EVALUATION KIT AVAILABLE MAX9938 nanoPower, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier General Description Features The MAX9938 high-side current-sense amplifier offers ● Ultra-Low Supply Current of 1μA (max) precision accuracy specifications of VOS less than 500μV ● Low 500μV (max) Input Offset Voltage (max) and gain error less than 0.5% (max). Quiescent ● Low < 0.5% (max) Gain Error supply current is an ultra-low 1μA. The MAX9938 fits in a tiny, 1mm x 1mm UCSP™ package size or a 5-pin ● Input Common Mode: +1.6V to +28V SOT23 package, making the part ideal for applications in ● Voltage Output notebook computers, cell phones, PDAs, and all battery- ● Four Gain Versions Available operated portable devices where accuracy, low quiescent • +25V/V (MAX9938T) current, and small size are critical. • 50V/V (MAX9938F) The MAX9938 features an input common-mode voltage • 100V/V (MAX9938H) range from 1.6V to 28V. These current-sense ampli- • 200V/V (MAX9938W) fiers have a voltage output and are offered in four gain ● Tiny 1mm x 1mm x 0.6mm, 4-Bump UCSP, 5-Pin versions: 25V/V (MAX9938T), 50V/V (MAX9938F), SOT23, or 2mm x 2mm x 0.8mm, 6-Pin μDFN 100V/V (MAX9938H), and 200V/V (MAX9938W). Packages The four gain selections offer flexibility in the choice of the external current-sense resistor. The very low 500μV Ordering Information (max) input offset voltage allows small 25mV to 50mV PIN- GAIN TOP full-scale VSENSE voltage for very low voltage drop at PART PACKAGE (V/V) MARK full-current measurement. MAX9938TEBS+G45 4 UCSP 25 +AGD The MAX9938 is offered in tiny 4-bump, UCSP (1mm x MAX9938FEBS+G45 4 UCSP 50 +AGE 1mm x 0.6mm footprint), 5-pin SOT23, and 6-pin μDFN (2mm x 2mm x 0.8mm) packages specified for operation MAX9938HEBS+G45 4 UCSP 100 +AGF over the -40°C to +85°C extended temperature range. MAX9938WEBS+G45 4 UCSP 200 +AGI MAX9938TEUK+ 5 SOT23 25 +AFFB Applications MAX9938FEUK+ 5 SOT23 50 +AFFC ● Cell Phones MAX9938HEUK+ 5 SOT23 100 +AFFD ● PDAs MAX9938WEUK+ 5 SOT23 200 +AFGZ ● Power Management Systems ● Portable/Battery-Powered Systems MAX9938FELT+ 6 µDFN 50 +ACM ● Notebook Computers +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. UCSP is a trademark of Maxim Integrated Products, Inc. Pin Configurations TOP VIEW TOP VIEW RS+ RS- (BUMPS ON BOTTOM) (PADS ON BOTTOM) 5 4 RS+ A1 A2 RS- OUT 1 6 RS- MAX9938T MAX9938T MAX9938F MAX9938F MMAAXX99993388WH MAX9938H N.C. 2 MAX9938FELT 5 N.C. MAX9938W GND B1 B2 OUT GND 3 4 RS+ UCSP 1 2 3 GND GND OUT SOT23 µDFN DRAWINGS NOT TO SCALE 19-4110; Rev 7; 4/17

MAX9938 nanoPower, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier Absolute Maximum Ratings RS+, RS- to GND ..................................................-0.3V to +30V Operating Temperature Range ...........................-40°C to +85°C OUT to GND ............................................................-0.3V to +6V Junction Temperature ......................................................+150°C RS+ to RS- ..........................................................................±30V Storage Temperature Range ............................-65°C to +150°C Short-Circuit Duration: OUT to GND .........................Continuous Lead Temperature (excluding UCSP, soldering, 10s) .....+300°C Continuous Input Current (Any Pin) .................................±20mA Soldering Temperature (reflow) .......................................+260°C 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 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 TYP MAX UNITS VRS+ = 5V, TA = +25°C 0.5 0.85 VRS+ = 5V, -40°C < TA < +85°C 1.1 Supply Current (Note 2) ICC µA VRS+ = 28V, TA = +25°C 1.1 1.8 VRS+ = 28V, -40°C < TA < +85°C 2.5 Common-Mode Input Range VCM Guaranteed by CMRR , -40°C < TA < +85°C 1.6 28 V Common-Mode Rejection Ratio CMRR 1.6V < VRS+ < 28V, -40°C < TA < +85°C 94 130 dB TA = +25°C ±100 ±500 Input Offset Voltage (Note 3) VOS µV -40°C < TA < +85°C ±600 MAX9938T 25 MAX9938F 50 Gain G V/V MAX9938H 100 MAX9938W 200 MAX9938T/MAX9938F/ TA = +25°C ±0.1 ±0.5 MAX9938H -40°C < TA < +85°C ±0.6 Gain Error (Note 4) GE % TA = +25°C ±0.1 ±0.7 MAX9938W -40°C < TA < +85°C ±0.8 MAX9938T/F/H 7.0 10 13.2 Output Resistance ROUT (Note 5) kΩ MAX9938W 14.0 20 26.4 Gain = 25 1.5 15 Gain = 50 3 30 OUT Low Voltage VOL mV Gain = 100 6 60 Gain = 200 12 120 OUT High Voltage VOH VOH = VRS- - VOUT (Note 6) 0.1 0.2 V VSENSE = 50mV, gain = 25 125 V Small-Signal Bandwidth VSENSE = 50mV, gain = 50 60 BW (Note 5) VSENSE = 50mV, gain = 100 30 kHz VSENSE = 50mV, gain = 200 15 Output Settling Time tS 1% final value, VSENSE = 50mV 100 µs www.maximintegrated.com Maxim Integrated │ 2

MAX9938 nanoPower, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier Electrical Characteristics (continued) (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) Note 1: All devices are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design. Note 2: VOUT = 0. ICC is the total current into RS+ plus RS- pins. Note 3: VOS is extrapolated from measurements for the gain-error test. Note 4: 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. Gain = 200, VSENSE is 2.5mV and 15mV. 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. Typical Operating Characteristics (VRS+ = VRS- = 3.6V, TA = +25°C, unless otherwise noted.) SUPPLY CURRENT INPUT OFFSET VOLTAGE HISTOGRAM GAIN ERROR HISTOGRAM vs. TEMPERATURE 2350 MAX9938 toc01 2350 MAX9938 toc02 11..24 28V MAX9938 toc03 A) µ 1.0 20 20 T ( N %) %) RRE 0.8 N ( 15 N ( 15 CU 3.6V Y 0.6 L P 10 10 P SU 0.4 1.8V 5 5 0.2 0 0 0 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 -40 -15 10 35 60 85 INPUT OFFSET VOLTAGE (mV) GAIN ERROR (%) TEMPERATURE (°C) INPUT OFFSET INPUT OFFSET SUPPLY CURRENT vs. COMMON-MODE VOLTAGE vs. TEMPERATURE vs. COMMON-MODE VOLTAGE --3350 MAX9938 toc04 5600 MAX9938 toc05 11..24 MAX9938 toc06 A) FFSET (µV) -40 FFSET (µV) 3400 URRENT (µ 10..08 O O C UT -45 UT LY 0.6 NP NP 20 PP I I SU 0.4 -50 10 0.2 -55 0 0 0 5 10 15 20 25 30 -40 -15 10 35 60 85 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V) TEMPERATURE (°C) SUPPLY VOLTAGE (V) www.maximintegrated.com Maxim Integrated │ 3

MAX9938 nanoPower, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier Typical Operating Characteristics (continued) (VRS+ = VRS- = 3.6V, TA = +25°C, unless otherwise noted.) GAIN ERROR GAIN ERROR VOUT vs. VSENSE vs. COMMON-MODE VOLTAGE vs. TEMPERATURE (SUPPLY = 3.6V) 0.01 MAX9938 toc07 00..0078 MAX9938 toc08 34..50 MAX9938 toc09 0.06 3.0 %) -0.1 %) G = 100 RROR ( -0.2 RROR (00..0054 (V)UT 22..05 G = 50 E E O N N V AI AI0.03 1.5 G = 25 G -0.3 G 0.02 1.0 -0.4 0.01 0.5 -0.5 0 0 0 5 10 15 20 25 30 -40 -15 10 35 60 85 0 50 100 150 VOLTAGE (V) TEMPERATURE (°C) VSENSE (mV) VOUT vs. VSENSE SMALL SIGNAL GAIN CMRR (SUPPLY = 1.6V) vs. FREQUENCY vs. FREQUENCY 111...468 MAX9938 toc10 05 AV = 25V/V MAX9938 toc11 -200 G = 25 MAX9938 toc12 -5 AV = 100V/V -40 1.2 G = 50 V (V)OUT 01..80 G =G 5 =0 100 GAIN (dB) --1105 AV = 50V/V CMRR (dB) --6800 -100 G = 100 0.6 G = 25 -20 0.4 -120 0.2 -25 -140 0 -30 -160 0 20 40 60 80 100 1Hz 10Hz 100Hz 1kHz 10kHz 100kHz 1MHz 1Hz 10Hz 100Hz 1kHz 10kHz 100kHz 1MHz VSENSE (mV) FREQUENCY (kHz) FREQUENCY (kHz) SMALL-SIGNAL PULSE RESPONSE SMALL-SIGNAL PULSE RESPONSE (GAIN = 100) (GAIN = 50) MAX9938 toc13a MAX9938 toc13b 15mV 30mV VSENSE 10mV VSENSE 20mV 1.5V 1.5V VOUT 1V VOUT 1V 20µs/div 25µs/div www.maximintegrated.com Maxim Integrated │ 4

MAX9938 nanoPower, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier Typical Operating Characteristics (continued) (VRS+ = VRS- = 3.6V, TA = +25°C, unless otherwise noted.) SMALL-SIGNAL PULSE RESPONSE LARGE-SIGNAL PULSE RESPONSE (GAIN = 25) (GAIN = 100) MAX9938 toc13c MAX9938 toc14a 60mV 30mV VSENSE VSENSE 40mV 10mV 1.5V 3V VOUT VOUT 1V 1V 25µs/div 20µs/div LARGE-SIGNAL PULSE RESPONSE LARGE-SIGNAL PULSE RESPONSE (GAIN = 50) (GAIN = 25) MAX9938 toc14b MAX9938 toc14c 60mV 120mV VSENSE VSENSE 10mV 20mV 3V 3V VOUT VOUT 0.5V 0.5V 25µs/div 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. www.maximintegrated.com Maxim Integrated │ 5

MAX9938 nanoPower, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier Typical Operating Circuit ILOAD RSENSE VBATT = 1.6V TO 28V RS+ RS- R1 R1 VDD = 3.3V LOAD µC P MAX9938 OUT ADC ROUT 10kΩ GND Detailed Description same value as R1 to minimize offset voltage. The cur- The MAX9938 unidirectional high-side, current-sense rent through R1 is sourced by a high-voltage p-channel FET. Its source current is the same as its drain current, amplifier features a 1.6V to 28V input common-mode range. This feature allows the monitoring of current out which flows through a second gain resistor, ROUT. This of a battery with a voltage as low as 1.6V. The MAX9938 produces an output voltage, VOUT, whose magnitude is monitors current through a current-sense resistor and ILOAD x RSENSE x ROUT/R1. The gain accuracy is based amplifies the voltage across that resistor. on the matching of the two gain resistors R1 and ROUT (see Table 1). Total gain = 25V/V for the MAX9938T, The MAX9938 is a unidirectional current-sense amplifier 50V/V for the MAX9938F, 100V/V for the MAX9938H, and that has a well-established history. An op amp is used 200V/V for the MAX9938W. The output is protected from to force the current through an internal gain resistor at input overdrive by use of an output current limiting circuit RS+, which has a value of R1, such that its voltage drop of 7mA (typical) and a 6V clamp protection circuit. equals the voltage drop across an external sense resis- tor, RSENSE. There is an internal resistor at RS- with the Table 1. Internal Gain Setting Resistors (Typical Values) GAIN (V/V) R1 (Ω) ROUT (kΩ) 200 100 20 100 100 10 50 200 10 25 400 10 www.maximintegrated.com Maxim Integrated │ 6

MAX9938 nanoPower, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier Applications Information Efficiency and Power Dissipation Choosing the Sense Resistor At high current levels, the I2R losses in RSENSE can be significant. Take this into consideration when choosing the Choose RSENSE based on the following criteria: resistor value and its power dissipation (wattage) rating. Voltage Loss Also, the sense resistor’s value might drift if it is allowed to A high RSENSE value causes the power-source voltage heat up excessively. The precision VOS of the MAX9938 allows the use of small sense resistors to reduce power to drop due to IR loss. For minimal voltage loss, use the dissipation and reduce hot spots. lowest RSENSE value. Kelvin Connections OUT Swing vs. VRS+ and VSENSE The MAX9938 is unique since the supply voltage is the Because of the high currents that flow through RSENSE, take care to eliminate parasitic trace resistance from input common-mode voltage (the average voltage at RS+ causing errors in the sense voltage. Either use a four- and RS-). There is no separate VCC supply voltage pin. terminal current-sense resistor or use Kelvin (force and Therefore, the OUT voltage swing is limited by the mini- sense) PCB layout techniques. mum voltage at RS+. VOUT (max) = VRS+ (min) - VSENSE (max) - VOH Optional Output Filter Capacitor and When designing a system that uses a sample-and-hold stage in the ADC, the sampling capacitor momentarily V (max) OUT R = loads OUT and causes a drop in the output voltage. If SENSE G×I (max) LOAD sampling time is very short (less than a microsecond), consider using a ceramic capacitor across OUT and VSENSE full scale should be less than VOUT/gain at the GND to hold VOUT constant during sampling. This also minimum RS+ voltage. For best performance with a 3.6V decreases the small-signal bandwidth of the current- supply voltage, select RSENSE to provide approximately sense amplifier and reduces noise at OUT. 120mV (gain of 25V/V), 60mV (gain of 50V/V), 30mV (gain Input Filters of 100V/V), or 15mV (gain of 200V/V) of sense voltage for the full-scale current in each application. These can be Some applications of current-sense amplifiers need to increased by use of a higher minimum input voltage. measure currents accurately even in the presence of both differential and common-mode ripple, as well as a wide Accuracy variety of input transient conditions. For example, high- In the linear region (VOUT < VOUT(max)), there are two frequency ripple at the output of a switching buck or boost components to accuracy: input offset voltage (VOS) and regulator results in a common-mode voltage at the inputs gain error (GE). For the MAX9938, VOS = 500μV (max) of the MAX9938. Alternatively, fast load-current tran- and gain error is 0.5% (max). Use the linear equation: sients, when measuring at the input of a switching buck VOUT = (gain ± GE) x VSENSE ± (gain x VOS) or boost regulator, can cause high-frequency differential sense voltages to occur at the inputs of the MAX9938, to calculate total error. A high RSENSE value allows lower although the signal of interest is the average DC value. currents to be measured more accurately because offsets Such high-frequency differential sense voltages may are less significant when the sense voltage is larger. result in a voltage offset at the MAX9938 output. www.maximintegrated.com Maxim Integrated │ 7

MAX9938 nanoPower, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier The MAX9938 allows two methods of filtering to help Placing RIN at the RS- input does not affect the gain improve performance in the presence of input common- error of the device because the gain is given by the ratio mode voltage and input differential voltage transients. between ROUT and R1 at RS+. Figure 1 shows a differential input filter. Figure 2 shows the input common-mode filter. The capacitor CIN between RS+ and RS- along with the Again, the corner frequency of the filter is determined by resistor RIN between the sense resistor and RS- helps the choice of RIN, CIN and is affected by R1. filter against input differential voltages and prevents them from reaching the MAX9938. In this case RIN affects both gain error and input offset voltage. RIN should be smaller than R1 so that it has neg- The corner frequency of this filter is determined by the ligible effect on the device gain. If, for example, a filter with choice of RIN, CIN, and the value of the input resistance RIN = 10Ω and CIN = 1μF is built, then depending upon the at RS- (R1). See Table 1 for R1 values at the different gain selection, the gain error is affected by either 2.5% (G = gain options. 25V/V, R1 = 400Ω) or 5% (G = 50V/V, R1 = 200Ω) or 10% The value of RIN should be chosen to minimize its effect (G = 100V/V, R1 = 100Ω) or 10% (G = 200V/V, R1 = 100Ω). on the input offset voltage due to the bias current at RS-. RIN x IBIAS contributes to the input voltage offset. IBIAS is typically 0.2μA. RSENSE RSENSE RIN RIN RIN LOAD LOAD CIN CIN CIN RS+ RS- RS+ RS- OUT MAX9938 OUT MAX9938 GND GND Figure 1. Differential Input Filter Figure 2. Input Common-Mode Filter www.maximintegrated.com Maxim Integrated │ 8

MAX9938 nanoPower, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier Bidirectional Application UCSP Applications Information Battery-powered systems may require a precise bidi- For the latest application details on UCSP construction, rectional current-sense amplifier to accurately monitor the dimensions, tape carrier information, PCB techniques, battery’s charge and discharge currents. Measurements bump-pad layout, and recommended reflow tempera- of the two separate outputs with respect to GND yields an ture profile, as well as the latest information on reliabil- accurate measure of the charge and discharge currents ity testing results, refer to the Application Note 1891: respectively (Figure 3). Wafer-Level Packaging (WLP) and Its Applications available on Maxim’s website at www.maximintegrated. com/ucsp. ILOAD RSENSE TO WALL-CUBE/ VBATT = 1.6V TO 28V CHARGER RS+ RS- RS+ RS- LOAD R1 R1 R1 R1 P P MAX9938 MAX9938 VDD = 3.3V OUT OUT ROUT 10kΩ ROUT 10kΩ C GND GND ADC ADC Figure 3. Bidirectional Application Chip Information PROCESS: BiCMOS www.maximintegrated.com Maxim Integrated │ 9

MAX9938 nanoPower, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. LAND PACKAGE TYPE PACKAGE CODE OUTLINE NO. PATTERN NO. 2 x 2 UCSP B4+1 21-0117 — 5 SOT23 U5-2 21-0057 90-0174 6 μDFN L622+1 21-0164 90-0004 www.maximintegrated.com Maxim Integrated │ 10

MAX9938 nanoPower, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier Package Information (continued) For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. S P E L . 5 3 2 T- O S www.maximintegrated.com Maxim Integrated │ 11

MAX9938 nanoPower, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier Package Information (continued) For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. www.maximintegrated.com Maxim Integrated │ 12

MAX9938 nanoPower, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier Package Information (continued) For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. www.maximintegrated.com Maxim Integrated │ 13

MAX9938 nanoPower, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier Revision History REVISION REVISION PAGES DESCRIPTION NUMBER DATE CHANGED 0 4/08 Initial release — 1 9/08 Added μDFN package information 1, 2, 4, 5, 9 2 2/09 Added G45 designation to part number 1 3 10/09 Added Input Filters section and MAX9938W to the data sheet 1, 2, 6–9 4 2/10 Updated EC table and Input Filters section 2, 8 5 8/10 Removed Power-Up Time parameter 2 6 1/11 Corrected error on Figure 2 8 7 4/17 Updated title of data sheet to include “nanoPower” 1–14 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2017 Maxim Integrated Products, Inc. │ 14

Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: M axim Integrated: MAX9938FELT+T MAX9938FEUK+T MAX9938HEBS+T MAX9938HEUK+T MAX9938TEBS+T MAX9938TEUK+T MAX9938FEBS+TG45 MAX9938HEBS+TG45 MAX9938TEBS+TG45 MAX9938WEUK+T MAX9938WEBS+TG45