current Change over Temperature (V = 5 V) Figure 13. Fall Time (Differential Input = 5 mV) S INPUT 50mV/DIV INPUT 5mV/DIV OUTPUT 2V/DIV OUTPUT 200mV/DIV 5µs/DIV 1µs/DIV Figure 14. Fall Time (Differential Input = 50 mV) Figure 11. Rise Time (Differential Input = 5 mV) Rev. A | Page 7 of 12 SUPPLY CURRENT (µA) SUPPLY CURRENT (µA) 09415-109 09415-103 09415-102 09415-112 09415-111 09415-110 AD8219 7.0 INPUT 6.5 100mV/DIV 6.0 5.5 OUTPUT 2V/DIV 5.0 4.5 4.0 –40 –20 0 20 40 60 80 100 120 5µs/DIV TEMPERATURE (°C) Figure 15. Differential Overload Recovery, Falling Figure 18. Maximum Output Source Current vs. Temperature 5.0 +125°C +25°C –40°C 4.8 4.5 INPUT 4.3 100mV/DIV 4.0 3.8 OUTPUT 3.5 2V/DIV 3.3 3.0 03 0.5 1.0 1.5 2.0 2.5.0 5µs/DIV SOURCE CURRENT (mA) Figure 16. Differential Overload Recovery, Rising Figure 19. Output Voltage Range vs. Output Source Current (VS = 5 V) 12 0.40 +125°C +25°C –40°C 0.35 11 0.30 10 0.25 9 0.20 8 0.15 7 0.10 6 0.05 5 0 –40 –20 0 20 40 60 80 100 120 04 0.5 1.0 1.5 2.0 2.5 3.0 3.5.0 TEMPERATURE (°C) SINK CURRENT (mA) Figure 17. Maximum Output Sink Current vs. Temperature Figure 20. Output Voltage Range From Ground vs. Output Sink Current (V = 5 V) S Rev. A | Page 8 of 12 MAXIMUM OUTPUT SINK CURRENT (mA) 09415-114 09415-113 09415-107 OUTPUT VOLTAGE FROM GROUND (V) OUTPUT VOLTAGE FROM RAIL (V) MAXIMUM OUTPUT SOURCE CURRENT (mA) 09415-129 09415-106 09415-108 AD8219 70 60 INPUT COMMON MODE 50V/DIV 50 40 30 OUTPUT 200mV/DIV 20 10 0 –6 –4 –2 0 2 4 6 GAIN DRIFT (ppm/°C) 2µs/DIV Figure 24. Gain Drift Distribution Figure 21. Common-Mode Step Response (Falling) 35 30 25 INPUT COMMON MODE 50V/DIV 20 15 10 OUTPUT 200mV/DIV 5 0 –0.6 –0.4 –0.2 0 0.2 0.4 0.6 OFFSET DRIFT (µV/°C) 1µs/DIV Figure 22. Common-Mode Step Response (Rising) Figure 25. Input Offset Drift Distribution 50 40 30 20 10 0 –150 –100 –50 0 50 100 150 V (µV) OSI Figure 23. Input Offset Distribution Rev. A | Page 9 of 12 COUNT 09415-116 09415-115 09415-118 COUNT COUNT 09415-119 09415-117 AD8219 THEORY OF OPERATION SUPPLY CONNECTIONS AMPLIFIER CORE The AD8219 includes an internal LDO, which allows the user In typical applications, the AD8219 amplifies a small differential to connect the V pin to the inputs, or use a separate supply at S input voltage generated by the load current flowing through Pin 2 (V ) to power the device. The input range of the supply S a shunt resistor. The AD8219 rejects high common-mode vol- pin is equivalent to the input common-mode range of 4 V to tages (up to 80 V) and provides a ground referenced, buffered 80 V. The user must ensure that VS is always connected to the output that interfaces with an analog-to-digital converter (ADC). +IN pin or a separate low impedance supply, which can range Figure 26 shows a simplified schematic of the AD8219. from 4 V to 80 V. The VS pin should not be floating. 4V TO 80V OUTPUT CLAMPING V GND S When the input common-mode voltage in the application is R4 above 5.6 V, the internal LDO output of the AD8219 also I LOAD LDO R1 –IN reaches its maximum value of 5.6 V, which is the maximum V 2 LOAD SHUNT OUT output range of the AD8219. Because in typical applications +IN V 1 the output interfaces with a converter, clamping the AD8219 R2 4V R3 TO output voltage to 5.6 V ensures the ADC input is not damaged AD8219 80V due to excessive overvoltage. GND OUTPUT LINEARITY Figure 26. Simplified Schematic In all current sensing applications where the common-mode The AD8219 is configured as a difference amplifier. The voltage can vary significantly, it is important that the current transfer function is sensor maintain the specified output linearity, regardless of OUT = (R4/R1) × (V − V ) the input differential or common-mode voltage. The AD8219 1 2 maintains a very high input-to-output linearity even when the Resistors R4 and R1 are matched to within 0.01% and have differential input voltage is very small. values of 1.5 MΩ and 25 kΩ, respectively, meaning an input 0.7 to output total gain of 60 V/V for the AD8219, while the difference at V1 and V2 is the voltage across the shunt resistor 0.6 or V . Therefore, the input-to-output transfer function for the IN AD8219 is 0.5 OUT = (60) × (V ) IN 0.4 The AD8219 accurately amplifies the input differential signal, 0.3 rejecting high voltage common modes ranging from 4 V to 80 V. The main amplifier uses a novel zero drift architecture, providing 0.2 the end user with breakthrough temperature stability. The offset 0.1 drift is typically less than ±100 nV/°C. This performance leads to optimal accuracy and dynamic range. 0 01 1 2 3 4 5 6 7 8 90 DIFFERENTIAL INPUT VOLTAGE (mV) Figure 27. Typical Gain Linearity at Small Differential Inputs (VCM = 4 V to 80 V) Regardless of the common mode, the AD8219 provides a correct output voltage when the input differential is at least 1 mV. The ability of the AD8219 to work with very small differential inputs, regardless of the common-mode voltage, allows for optimal dynamic range, accuracy, and flexibility in any current sensing application. Rev. A | Page 10 of 12 09415-024 OUTPUT VOLTAGE (V) 09415-127 AD8219 APPLICATIONS INFORMATION HIGH-SIDE CURRENT SENSING MOTOR CONTROL CURRENT SENSING In this configuration, the shunt resistor is referenced to the The AD8219 is a practical, accurate solution for high-side battery (see Figure 28). High voltage is present at the inputs current sensing in motor control applications. In cases where of the current sense amplifier. When the shunt is battery the shunt resistor is referenced to a battery and the current referenced, the AD8219 produces a linear ground referenced flowing is unidirectional (as shown in Figure 30), the AD8219 analog output. monitors the current with no additional supply pin necessary provided the battery voltage in the following circuit is in the 4 V I LOAD to 80 V range. 4V BATTERY SHUNT TO LOAD 80V I MOTOR –IN +IN AD8219 MOTOR +IN –IN V OUT S GND AD8219 V OUT S GND Figure 28. Battery Referenced Shunt Resistor Figure 28 shows the supply pin, V , connected directly to the S Figure 30. High-Side Current Sensing in Motor Control positive input (+IN) pin. In this mode, the internal LDO powers the AD8219 as long as the common-mode voltage at the input pins is 4 V to 80 V. Additionally, VS can also be connected to a standalone supply that can vary from 4 V to 80 V as shown in Figure 29. I LOAD 4V SHUNT TO LOAD 80V –IN +IN AD8219 V OUT S 4V GND TO 80V Figure 29. Standalone Supply Operation Rev. A | Page 11 of 12 09415-029 09415-026 09415-027 AD8219 OUTLINE DIMENSIONS 3.20 3.00 2.80 8 5 5.15 3.20 4.90 3.00 4.65 1 2.80 4 PIN 1 IDENTIFIER 0.65 BSC 0.95 15° MAX 0.85 1.10 MAX 0.75 0.80 0.15 0.23 6° 0.55 0.40 0.05 0.09 0° 0.40 0.25 COPLANARITY 0.10 COMPLIANT TO JEDEC STANDARDS MO-187-AA Figure 31. 8-Lead Mini Small Outline Package [MSOP] (RM-8) Dimensions shown in millimeters ORDERING GUIDE 1 Model Temperature Range Package Description Package Option Branding AD8219BRMZ −40°C to +125°C 8-Lead Mini Small Outline Package [MSOP] RM-8 Y3S AD8219BRMZ-RL −40°C to +125°C 8-Lead Mini Small Outline Package [MSOP] RM-8 Y3S 1 Z = RoHS Compliant Part. ©2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D09415-0-2/11(A) Rev. A | Page 12 of 12 10-07-2009-B