Low Cost, Voltage Output, High-Side, Current-Sense Amplifier ADM4073 FUNCTIONAL BLOCK DIAGRAM ILOAD RSENSE 2V TO 28V 0.1µF IRG1 VCC RG1 RG2 AV ADM4073 VOUT CURRENT MIRROR RGD = 12kΩ IRGD GND Figure 1. APPLICATIONS Cell phones, PDAs Notebook computers Portable/battery-powered systems Smart battery packs/chargers Automotive Power management systems PA bias control General system/board-level current monitoring Precision current sources RS– RS+ 3V TO 28V VOUT 05131-003 Low cost, compact, current-sense solution Three available gain versions 20 V/V (ADM4073T) 50 V/V (ADM4073F) 100 V/V (ADM4073H) Typical ±1.0% full-scale accuracy 500 μA supply current Wide 1.8 MHz bandwidth 3 V to 28 V operating supply Wide 2 V to 28 V common-mode range Independent of supply voltage Operates from −40°C to +125°C Available in a 6-lead SOT-23 package Pin-to-pin compatibility with the MAX4073 APPLICATION DIAGRAM RSENSE 2V TO 28V RS+ 3V TO 28V VOUT RS– VCC OUT 0.1µF ADC ADM4073 GND 05131-001 FEATURES Figure 2. GENERAL DESCRIPTION The ADM4073 is a low cost, high-side, current-sense amplifier ideal for small portable applications such as cell phones, notebook computers, PDAs, and other systems where current monitoring is required. The device is available in three different gain models, eliminating the need for gain-setting resistors. Because the ground path is not interrupted, the ADM4073 is particularly useful in rechargeable battery-powered systems, while its wide 1.8 MHz bandwidth makes it suitable for use inside battery-charger control loops. The input common-mode range of 2 V to 28 V is independent of the supply voltage. The voltage on the output pin is determined by the current flowing through the selectable external sense resistor and the gain of the version selected. The operating range is 3 V to 28 V with a typical supply current of 500 μA. The ADM4073 is available in a 6-lead SOT-23 package and is specified over the automotive operating temperature range (−40°C to +125°C). 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 ©2006 Analog Devices, Inc. All rights reserved. ADM4073 TABLE OF CONTENTS Features .............................................................................................. 1 ESD Caution...................................................................................4 Applications....................................................................................... 1 Pin Configuration and Function Descriptions..............................5 Functional Block Diagram .............................................................. 1 Typical Performance Characteristics ..............................................6 Application Diagram........................................................................ 1 Theory of Operation ...................................................................... 10 General Description ......................................................................... 1 RSENSE............................................................................................. 10 Revision History ............................................................................... 2 Output (OUT)............................................................................. 10 Specifications..................................................................................... 3 Outline Dimensions ....................................................................... 11 Absolute Maximum Ratings............................................................ 4 Ordering Guide .......................................................................... 11 Thermal Characteristics .............................................................. 4 REVISION HISTORY 7/06—Revision 0: Initial Version Rev. 0 | Page 2 of 12 ADM4073 SPECIFICATIONS VRS+ = 2 V to 28 V, VSENSE = (VRS+ − VRS−) = 0, VCC = 3 V to 28 V, TA = −40°C to +125°C, unless otherwise noted. Typical values are at TA = 25°C. 1 Table 1. Parameter POWER SUPPLY Operating Voltage Range, VCC Common-Mode Input Range, VCMR Common-Mode Input Rejection, CMR Supply Current, ICC Leakage Current, IRS+/IRS− Input Bias Current, IRS+ Input Bias Current, IRS− Full Scale Sense Voltage, VSENSE Total Out Voltage Error 2 Min Typ 3 2 90 0.5 0.05 20 40 150 ±1 ±1.0 ±1.0 Extrapolated Input Offset Voltage, VOS Out High Voltage (VCC − VOH) DYNAMIC CHARACTERISTICS Bandwidth, BW Gain, AV Gain Accuracy, dAV ±7.5 1.0 0.8 0.8 0.8 1.8 1.7 1.6 600 20 50 100 ±1.0 ±1.0 OUT Settling Time to 1% of Final Value Output Resistance, ROUT Power Supply Rejection Ratio, PSRR Power-Up Time 4 Saturation Recovery Time 5 400 800 12 78 85 90 5 5 Max Unit Conditions 28 28 Inferred from PSRR test Inferred OUT voltage error test VSENSE = 100 mV, VCC = 12 V VCC = 28 V VCC = 0 V, VRS+ = 28 V, TA = 85°C 1.2 1.2 1.2 V V dB mA μA μA μA mV % % % % % % mV V V V ±2.0 MHz MHz MHz kHz V/V V/V V/V % ±2.0 % ±1.5 % ±3.0 % VSENSE = 100 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF (ADM4073T) VSENSE = 100 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF (ADM4073F) VSENSE = 100 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF (ADM4073H) VSENSE = 6.25 mV,3 VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF (ADM4073T/F/H) ADM4073T ADM4073F ADM4073H VSENSE = 10 mV to 150 mV, VCC = 12 V, VRS+ = 12 V, TA = +25°C (ADM4073T/F) VSENSE = 10 mV to 150 mV, VCC = 12 V, VRS+ = 12 V, TA = −40°C to +125°C (ADM4073T/F) VSENSE = 10 mV to 100 mV, VCC = 12 V, VRS+ = 12 V, TA = +25°C (ADM4073H) VSENSE = 10 mV to 100 mV, VCC = 12 V, VRS+ = 12 V, TA = −40°C to +125°C (ADM4073H) VSENSE = 6.25 mV to 100 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF VSENSE = 100 mV to 6.25 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF 1.2 2 60 120 ±5.0 ±5.0 ±5.0 ±5.0 ns ns kΩ dB dB dB μs μs VSENSE = (VRS+ − VRS−) VSENSE = 100 mV, VCC = 12 V, VRS+ = 2 V VSENSE = 100 mV, VCC = 12 V, VRS+ = 12 V, TA = +25°C VSENSE = 100 mV, VCC = 12 V, VRS = 12V, TA = −40°C to +125°C VSENSE = 100 mV, VCC = 28 V, VRS = 28 V, TA = +25°C VSENSE = 100 mV, VCC = 28 V, VRS = 28 V, TA = −40°C to +125°C VSENSE = 6.25 mV, 3 VCC = 12 V, VRS = 12 V VCC = VRS+ = 12 V, VSENSE > 10 mV VCC = 3 V, VSENSE = 150 mV (ADM4073T) VCC = 7.5 V, VSENSE = 150 mV (ADM4073F) VCC = 15 V, VSENSE = 150 mV (ADM4073H), TA = 25°C VSENSE = 60 mV, VCC = 3 V to 28 V (ADM4073T) VSENSE = 24 mV, VCC = 3 V to 28 V (ADM4073F) VSENSE = 12 mV, VCC = 3 V to 28 V (ADM4073H) CLOAD = 5 pF, VSENSE = 100 mV CLOAD = 5 pF, VCC = 12 V, VRS+ = 12 V 1 100% production tested at TA = 25°C. Specifications over temperature limit are guaranteed by design. Total out voltage error is the sum of the gain and offset errors. 3 6.25 mV = 1/16th of 100 mV full-scale sense voltage. 4 Output settles to within 1% of final value. 5 The device does not experience phase reversal when overdriven. 2 Rev. 0 | Page 3 of 12 ADM4073 ABSOLUTE MAXIMUM RATINGS Table 2. Parameter VCC to GND RS± to GND OUT to GND OUT Short-Circuit to GND Differential Input Voltage (VRS+ − VRS−) Current into any Pin Storage Temperature Range Operating Temperature Range Lead Temperature, Soldering (10 sec) Junction Temperature Rating −0.3 V to +30 V −0.3 V to +30 V −0.3 V to (VCC + 0.3 V) Continuous ±5 V ±20 mA −65°C to +125°C −40°C to +125°C 300°C 150°C 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. THERMAL CHARACTERISTICS θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 3. Thermal Resistance Package Type 6-Lead SOT-23 ESD CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. Rev. 0 | Page 4 of 12 θJA 169.5 Unit °C/W ADM4073 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS ADM4073xWRJ GND 1 6 OUT VCC 3 4 RS+ 05131-002 TOP VIEW GND 2 (Not to Scale) 5 RS– Figure 3. Pin Configuration Table 4. Pin Function Descriptions Pin No. 1, 2 3 4 5 6 Mnemonic GND VCC RS+ RS− OUT Description Chip Ground Pin. Chip Power Supply. Requires a 0.1μF capacitor to ground. Power-Side Connection to the External Sense Resistor. Load-Side Connection to the External Sense Resistor. Voltage Output. VOUT is proportional to VSENSE. Output impedence is approximately 12 kΩ. Rev. 0 | Page 5 of 12 ADM4073 TYPICAL PERFORMANCE CHARACTERISTICS 0.45 0.60 VSENSE = 6.25mV VSENSE = 6.25mV 0.43 SUPPLY CURRENT (mA) 0.50 ADM4073H 0.45 ADM4073F 0.40 ADM4073T ADM4073T 0.39 ADM4073F 5 10 15 20 25 30 SUPPLY VOLTAGE (V) 0.35 05131-005 0 0 VSENSE = 100mV SUPPLY CURRENT (mA) 1.1 1.0 0.9 ADM4073F 0.7 1.1 0.9 10 15 20 25 30 05131-006 0.5 5 0 ADM4073F ADM4073T 0 5 10 15 20 25 30 30 VRS+ (V) Figure 8. Supply Current vs. RS+ Voltage (VSENSE = 100 mV) Figure 5. Supply Current vs. Supply Voltage (VSENSE = 100 mV) 0.7 1.0 VSENSE = 0mV VCC = 28V VSENSE = 100mV TOTAL OUTPUT ERROR (%) 0.8 0.5 0.4 0.3 0.2 0.6 ADM4073F 0.4 ADM4073T 0.2 0 ADM4073H –0.2 –0.4 –0.6 0.1 –0.8 0 –50 –25 0 25 50 75 100 TEMPERATURE (°C) 125 150 –1.0 05131-007 SUPPLY CURRENT (mA) ADM4073H ADM4073T SUPPLY VOLTAGE (V) 0.6 30 1.3 0.7 0.6 25 05131-009 SUPPLY CURRENT (mA) ADM4073H 1.2 0.5 20 VSENSE = 100mV 1.5 0.8 15 Figure 7. Supply Current vs. RS+ Voltage (VSENSE = 6.25 mV) 1.5 1.3 10 VRS+ (V) Figure 4. Supply Current vs. Supply Voltage (VSENSE = 6.25mV) 1.4 5 05131-008 0.37 0.35 0.30 ADM4073H 0.41 05131-010 SUPPLY CURRENT (mA) 0.55 0 5 10 15 20 25 SUPPLY VOLTAGE (V) Figure 6. Supply Current vs. Temperature Figure 9. Total Output Error vs. Supply Voltage (VSENSE = 100 mV) Rev. 0 | Page 6 of 12 ADM4073 1.0 2.0 VSENSE = 6.25mV 1.5 0.6 1.0 0.4 GAIN ACCURACY (%) ADM4073F 0.2 0 ADM4073T –0.2 –0.4 0.5 0 –0.5 –1.0 –0.6 ADM4073H 5 10 15 20 25 30 SUPPLY VOLTAGE (V) –2.0 –50 25 75 100 125 150 150 1.4 ADM4073F 0.5 1.2 ADM4073H ADM4073H 0 1.0 VCC – VOH (V) ADM4073T –0.5 –1.0 –1.5 0.8 ADM4073F 0.6 0.4 –2.0 ADM4073T 0.2 –2.5 0 5 10 15 20 25 30 COMMON-MODE VOLTAGE (V) 0 –50 05131-012 –3.0 50 Figure 13. Gain Accuracy vs. Temperature 1.0 TOTAL OUTPUT ERROR (%) 0 TEMPERATURE (°C) Figure 10. Total Output Error vs. Supply Voltage (VSENSE = 6.25 mV) 0 50 100 TEMPERATURE (°C) Figure 11. Total Output Error vs. Common-Mode Voltage Figure 14. O/P High Voltage (VCC − VOH) vs. Temperature 70 0.10 ADM4073F 0.08 60 0.06 VCC = 28V 0.04 0.02 50 VCC = 12V PSRR (dB) TOTAL OUTPUT ERROR (%) –25 05131-014 0 05131-011 –1.0 05131-015 –1.5 –0.8 0 –0.02 –0.04 40 ADM4073T 30 20 –0.06 –0.08 0 50 100 TEMPERATURE (°C) 150 0 0.1 05131-013 –0.10 –50 ADM4073H 10 1 10 100 FREQUENCY (kHz) Figure 15. PSRR vs. Frequency Figure 12. Total Output Error vs. Temperature Rev. 0 | Page 7 of 12 1000 10000 05131-016 TOTAL OUTPUT ERROR (%) 0.8 ADM4073 45 ADM4073H 100mV 40 ADM4073F 35 GAIN (dB) 30 VSENSE 2.5mV/DIV ADM4073T 95mV 25 20 10V 15 10 OUT 250mV/DIV 100 1000 10000 1µs/DIV Figure 19. ADM4073H Small Signal Transient Response Figure 16. Small Signal Gain vs. Frequency 100mV VSENSE 2.5mV/DIV 100mV VSENSE 45mV/DIV 95mV 6.25mV 2V OUT 50mV/DIV 2V OUT 0.9V/DIV 05131-018 1.9V 1µs/DIV 0.120V 1µs/DIV Figure 17. ADM4073T Small Signal Transient Response Figure 20. ADM4073T Large Signal Transient Response 100mV VSENSE 2.5mV/DIV 100mV VSENSE 45mV/DIV 95mV 6.25mV 5V OUT 125mV/DIV 5V OUT 2.35V/DIV 05131-019 4.75V 1µs/DIV 05131-021 10 FREQUENCY (kHz) Figure 18. ADM4073F Small Signal Transient Response 0.3V 1µs/DIV Figure 21. ADM4073F Large Signal Transient Response Rev. 0 | Page 8 of 12 05131-022 1 05131-017 0 0.1 9.5V 05131-020 5 ADM4073 VCC = 0V TO 4V 100mV 6.25mV VCC 2V/DIV 0V 10V OUT 4.7V/DIV 2V OUT 1V/DIV 05131-023 0.6V 1µs/DIV Figure 22. ADM4073H Large Signal Transient Response 250mV 50mV VOH OUT 600mV/DIV 05131-024 1V 1µs/DIV 1µs/DIV Figure 24. ADM4073T Start-Up Delay VCC = 3V VSENSE 100mV/DIV 0V Figure 23. ADM4073T Overdrive Response Rev. 0 | Page 9 of 12 05131-025 VSENSE 45mV/DIV 4V ADM4073 THEORY OF OPERATION The current from the source flows through RSENSE, which generates a voltage drop, VSENSE, across the RS+ and RS− terminals of the sense amplifier. The Input Stage Amplifier A1 regulates its inputs to be equal, thereby shunting a current proportional to VSENSE/RG1 to the output current mirror. This current is then multiplied by a gain factor b in the output stage current mirror and flows through RGD to generate VOUT. Therefore, VOUT is related to VSENSE by the ratio of R G1 to RGD and the current gain b. VOUT = AV × VSENSE where: To measure lower currents accurately, as large a sense resistor as possible should be used to utilize the higher end of the sense voltage range. This reduces the effects of the offset voltage errors in the internal amplifier. When currents are very large, it is important to take the I2R power losses across the sense resistor into account. If the sense resistor’s rated power dissipation is not sufficient, its value can drift, giving an inaccurate output voltage, or it could fail altogether. This, in turn, causes the voltage across the RS+ and RS− pins to exceed the absolute maximum ratings. If the monitored supply rail has a large amplitude high frequency component, a sense resistor with low inductance should be chosen. AV = RGD/R G1 × b where: RSENSE INPUT AV = 20 V/V (for ADM4073T). AV = 50 V/V (for ADM4073H). AV = 100 V/V (for ADM4073F). RS+ ILOAD VCC OUT ADM4073 GND RG2 05131-004 RG1 OUTPUT RS– 0.1µF IRG1 VCC 0.1µF VOUT RS– RS+ 3V TO 28V 3V TO 28V RSENSE 2V TO 28V COPPER PCB TRACE Figure 26. Using PCB Trace for Current Sensing AV OUTPUT (OUT) ADM4073 VOUT CURRENT MIRROR RGD = 12kΩ GND 05131-003 IRGD The output stage of the ADM4073 is a current source driving a pull-down resistance. To ensure optimum accuracy, care must be taken not to load this output externally. To minimize output errors, ensure OUT is connected to a high impedance input stage. If this is not possible, output buffering is recommended. Figure 25. Functional Block Diagram The percent error introduced by output loading is determined with the following formula: RSENSE The ADM4073 has the ability to sense a wide variety of currents by selecting a particular sense resistor. Select a suitable output voltage for full-scale current, for example, 10 V for 10 A. Then select a gain model that gives the most efficient use of the sense voltage range (150 mV max). % Error = 100 ((RLOAD / ROUT _ INT + RSENSE ) − 1) where: RLOAD is the external load applied to OUT. ROUT_INT is the internal output resistance (12 kΩ). In the example above, using the ADM4073H (gain of 100) give an output voltage of 10 V when the sense voltage is 100 mV. Use the following equation to determine what value of sense resistor gives 100 mV with 10 A flowing through it: RSENSE = 100 mV/10 A RSENSE = 10 mΩ VOUT = (ILOAD × RSENSE) × AV Rev. 0 | Page 10 of 12 ADM4073 OUTLINE DIMENSIONS 2.90 BSC 6 5 4 1 2 3 2.80 BSC 1.60 BSC PIN 1 INDICATOR 0.95 BSC 1.30 1.15 0.90 1.90 BSC 1.45 MAX 0.15 MAX 0.50 0.30 0.22 0.08 SEATING PLANE 10° 4° 0° 0.60 0.45 0.30 COMPLIANT TO JEDEC STANDARDS MO-178-AB Figure 27. 6-Lead Small Outline Transistor Package [SOT-23] (RJ-6) Dimensions shown in millimeters ORDERING GUIDE Model ADM4073TWRJZ-REEL7 1 ADM4073FWRJZ-REEL71 ADM4073HWRJZ-REEL71 1 Gain 20 50 100 Temperature Range −40°C to +125°C −40°C to +125°C −40°C to +125°C Package Description 6-Lead SOT-23 6-Lead SOT-23 6-Lead SOT-23 Z = Pb-free part. Rev. 0 | Page 11 of 12 Package Option RJ-6 RJ-6 RJ-6 Branding M2E M2C M2D ADM4073 NOTES ©2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 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