MAX4375HEUB

Product Overview of the MAX4373/MAX4374/MAX4375 Series

The MAX4373/MAX4374/MAX4375 series represents a family of integrated current-sensing supervisors designed to address the monitoring requirements of modern battery-powered and power-managed systems. These devices combine three functional blocks into a single package: a high-side current-sense amplifier, an internal bandgap reference, and one or more comparators with latching capability. This integration eliminates the need for external gain-setting resistors and reduces the component count required for current monitoring applications.

The primary advantage of high-side current sensing lies in its non-intrusive measurement approach. Unlike low-side sensing, which measures current through a resistor connected to ground, high-side sensing monitors current at the positive supply rail. This topology preserves the integrity of the ground path in battery chargers and power distribution systems, making it particularly suitable for battery management applications where ground continuity is critical for proper charger operation.

The MAX4373/MAX4374/MAX4375 series operates across a wide supply voltage range from 2.7V to 28V, accommodating everything from single-cell battery systems to multi-cell battery packs and industrial power supplies. The devices consume only 50 microamperes of supply current, making them suitable for always-on monitoring functions in battery-powered equipment where power consumption directly impacts operational lifetime.

Architectural Foundation: Core Components of the MAX4373/MAX4374/MAX4375 Integrated Solution

Current-Sense Amplifier Architecture in the MAX4373/MAX4374/MAX4375

The current-sense amplifier within the MAX4373/MAX4374/MAX4375 series forms the foundation of the measurement system. This amplifier accepts differential voltage inputs across an external sense resistor and produces a proportional output voltage. The amplifier's input common-mode range extends from 0V to 28V, independent of the supply voltage applied to the device. This independence proves particularly valuable in battery applications where the sense resistor may be connected across the output of a battery in deep discharge state, where the voltage may fall below the device's supply voltage.

The amplifier achieves a maximum input offset voltage of 1 millivolt, contributing to the overall measurement accuracy. When combined with the external sense resistor, this low offset voltage ensures that small load currents produce measurable output voltages without significant error. The amplifier's gain is fixed at one of three values depending on the device variant selected: 20V/V, 50V/V, or 100V/V. These gain options allow designers to match the amplifier sensitivity to the expected current range of their application.

The relationship between load current and output voltage follows a straightforward calculation. When current flows through the external sense resistor, it develops a voltage across the resistor terminals. The amplifier multiplies this sense voltage by its fixed gain to produce the output voltage. For example, with a 100-milliohm sense resistor and a 50V/V gain amplifier, a 1-ampere load current produces a 5-millivolt sense voltage, which the amplifier amplifies to 250 millivolts at the output.

The full-scale sense voltage varies by gain configuration. For the 20V/V and 50V/V gain versions, the full-scale sense voltage is 150 millivolts. For the 100V/V gain version, the full-scale sense voltage is 100 millivolts. These values represent the maximum differential voltage that should be applied across the sense resistor terminals to maintain accuracy and prevent saturation. The output voltage is internally clamped at 12 volts for the 100V/V gain version, preventing excessive output levels even if the sense voltage exceeds design limits.

Internal Bandgap Reference and Comparator Design in the MAX4373/MAX4374/MAX4375

The MAX4373/MAX4374/MAX4375 series incorporates an internal bandgap reference that generates a stable 600-millivolt reference voltage with a typical accuracy of ±1.6 percent across the operating temperature range. This reference voltage serves as the threshold for the internal comparators and eliminates the need for external reference components. The bandgap reference maintains its accuracy across the full supply voltage range and temperature extremes, ensuring consistent threshold behavior regardless of operating conditions.

The comparator architecture in the MAX4373/MAX4374/MAX4375 series employs open-drain output stages, allowing the comparator outputs to be wire-ORed together or pulled up to external voltage supplies independent of the device's supply voltage. This flexibility enables integration with logic circuits operating at different voltage levels, such as 3.3V or 5V microcontroller interfaces in systems powered by higher voltage supplies.

Latching Comparator Output Mechanism in the MAX4373/MAX4374/MAX4375

The latching comparator output represents a key differentiator of the MAX4373/MAX4374/MAX4375 series compared to conventional comparators. In a standard comparator, the output continuously tracks the input signal, oscillating between high and low states as the input crosses the threshold. This oscillation can cause problems in power management applications where the comparator output controls a power switch. Repeated switching at the threshold can damage the switch and waste power through unnecessary transitions.

The MAX4373/MAX4374/MAX4375 series addresses this problem through a latching mechanism. Once the comparator input exceeds the 600-millivolt threshold and the RESET pin is held low, the output latches into the open-drain OFF state and remains there even if the input subsequently drops below the threshold. This latched state persists until the RESET pin is pulsed low for at least 1.5 microseconds, which resets the latch and allows the output to respond to new input conditions. Alternatively, holding the RESET pin low makes the latch transparent, allowing the output to track the input in real-time.

Operating Specifications and Performance Characteristics of the MAX4373/MAX4374/MAX4375

Supply Voltage and Power Consumption Parameters of the MAX4373/MAX4374/MAX4375

The MAX4373/MAX4374/MAX4375 series operates from a single supply voltage ranging from 2.7V to 28V. This wide supply range accommodates diverse system architectures, from single-cell lithium-ion batteries at 3.7V nominal voltage to 24V industrial power supplies. The minimum supply voltage of 2.7V allows operation even as battery voltage declines during discharge, extending the monitoring capability into the deep-discharge region where battery management becomes critical.

The supply current consumption of the MAX4373/MAX4374/MAX4375 series is specified at 50 microamperes typical. This low quiescent current makes the devices suitable for always-on monitoring functions in battery-powered systems. In a notebook computer or portable device operating for 8 hours per day, the current-sense supervisor contributes less than 1.4 milliamp-hours to the daily battery drain, a negligible amount compared to the total battery capacity.

The minimum supply voltage requirement of 2.7V plus the output voltage determines the practical lower limit for the supply voltage in any given application. The device requires a minimum of 0.25 volts between the output and ground to maintain proper operation. Therefore, if an application requires a 5-volt output from the current-sense amplifier, the minimum supply voltage must be at least 5.25 volts.

Input Common-Mode Range and Measurement Accuracy in the MAX4373/MAX4374/MAX4375

The input common-mode range of 0V to 28V, independent of supply voltage, represents one of the most significant performance characteristics of the MAX4373/MAX4374/MAX4375 series. This specification means that the sense resistor can be connected across the output of a battery or power supply without regard to the voltage level at that point. In battery applications, this capability allows the device to monitor current even when the battery voltage has dropped to near zero during deep discharge.

The measurement accuracy of the MAX4373/MAX4374/MAX4375 series is specified as 2 percent of full scale maximum. This accuracy encompasses both the gain error and the input offset voltage error. The 1-millivolt maximum input offset voltage contributes to this overall accuracy specification. For applications requiring higher absolute accuracy, the designer can select a sense resistor value that produces a larger full-scale sense voltage, reducing the relative impact of the fixed offset voltage.

The total output voltage error combines the gain accuracy and offset voltage contributions. For the 100V/V gain version with a 100-millivolt full-scale sense voltage, the maximum total output voltage error is 2 millivolts plus the offset voltage contribution. This means that at full scale, the output voltage could be anywhere from 1.98 volts to 2.02 volts, representing a ±1 percent error band around the ideal 2-volt output.

Gain Configurations and Output Voltage Characteristics of the MAX4373/MAX4374/MAX4375

The MAX4373/MAX4374/MAX4375 series is available in three gain configurations, each optimized for different current ranges and sense resistor values. The 20V/V gain version suits applications with large sense resistors and low current ranges. The 50V/V gain version provides a middle ground for moderate current ranges. The 100V/V gain version accommodates small sense resistors and high current ranges.

The selection of gain version depends on the maximum load current and the desired full-scale output voltage. For a notebook computer battery charger monitoring currents up to 5 amperes, a designer might select the 50V/V gain version with a 30-milliohm sense resistor. This combination produces a 150-millivolt sense voltage at full scale, which the amplifier amplifies to 7.5 volts at the output. This output voltage provides good resolution for analog-to-digital conversion while remaining well within the 12-volt output clamp limit.

The output voltage is internally clamped at 12 volts for the 100V/V gain version. This clamping prevents excessive output voltages if the sense voltage exceeds the design limit due to transient overcurrent conditions or component failures. The clamping does not introduce phase reversal, meaning the output voltage increases monotonically with increasing sense voltage without any discontinuities or reversals.

Temperature Range and Thermal Performance of the MAX4373/MAX4374/MAX4375

The MAX4373/MAX4374/MAX4375 series is specified for operation across an extended temperature range from -40°C to +85°C. This range covers typical consumer electronics applications from cold storage environments to warm operating conditions. The device maintains its specified accuracy across this entire temperature range, with all temperature limits guaranteed by design rather than by production testing at temperature extremes.

The thermal performance of the MAX4373/MAX4374/MAX4375 series depends on the package type selected. The 8-pin microMAX package dissipates a maximum of 330 milliwatts at 70°C, with a derating factor of 4.1 milliwatts per degree Celsius above 70°C. The 10-pin microMAX package dissipates a maximum of 444 milliwatts at 70°C, with a derating factor of 5.6 milliwatts per degree Celsius. These thermal specifications allow designers to calculate the maximum allowable power dissipation at any operating temperature within the specified range.

Functional Capabilities and Differentiation Among MAX4373/MAX4374/MAX4375 Variants

Single Comparator Configuration in the MAX4373

The MAX4373 variant contains a single comparator with latching output, making it suitable for simple overcurrent detection applications. The comparator's positive input terminal is accessible at the CIN1 pin, allowing external circuits to apply a threshold voltage. However, in the standard configuration, the comparator's negative input is connected to the internal 600-millivolt reference, and the positive input is driven by the output of the current-sense amplifier through an internal connection.

When the current-sense amplifier output exceeds 600 millivolts, indicating that the load current has exceeded the threshold set by the sense resistor value and gain configuration, the comparator output latches into the open-drain OFF state. This latched state persists until the RESET pin is pulsed low, allowing the circuit to implement a simple overcurrent shutdown function without additional external logic.

Dual Comparator Architecture in the MAX4374/MAX4375 for Window Detection

The MAX4374 and MAX4375 variants extend the functionality of the MAX4373 by adding a second comparator, enabling window detection capabilities. Window detection allows the circuit to monitor whether the load current remains within a specified range, triggering an alarm or shutdown if the current falls below a minimum threshold or exceeds a maximum threshold.

The MAX4374 and MAX4375 differ in the configuration of their second comparator. In the MAX4374, the second comparator's negative input is connected to the internal 600-millivolt reference, and its positive input is accessible at the CIN2 pin. In the MAX4375, the configuration is reversed: the positive input is connected to the internal reference, and the negative input is accessible at the CIN2 pin. This difference allows designers to implement window detection by connecting external resistor dividers to the CIN2 pin to set the lower and upper current thresholds.

Design Implementation Considerations for the MAX4373/MAX4374/MAX4375

Current-Sense Resistor Selection and Calculation for MAX4373/MAX4374/MAX4375 Applications

The selection of the current-sense resistor represents one of the most critical design decisions in any MAX4373/MAX4374/MAX4375 application. The sense resistor value directly determines the relationship between load current and output voltage. A smaller resistor value produces a smaller sense voltage for a given load current, requiring higher amplifier gain to achieve the desired output voltage. Conversely, a larger resistor value produces a larger sense voltage but dissipates more power.

The maximum sense resistor value is constrained by the full-scale sense voltage specification. For the 20V/V and 50V/V gain versions, the full-scale sense voltage is 150 millivolts. For the 100V/V gain version, the full-scale sense voltage is 100 millivolts. The designer should calculate the maximum sense resistor value using the formula: R_SENSE(MAX) = V_SENSE(MAX) / I_LOAD(MAX), where I_LOAD(MAX) is the maximum load current expected in the application.

For example, in a 5-ampere battery charger application using the 50V/V gain version, the maximum sense resistor value would be 150 millivolts divided by 5 amperes, yielding 30 milliohms. This 30-milliohm resistor would dissipate 750 milliwatts at maximum load current, requiring a resistor rated for at least 1 watt to ensure reliable operation and prevent thermal drift.

The designer should select the highest practical sense resistor value to maximize the sense voltage and minimize the relative impact of the amplifier's input offset voltage. A larger sense voltage produces a larger output voltage, improving the signal-to-noise ratio and reducing the relative error contribution from the fixed 1-millivolt offset voltage. However, the sense resistor must be capable of dissipating the I²R power loss without exceeding its temperature rating or experiencing significant resistance drift.

Resistors specified for current-sensing applications offer superior stability and temperature coefficients compared to general-purpose resistors. These specialized resistors maintain their resistance value within tight tolerances across the operating temperature range and under sustained high current conditions. Using general-purpose resistors in high-current applications risks unpredictable resistance drift, which would cause the measured current to deviate from the actual load current.

Power Supply Bypassing and Transient Protection in MAX4373/MAX4374/MAX4375 Circuits

The power supply bypassing strategy for the MAX4373/MAX4374/MAX4375 series must account for the potential for large, fast voltage transients at the supply pin. In battery-powered systems, plugging in or removing a battery, AC adapter, or charger can cause voltage transients exceeding 5 volts per microsecond. These fast transients can couple into the device's internal circuits through parasitic capacitances, potentially causing measurement errors or false comparator triggering.

The recommended approach is to bypass the VCC pin to ground with at least a 0.1-microfarad ceramic capacitor. This capacitor provides local charge storage to supply the device during brief supply interruptions and attenuates high-frequency noise. For applications with particularly fast supply transients, an additional resistor can be placed in series with the VCC pin to create an RC time constant that slows the rise time of the transient. A 1-kilohm resistor in series with a 0.1-microfarad capacitor creates a time constant of 100 microseconds, effectively filtering transients with rise times faster than this value.

The voltage drop across the series resistor must be considered in the supply voltage budget. With the MAX4373/MAX4374/MAX4375 consuming less than 100 microamperes of supply current, a 1-kilohm series resistor drops only 100 millivolts at maximum current. For most applications, this voltage drop is acceptable and can be easily accommodated by selecting a supply voltage slightly higher than the minimum required.

An alternative approach is to run the VCC pin from a better-regulated supply, such as a 5-volt linear regulator, rather than directly from the battery or primary power supply. This approach provides superior noise rejection and transient immunity at the cost of additional components and power dissipation in the regulator. The choice between these approaches depends on the specific application requirements and the available board space.

RESET Pin Management and Power-Up Sequencing for MAX4373/MAX4374/MAX4375 Devices

The RESET pin controls the latching function of the first comparator in the MAX4373/MAX4374/MAX4375 series. Proper management of this pin during power-up is essential to prevent false latching of the comparator output. The device contains no internal circuitry to control the RESET function during power-up, placing the responsibility on the system designer.

When the RESET pin is held low (below 2.0 volts), the internal latch is active. Once the current-sense amplifier output rises above 600 millivolts, the comparator output latches into the open-drain OFF state. This latched state persists until the RESET pin is pulsed low for at least 1.5 microseconds, which resets the latch and allows the output to respond to new input conditions.

During power-up, the supply voltage rises from zero to the operating voltage. If the RESET pin is not held low during this rise, the comparator output may latch prematurely due to noise or transient signals on the current-sense amplifier output. To prevent this false latching, the RESET pin must be held low until the VCC supply voltage has risen above the 2.7-volt minimum operating threshold.

If the RESET pin is controlled by a microcontroller or logic gate, this requirement is easily satisfied by holding the RESET pin low in software until the power supply has stabilized. However, if the RESET pin is to be permanently connected high, an RC network must be added between VCC, the RESET pin, and ground to delay the rise of the RESET pin voltage until after the supply voltage has stabilized.

The RC time constant can be calculated using the formula: RC = T / ln(2.7V / (2.7V - 0.8V)) = T / 0.3514, where T is the maximum time for VCC to reach 2.7 volts and 0.8 volts is the maximum RESET logic low voltage. For example, a 470-kilohm resistor and 0.22-microfarad capacitor will keep the RESET pin low during a power-up time of up to 36 milliseconds. A faster power-up time is also safe with the calculated R and C values, since the capacitor will have even less time to charge.

The RESET pin voltage cannot exceed VCC plus 0.3 volts or 12 volts, whichever is less. This constraint must be considered when designing the RC network or when connecting the RESET pin to external logic circuits operating at higher voltage levels.

Application Circuits and System Integration with the MAX4373/MAX4374/MAX4375

Overcurrent Protection Implementation Using the MAX4373

The overcurrent protection circuit represents one of the most common applications for the MAX4373. In this circuit, the MAX4373 monitors the current flowing through a power supply and shuts down the supply if the current exceeds a preset threshold. The circuit uses an external P-channel MOSFET as the power switch, controlled by the latching comparator output of the MAX4373.

In normal operation, the load current flows through the sense resistor and the MOSFET. The current-sense amplifier measures this current and produces an output voltage proportional to the load current. As long as the load current remains below the threshold set by the sense resistor value and amplifier gain, the comparator output remains high (open-drain state), allowing the MOSFET to conduct and supply current to the load.

When the load current exceeds the threshold, the comparator output latches into the low state, turning off the MOSFET and interrupting the current path. The latched output prevents the circuit from oscillating at the threshold, which would cause repeated switching and potential damage to the MOSFET. Once the overcurrent condition has been cleared, a pushbutton connected to the RESET pin can be pressed to reset the latch and restore current flow to the load.

This circuit topology provides a simple, reliable overcurrent protection mechanism without requiring external logic or microcontroller intervention. The latching output ensures that the MOSFET remains off until the operator explicitly resets the circuit, preventing the system from repeatedly attempting to power up during a sustained overcurrent condition.

Window Detection Circuit Design with the MAX4375

The window detection circuit uses the dual comparators in the MAX4375 to monitor whether the load current remains within a specified range. This capability is useful in applications where both overcurrent and undercurrent conditions must be detected, such as battery chargers that need to verify that the battery is accepting charge at the expected rate.

In the window detection circuit, external resistor dividers are connected to the CIN2 pin to set the lower and upper current thresholds. The first comparator (COUT1) triggers when the current falls below the lower threshold, while the second comparator (COUT2) triggers when the current exceeds the upper threshold. By connecting COUT1 and COUT2 together through a wire-OR configuration, the resulting output is high when the current is within the window and low when the current is outside the window.

The lower threshold current (I_UNDER) is calculated using the formula: I_UNDER = V_REF / (R_SENSE × A_V) × ((R4 + R5) / R5), where V_REF is the internal reference voltage (0.6 volts typical), R_SENSE is the sense resistor value, A_V is the amplifier gain, and R4 and R5 are the resistor divider components. Similarly, the upper threshold current (I_OVER) is calculated using: I_OVER = V_REF / (R_SENSE × A_V) × ((R1 + R2) / R2).

This window detection capability allows the system to verify that the battery charger is operating within its expected current range. If the current falls below the lower threshold, the charger may have become disconnected or the battery may be fully charged. If the current exceeds the upper threshold, a fault condition such as a short circuit may have occurred. The system can respond to either condition by logging an error, alerting the user, or taking corrective action.

Packaging and Environmental Specifications of the MAX4373/MAX4374/MAX4375

The MAX4373/MAX4374/MAX4375 series is available in multiple package options to accommodate different application requirements and board space constraints. The 8-pin microMAX package provides a compact solution for space-constrained applications, while the 10-pin microMAX package offers additional pins for enhanced functionality. The 8-pin and 14-pin SO (small-outline) packages provide alternative options for applications requiring larger package sizes or different thermal characteristics.

The microMAX packages offer superior thermal performance compared to traditional DIP packages due to their smaller size and improved heat dissipation characteristics. The 8-pin microMAX package dissipates a maximum of 330 milliwatts at 70°C, while the 10-pin microMAX package dissipates 444 milliwatts. These thermal specifications allow designers to calculate the maximum allowable power dissipation at any operating temperature.

All package options are available in lead-free, RoHS-compliant versions, meeting the environmental requirements of modern electronics manufacturing. The devices are specified for storage temperatures from -65°C to +150°C and junction temperatures up to +150°C. The lead temperature during soldering can reach +300°C for 10 seconds, and the reflow soldering temperature is specified at +260°C.

Conclusion

The MAX4373/MAX4374/MAX4375 series provides an integrated solution for high-side current monitoring in battery-powered and power-managed systems. By combining a precision current-sense amplifier, internal bandgap reference, and latching comparator(s) into a single package, these devices simplify circuit design and reduce component count compared to discrete implementations. The wide input common-mode range, low power consumption, and multiple gain options make the MAX4373/MAX4374/MAX4375 series suitable for diverse applications ranging from simple overcurrent protection to sophisticated window detection functions. Proper selection of the sense resistor, careful attention to power supply bypassing, and correct RESET pin management during power-up ensure reliable operation across the full range of specified operating conditions.

Frequently Asked Questions (FAQ)

Q1. What is the primary advantage of high-side current sensing compared to low-side current sensing?

A1. High-side current sensing measures current at the positive supply rail without interrupting the ground path, making it ideal for battery chargers and power distribution systems where ground continuity is critical. Low-side sensing, which measures current through a resistor connected to ground, can interfere with the charger's ground reference and is less suitable for battery management applications.

Q2. How does the latching comparator output in the MAX4373/MAX4374/MAX4375 prevent oscillation in overcurrent protection circuits?

A2. Once the comparator output latches into the OFF state when the current exceeds the threshold, it remains latched even if the current subsequently drops below the threshold. This prevents the output from oscillating at the threshold, which would cause repeated switching of the power MOSFET and potential damage. The latch must be explicitly reset by pulsing the RESET pin low for at least 1.5 microseconds.

Q3. What factors should be considered when selecting the current-sense resistor value for a MAX4373/MAX4374/MAX4375 application?

A3. The sense resistor value must not exceed the full-scale sense voltage divided by the maximum load current. The resistor should be as large as practical to maximize the sense voltage and minimize the relative impact of the amplifier's input offset voltage. The resistor must be capable of dissipating the I²R power loss without exceeding its temperature rating, and resistors specified for current-sensing applications should be used to ensure stability across the operating temperature range.

Q4. Why is the input common-mode range of 0V to 28V, independent of supply voltage, significant for battery applications?

A4. This specification allows the sense resistor to be connected across the output of a battery or power supply without regard to the voltage level at that point. In battery applications, this capability enables the device to monitor current even when the battery voltage has dropped to near zero during deep discharge, extending the monitoring capability into the critical deep-discharge region where battery management is most important.

Q5. How should the RESET pin be managed during power-up to prevent false latching of the comparator output?

A5. The RESET pin must be held low until the VCC supply voltage has risen above the 2.7-volt minimum operating threshold. If the RESET pin is controlled by a microcontroller or logic gate, this is easily accomplished in software. If the RESET pin is to be permanently connected high, an RC network must be added between VCC, the RESET pin, and ground to delay the rise of the RESET pin voltage until after the supply voltage has stabilized.

Q6. What is the difference between the MAX4373, MAX4374, and MAX4375 variants?

A6. The MAX4373 contains a single latching comparator suitable for simple overcurrent detection. The MAX4374 and MAX4375 add a second comparator for window detection capabilities. The MAX4374 and MAX4375 differ in the configuration of their second comparator, allowing different window detection implementations. The choice between variants depends on whether simple overcurrent protection or more sophisticated window detection is required.

Q7. How does the internal bandgap reference contribute to the accuracy and reliability of the MAX4373/MAX4374/MAX4375?

A7. The internal bandgap reference generates a stable 600-millivolt threshold voltage with ±1.6 percent accuracy across the operating temperature range and supply voltage range. This eliminates the need for external reference components and ensures consistent threshold behavior regardless of operating conditions. The bandgap reference maintains its accuracy across the full -40°C to +85°C temperature range, allowing the device to provide reliable current monitoring in diverse environments.

Q8. What power supply bypassing strategy is recommended for the MAX4373/MAX4374/MAX4375 to handle fast supply transients?

A8. A 0.1-microfarad ceramic capacitor should be connected between the VCC pin and ground to provide local charge storage and attenuate high-frequency noise. For applications with particularly fast supply transients exceeding 5 volts per microsecond, a 1-kilohm resistor can be placed in series with the VCC pin to create an RC time constant that slows the rise time of the transient. Alternatively, the VCC pin can be powered from a better-regulated supply such as a 5-volt linear regulator.

Q9. How do the three gain versions of the MAX4373/MAX4374/MAX4375 differ, and how should the appropriate version be selected?

A9. The MAX4373/MAX4374/MAX4375 series is available in three gain configurations: 20V/V, 50V/V, and 100V/V. The 20V/V version suits applications with large sense resistors and low current ranges. The 50V/V version provides a middle ground for moderate current ranges. The 100V/V version accommodates small sense resistors and high current ranges. The selection depends on the maximum load current and the desired full-scale output voltage, with the goal of maximizing the sense voltage to minimize measurement error.

Q10. What is the significance of the 2 percent full-scale accuracy specification for the MAX4373/MAX4374/MAX4375?

A10. The 2 percent full-scale accuracy encompasses both the gain error and the input offset voltage error, ensuring that the measured output voltage remains within ±2 percent of the ideal value across the operating temperature range and supply voltage range. This accuracy specification allows designers to predict the measurement error and select appropriate sense resistor values and amplifier gains to meet their application requirements.

Q11. Can the MAX4373/MAX4374/MAX4375 be used for low-side current sensing applications?

A11. While the MAX4373/MAX4374/MAX4375 is primarily designed for high-side current sensing, it can be used for low-side current sensing. However, the total output voltage error will increase when the sense resistor voltage falls below 2 volts, as shown in the electrical characteristics. For applications requiring low-side sensing with high accuracy, alternative devices specifically optimized for low-side sensing may be more appropriate.

Q12. What is the maximum output voltage of the MAX4373/MAX4374/MAX4375, and why is it clamped?

A12. The output voltage is internally clamped at 12 volts for the 100V/V gain version. This clamping prevents excessive output voltages if the sense voltage exceeds the design limit due to transient overcurrent conditions or component failures. The clamping does not introduce phase reversal, meaning the output voltage increases monotonically with increasing sense voltage without any discontinuities or reversals, ensuring predictable circuit behavior during fault conditions.