FAN4010 High-Side Current Sensor

Transcription

1 November 213 FAN41 High-Side Current Sensor Features a +5 V Low Cost, Accurate, High-Side Current Sensing Output Voltage Scaling Up to 2.5 V Sense Voltage 2 V to 6 V Supply Range 2 μa Typical Offset Current 3.5 μa Quiescent Current -.2% Accuracy 6-Lead MicroPak MLP Package Applications Battery Chargers Battery Chargers Smart Battery Packs DC Motor Control Over-Current Monitor Power Management Programmable Current Source Description The FAN41 is a high-side current sense amplifier designed for battery-powered systems. Using the FAN41 for high-side power-line monitoring does not interfere with the battery charger s ground path. The FAN41 is designed for portable PCs, cellular phones, and other portable systems where battery / DC powerline monitoring is critical. To provide a high level of flexibility, the FAN41 functions with an external sense resistor to set the range of load current to be monitored. It has a current output that can be converted to a ground-referred voltage with a single resistor, accommodating a wide range of battery voltages and currents. The FAN41 features allow it to be used for gas gauging as well as uni-directional or bi-directional current monitoring. Ordering Information Part Number FAN41IL6X FAN41IL6X_F113 (1) Operating Temperature Range Top Mark Package -4 C to +85 C PX 6-Lead, Molded Leadless Package (MLP) Notes: 1. Legacy product number; please order FAN41IL6X for new designs. 2. All packages are lead free per JEDEC: J-STD-2B standard. 3. Moisture sensitivity level for all parts is MSL-1. Packing Method Tape & Reel MicroPak is a trademark of Fairchild Semiconductor Corporation. FAN41 Rev. 1..6

2 Block Diagram and Typical Circuit R sense V IN Load 1 1 V IN Load 6 2 NC GND 5 R Load V OUT 3 I OUT NC 4 R OUT I OUT Figure 1. Functional Block Diagram Figure 2. Typical Circuit Pin Configuration Figure 3. Pin Assignment (Top Through View) Pin Descriptions Name Type Description 2, 4 NC No Connect; leave pin floating 5 GND Ground 3 I OUT Output Current, proportional to V IN-V LOAD 1 V IN Input Voltage, Supply Voltage 6 Load Connection to load or battery FAN41 Rev

3 Absolute Maximum Ratings Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only. Symbol Parameter Min. Typ. Max. Unit V S Supply Voltage 6.3 V V IN Input Voltage Range 6.3 V T J Junction Temperature +15 C T STG Storage Temperature Range C T L Reflow Temperature, Soldering +26 C JA Package Thermal Resistance (4) 456 C/W ESD Electrostatic Discharge Protection Human Body Model, JESD22-A114 5 Charged Device Model, JESD22-C11 1 Note: 4. Package thermal resistance ( JA), JEDEC standard, multi-layer test boards, still air. V Recommended Operating Conditions The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend exceeding them or designing to Absolute Maximum Ratings. Symbol Parameter Min. Max. Unit T A Operating Temperature Range C V S Supply Voltage Range 2 6 V V IN Input Voltage 2 6 V V SENSE Sensor Voltage Range, V SENSE=V IN-V LOAD, R OUT= 2.5 V FAN41 Rev

4 Electrical Characteristics at+5 V T A = 25 C, V S = V IN = 5 V, R OUT = 1 Ω, R SENSE = 1 Ω, unless otherwise noted. Symbol Parameter Conditions Min. Typ. Max. Unit Frequency Domain Response B WSS Small Signal Bandwidth P IN=-4 dbm (5), V SENSE=1 mv 6 khz B WLS Large Signal Bandwidth P IN=-2 dbm (6), V SENSE=1 mv 2 MHz V IN Input Voltage Range V IN=V S 2 6 V I OUT Output Current (7,8) V SENSE= mv 1 9 V SENSE=1 mv V SENSE=1 mv V SENSE=2 mv V SENSE=1 V I S Supply Current (7) V SENSE= V, GND Pin Current µa I SENSE Load Pin Input Current 2 na A CY Accuracy R SENSE=1 R SENSE=2 mv (7) % G m Transconductance I OUT/V SENSE 1 µa/v Notes: dbm = 6.3 mvpp into 5 Ω dbm = 63 mvpp into 5 Ω. 7. 1% tested at 25 C. 8. Includes input offset voltage contribution. µa ma FAN41 Rev

5 Normalized Gain (db) FAN41 High-Side Current Sensor Typical Performance Characteristics T A = 25 C, V S = V IN = 5 V, R OUT = 1 Ω, R SENSE = 1 Ω, unless otherwise noted. Figure 4. V SENSE vs. Output Current Figure 5. Output Current Error vs. V SENSE V SENSE = 1V V IN = 5V R L = Ω 3 V s = 5V R OUT = 1Ω V SENSE = 1V IOUT (ma) V SENSE =.1V V SENSE =.1V Temperature ( C) Figure 6. Output Current vs. Temperature Figure 7. Frequency Response P IN = -2dBm of V SENSE =.1V & 1V P IN = -4dBm of V SENSE =.1V Frequency (MHz) 12 1 R OUT = Ω V SENSE = 1V 12 1 R OUT = 1Ω V SENSE = 1V 8 V SENSE =.8V 8 V SENSE =.8V IOUT (ma) V SENSE =.6V V SENSE =.4V V SENSE =.2V IOUT (ma) V SENSE =.6V V SENSE =.4V V SENSE =.2V V IN (V) V IN (V) Figure 8. Transfer Characteristics Figure 9. Transfer Characteristics FAN41 Rev

6 Typical Performance Characteristics (Continued) T A = 25 C, V S = V IN = 5 V, R OUT = 1 Ω, R SENSE = 1 Ω, unless otherwise noted. Figure 1. CMRR vs. Frequency Figure 11. V IN vs. Output Current Error V IN = 5V R OUT = 1Ω V SENSE (V) Figure 12. Supply Current vs. V SENSE FAN41 Rev

7 Application Information Detailed Description The FAN41 measures the voltage drop (V SENSE) across an external sense resistor in the high-voltage side of the circuit. V SENSE is converted to a linear current via an internal operational amplifier and precision 1 Ω resistor. The value of this current is V SENSE/1 Ω (internal). Output current flows from the I OUT pin to an external resistor R OUT to generate an output voltage proportional to the current flowing to the load. Use the following equations to scale a load current to an output voltage: must be taken not to exceed the maximum power dissipation of the copper trace. INPUT.3in COPPER 1 V IN R SENSE.1in COPPER Load 6 LOAD.3in COPPER V SENSE = I LOAD R SENSE (1) V OUT =.1 V SENSE R OUT (2) V OUT 2 NC GND 5 3 I OUT NC 4 Load 6 V OUT 3 I OUT + R sense V sense 1 - V 1 IN V IN R Load R OUT Figure 14. Using PCB Trace for R SENSE R OUT Figure 13. Functional Circuit Selecting R SENSE Selection of R SENSE is a balance between desired accuracy and allowable voltage loss. Although the FAN41 is optimized for high accuracy with low V SENSE values, a larger R SENSE value provides additional accuracy. However, larger values of R SENSE create a larger voltage drop, reducing the effective voltage available to the load. This can be troublesome in lowvoltage applications. Because of this, the maximum expected load current and allowable load voltage should be well understood. Although higher values of V SENSE can be used, R SENSE should be chosen to satisfy the following condition: 1mV < V SENSE < 2mV (3) For low-cost applications where accuracy is not as important, a portion of the printed circuit board (PCB) trace can be used as an R SENSE resistor. Figure 14 shows an example of this configuration. The resistivity of a.1-inch wide trace of two-ounce copper is about 3 mω/ft. Unfortunately, the resistance temperature coefficient is relatively large (approximately.4%/ C), so systems with a wide temperature range may need to compensate for this effect. Additionally, self heating due to load currents introduces a nonlinearity error. Care Selecting R OUT R OUT can be chosen to obtain the output voltage range required for the particular downstream application. For example, if the output of the FAN41 is intended to drive an analog-to-digital convertor (ADC), R OUT should be chosen such that the expected full-scale output current produces an input voltage that matches the input range of the ADC. For instance, if expected loading current ranges from to 1 A, an R SENSE resistor of 1 Ω produces an output current that ranges from to 1 ma. If the input voltage range of the ADC is to 2 V, an R OUT value of 2 Ω should be used. The input voltage and full-scale output current (I OUT_FS) needs to be taken into account when setting up the output range. To ensure sufficient operating headroom, choose: R OUT I OU TFS such that V IN V SENSE R OUT I OU TFS > 1.6V Output current accuracy for the recommended V SENSE between 1 mv and 2 mv are typically better than 1%. As a result, the absolute output voltage accuracy is dependent on the precision of the output resistor. Make sure the input impedance of the circuit connected to V OUT is much higher than R OUT to ensure accurate V OUT values. Since the FAN41 provides a trans-impedance function, it is suitable for applications involving current rather than voltage sensing. (4) FAN41 Rev

8 Physical Dimensions 2X.5 C 1.45 B 2X.5 C (1) (.254) 1. (.49) 5X (.75) PIN 1 IDENTIFIER 5.5 C DETAIL A TOP VIEW.55MAX C X A.5 C (.52) 1X PIN 1.1 C B A.5 C (.3) 6X RECOMMENED LAND PATTERN.1. 6X X Notes: (.5) 6X.5 BOTTOM VIEW X 45 CHAMFER 1. CONFORMS TO JEDEC STANDARD M-252 VARIATION UAAD 2. DIMENSIONS ARE IN MILLIMETERS 3. DRAWING CONFORMS TO ASME Y14.5M FILENAME AND REVISION: MAC6AREV4 5. PIN ONE IDENTIFIER IS 2X LENGTH OF ANY OTHER LINE IN THE MARK CODE LAYOUT. 5X (.13) 4X DETAIL A PIN 1 TERMINAL Figure Lead MicroPak Molded Leadless Package (MLP) Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild s worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor s online packaging area for the most recent package drawings: FAN41 Rev

9 FAN41 Rev FAN41 High-Side Current Sensor