Analog Devices Inc./Maxim Integrated MAX9118EXK-T

Product Summary MAX9118EXK+T Ultra-Low Power Comparator with Integrated Voltage Reference

The MAX9118EXK+T from Analog Devices Inc./Maxim Integrated is a nanopower comparator featuring an integrated voltage reference and designed for use in compact, low-power electronic systems. Housed in a space-saving 5-pin SC70 package, the MAX9118EXK+T is built with Analog Devices’ Beyond-the-Rails™ input architecture and guarantees reliable operation at supply voltages as low as +1.6V, making it highly suitable for battery-powered and portable applications. With an open-drain output and an onboard, precision 1.252V reference, the MAX9118EXK+T addresses the needs of modern designs where both power efficiency and PCB area are critical considerations.

Primary Attributes and Unique Advantages of MAX9118EXK+T

The MAX9118EXK+T is part of the MAX9117–MAX9120 comparator family, differentiated by its integrated voltage reference and open-drain output configuration. Critical features include:

Ultra-low supply current of 600nA per comparator (with reference), optimizing it for extended battery life in portable applications.

Guaranteed operation with supply voltages from +1.6V up to +6V.

Input common-mode voltage extends 200mV beyond both supply rails, supporting flexibility in signal interfacing (“Beyond-the-Rails”).

Internal 1.252V ±1.75% voltage reference with low drift over temperature, simplifying design and increasing threshold accuracy.

Open-drain output suitable for mixed-voltage logic and wired-OR connections.

Crowbar-current-free switching: The output structure is engineered to limit supply current surges during state changes, distinctly reducing supply glitches common with standard comparators.

Internal hysteresis for noise immunity and clean switching, particularly valuable in noisy or slowly varying input environments.

Wide operating temperature range from –40°C to +85°C.

Miniature SC70-5 package (half the size of SOT23), ideal for high-density PCB layouts.

Operational Description of MAX9118EXK+T

The heart of the MAX9118EXK+T’s design is its combination of a nanopower architecture, a precision voltage reference, and a robust open-drain output stage. Key aspects include:

Input Stage: Supports voltages from VEE–0.2V to VCC+0.2V, protected against overvoltage by ESD diodes, and features a typical bias current of ±0.15nA, keeping input loading minimal.

Voltage Reference: Delivers a precise 1.252V with a temperature coefficient of 100ppm/°C. The reference is suitable for threshold generation but should not drive large external loads, due to its high output impedance. For lower impedance, buffering with a low-leakage op-amp is advised.

Output Stage: The open-drain NMOS configuration allows output voltages above VCC (up to +6V absolute max), supporting flexible interfacing. This configuration is also adept for applications like logic-level translation and wired-OR logic connections.

Internal Hysteresis: A built-in 4mV hysteresis band mitigates switching instability and oscillations around the trip point. When required, additional hysteresis can be generated using positive feedback with external resistors.

Electrical Characteristics and Ratings of MAX9118EXK+T

Key electrical parameters (measured at VCC = +5V, VEE = 0V, TA = 25°C unless otherwise noted):

Supply Voltage Range: +1.6V to +6V

Supply Current: 600nA (typical, with reference active)

Input Common-Mode Voltage: VEE–0.2V to VCC+0.2V

Reference Voltage: 1.252V ±1.75%, temperature coefficient 100ppm/°C

Output Configuration: Open-drain, capable of being pulled up to +6V

Output Sink Capability: Up to ±5mA

Input Bias Current: ±0.15nA (typical)

Input Offset Voltage: Centered within hysteresis band

Internal Hysteresis: 4mV

Operating Temperature Range: –40°C to +85°C

Maximum Power Dissipation (SC70-5): 200mW at 70°C (derate above this)

Absolute maximum ratings should be followed meticulously to avoid device degradation. Device operation is not implied beyond the limits specified for functional and absolute maximum conditions.

Use Cases and Applications of MAX9118EXK+T

The MAX9118EXK+T’s combination of low power, small form factor, and precision reference targets a range of ultra-low-power devices and portable systems:

2-cell battery monitoring/management (portable medical, energy harvesting, safety-critical systems)

Threshold detection in smart sensors, telemetry, or wireless modules

Mixed-voltage digital systems (notebooks, PDAs, mobile communications) for signal threshold crossing or level translation

Ground or supply line voltage sensing in compact battery-powered applications

Remote sensor interfaces and medical instrumentation demanding extended operating life

In a practical scenario, MAX9118EXK+T can provide early undervoltage lockout detection in wearable health monitors, with its reference setting a precise threshold at only a fraction of microamps, maximizing operational life without increasing system complexity.

Design Guidelines and Integration Tips for MAX9118EXK+T

To maximize performance, these layout and application guidelines should be heeded:

Pull-up Resistor: The open-drain output requires an external pull-up resistor; the value should suit both the system's voltage level and the required switching speed.

Bypassing: While not strictly necessary due to low supply current surges, a 100nF ceramic capacitor close to the supply pin is recommended if supply leads are long, if the supply impedance is high, or if local supply noise is expected.

Board Layout: Minimize input and output trace lengths to reduce parasitic capacitance and noise pickup. Implement a ground plane and use surface-mount components to further suppress external noise.

Reference Output Loading: Avoid heavily loading the voltage reference pin. If the reference is used for driving anything other than a very high-impedance node, buffer it.

Hysteresis Customization: To improve noise immunity in electrically noisy environments, customize the hysteresis function with external resistors, following the calculation procedures for resistor selection provided in the technical section.

Package Details and Physical Specifications of MAX9118EXK+T

The MAX9118EXK+T is offered in an industry-standard 5-pin SC70 package:

Dimensions compliant with JEDEC MO-203 and JEITA SC-88A standards

Half the footprint of the SOT23, aiding in miniaturized layouts

Maximum package coplanarity is 0.10mm

Designed for automated surface-mount assembly

Marking for orientation reference; ensures proper placement in pick-and-place processes

Alternative or Substitute Devices for MAX9118EXK+T

Evaluating functionally similar or replacement devices is key for robust sourcing:

MAX9117 (same family): Offers push-pull output instead of open-drain, but otherwise includes a voltage reference.

MAX9120: Open-drain output, but without the integrated voltage reference; requires external reference for threshold-based applications.

MAX9119: Push-pull output, without integrated reference.

For applications needing slightly different voltage references or package types, consult the broader Analog Devices/Maxim Integrated nanopower comparator family.

In most designs, the primary selection criteria will be output configuration (open-drain vs. push-pull), presence of a reference, and supply voltage range. Ensure the replacement matches these and package attributes as closely as possible.

Conclusion

The MAX9118EXK+T nanopower comparator integrates a high-precision voltage reference and open-drain output in an ultra-miniature SC70-5 package, positioning it as an optimal choice for engineers designing battery-powered, space-constrained, and power-critical electronic systems. Its unique Beyond-the-Rails input capability, ultra-low quiescent current draw, and flexible output stage streamline the realization of robust threshold detection, battery monitoring, and logic interface functions. For teams considering a comparator for their next instrumentation, portable, or remote-sensing application, the MAX9118EXK+T stands out as a solution that minimizes power and board space—enabling innovative, energy-efficient designs.