19-1630; Rev 0; 3/00 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs Features ♦ Current-Sense Amplifier plus Internal Comparator and Bandgap Reference ♦ 50µA Supply Current ♦ Single +2.7V to +28V Operating Supply ♦ 0.66% Full-Scale Accuracy ♦ Internal Bandgap Reference ♦ Latching Comparator Output ♦ Three Gain Versions Available (+20V/V, +50V/V, +100V/V) ♦ Wide 0 to +28V Common-Mode Range, Independent of Supply Voltage Ordering Information PART TEMP. RANGE PINPACKAGE GAIN (V/V) MAX4373TEUA MAX4373TESA MAX4373FEUA MAX4373FESA MAX4373HEUA MAX4373HESA -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C 8 µMAX 8 SO 8 µMAX 8 SO 8 µMAX 8 SO +20 +20 +50 +50 +100 +100 Ordering Information continues at end of data sheet. Typical Operating Circuit ________________________Applications Notebook Computers Portable/Battery-Powered Systems ILOAD + VSENSE VIN = 0 TO 28V RSENSE Smart Battery Packs/Chargers RS+ Cell Phones Power-Management Systems General-System/Board-Level Current Monitoring VCC = 2.7V TO 28V LOAD/ BATTERY RS- VCC C1 0.1µF MAX4373 Precision Current Sources OUT VPULL-UP = 5V R1 R3 CIN COUT R2 RESET GND Pin Configurations appear at end of data sheet. ________________________________________________________________ Maxim Integrated Products 1 For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. MAX4373/MAX4374/MAX4375 General Description The MAX4373/MAX4374/MAX4375 low-cost, micropower, high-side current-sense supervisors contain a highside current-sense amplifier, bandgap reference, and comparator with latching output. They feature a voltage output that eliminates the need for gain-setting resistors, making them ideal for today’s notebook computers, cell phones, and other systems where battery/DC current monitoring is critical. High-side current monitoring is especially useful in battery-powered systems since it does not interfere with the ground path of the battery charger. The 0 to +28V input common-mode range is independent of the supply voltage, which ensures that the current-sense feedback remains viable even when connected to a battery pack in deep discharge. The comparator output of the MAX4373/MAX4374/ MAX4375 is latched to provide a turn-off flag that doesn’t oscillate. In addition, the MAX4374/MAX4375 contain a second comparator for use in window-detection functions. The MAX4373/MAX4374/MAX4375 are available in three different gain versions (T = +20V/V, F = +50V/V, H = +100V/V) and use an external sense resistor to set the sensitivity of the input voltage to the load current. These features offer a high level of integration, resulting in a simple and compact currentsense solution. The MAX4373/MAX4374/MAX4375 operate from a single +2.7V to +28V supply and consume 50µA. They are specified for the extended operating temperature range (-40°C to +85°C) and are available in 8-pin and 10-pin µMAX packages. MAX4373/MAX4374/MAX4375 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs ABSOLUTE MAXIMUM RATINGS VCC, RS+, RS- to GND ...........................................-0.3V to +30V OUT to GND ................................................-0.3V to the lesser of (VCC + 0.3V) or +15V CIN1, CIN2, RESET to GND ........................-0.3V to the lesser of (VCC + 0.3V) or +12V Differential Input Voltage (VRS+ - VRS-) ..............................±0.3V COUT1, COUT2 to GND........................................-0.3V to +6.0V Current into Any Pin..........................................................±10mA Continuous Power Dissipation (TA = +70°C) 8-Pin µMAX (derate 4.1mW/°C above +70°C) .............330mW 8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW 10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW 14-Pin SO (derate 8.3mW/°C above +70°C)................667mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°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 (VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0, V RESET = 0, RLOAD= 1MΩ, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Operating Voltage Range (Note 2) SYMBOL CONDITIONS MIN TYP MAX UNITS VCC 2.7 28 V Common-Mode Input Range (Note 3) VCMR 0 28 V Common-Mode Rejection CMR Supply Current Leakage Current ICC 85 VRS+ > 2V, VSENSE = 5mV 50 100 µA ±0.015 ±0.5 µA IRS+, IRS- VCC = 0 IRS+ Input Bias Current IRSFull-Scale Sense Voltage (Note 4) VRS+ > 2V VSENSE Full-Scale Accuracy (Note 5) VRS+ > 2V 0 2.5 VRS+ ≤ 2V -25 2.0 VRS+ > 2V 0 4 VRS+ ≤ 2V -50 Gain = +20V/V, +50V/V 150 170 Gain = +100V/V 100 120 VSENSE = 100mV, VCC = 12V, VRS+ = 12V, TA = +25°C VSENSE = 100mV (Note 6) ±0.66 ±0.55 VCC = 12V, VRS+ = 0.1V ±5.0 IOUT = 100µA 8.5 VCC = 2.7V OUT Voltage High VCC VOH VCC = 2.7V, IOUT = -500µA 2 % ±7.5 ±5.0 2.5 VOUT ±5.5 % IOUT = 10µA OUT Voltage Low mV ±7.5 VCC = 28V, VRS+ = 28V, TA = TMIN to TMAX VSENSE = 6.25mV, VCC = 12V, VRS+ = 12V (Note 7) µA 4 VCC = 12V, VRS+ = 12V, TA = TMIN to TMAX Total OUT Voltage Error (Note 5) dB _______________________________________________________________________________________ 65 0.25 mV V Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs (VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0, V RESET = 0, RLOAD= 1MΩ, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER -3dB Bandwidth SYMBOL BW CONDITIONS VRS+ = 12V, VCC = 12V, CLOAD = 10pF MIN 200 VSENSE = 100mV, Gain = +50V/V 120 VSENSE = 100mV, Gain = +100V/V 110 VSENSE = 6.25mV AV ∆AV Gain Accuracy Capacitive Load Stability UNITS kHz +20 MAX437_F +50 MAX437_H +100 VSENSE = TA = +25°C 20mV to 150mV; VCC = 12V; VRS+ = 12V; TA = -40°C to +85°C Gain = 20, 50 ±0.64 VSENSE = TA = +25°C 20mV to 100mV, VCC = 12V, VRS+ = 12V, TA = -40°C to +85°C Gain = 100 ±0.62 V/V ±5.2 ±7.2 % Gain = +20V/V, VCC = 12V, VRS+ = 12V, CLOAD = 10pF OUT Settling Time to 1% of Final Value MAX 50 MAX437_T Gain TYP VSENSE = 100mV, Gain = +20V/V ±7.2 VSENSE = 6.25mV to 100mV 20 VSENSE = 100mV to 6.25mV 20 µs No sustained oscillations OUT Output Resistance ROUT VSENSE = 100mV Power-Supply Rejection PSR VOUT = 2V, VRS+ > 2V ±5.0 1000 72 pF 1.5 Ω 87 dB Power-Up Time to 1% of Final Value VSENSE = 100mV, CLOAD = 10pF, VCC = 12V, VRS+ = 12V 0.5 ms Saturation Recovery Time (Note 8) VCC = 12V, VRS+ = 12V, CLOAD = 10pF 0.1 ms COMPARATOR (Note 9) Comparator Threshold 580 Comparator Hysteresis Input Bias Current 618 -9 IB ±2.2 CL = 10pF, RL = 10kΩ pull-up to 5V, 5mV of overdrive Propagation Delay Output Low Voltage 600 VOL ISINK = 1mA mV mV ±15 4 nA µs 0.6 V _______________________________________________________________________________________ 3 MAX4373/MAX4374/MAX4375 ELECTRICAL CHARACTERISTICS (continued) ELECTRICAL CHARACTERISTICS (continued) (VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0, V RESET = 0, RLOAD= 1MΩ, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL Output High Leakage Current CONDITIONS INTYP MAX UNITS VCC = 28V, VPULL-UP = 5V (Note 10) RESET Input High Voltage VIH RESET Input Low Voltage VIL 1 2.0 V V 0.5 µA IIL, IIH tRPW 1.5 µs RESET Propagation Delay tRPD 3 µs Note 7: Note 8: Note 9: Note 10: -0.5 0.8 Minimum RESET Pulse Width Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: VIL = 0, VIH = 5.5V, VCC = 28V µA Logic Input Current All devices are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design. Guaranteed by PSR test. Guaranteed by OUT Voltage Error test. Guaranteed by Gain Accuracy test. Output voltage is internally clamped not to exceed 12V. Total OUT Voltage Error and Full-Scale Accuracy are the sum of gain and offset voltage errors. Measured at IOUT = -500µA (RLOAD = 4kΩ for gain of +20V/V, RLOAD = 10kΩ for gain of +50V/V, RLOAD = 20kΩ for gain of +100V/V). +6.25mV = 1/16 of +100mV full-scale voltage. The device will not experience phase reversal when overdriven. All comparator tests are done with VRS+ = +12V. VPULL-UP is defined as an externally applied voltage through a resistor to pull up the comparator output. Typical Operating Characteristics (VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless otherwise noted.) SUPPLY CURRENT vs. COMMON-MODE VOLTAGE 51 MAX4373 30 20 50 1.0 49 48 47 MAX4373 10 15 20 SUPPLY VOLTAGE (V) 4 AV = +20V/V -0.5 -2.0 44 5 AV = +50V/V 0 VSENSE = 5mV 0 0 AV = +100V/V -1.5 45 VSENSE = 5mV 0.5 -1.0 46 10 1.5 MAX4374/MAX4375 OUTPUT ERROR (%) SUPPLY CURRENT (µA) 50 2.0 MAX4373 toc02 MAX4374/MAX4375 40 52 MAX4373 toc01 60 TOTAL OUTPUT ERROR vs. SUPPLY VOLTAGE MAX4373 toc03 SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT (µA) MAX4373/MAX4374/MAX4375 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs 25 30 0 5 10 15 20 25 COMMON-MODE VOLTAGE (V) 30 2 4 6 8 10 12 14 16 18 20 22 24 26 28 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs TOTAL OUTPUT ERROR vs. SUPPLY VOLTAGE 1.0 AV = +20V/V -2 -3 -4 -5 AV = +100V/V AV = +20V/V -0.5 -1.0 AV = +50V/V -1.5 -2.0 25 50 75 100 125 10 OUTPUT ERROR (%) AV = +100V/V 2.0 AV = +50V/V 1.5 AV = +20V/V 125 AV = +50V/V 2 -2 AV = +20V/V 2 4 6 8 10 12 14 16 18 20 22 24 26 28 150 COMMON-MODE VOLTAGE (V) VSENSE (mV) SMALL-SIGNAL PULSE RESPONSE (AV = +20V/V) SMALL-SIGNAL PULSE RESPONSE (AV = +100V/V) SMALL-SIGNAL PULSE RESPONSE (AV = +50V/V) MAX4373 toc11 MAX4373 toc10 INPUT 30mV 30mV INPUT MAX4373 toc09 30mV 150 4 0 100 125 6 0 75 100 AV = +100V/V 8 0.5 50 75 MAX4373 toc08 12 MAX4373 toc07 2.5 OUTPUT ERROR (%) 50 TOTAL OUTPUT ERROR vs. COMMON-MODE VOLTAGE VCC = +28V 10mV 10mV 10mV 600mV 1.5V 3V 200mV OUTPUT INPUT 25 VSENSE (mV) TOTAL OUTPUT ERROR vs. SENSE VOLTAGE 20µs/div 0 150 VSENSE (mV) SUPPLY VOLTAGE (V) 25 AV = +50V/V -0.5 -2.0 0 3.0 AV = +20V/V 0 -1.0 -2.5 0 AV = +100V/V 0.5 -1.5 2 4 6 8 10 12 14 16 18 20 22 24 26 28 1.0 1.0 OUTPUT 0 -1 OUTPUT ERROR (%) OUTPUT ERROR (%) 1 1.5 0.5 0 MAX4373 toc06 VCC = +5.5V 2 OUTPUT OUTPUT ERROR (%) AV = +50V/V 2.0 MAX4373 toc05 4 AV = +100V/V 1.5 MAX4373 toc04 5 3 TOTAL OUTPUT ERROR vs. SENSE VOLTAGE TOTAL OUTPUT ERROR vs. SENSE VOLTAGE 1V 500mV 20µs/div 20µs/div _______________________________________________________________________________________ 5 MAX4373/MAX4374/MAX4375 Typical Operating Characteristics (continued) (VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless otherwise noted.) LARGE-SIGNAL PULSE RESPONSE (AV = +50V/V) LARGE-SIGNAL PULSE RESPONSE (AV = +20V/V) MAX4373 toc14 150mV 5mV 3V 7.5V 9.5V 2.5V 20µs/div POWER-SUPPLY REJECTION vs. FREQUENCY COMMON-MODE REJECTION vs. FREQUENCY -20 -30 -30 -40 -40 PSR (dB) -50 -60 -70 -70 -80 -80 -90 -90 -100 -100 100 1k 10k 100 1k 10k FREQUENCY (Hz) SMALL-SIGNAL GAIN vs. FREQUENCY LARGE-SIGNAL GAIN vs. FREQUENCY 5 MAX4373 toc17 3 2 3 2 AV = +20V/V AV = +50V/V 0 AV = +100V/V -3 -4 -4 -5 -5 1000k AV = +50V/V 0 -3 100k 100k -1 -2 FREQUENCY (Hz) AV = +20V/V 1 -2 10k VIN = 100mVp-p (20, 50) VIN = 50mVp-p (100) 4 GAIN (dB) GAIN (dB) 10 100k FREQUENCY (Hz) 4 1k MAX4373 toc16 -50 -60 MAX4373 toc18 CMR (dB) -10 -20 5 6 0 MAX4373 toc15 0 -10 -1 500mV 20µs/div 20µs/div 1 OUTPUT 50mV OUTPUT 50mV 1V 10 95mV INPUT INPUT 150mV INPUT LARGE-SIGNAL PULSE RESPONSE (AV = +100V/V) MAX4373 toc13 MAX4373 toc12 OUTPUT MAX4373/MAX4374/MAX4375 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs AV = +100V/V 1k 10k FREQUENCY (Hz) _______________________________________________________________________________________ 100k Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs COMPARATOR POWER-UP DELAY POWER-UP DELAY MAX4373 toc20 MAX4373 toc19 VCC = VPULL-UP AV = +20V/V 5V 6V VCC VCC 0 0 2V 5V OUTPUT OUTPUT 0 10µs/div COMPARATOR TRIP POINT vs. SUPPLY VOLTAGE COMPARATOR PROPAGATION DELAY MAX4373 toc21 599 598 597 MAX4373 toc22 100µs/div 600 TRIP POINT (mV) 0 VOD = 5mV INPUT 125mV/div 596 595 594 593 OUTPUT 2.5V/div 592 591 590 0 5 10 15 20 25 30 2µs/div SUPPLY VOLTAGE (V) COMPARATOR PROPAGATION DELAY vs. OVERDRIVE VOLTAGE VOD = 5mV 6 PROPAGATION DELAY (µs) 3.4 3.2 3.0 2.8 2.6 2.4 MAX4373 toc26 3.6 PROGAGATION DELAY (µs) 7 MAX4373 toc24 3.8 COMPARATOR PROPAGATION DELAY vs. TEMPERATURE 5 4 3 2 1 2.2 2 0 0 20 40 60 80 100 120 140 160 180 200 OVERDRIVE VOLTAGE (mV) -50 -30 -10 10 30 50 70 90 TEMPERATURE (°C) _______________________________________________________________________________________ 7 MAX4373/MAX4374/MAX4375 Typical Operating Characteristics (continued) (VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless otherwise noted.) COMPARATOR RESET VOLTAGE vs. SUPPLY VOLTAGE MAX4373 toc28 1.8 80 70 60 1.6 VOL (mV) RESET VOLTAGE (V) COMPARATOR VOL vs. ISINK 90 MAX4373 toc27 2.0 1.4 50 40 30 1.2 20 1.0 10 0 0.8 10 15 20 25 0 30 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 ISINK (mA) SUPPLY VOLTAGE (V) TOTAL OUTPUT ERROR vs. TEMPERATURE SUPPLY CURRENT vs. TEMPERATURE COMPARATOR AC RESPONSE MAX4373 toc31 750mV 60 MAX4374 MAX4375 5V OUTPUT SUPPLY CURRENT (µA) INPUT 250mV MAX4373 toc32 70 50 40 MAX4373 30 20 1.0 MAX4373 toc33 5 TOTAL OUTPUT ERROR (%) 0 0.8 0.6 0.4 0.2 0 10 VSENSE = 5mV 0 0 10µs/div -60 -40 -20 0 20 40 60 80 -60 100 -40 -20 GAIN ACCURACY vs. TEMPERATURE 20 40 COMPARATOR TRIP POINT vs. TEMPERATURE AV = +20V/V, +50V/V AV = +100V/V 0.4 0.2 MAX4373 toc35 0.8 605 604 COMPARATOR TRIP POINT (mV) MAX4373 toc34 1.0 0.6 0 TEMPERATURE (°C) TEMPERATURE (°C) GAIN ACCURACY (%) MAX4373/MAX4374/MAX4375 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs 603 602 601 600 599 598 597 596 595 0 -60 -40 -20 0 20 40 TEMPERATURE (°C) 8 60 80 100 -60 -40 -20 0 20 40 60 TEMPERATURE (°C) _______________________________________________________________________________________ 80 100 60 80 100 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs PIN NAME FUNCTION MAX4373 MAX4374/MAX4375 µMAX/SO µMAX SO 1 1 1 VCC Supply Voltage Input 2 2 2 OUT Voltage Output. VOUT is proportional to VSENSE (VRS+ - VRS-). 3 3 4 CIN1 Comparator Input 1. Positive input of an internal comparator. The negative terminal is connected to a 0.6V internal reference. — 4 5 CIN2 Comparator Input 2. Terminal of a second internal comparator. The positive terminal for the MAX4374 and the negative terminal for the MAX4375. The other terminal is connected to a 0.6V internal reference. 4 5 7 GND Ground 5 6 8 RESET Reset Input. Resets the output latch of the comparator at CIN1. 6 8 11 COUT1 Comparator Output. Latching output of the comparator controlled by CIN1. Connect RESET to GND to disable the latch. — 7 10 COUT2 Comparator Output. Output of the second unlatched internal comparator. 7 9 13 RS- Load-Side Connection for the External Sense Resistor 8 10 14 RS+ Power Connection to the External Sense Resistor — — 3, 6, 9, 12 N.C. No Connection. Not internally connected. FUNCTION Detailed Description + VSENSE - VIN = 0 TO 28V RSENSE RS+ LOAD RS- VCC CURRENTSENSE AMPLIFIER VPULL-UP = 5V R3 VPULL-UP = 5V COUT1 + - OUT R1 Current-Sense Amplifier R2 RESET R6 R4 CIN1 COUT2 +(-) -(+) CIN2 0.6V BANDGAP REFERENCE MAX4374/MAX4375 GND The MAX4373 high-side current-sense supervisor features a high-side current-sense amplifier, bandgap reference, and comparator with latching output to monitor a supply for an overcurrent condition (Figure 1). The latching output allows the comparator to shut down a power supply without oscillations. The MAX4374/ MAX4375 offer an additional comparator to allow window detection of the current. R5 The internal current-sense amplifier features a 0V to +28V input common-mode range that is independent of the supply voltage. With this feature, the device can monitor the output current of a battery in deep discharge and also high-side current-sensing voltages exceeding VCC. The current-sense amplifier is also suitable for low-side current sensing. However, the total output voltage error will increase when VRS+ falls below 2V, as shown in Figure 1. Functional Diagram _______________________________________________________________________________________ 9 MAX4373/MAX4374/MAX4375 Pin Description MAX4373/MAX4374/MAX4375 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs the Electrical Characteristics and Typical Operating Characteristics. Internal Comparator(s) The MAX4373/MAX4374/MAX4375 contain a latching output comparator. The negative terminal of the comparator is internally connected to the internal reference. The positive terminal is accessible at CIN1. When RESET is high, the comparator output latches high once the comparator threshold is exceeded. When RESET is low, the latch is transparent. The MAX4374 and MAX4375 each contain an additional comparator for use in window detection. The negative terminal of the MAX4374 and the positive terminal of the MAX4375 are internally connected to the internal reference. The positive terminal of the MAX4374 and the negative terminal of the MAX4375 are accessible at CIN2. LOAD RS+ RS- 2.7V TO 5.5V OUT COUT1 VCC MAX4373 CIN1 RESET PUSHBUTTON GND ___________Applications Information Recommended Component Values Ideally, the maximum load current will develop the fullscale sense voltage across the current-sense resistor. Choose the gain version needed to yield the maximum output voltage required for the application: VOUT = VSENSE × AV where VSENSE is the full-scale sense voltage, 150mV for gains of +20V/V and +50V/V or 100mV for a gain of +100V/V. AV is the gain of the device. The minimum supply voltage is VOUT + 0.25V. Note that the output for the gain of +100V/V is internally clamped at 12V. Calculate the maximum value for RSENSE so that the differential voltage across RS+ and RS- does not exceed the full-scale sense voltage: RSENSE(MAX) = VSENSE(MAX) ILOAD Choose the highest value resistance possible to maximize VSENSE and thus minimize total output error. In applications monitoring high current, ensure that RSENSE is able to dissipate its own I2R loss. If the resistor’s power dissipation is exceeded, its value may drift or it may fail altogether, causing a differential voltage across the terminals in excess of the absolute maximum ratings. Use resistors specified for current-sensing applications. 10 Figure 2. MAX4373 Overcurrent Protection Circuit Overcurrent Protection Circuit The overcurrent protection circuit, shown in Figure 2, uses the MAX4373 to control an external P-channel MOSFET. The MOSFET controlled by the MAX4373 opens the current path under overload conditions. The latched output of the MAX4373’s comparator prevents the circuit from oscillating, and the pushbutton resets the current path after an overcurrent condition. Window Detection Circuit Figure 3 shows a simple circuit suitable for window detection. Let I OVER be the minimum load current (ILOAD) required to cause a low state at COUT2, and let IUNDER be the maximum load current required to cause a high state at COUT1: IUNDER = R4 + R5 VREF RSENSE × AV R5 and IOVER = R1 + R2 VREF RSENSE × AV R2 where AV is the gain of the device and VREF is the internal reference voltage (0.6V typ). Connect COUT1 and COUT2; the resulting comparator output will be high when the current is inside the current window and low when the current is outside the window. The window is defined as load currents less than IOVER and greater than IUNDER. ______________________________________________________________________________________ Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs PART TEMP. RANGE PINPACKAGE GAIN (V/V) MAX4374TEUB MAX4374TESD MAX4374FEUB MAX4374FESD MAX4374HEUB MAX4374HESD MAX4375TEUB MAX4375TESD MAX4375FEUB MAX4375FESD MAX4375HEUB -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C 10 µMAX 14 SO 10 µMAX 14 SO 10 µMAX 14 SO 10 µMAX 14 SO 10 µMAX 14 SO 10 µMAX +20 +20 +50 +50 +100 +100 +20 +20 +50 +50 +100 MAX4375HESD -40°C to +85°C 14 SO +100 VIN = 0 TO 28V RSENSE LOAD RS+ VCC = 2.7V TO 28V RS- VCC OUT VPULL-UP = 5V R1 MAX4375 R3 CIN2 COUT1 R4 R2 CIN1 COUT2 VCC RESET R5 GND ___________________Chip Information TRANSISTOR COUNT: 390 SUBSTRATE CONNECTED TO GND Figure 3. MAX4375 Window Detector Pin Configurations TOP VIEW VCC 1 OUT 2 CIN1 8 MAX4373 7 RS+ RS- 3 6 COUT1 GND 4 5 RESET µMAX/SO VCC 1 OUT 2 CIN1 3 MAX4374 MAX4375 CIN2 4 VCC 1 14 RS+ OUT 2 13 RS- 10 RS+ N.C. 3 12 N.C. 9 RS- CIN1 4 COUT1 CIN2 5 COUT2 N.C. 6 9 N.C. RESET GND 7 8 RESET 8 7 GND 5 6 µMAX MAX4374 MAX4375 11 COUT1 10 COUT2 SO ______________________________________________________________________________________ 11 MAX4373/MAX4374/MAX4375 Ordering Information (continued) ILOAD + VSENSE - Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs 10LUMAX.EPS 8LUMAXD.EPS MAX4373/MAX4374/MAX4375 Package Information 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. 12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.