19-4110; Rev 2; 2/09 KIT ATION EVALU E L B AVAILA 1µA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier Features ♦ Ultra-Low Supply Current of 1µA (max) The MAX9938 high-side current-sense amplifier offers precision accuracy specifications of V OS less than 500μV (max) and gain error less than 0.5% (max). Quiescent supply current is an ultra-low 1μA. The MAX9938 fits in a tiny, 1mm x 1mm UCSP™ package size or a 5-pin SOT23 package, making the part ideal for applications in notebook computers, cell phones, PDAs, and all battery-operated portable devices where accuracy, low quiescent current, and small size are critical. The MAX9938 features an input common-mode voltage range from 1.6V to 28V. These current-sense amplifiers have a voltage output and are offered in three gain versions: 25V/V (MAX9938T), 50V/V (MAX9938F), and 100V/V (MAX9938H). ♦ Low 500µV (max) Input Offset Voltage ♦ Low < 0.5% (max) Gain Error ♦ Input Common Mode: +1.6V to +28V ♦ Voltage Output ♦ Three Gain Versions Available 25V/V (MAX9938T) 50V/V (MAX9938F) 100V/V (MAX9938H) ♦ Tiny 1mm x 1mm x 0.6mm, 4-Bump UCSP, 5-Pin SOT23, or 2mm x 2mm x 0.8mm, 6-Pin µDFN Packages The three gain selections offer flexibility in the choice of the external current-sense resistor. The very low 500μV (max) input offset voltage allows small 25mV to 50mV full-scale VSENSE voltage for very low voltage drop at full-current measurement. The MAX9938 is offered in tiny 4-bump, UCSP (1mm x 1mm x 0.6mm footprint), 5-pin SOT23, and 6-pin μDFN (2mm x 2mm x 0.8mm) packages specified for operation over the -40°C to +85°C extended temperature range. Ordering Information PINPACKAGE PART Applications Cell Phones PDAs GAIN (V/V) TOP MARK MAX9938TEBS+G45 4 UCSP 25 +AGD MAX9938FEBS+G45 4 UCSP 50 +AGE MAX9938HEBS+G45 4 UCSP 100 +AGF MAX9938TEUK+ 5 SOT23 25 +AFFB MAX9938FEUK+ 5 SOT23 50 +AFFC MAX9938HEUK+ 5 SOT23 100 +AFFD MAX9938FELT+ 6 μDFN 50 +ACM +Denotes a lead(Pb)-free/RoHS-compliant package. G45 indicates protective die coating. Note: All devices are specified over the -40°C to +85°C extended temperature range. Power Management Systems Portable/Battery-Powered Systems Notebook Computers UCSP is a trademark of Maxim Integrated Products, Inc. Pin Configurations TOP VIEW (BUMPS ON BOTTOM) RS+ A1 A2 RS+ 5 RS- MAX9938T/F/H MAX9938T/F/H GND B1 B2 UCSP TOP VIEW (PADS ON BOTTOM) RS4 OUT 1 N.C. 2 GND 3 MAX9938FELT 6 RS- 5 N.C. 4 RS+ OUT 1 GND 2 GND SOT23 3 OUT μDFN DRAWINGS NOT TO SCALE ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX9938 General Description MAX9938 1µA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier ABSOLUTE MAXIMUM RATINGS RS+, RS- to GND....................................................-0.3V to +30V OUT to GND .............................................................-0.3V to +6V RS+ to RS- ...........................................................................±30V Short-Circuit Duration: OUT to GND ..........................Continuous Continuous Input Current (Any Pin)..................................±20mA Continuous Power Dissipation (TA = +70°C) 4-Bump UCSP (derate 3.0mW/°C above +70°C).........238mW 5-Pin SOT23 (derate 3.9mW/°C above +70°C)............312mW 6-Pin μDFN (derate 4.5mW/°C above +70°C) .............358mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range ............................-65°C to +150°C Bump Temperature (soldering) Reflow............................+260°C Lead Temperature (soldering, 10s) .................................+300°C Lead Temperature (reflow) ..............................................+260°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VRS+ = VRS- = 3.6V, VSENSE = (VRS+ - VRS-) = 0V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN VRS+ = 5V, TA = +25°C Supply Current (Note 2) ICC TYP MAX 0.5 0.85 1.1 1.8 VRS+ = 5V, -40°C < TA < +85°C 1.1 VRS+ = 28V, TA = +25°C VRS+ = 28V, -40°C < TA < +85°C Common-Mode Input Range Common-Mode Rejection Ratio Input Offset Voltage (Note 3) Gain VCM CMRR VOS G Gain Error (Note 4) GE Output Resistance ROUT 1.6 1.6V < VRS+ < 28V, -40°C < TA < +85°C 94 TA = +25°C OUT Low Voltage VOL OUT High Voltage VOH Small-Signal Bandwidth (Note 5) BW Output Settling Time Power-Up Time 28 130 ±100 -40°C < TA < +85°C 25 MAX9938F 50 MAX9938H 100 TA = +25°C ±0.1 -40°C < TA < +85°C ±500 ±0.5 10 13.2 1.5 15 Gain = 50 3 30 Gain = 100 6 60 VOH = VRS- - VOUT (Note 6) 0.1 0.2 VSENSE = 50mV, gain = 25 125 VSENSE = 50mV, gain = 50 60 VSENSE = 50mV, gain = 100 30 % kΩ mV V kHz tS 1% final value, VSENSE = 50mV 100 μs tON 1% final value, VSENSE = 50mV 200 μs All devices are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design. VOUT = 0. ICC is the total current into RS+ plus RS- pins. VOS is extrapolated from measurements for the gain-error test. Gain error is calculated by applying two values of VSENSE and calculating the error of the slope vs. the ideal: Gain = 25, VSENSE is 20mV and 120mV. Gain = 50, VSENSE is 10mV and 60mV. Gain = 100, VSENSE is 5mV and 30mV. Note 5: The device is stable for any external capacitance value. Note 6: VOH is the voltage from VRS- to VOUT with VSENSE = 3.6V/gain. Note 1: Note 2: Note 3: Note 4: 2 μV V/V ±0.6 7.0 V dB ±600 MAX9938T Gain = 25 μA 2.5 Guaranteed by CMRR , -40°C < TA < +85°C (Note 5) UNITS _______________________________________________________________________________________ 1µA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier 20 N (%) 15 10 10 5 5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.4 1.8V 0 0.1 0.2 -40 0.3 0.4 -15 10 35 60 GAIN ERROR (%) TEMPERATURE (°C) INPUT OFFSET vs. COMMON-MODE VOLTAGE INPUT OFFSET vs. TEMPERATURE SUPPLY CURRENT vs. COMMON-MODE VOLTAGE -45 -50 40 30 20 10 5 10 15 20 25 0.8 0.6 0.4 0 -40 30 1.0 0.2 0 -55 -15 10 35 60 0 85 5 10 15 20 SUPPLY VOLTAGE (V) TEMPERATURE (°C) SUPPLY VOLTAGE (V) GAIN ERROR vs. COMMON-MODE VOLTAGE GAIN ERROR vs. TEMPERATURE VOUT vs. VSENSE (SUPPLY = 3.6V) 0.07 GAIN ERROR (%) -0.1 -0.2 -0.3 -0.4 -0.5 10 15 VOLTAGE (V) 20 25 30 3.5 0.06 3.0 0.05 2.5 30 G = 100 0.04 G = 50 2.0 0.03 1.5 0.02 1.0 0.01 0.5 G = 25 0 0 5 4.0 VOUT (V) 0 25 MAX9938 toc09 0.08 MAX9938 toc07 0.1 85 MAX9938 toc06 1.2 SUPPLY CURRENT (μA) 50 INPUT OFFSET (μV) -40 1.4 MAX9938 toc05 60 MAX9938 toc04 -35 0 3.6V 0.6 INPUT OFFSET VOLTAGE (mV) -30 0 0.8 0 -0.4 -0.3 -0.2 -0.1 0.3 0.4 28V 1.0 0.2 0 0 INPUT OFFSET (μV) 15 MAX9938 toc08 N (%) 20 1.2 MAX9938 toc03 25 SUPPLY CURRENT (μA) 25 1.4 MAX9938 toc02 30 MAX9938 toc01 30 GAIN ERROR (%) SUPPLY CURRENT vs. TEMPERATURE GAIN ERROR HISTOGRAM INPUT OFFSET VOLTAGE HISTOGRAM -40 -15 10 35 TEMPERATURE (°C) 60 85 0 50 100 150 VSENSE (mV) _______________________________________________________________________________________ 3 MAX9938 Typical Operating Characteristics (VRS+ = VRS- = 3.6V, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VRS+ = VRS- = 3.6V, TA = +25°C, unless otherwise noted.) 1.4 AV = 25V/V 0 GAIN (dB) G = 100 G = 50 0.8 AV = 50V/V -10 -15 -25 20 40 60 80 -160 1Hz 100 G = 100 -140 -30 0 -80 -120 0.4 0 G = 50 -60 -100 -20 0.2 G = 25 -40 G = 25 0.6 -20 AV = 100V/V -5 1.2 0 GAIN (dB) 1.6 MAX9938 toc11 5 MAX9938 toc10 1.8 1.0 CMRR vs. FREQUENCY SMALL SIGNAL GAIN vs. FREQUENCY MAX9938 toc12 VOUT vs. VSENSE (SUPPLY = 1.6V) VOUT (V) MAX9938 1µA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier 10Hz 100Hz 1kHz 1Hz 10kHz 100kHz 1MHz 10Hz 100Hz SMALL-SIGNAL PULSE RESPONSE (GAIN = 100) 1kHz SMALL-SIGNAL PULSE RESPONSE (GAIN = 50) MAX9938 toc13a MAX9938 toc13b 15mV 30mV VSENSE 10mV VSENSE 20mV 1.5V 1.5V VOUT 1V VOUT 1V 20μs/div 25μs/div SMALL-SIGNAL PULSE RESPONSE (GAIN = 25) MAX9938 toc13c 60mV VSENSE 40mV 1.5V VOUT 1V 25μs/div 4 10kHz 100kHz 1MHz FREQUENCY (kHz) FREQUENCY (kHz) VSENSE (mV) _______________________________________________________________________________________ 1µA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier LARGE-SIGNAL PULSE RESPONSE (GAIN = 100) LARGE-SIGNAL PULSE RESPONSE (GAIN = 50) MAX9938 toc14a MAX9938 toc14b 30mV 60mV VSENSE VSENSE 10mV 10mV 3V 3V VOUT VOUT 1V 0.5V 20μs/div 25μs/div LARGE-SIGNAL PULSE RESPONSE (GAIN = 25) MAX9938 toc14c 120mV VSENSE 20mV 3V VOUT 0.5V 25μs/div Pin Description PIN NAME FUNCTION UCSP SOT23 µDFN A1 5 4 RS+ External Sense Resistor Power-Side Connection A2 4 6 RS- External Sense Resistor Load-Side Connection B1 1, 2 3 GND Ground B2 3 1 OUT Output Voltage. VOUT is proportional to VSENSE = VRS+ - VRS-. — — 2, 5 N.C. No Connection. Not internally connected. _______________________________________________________________________________________ 5 MAX9938 Typical Operating Characteristics (continued) (VRS+ = VRS- = 3.6V, TA = +25°C, unless otherwise noted.) 1µA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier MAX9938 Typical Operating Circuit ILOAD RSENSE VBATT = 1.6V TO 28V RS+ RS- R1 R1 VDD = 3.3V LOAD μC P MAX9938 ROUT OUT ADC 10kΩ GND Detailed Description The MAX9938 unidirectional high-side, current-sense amplifier features a 1.6V to 28V input common-mode range. This feature allows the monitoring of current out of a battery with a voltage as low as 1.6V. The MAX9938 monitors current through a current-sense resistor and amplifies the voltage across that resistor. The MAX9938 is a unidirectional current-sense amplifier that has a well-established history. An op amp is used to force the current through an internal gain resistor at RS+, which has a value of R1, such that its voltage drop equals the voltage drop across an external sense resistor, RSENSE. There is an internal resistor at RS- with the Table 1. Internal Gain Setting Resistors (Typical Values) GAIN (V/V) 6 R1 (Ω) ROUT (kΩ) 100 100 10 50 200 10 25 400 10 same value as R1 to minimize offset voltage. The current through R1 is sourced by a high-voltage p-channel FET. Its source current is the same as its drain current, which flows through a second gain resistor, ROUT. This produces an output voltage, VOUT, whose magnitude is I LOAD x R SENSE x R OUT /R 1 . The gain accuracy is based on the matching of the two gain resistors R1 and R OUT (see Table 1). Total gain = 25V/V for the MAX9938T, 50V/V for the MAX9938F, and 100V/V for the MAX9938H. The output is protected from input overdrive by use of an output current limiting circuit of 7mA (typical) and a 6V clamp protection circuit. Applications Information Choosing the Sense Resistor Choose RSENSE based on the following criteria: Voltage Loss A high RSENSE value causes the power-source voltage to drop due to IR loss. For minimal voltage loss, use the lowest RSENSE value. _______________________________________________________________________________________ 1µA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier VOUT (max) = VRS+ (min) - VSENSE (max) - VOH and VOUT (max) RSENSE = G × I LOAD (max) VSENSE full scale should be less than VOUT/gain at the minimum RS+ voltage. For best performance with a 3.6V supply voltage, select RSENSE to provide approximately 120mV (gain of 25V/V), 60mV (gain of 50V/V), or 30mV (gain of 100V/V) of sense voltage for the fullscale current in each application. These can be increased by use of a higher minimum input voltage. Accuracy In the linear region (VOUT < VOUT(max)), there are two components to accuracy: input offset voltage (VOS) and gain error (GE). For the MAX9938, VOS = 500μV (max) and gain error is 0.5% (max). Use the linear equation: Efficiency and Power Dissipation At high current levels, the I2R losses in RSENSE can be significant. Take this into consideration when choosing the resistor value and its power dissipation (wattage) rating. Also, the sense resistor’s value might drift if it is allowed to heat up excessively. The precision VOS of the MAX9938 allows the use of small sense resistors to reduce power dissipation and reduce hot spots. Kelvin Connections Because of the high currents that flow through RSENSE, take care to eliminate parasitic trace resistance from causing errors in the sense voltage. Either use a fourterminal current-sense resistor or use Kelvin (force and sense) PCB layout techniques. Optional Output Filter Capacitor When designing a system that uses a sample-and-hold stage in the ADC, the sampling capacitor momentarily loads OUT and causes a drop in the output voltage. If sampling time is very short (less than a microsecond), consider using a ceramic capacitor across OUT and GND to hold VOUT constant during sampling. This also decreases the small-signal bandwidth of the currentsense amplifier and reduces noise at OUT. VOUT = (gain ± GE) x VSENSE ± (gain x VOS) to calculate total error. A high RSENSE value allows lower currents to be measured more accurately because offsets are less significant when the sense voltage is larger. _______________________________________________________________________________________ 7 MAX9938 OUT Swing vs. VRS+ and VSENSE The MAX9938 is unique since the supply voltage is the input common-mode voltage (the average voltage at RS+ and RS-). There is no separate VCC supply voltage pin. Therefore, the OUT voltage swing is limited by the minimum voltage at RS+. MAX9938 1µA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier ILOAD RSENSE TO WALL-CUBE/ CHARGER VBATT = 1.6V TO 28V RS+ RS- RS+ RSLOAD R1 R1 R1 P P MAX9938 ROUT R1 MAX9938 OUT 10kΩ GND ROUT OUT VDD = 3.3V 10kΩ μC GND ADC ADC Figure 1. Bidirectional Application Bidirectional Application Battery-powered systems may require a precise bidirectional current-sense amplifier to accurately monitor the battery’s charge and discharge currents. Measurements of the two separate outputs with respect to GND yields an accurate measure of the charge and discharge currents respectively (Figure 1). UCSP Applications Information For the latest application details on UCSP construction, dimensions, tape carrier information, PCB techniques, bump-pad layout, and recommended reflow temperature profile, as well as the latest information on reliability testing results, refer to the Application Note 1891: Understanding the Basics of the Wafer-Level ChipScale Package (WL-CSP) available on Maxim’s website at www.maxim-ic.com/ucsp. Chip Information PROCESS: BiCMOS 8 _______________________________________________________________________________________ 1µA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier PACKAGE CODE DOCUMENT NO. 2 x 2 UCSP R41A1+1 21-0242 5 SOT23 U5-2 21-0057 6 μDFN L622+1 21-0164 2x2 UCSP.EPS PACKAGE TYPE _______________________________________________________________________________________ 9 MAX9938 Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Package Information (continued) For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. SOT-23 5L .EPS MAX9938 1µA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier 10 ______________________________________________________________________________________ 1µA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier b e 6, 8, 10L UDFN.EPS A D N AAA AAA SOLDER MASK COVERAGE E PIN 1 0.10x45∞ L PIN 1 INDEX AREA L1 1 SAMPLE MARKING A A (N/2 -1) x e) 7 C L C L b L A A2 A1 L e e EVEN TERMINAL ODD TERMINAL PACKAGE OUTLINE, 6, 8, 10L uDFN, 2x2x0.80 mm 21-0164 B 1 2 ______________________________________________________________________________________ 11 MAX9938 Package Information (continued) For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. MAX9938 1µA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier Package Information (continued) For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. COMMON DIMENSIONS MAX. SYMBOL A MIN. NOM. 0.70 0.75 0.80 A1 0.15 0.20 0.25 A2 D E 0.020 1.95 1.95 0.025 2.00 2.00 0.035 2.05 2.05 L 0.30 0.40 0.10 REF. 0.50 L1 PACKAGE VARIATIONS PKG. CODE N e b (N/2 -1) x e L622-1 6 0.65 BSC 0.30±0.05 1.30 REF. L822-1 8 0.50 BSC 0.25±0.05 1.50 REF. L1022-1 10 0.40 BSC 0.20±0.03 1.60 REF. PACKAGE OUTLINE, 6, 8, 10L uDFN, 2x2x0.80 mm 21-0164 12 ______________________________________________________________________________________ B 2 2 1µA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier REVISION NUMBER REVISION DATE 0 4/08 Initial release 1 9/08 Added μDFN package information 2 2/09 Added G45 designation to part number DESCRIPTION PAGES CHANGED — 1, 2, 4, 5, 9 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13 © 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc. MAX9938 Revision History