EVALUATION KIT AVAILABLE MAX9928/MAX9929 -0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers General Description The MAX9928/MAX9929 low-cost, uni-/bidirectional, high-side, current-sense amplifiers are ideal for monitoring battery charge and discharge currents in notebooks, cell phones, and other portable equipment. These devices feature a wide -0.1V to +28V input common-mode voltage range, low 20A supply current with VOS less than 0.4mV, and a gain accuracy better than 1.0%. The input commonmode range is independent of the supply voltage, ensuring that the current-sense information remains accurate even when the measurement rail is shorted to ground. The MAX9928F features a current output with a transconductance ratio of 5A/mV. An external resistor converts the output current to a voltage, allowing adjustable gain so that the input sense voltage can be matched to the maximum ADC input swing. The MAX9929F has a voltage output and integrates a 10k output resistor for a fixed voltage gain of 50V/V. Features Wide -0.1V to +28V Common-Mode Range, Independent of Supply Voltage 2.5V to 5.5V Operating Supply Voltage 20A Quiescent Supply Current 0.4mV (max) Input Offset Voltage Gain Accuracy Better than 1% (max) SIGN Output Indicates Current Polarity Transconductance and Gain Versions Available * 5A/mV (MAX9928F) * 50V/V (MAX9929F) Pin Compatible with the MAX4372 in UCSP Available in Ultra-Small, 3x2 UCSP (1mm x 1.5mm) and 8-Pin MAX Packages Applications The MAX9928/MAX9929 are fully specified over the -40C to +125C automotive temperature range, and available in 6-bump UCSPTM (1mm x 1.5mm) and 8-pin MAX(R) packages. The UCSP package is bump-to-bump compatible with the MAX4372_EBT. Monitoring Charge/Discharge Currents in Portable/ Battery-Powered Systems Notebook Computers General-System/Board-Level Current Monitoring Smart-Battery Packs/Chargers Precision Current Sources Smart Cell Phones Super Capacitor Charge/Discharge UCSP is a trademark and MAX is a registered trademark of Maxim Integrated Products, Inc. Pin Configurations and Typical Operating Circuit appear at end of data sheet. A digital SIGN output indicates direction of current flow, so the user can utilize the full ADC input range for measuring both charging and discharging currents. Ordering Information PART OUTPUT TYPE GAIN PIN-PACKAGE MAX9928FAUA+ Current Gm = 5A/mV 8 MAX MAX9928FABT+T Current Gm = 5A/mV 3x2 UCSP MAX9929FAUA+ Voltage AV = 50V/V 8 MAX MAX9929FABT+T Voltage AV = 50V/V 3x2 UCSP Note: All devices are specified over the -40C to +125C operating temperature range. +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. 19-4251; Rev 4; 9/14 TOP MARK -- +AAF -- +ADI MAX9928/MAX9929 -0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers Absolute Maximum Ratings VCC, SIGN to GND..................................................-0.3V to +6V RS+, RS- to GND...................................................-0.3V to +30V OUT to GND.............................................. -0.3V to (VCC + 0.3V) Differential Input Voltage (VRS+ - VRS-)...............................30V OUT, SIGN Short Circuit to VCC or GND...................Continuous Current into Any Pin..........................................................20mA Continuous Power Dissipation (TA = +70C) 6-Bump 1mm x 1.5mm UCSP (derate 3.9mW/C above +70C)...........................308.3mW 8-Pin MAX (derate 4.8mW/C above +70C).............388mW Operating Temperature Range.......................... -40C to +125C Storage Temperature Range............................. -65C to +150C Junction Temperature.......................................................+150C Lead Temperature (soldering, 10s).................................. +300C Soldering Temperature (reflow)........................................+260C 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+ = -0.1V to +28V, VCC = 3.3V, VSENSE = (VRS+ - VRS-) = 0V, ROUT = 10k for MAX9928F, TA = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX 0.1 0.4 UNITS AMPLIFIER DC ELECTRICAL CHARACTERISTICS VRS+ = 3.6V Input Offset Voltage (Note 2) VOS VRS+ = -0.1V Common-Mode Input Range VCMR Full-Scale Sense Voltage (Note 2) Gain (Note 2) CMRR Transconductance (Note 2) MAX992_F AV MAX9929F GM Transconductance Accuracy (Note 2) Input Bias Current (Note 4) Input Offset Bias Current (Note 4) Input Leakage Current www.maximintegrated.com -0.1V VRS+ +2V VSENSE Gain Accuracy (Notes 2, 6) IRS+, IRSIOS IRS+, IRS- TA = -40C to +125C 0.8 TA = +25C 0.6 TA = -40C to +125C (Note 3) 2V VRS+ 28V Common-Mode Rejection Ratio TA = +25C 1.0 3.0 -0.1 TA = +25C 93 TA = -40C to +125C 87 TA = +25C 60 TA = -40C to +125C 54 +28 dB 72 mV 50 MAX9929F, VRS+ = 3.6V TA = +25C 0.3 MAX9929F, VRS+ = -0.1V TA = +25C 0.3 TA = -40C to +125C V/V 1.0 2.5 TA = -40C to +125C 1.0 % 2.8 MAX9928F 5 MAX9928F, VRS+ = 3.6V TA = +25C 0.3 MAX9928F, VRS+ = -0.1V TA = +25C 0.3 TA = -40C to +125C A/mV 1.0 2.5 TA = -40C to +125C -0.1V VRS+ +2V V 104 50 2V VRS+ 28V mV 1.0 % 2.8 0 1.6 -80 6 +6 2V VRS+ 28V 0.05 1 -0.1V VRS+ +2V 0.2 2 VCC = 0V, VRS+ = VRS- = 28V (Note 5) 0.05 1.0 A A A Maxim Integrated 2 MAX9928/MAX9929 -0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers Electrical Characteristics (continued) (VRS+ = -0.1V to +28V, VCC = 3.3V, VSENSE = (VRS+ - VRS-) = 0V, ROUT = 10k for MAX9928F, TA = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER Output Resistance Output High Voltage (Note 6) SYMBOL ROUT VOH CONDITIONS MIN MAX9928F 6.4 MAX9928F, ROUT = 10k MAX9929F VOL MAX9929F Minimum Output Current (Note 7) IOL MAX9928F MAX 5 MAX9929F Minimum Output Voltage (Note 7) TYP TA = +25C M 10 13.6 k (VCC 0.1) (VCC 0.1) (VCC 0.45) (VCC 0.45) V 0.25 2.0 TA = -40C to +125C 15 TA = +25C UNITS 0.025 TA = -40C to +125C 0.2 1.5 mV A SIGN COMPARATOR DC ELECTRICAL CHARACTERISTICS Discharge to Charge Trip Point (Note 8) VRS+ = 3.6V VTDC VRS+ = -0.1V Charge to Discharge Trip Point (Note 8) VTCD Hysteresis Width VHYS Common-Mode Input Range (Note 9) VCMR Common-Mode Rejection Ratio (Note 9) CMRR Output Low Voltage VOL Output High Voltage Internal Pullup Resistor TA = +25C -1.6 TA = -40C to +125C -2.15 TA = +25C -2.5 TA = -40C to +125C -4.6 -1.2 -0.15 -1.2 +0.25 mV +2.3 VRS+ = 3.6V TA = +25C -1.8 VRS+ = -0.1V TA = +25C -1.8 VRS+ = 3.6V, -0.1V TA = +25C 0.6 -0.1 mV mV +28 2V VRS+ 28V 102 -0.1V VRS+ +2V 74 ISINK = 100A -0.5 V dB 0.03 0.1 V VOH (VCC 0.01) (VCC 0.04) V RPULL-UP 1 M POWER SUPPLY Supply Voltage Range (Note 10) VCC Amplifier Power-Supply Rejection Ratio (Note 10) PSRRA Comparator Power-Supply Rejection Ratio PSRRC Quiescent Supply Current ICC www.maximintegrated.com TA = +25C 2.5 5.5 TA = -40C to +125C 2.8 5.5 VRS+ = 3.6V 72 90 VRS+ = -0.1V 66 86 V dB VRS+ = 3.6V 90 VRS+ = -0.1V 86 2V VRS+ 28V 20 30 -0.1V VRS+ < +2V 115 200 dB A Maxim Integrated 3 MAX9928/MAX9929 -0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers Electrical Characteristics (continued) (VRS+ = -0.1V to +28V, VCC = 3.3V, VSENSE = (VRS+ - VRS-) = 0V, ROUT = 10k for MAX9928F, TA = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS AC ELECTRICAL CHARACTERISTICS -3dB Bandwidth OUT Settling to 1% of Final Value BW MAX992_F, VSENSE = 50mV tSET VRS+ = 3.6V, CLOAD = 10pF, ROUT = 10k for MAX9928F 150 MAX992_F, VSENSE = 5mV to 50mV step 6 MAX992_F, VSENSE = 50mV to 5mV step 15 kHz s Overdrive = 1mV 80 Overdrive = 5mV 30 Overdrive = 1mV 50 Overdrive = 5mV 13 Power-Up Time to 1% of Final Value VSENSE = 50mV for MAX992_F, VRS+ = 3.6V, CLOAD = 10pF 50 s Saturation Recovery Time 100mV VSENSE P 50mV for MAX992_F, VRS+ = 3.6V, CLOAD = 10pF 4 ms SIGN Comparator Propagation Delay (Low to High) tPROP_LH SIGN Comparator Propagation Delay (High to Low) tPROP_HL s s Note 1: Note 2: Note Note Note Note Note Note Note Note All devices are 100% production tested at TA = +25C. All temperature limits are guaranteed by design. VOS is extrapolated from two point transconductance and gain accuracy tests. Measurements are made at VSENSE = +5mV and VSENSE = +50mV for MAX992_F. These measurements are also used to test the full-scale sense voltage, transconductance, and gain. These VOS specifications are for the trimmed direction only (VRS+ > VRS-). For current flowing in the opposite direction (VRS- > VRS+), VOS is 1mV (max) at +25C and 1.8mV (max) over temperature, when VRS+ is at 3.6V. See the Detailed Description for more information. 3: Guaranteed by common-mode rejection ratio. Extrapolated VOS as described in Note 2 is used to calculate common-mode rejection ratio. 4: Includes input bias current of SIGN comparator. 5: Leakage in to RS+ or RS- when VCC = 0V. Includes input leakage current of SIGN comparator. This specification does not add to the bias current. 6: Output voltage should be 650mV below VCC to achieve full accuracy. 7: IOL is the minimum output current in the VSENSE - IOUT transfer characteristics. VOL is the minimum output voltage in the VSENSE - VOUT transfer characteristic. 8: VSENSE voltage required to switch comparator. 9: Discharge to charge trip point is functionally tested at VCM = -0.1V, +3.6V, and +28V. 10: Guaranteed by PSRR test. Extrapolated VOS as described in Note 2 is used to calculate the power-supply rejection ratio. VSENSE has to be such that the output voltage is 650mV below VCC to achieve full accuracy. www.maximintegrated.com Maxim Integrated 4 MAX9928/MAX9929 -0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers Typical Operating Characteristics (VCC = 3.3V, VRS+ = 12V, TA = +25C, unless otherwise noted.) 25 20 15 20 15 10 10 5 5 0.6 0.4 0.2 0 -0.2 -0.4 150 VRS+ = 0V 75 50 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 VRS+ = 3.6V 2.5 TEMPERATURE (C) 3.0 3.5 4.0 4.5 MAX9928 toc03 3 28 90 VCC = 5.5V 60 VCC = 2.5V 5.0 0 5.5 -0.5 0 0.5 1.0 1.5 2.0 28 COMMON-MODE VOLTAGE (V) 100 75 50 VRS+ = 3.6V MAX9928 toc08 VRS+ = 0V 10 0 INPUT BIAS CURRENT (A) MAX9928 toc07 INPUT BIAS CURRENT vs. COMMON-MODE VOLTAGE VSENSE = 0V 25 2 120 SUPPLY VOLTAGE (V) 125 1 150 30 SUPPLY CURRENT vs. TEMPERATURE SUPPLY CURRENT (A) 0 -1 COMMON-MODE VOLTAGE (V) 100 -0.8 0 -1.0 SUPPLY CURRENT vs. COMMON-MODE VOLTAGE VSENSE = 0V 25 150 -0.5 -2.0 -1.0 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1.0 GAIN ACCURACY (%) 125 -0.6 -1.0 0 MAX9928 toc06 VCM = 3.6V 0.5 SUPPLY CURRENT vs. SUPPLY VOLTAGE OFFSET VOLTAGE vs. TEMPERATURE SUPPLY CURRENT (A) OFFSET VOLTAGE (mV) 0.8 1.0 -1.5 SUPPLY CURRENT (A) 1.0 0 -0.40 -0.30 -0.20 -0.10 0 0.10 0.20 0.30 0.40 VOS (mV) MAX9928 toc04 0 1.5 OFFSET VOLTAGE (mV) 30 OFFSET VOLTAGE vs. COMMON-MODE VOLTAGE 2.0 MAX9928 toc02 25 FREQUENCY (%) FREQUENCY (%) 35 AV = 50V/V MAX9928 toc05 40 AV = 50V/V GAIN ACCURACY HISTOGRAM 30 MAX9928 toc01 45 VOS HISTOGRAM -10 -20 -30 -40 -50 -60 -70 -50 -25 0 25 50 75 TEMPERATURE (C) www.maximintegrated.com 100 125 -80 -2 -0.1 0 2 4 6 8 10 28 COMMON-MODE VOLTAGE (V) Maxim Integrated 5 MAX9928/MAX9929 -0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers Typical Operating Characteristics (continued) (VCC = 3.3V, VRS+ = 12V, TA = +25C, unless otherwise noted.) VOUT (V) TA = +125C 1000 1 0.1 0.2 0.3 0.4 20 40 60 80 100 120 GAIN ACCURACY vs. SUPPLY VOLTAGE MINIMUM OUTPUT VOLTAGE vs. TEMPERATURE MAX9928 toc12 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 2.6 2.0 140 5.0 1.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 5.5 -0.4 -0.6 1.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 SUPPLY VOLTAGE (V) TEMPERATURE (C) MAX992_F 90 29 CMRR (dB) GAIN (dB) MAX9928 toc16 VCM = 3.6V CMRR vs. FREQUENCY 120 MAX9928 toc15 35 26 60 30 23 20 0.01 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) SMALL-SIGNAL GAIN vs. FREQUENCY 32 GAIN ACCURACY vs. TEMPERATURE 0 -0.8 5.0 90 -0.2 -1.0 4.5 80 0.2 0 4.0 70 0.4 -1.0 3.5 60 0.6 0.5 3.0 50 0.8 -0.8 2.5 40 30 VSENSE (mV) GAIN ACCURACY (%) GAIN ACCURANCY (%) 0 VSENSE (mV) 0.8 TA = +125C 2.4 VSENSE (V) 1.0 TA = +25C 2.8 2.2 0 0.5 VCC = 2.7V MAX9928 toc13 0 MINIMUM OUTPUT VOLTAGE (mV) 0 VCC = 3.3V VCC = 2.5V TA = -40C 3.2 3.0 3 2 500 3.4 VCC = 5.5V 4 TA = +25C IOUT (A) 5 MAX9929F VOUT vs. VSENSE MAX9928 toc11 2000 1500 6 VOUT (V) TA = -40C MAX9928 toc10 VOUT = 0V MAX9928 toc09 2500 MAX9929F VOUT vs. VSENSE MAX9928 toc14 MAX9928F IOUT vs. VSENSE 0.1 1 10 FREQUENCY (kHz) www.maximintegrated.com 100 1000 0 10 100 1k 10k 100k 1M FREQUENCY (Hz) Maxim Integrated 6 MAX9928/MAX9929 -0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers Typical Operating Characteristics (continued) (VCC = 3.3V, VRS+ = 12V, TA = +25C, unless otherwise noted.) MAX9929F LARGE-SIGNAL TRANSIENT RESPONSE PSRR vs. FREQUENCY MAX9928 toc18 MAX9928 toc17 20 0 PSRR (dB) -20 VSENSE 50mV/div -40 -60 -80 VOUT 1V/div -100 -120 0.1 1 10 100 1k 10k 100k 100s/div FREQUENCY (Hz) VSIGN AND VOUT vs. VSENSE OVERDRIVE RECOVERY MAX9928 toc20 MAX9928 toc19 VSIGN (V) 4 3 VSENSE 100mV/div 2 1 VOUT (mV) 0 150 VOUT 500mV/div 100 50 0 -3 -2 -1 0 1 2 400s/div 3 VSENSE (mV) COMPARATOR PROPAGATION DELAY (RS+ = 3.6V, 5mV OVERDRIVE) POWER-UP DELAY MAX9928 toc21 VCC 1V/div VSENSE 2mV/div VOUT 1V/div VOUT 1V/div 40s/div www.maximintegrated.com MAX9928 toc22 40s/div Maxim Integrated 7 MAX9928/MAX9929 -0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers Pin Configuration PIN BUMP MAX UCSP 1 B3 RS- 2 B2 SIGN SIGN Output. Indicates polarity of VSENSE. SIGN = H indicates VRS+ > VRSSIGN = L indicates VRS+ < VRS- 3 B1 RS+ Positive Current-Sense Input. Power-side connection to the external sense resistor. 4, 5 -- N.C. No Connection. Not internally connected. 6 A1 VCC Supply Voltage Input. Bypass to GND with a 0.1F capacitor. 7 A2 GND Circuit Ground 8 A3 OUT Current-Sense Output. MAX9928: Current output (IOUT is proportional to |VSENSE|). MAX9929: Voltage output (VOUT is proportional to |VSENSE|). NAME FUNCTION Negative Current-Sense Input. Load-side connection for the external sense resistor. Detailed Description The MAX9928F/MAX9929F micropower uni-/bidirectional, current-sense amplifiers feature -0.1V to +28V input common-mode range that is independent of the supply voltage. This wide input voltage range feature allows the monitoring of the current flow out of a power supply during short-circuit/fault conditions, and also enables highside current sensing at voltages far in excess of the supply voltage (VCC). The MAX9928F/MAX9929F operate from a 2.5V to 5.5V single supply and draw a low 20A quiescent supply current. Current flows through the sense resistor, generating a sense voltage VSENSE (Figure 1). The comparator senses the direction of the sense voltage and configures the amplifier for either positive or negative sense voltages by controlling the S1 and S2 switches. For positive VSENSE voltage, the amplifier's inverting input is high impedance and equals VIN - VSENSE. The amplifier's output drives the base of Q1, forcing its noninverting input terminal to (VIN - VSENSE); this causes a current to flow through RG1 equal to |VSENSE|/RG1. Transistor Q2 and the current mirror amplify the current by a factor of M. For negative VSENSE voltage, the amplifier's noninverting input is high impedance and the voltage on RS- terminal equals VIN + VSENSE. The amplifier's output drives the base of Q1 forcing its inverting input terminal to match the voltage at the noninverting input terminal; this causes a current to flow through RG2 equal to |VSENSE|/RG2. Again, transistor Q2 and the current mirror amplify the current by a factor of M. www.maximintegrated.com +VSENSE vs. -VSENSE The amplifier is configured for either positive VSENSE or negative VSENSE by the SIGN comparator. The comparator has a built-in offset skew of -1.2mV so that random offsets in the comparator do not affect the precision of IOUT (VOUT) with positive VSENSE. The comparator has a small amount of hysteresis (typically 0.6mV) to prevent its output from oscillating at the crossover sense voltage. The ideal transfer characteristic of IOUT (VOUT) and the output of the comparator (SIGN) is shown in Figure 2. The amplifier VOS is only trimmed for the positive VSENSE voltages (VRS+ > VRS-). The SIGN comparator reconfigures the internal structure of the amplifier to work with negative VSENSE voltages (VRS- > VRS+) and the precision VOS trim is no longer effective and the resulting VOS is slightly impacted. See details in the Electrical Characteristics Note 2. The user can choose the direction that needs the best precision to be the direction where VRS+ > VRS-. For example, when monitoring Li+ battery currents, the discharge current should be VRS+ > VRS- to give the best accuracy over the largest dynamic range. When the battery charger is plugged in, the charge current flows in the opposite direction and is usually much larger, and a higher VOS error can be tolerated. See the Typical Operating Circuit. For applications with unidirectional currents (e.g., battery discharge only), the SIGN output can be ignored. Note that as VSENSE increases, the output current (IOUT for the MAX9928 or VOUT/10k for the MAX9929) also increases. This additional current is supplied from VCC. Maxim Integrated 8 MAX9928/MAX9929 2.5V TO 5.5V -0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers VCC RC1 80k VCC MAX9928F MAX9929F 1M SIGN C RC2 80k TO C CURRENT MIRROR VIN -0.1V TO +28V (VBATT) VSENSE RSENSE + - S2 RG1 80k RS+ RG2 80k RS- A TO LOAD/CHARGER S1 Q1 OUT Q2 TO ADC 10k* GND *INTERNAL 10k RESISTOR FOR MAX9929_ ONLY. Figure 1. Functional Diagram For both positive and negative VSENSE voltages, the current flowing out of the current mirror is equal to: IOUT = M x |VSENSE|/RG1 SIGN For the MAX9928F, the transconductance of the device is trimmed so that IOUT/|VSENSE| = 5A/mV. For the MAX9929F, the voltage gain of the device is trimmed so that VOUT/|VSENSE| = 50V/V. The SIGN output from the comparator indicates the polarity of VSENSE. Current Output (MAX9928F) -3.0 -1.8 -1.2 0 VSENSE (mV) 1.0 2.0 3.0 The output voltage equation for the MAX9928_ is given below: VOUT = (RSENSE x ILOAD) x (Gm X ROUT) IOUT (VOUT) where VOUT = the desired full-scale output voltage, ILOAD = the full-scale current being sensed, RSENSE = the current-sense resistor, ROUT = the voltage-setting resistor, and Gm = MAX9928F transconductance (5A/mV). -3.0 -1.8 -1.2 ( ) FOR THE MAX9929F. 0 VSENSE (mV) 1.0 2.0 3.0 Figure 2. Ideal Transfer Characteristics with 0mV Amplifier Input Offset Voltage and -1mV Comparator Input Offset Voltage www.maximintegrated.com The full-scale output voltage range can be set by changing the ROUT resistor value. The above equation can be modified to determine the ROUT required for a particular full-scale range: ROUT = (VOUT)/(ILOAD x RSENSE x Gm) OUT is a high-impedance current source and can drive an unlimited amount of capacitance. Maxim Integrated 9 MAX9928/MAX9929 -0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers Voltage Output (MAX9929F) The output voltage equation for the MAX9929_ is given below: VOUT = (RSENSE x ILOAD) x (AV) where VOUT = the desired full-scale output voltage, ILOAD = the full-scale current being sensed, RSENSE = the current-sense resistor, AV = MAX9929F voltage gain (50V/V). SIGN Output The current/voltage at OUT indicates magnitude. The SIGN output indicates the current's direction. The SIGN comparator compares RS+ to RS-. The sign output is high when RS+ is greater than RS- indicating positive current flow. The sign output is low when RS- is greater than RS+ indicating negative current flow. In battery-operated systems, this is useful for determining whether the battery is charging or discharging. The SIGN output might not correctly indicate the direction of load current when VSENSE is between -1.8mV to -1.2mV (see Figure 2). Comparator hysteresis of 0.6mV prevents oscillation of SIGN output. If current direction is not needed, leave SIGN unconnected. Applications Information Choosing RSENSE The MAX9928F/MAX9929F operate over a wide variety of current ranges with different sense resistors. Adjust the RSENSE value to monitor higher or lower current levels. Select RSENSE using these guidelines: Voltage Loss: A high RSENSE value causes the power-source voltage to drop due to IR loss. For least voltage loss, use the lowest RSENSE value. Accuracy: A high RSENSE value allows lower currents to be measured more accurately. This is because offsets become less significant when the sense voltage is larger. tor value and power dissipation (wattage) rating. Also, if the sense resistor is allowed to heat up excessively, its value could drift. Inductance: If there is a large high-frequency component to ISENSE, keep inductance low. Wire-wound resistors have the highest inductance, while metal film is somewhat better. Low-inductance metal-film resistors are available. Instead of being spiral wrapped around a core, as in metal film or wirewound resistors, these are a straight band of metal. They are made in values under 1. Use in Systems with Super Capacitors Since the input common-mode voltage range of the MAX9928/MAX9929 extends all the way from -0.1V to 28V, they are ideal to use in applications that require use of super capacitors for temporary or emergency energy storage systems. Some modern industrial systems use multifarad (1F-50F) capacitor banks to supply enough energy to keep critical systems alive even if the primary power source is removed or temporarily disabled. Unlike batteries, these capacitors can discharge all the way down to 0V. The MAX9928/MAX9929 can continuously help monitor their health and state of charge/discharge. 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, go to Maxim's website at www.maximintegrated.com/ucsp to find Application Note 1891: Wafer-Level Packaging (WLP) and its Applications. Chip Information PROCESS: BiCMOS Efficiency and Power Dissipation: At high current levels, the I2R losses in RSENSE might be significant. Take this into consideration when choosing the resis- www.maximintegrated.com Maxim Integrated 10 MAX9928/MAX9929 -0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers Pin Configurations TOP VIEW (BUMPS ON THE BOTTOM) TOP VIEW RS- 1 SIGN 2 RS+ 3 N.C. 4 + MAX9928F MAX9929F 8 OUT 7 GND 6 VCC 5 N.C. MAX A 1 2 3 VCC GND OUT MAX9928F MAX9929F B RS+ SIGN RS- UCSP (1mm x 1.5mm) Typical Operating Circuit VIN -0.1V TO +28V 2.5V TO 5.5V 0.1F WALL-CUBE CHARGER RSENSE RS+ LOAD RS- C VCC MAX9928F SIGN DIGITAL INPUT MAX9929F ADC OUT GND ROUT* GND *FOR THE MAX9928F ONLY www.maximintegrated.com Maxim Integrated 11 MAX9928/MAX9929 -0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers 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. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 8 MAX U8+1 21-0036 90-0092 6 UCSP B6+1 21-0097 -- www.maximintegrated.com Maxim Integrated 12 MAX9928/MAX9929 -0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers Revision History REVISION NUMBER REVISION DATE 0 12/08 Initial release 1 8/09 Removed MAX9928T and MAX9929T from data sheet 2 4/11 Updated top marks 1 3 4/12 Removed the R61A1+1 package code note and references 1 4 9/14 Removed automotive reference from data sheet. 10 DESCRIPTION PAGES CHANGED -- 1-5, 7-12 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. (c) 2014 Maxim Integrated Products, Inc. 13