ANALOG DEVICES AD8217

High Resolution, Zero-Drift Current Shunt Monitor AD8217 FEATURES FUNCTIONAL BLOCK DIAGRAM High common-mode voltage range R4 AD8217 4.5 V to 80 V operating 0 V to 85 V survival R1 –IN Buffered output voltage OUT +IN Wide operating temperature range: −40°C to +125°C R2 R3 Excellent ac and dc performance LDO ±100 nV/°C typical offset drift ±100 μV typical offset GND ±5 ppm/°C typical gain drift Figure 1. 100 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 AD8217 is a high voltage, high-resolution current shunt The AD8217 offers breakthrough performance throughout the amplifier. It features a set gain of 20 V/V, with a maximum −40°C to +125°C temperature range. It features a zero-drift ±0.35% gain error over the entire temperature range. The 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 AD8217 offers excellent common-mode rejection voltage range. Special attention is devoted to output linearity from 4.5 V to 80 V, and includes an internal LDO, which directly being maintained throughout the input differential voltage range powers the device from the high voltage rail. Therefore, no addi- of 0 mV to 250 mV, regardless of the common-mode voltage tional supply is necessary, provided that the input common-mode present, and the typical input offset voltage is ±100 μV. range is 4.5 V to 80 V. The AD8217 performs unidirectional The AD8217 is offered in a 8-lead MSOP package and is current measurements across a shunt resistor in a variety of specified from −40°C to +125°C. industrial and telecom applications including motor control, battery management, and base station power amplifier bias 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 ©2010–2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 09161-001 AD8217 TABLE OF CONTENTS Features .............................................................................................. 1 Amplifier Core............................................................................ 10 Applications....................................................................................... 1 Internal LDO............................................................................... 10 Functional Block Diagram .............................................................. 1 Application Notes........................................................................... 11 General Description ......................................................................... 1 Output Linearity......................................................................... 11 Revision History ............................................................................... 2 Applications Information .............................................................. 12 Specifications..................................................................................... 3 High-Side Current Sensing ....................................................... 12 Absolute Maximum Ratings............................................................ 4 Motor Control Current Sensing ............................................... 12 ESD Caution.................................................................................. 4 Outline Dimensions....................................................................... 13 Pin Configuration and Function Descriptions............................. 5 Ordering Guide .......................................................................... 13 Typical Performance Characteristics ............................................. 6 Theory of Operation ...................................................................... 10 REVISION HISTORY 3/11—Rev. 0 to Rev. A Changes to Features.......................................................................... 1 Changes to Figure 18........................................................................ 8 7/10—Revision 0: Initial Version Rev. A | Page 2 of 16 AD8217 SPECIFICATIONS TOPR = −40°C to +125°C, TA = 25°C, RL = 25 kΩ, input common-mode voltage (VCM = 4.5 V) (RL is the output load resistor), unless otherwise noted. Table 1. Parameter Min Typ Max Unit Test Conditions/Comments GAIN Initial 20 V/V Accuracy ±0.1 % VO ≥ 0.1 V dc, TA Accuracy over Temperature ±0.35 % TOPR Gain vs. Temperature ±5 ppm/°C T OPR VOLTAGE OFFSET 1 Offset Voltage (RTI) ±250 μV 25°C 1 Over Temperature (RTI) ±300 μV T OPR Offset Drift ±100 nV/°C T OPR INPUT 2 Bias Current 500 μA T A 800 μA T OPR Common-Mode Input Voltage Range 4.5 80 V Common-mode continuous 3 Differential Input Voltage Range 250 mV Differential input voltage Common-Mode Rejection (CMRR) 90 100 dB TOPR OUTPUT 4 Output Voltage Range Low 0.01 V TA 4 Output Voltage Range High 5 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 Power regulated from common mode Operating Range 4.5 80 V Quiescent Current Over Temperature 800 μA Throughout input common mode T Power Supply Rejection Ratio (PSRR) 90 110 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 250 mV typical because the output is internally clamped to 5 V. This ensures the output voltage does not exceed 5 V and can interface and not cause damage to any typical converter, regardless of the high voltage present at the inputs of the AD8217 (up to 80 V). 4 See Figure 17 and Figure 18 for further information on the output range of the AD8217 with various loads. The AD8217 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 (V − 100 mV). +IN Rev. A | Page 3 of 16 AD8217 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 V to 85 V rating only; functional operation of the device at these or any Differential Input Voltage (+IN to –IN) ±1 V other conditions above those indicated in the operational HBM (Human Body Model) ESD Rating ±2000 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 16 AD8217 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS +IN 1 8 –IN AD8217 NC 2 7 NC TOP VIEW NC 3 6 NC (Not to Scale) GND 4 5 OUT NC = NO CONNECT Figure 2. Pin Configuration Table 3. Pin Function Descriptions Pin No. Mnemonic Description 1 +IN Noninverting Input. Supply pin to the internal LDO. 2 NC No Connect. No internal connection to pin. 3 NC No Connect. No internal connection to pin. 4 GND Ground. 5 OUT Output. 6 NC No Connect. No internal connection to pin. 7 NC No Connect. No internal connection to pin. 8 −IN Inverting Input. Rev. A | Page 5 of 16 09161-002 AD8217 TYPICAL PERFORMANCE CHARACTERISTICS 40 30 27 38 24 36 21 34 18 15 32 12 30 9 28 6 26 3 0 24 1k 10k 100k 1M –40 –20 0 20 40 60 80 100 120 140 FREQUENCY (Hz) TEMPERATURE (°C) Figure 3. Typical Input Offset vs. Temperature Figure 6. Typical Small-Signal Bandwidth (V = 200 mV p-p) OUT 10 140 9 130 8 7 120 6 5 110 4 100 3 2 90 1 –40°C 80 0 +25°C +125°C –1 70 –2 –3 60 –4 –5 50 0 5 10 15 20 25 30 35 40 45 50 100 1000 10k 100k 1M DIFFERENTIAL INPUT (mV) FREQUENCY (Hz) Figure 4. Typical CMRR vs. Frequency Figure 7. Total Output Error vs. Differential Input Voltage 800 500 700 450 +IN 600 400 500 350 400 300 300 250 200 200 100 150 –IN 0 100 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 –40 –20 0 20 40 60 80 100 120 INPUT COMMON-MODE VOLTAGE (V) TEMPERATURE (°C) Figure 5. Typical Gain Error vs. Temperature Figure 8. Input Bias Current vs. Input Common-Mode Voltage (Differential Input Voltage = 5 mV) Rev. A | Page 6 of 16 V (µV) CMRR (dB) GAIN ERROR (ppm) OSI 09161-005 09161-004 09161-003 INPUT BIAS CURRENT (µA) MAGNITUDE (dB) TOTAL OUTPUT ERROR (%) 09161-007 09161-006 09161-008 AD8217 INPUT 100mV/DIV INPUT 5mV/DIV OUTPUT 2V/DIV OUTPUT 100mV/DIV 1µs/DIV 5µs/DIV Figure 9. Rise Time (Differential Input = 5 mV) Figure 12. Fall Time (Differential Input = 200 mV) INPUT 200mV/DIV INPUT 100mV/DIV OUTPUT OUTPUT 2V/DIV 2V/DIV 5µs/DIV 5µs/DIV Figure 10. Rise Time (Differential Input = 200 mV) Figure 13. Differential Overload Recovery, Rising INPUT INPUT 5mV/DIV 200mV/DIV OUTPUT OUTPUT 100mV/DIV 2V/DIV 1µs/DIV 5µs/DIV Figure 11. Fall Time (Differential Input = 5 mV) Figure 14. Differential Overload Recovery, Falling Rev. A | Page 7 of 16 09161-011 09161-010 09161-009 09161-014 09161-013 09161-012 AD8217 250 12.0 11.5 11.0 200 10.5 10.0 9.5 150 9.0 8.5 8.0 100 7.5 7.0 6.5 50 6.0 5.5 0 5.0 0 0.51.01.5 2.02.5 3.03.54.04.55.0 –40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 OUTPUT SINK CURRENT (mA) TEMPERATURE (°C) Figure 15. Maximum Output Sink Current vs. Temperature Figure 18. Output Voltage Range From GND vs. Output Sink Current 9.5 9.0 8.5 INPUT 8.0 50V/DIV 7.5 7.0 6.5 OUTPUT 6.0 1V/DIV 5.5 5.0 4.5 4.0 500ns/DIV TEMPERATURE (°C) Figure 16. Maximum Output Source Current vs. Temperature Figure 19. Common-Mode Step Response, Rising 5.010 5.000 4.990 INPUT 4.980 50V/DIV 4.970 OUTPUT 4.960 4.950 1V/DIV 4.940 4.930 4.920 4.910 4.900 1µs/DIV 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 OUTPUT SOURCE CURRENT (mA) Figure 17. Output Voltage Range vs. Output Source Current Figure 20. Common-Mode Step Response (Falling) Rev. A | Page 8 of 16 OUTPUT VOLTAGE SWING FROM RAIL (V) MAXIMUM OUTPUT SINK CURRENT (mA) MAXIMUM OUTPUT SOURCE CURRENT (mA) –40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 09161-016 09161-015 09161-017 OUTPUT VOLTAGE RANGE FROM GND (mV) 09161-020 09161-019 09161-018 AD8217 800 1200 700 600 1000 500 800 400 600 300 400 200 200 100 0 0 –200 –150 –100 –50 0 50 100 150 200 –0.4 –0.2 0 0.2 0.4 V (µV) OSI OFFSET DRIFT (µV/°C) Figure 21. Input Offset Distribution Figure 23. Input Offset Drift Distribution 1000 800 600 400 200 0 –10 –5 0 5 10 GAIN DRIFT (ppm/°C) Figure 22. Gain Drift Distribution Rev. A | Page 9 of 16 COUNT COUNT 09161-022 09161-021 COUNT 09161-023 AD8217 THEORY OF OPERATION The AD8217 accurately amplifies the input differential signal, AMPLIFIER CORE rejecting high voltage common modes ranging from 4.5 V to 80 V. In typical applications, the AD8217 amplifies a small differential The main amplifier uses a novel zero-drift architecture, providing input voltage generated by the load current flowing through the end user with an extremely stable part over temperature. a shunt resistor. The AD8217 rejects high common-mode vol- The offset drift is typically less than ±100 nV/°C. This perfor- tages (up to 80 V) and provides a ground-referenced, buffered mance leads to optimal accuracy and dynamic range. output that interfaces with an analog-to-digital converter (ADC). Figure 24 shows a simplified schematic of the AD8217. INTERNAL LDO R4 The AD8217 includes an internal LDO, which allows the device AD8217 to power directly from the common-mode voltage at the inputs. I LOAD –IN R1 No additional standalone supply is necessary, provided that the V 2 common-mode voltage at the +IN pin is at least 4.5 V and up to LOAD SHUNT OUT +IN V 1 80 V. Once the common-mode voltage is above 5.6 V, the LDO R2 R3 4.5V TO LDO output reaches its maximum value, that is 5.6 V. This is also the 80V maximum output voltage range of the AD8217. Because the AD8217 output typically interfaces with a converter, the 5.6 V GND maximum output range ensures the ADC input is not damaged Figure 24. Simplified Schematic due to excessive overvoltage. The AD8217 is configured as a difference amplifier. The The input bias current flowing through Pin +IN powers the transfer function is internal LDO and, therefore, doubles as the supply current for the AD8217. This current varies depending on the input OUT = (R4/R1) × (V1 − V2) common-mode voltage. See Figure 8 for additional information. Resistors R4 and R1 are matched to within 0.01% and have values of 1.5 MΩ and 75 kΩ, respectively, meaning an input to output total gain of 20 V/V for the AD8217. Rev. A | Page 10 of 16 09161-024 AD8217 APPLICATION NOTES Regardless of the common mode, the AD8217 provides a OUTPUT LINEARITY correct output voltage when the input differential is at least In all current sensing applications where the common-mode 1 mV. The ability of the AD8217 to work with very small voltage can vary significantly, it is important that the current differential inputs, regardless of the common-mode voltage, sensor maintain the specified output linearity, regardless of allows for optimal dynamic range, accuracy, and flexibility in the input differential or common-mode voltage. The AD8217 any current sensing application. maintains a very high input-to-output linearity even when the differential input voltage is very small. 200 180 160 140 120 100 80 60 40 20 0 01234 56789 10 DIFFERENTIAL INPUT (mV) Figure 25. Gain Linearity at Small Differential Inputs (VCM = 4.5 V to 80 V) Rev. A | Page 11 of 16 OUTPUT (mV) 09161-025 AD8217 APPLICATIONS INFORMATION HIGH-SIDE CURRENT SENSING MOTOR CONTROL CURRENT SENSING In this configuration, the shunt resistor is referenced to the The AD8217 is a practical, accurate solution for high-side battery (see Figure 26). 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 battery and the current referenced, the AD8217 produces a linear ground-referenced flowing is unidirectional (as shown in Figure 27), the AD8217 analog output. The AD8217 includes an internal LDO, which monitors the current with no additional supply pin necessary. allows the part to be powered from the high voltage rail, with BATTERY no need for an additional standalone supply. I MOTOR I LOAD 4.5V SHUNT TO ADC MOTOR +IN –IN 80V +IN –IN AD8217 AD8217 OUT OUT GND GND Figure 27. High-Side Current Sensing in Motor Control Figure 26. Battery-Referenced Shunt Resistor Rev. A | Page 12 of 16 09161-026 09161-027 AD8217 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 28. 8-Lead Mini Small Outline Package [MSOP] (RM-8) Dimensions shown in millimeters ORDERING GUIDE 1 Model Temperature Range Package Description Package Option Branding AD8217BRMZ −40°C to +125°C 8-Lead Mini Small Outline Package (MSOP) RM-8 Y2L AD8217BRMZ-RL −40°C to +125°C 8-Lead Mini Small Outline Package (MSOP) RM-8 Y2L AD8217BRMZ-R7 −40°C to +125°C 8-Lead Mini Small Outline Package (MSOP) RM-8 Y2L 1 Z = RoHS Compliant Part. Rev. A | Page 13 of 16 100709-B AD8217 NOTES Rev. A | Page 14 of 16 AD8217 NOTES Rev. A | Page 15 of 16 AD8217 NOTES ©2010–2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D09161-0-3/11(A) Rev. A | Page 16 of 16