Analog Devices Inc./Maxim Integrated MAX9918ASA/V+

Overview

MAX9918ASA/V+ from Maxim Integrated is an AEC-Q100 qualified, single-supply, high-accuracy current-sense amplifier optimized for automotive and industrial inductive load monitoring. It features a -20V to +75V input common-mode range, adjustable gain (30–90 V/V), ±50mV full-scale sense voltage, 400µV max input offset voltage, and operates over -40°C to +125°C in an 8-pin SOIC-EP package. It enables precision unidirectional or bidirectional current sensing in H-bridge motor control and solenoid drivers.

For engineers reviewing the MAX9918ASA/V+ datasheet, MAX9918ASA/V+ pinout, MAX9918ASA/V+ application, or MAX9918ASA/V+ equivalent, this page delivers verified technical context, validated pin functions, real-world automotive use cases, and confirmed alternative options - all grounded in official Maxim specifications and AEC-Q100 qualification data.

Technical Context

The MAX9918ASA/V+ employs dual-level-shifting input architecture to support operation across -20V to +75V common-mode voltages, enabling robust sensing during inductive kickback and reverse-battery conditions. Its instrumentation amplifier core delivers 0.6% max gain error and rail-to-rail output swing with 75kHz small-signal bandwidth.

Gain is set externally via FB pin using R1/R2 resistive divider (G = 1 + R2/R1), with minimum stable gain of 30V/V. Unidirectional operation uses REFIN = GND; bidirectional mode requires REFIN = VCC/2, supporting ±VSENSE measurement with output referenced to VREFIN.

Key Specifications

Pinout & Package

MAX9918ASA/V+ is housed in an 8-pin SOIC package with exposed pad (SO-EP, package code S8E+14), optimized for thermal dissipation in high-power automotive modules. The exposed pad must be connected to a solid ground plane for electrical stability and junction-to-ambient thermal resistance of 41°C/W (four-layer board).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar current-sense amplifier applications.

Compared with MAX9919FASA/V+, MAX9918ASA/V+ offers gain adjustability at the cost of lower bandwidth, while INA240A1QDRQ1 provides superior offset performance but demands board revision and sacrifices thermal efficiency due to missing EP.

Availability

MAX9918ASA/V+ is available at Aetrix Electronics and suitable for automotive powertrain control, industrial motor drives, and battery management systems requiring stable component supply, AEC-Q100 compliance, and extended temperature operation.

Supply support for MAX9918ASA/V+ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated, now part of Analog Devices, designs precision analog and mixed-signal ICs for automotive, industrial, and communications markets with emphasis on reliability and signal integrity.

The MAX9918 family targets high-voltage current sensing in harsh automotive environments, delivering AEC-Q100 qualified amplifiers with wide common-mode range, adjustable gain, and thermal robustness for under-hood deployment.

FAQ

What is the maximum common-mode voltage the MAX9918ASA/V+ can handle?

The MAX9918ASA/V+ supports an input common-mode voltage range of -20V to +75V. This specification is validated across the full -40°C to +125°C operating temperature range and enables reliable operation during reverse-battery events, inductive kickback in motor/solenoid circuits, and transient overvoltages in automotive 12V/24V systems. Absolute maximum ratings extend RS+/RS- to -30V/+80V at VCC = 5V.

How do I configure the MAX9918ASA/V+ for bidirectional current sensing?

To configure the MAX9918ASA/V+ for bidirectional current sensing, connect the REFIN pin to a low-impedance VCC/2 reference (e.g., via resistor divider or dedicated reference buffer). This sets the output midpoint to VCC/2, allowing positive VSENSE to produce VOUT > VCC/2 and negative VSENSE to produce VOUT < VCC/2. Ensure the REFIN voltage stays within 0V to VCC – 1.9V, and use a 100kΩ load or lower for stability. The MAX9918ASA/V+ will then output VOUT = VREFIN + G × VSENSE.

What is the minimum stable gain for the MAX9918ASA/V+ and how is it set?

The minimum stable gain for the MAX9918ASA/V+ is 30V/V, enforced by internal frequency compensation. Gain is set externally using resistors R1 and R2 connected between FB, GND, and VCC per the equation G = 1 + R2/R1. For example, R1 = 1kΩ and R2 = 29kΩ yields G = 30V/V. Lower gains risk instability and reduced bandwidth; Maxim specifies R2/R1 ≥ 29 for guaranteed performance. The FB pin must remain connected - floating FB disables gain control.

Does the MAX9918ASA/V+ require external components for basic operation?

Yes, the MAX9918ASA/V+ requires three external components for reliable operation: (1) a 0.1µF ceramic capacitor between VCC and GND for supply bypassing; (2) resistors R1 and R2 on the FB pin to set gain (G = 1 + R2/R1); and (3) a low-impedance source for REFIN (GND for unidirectional, VCC/2 for bidirectional). No external compensation or filtering is needed for standard applications, and the exposed pad must be soldered to a solid ground plane for thermal and electrical performance.

Is the MAX9918ASA/V+ pin-compatible with other devices in the MAX9918/MAX9919/MAX9920 family?

Yes, the MAX9918ASA/V+ is pin-compatible with MAX9919FASA/V+, MAX9919NASA/V+, and MAX9920ASA/V+ - all share identical 8-pin SOIC-EP packaging, pin numbering, and pin functions (RS+, RS-, SHDN, GND, OUT, FB, REFIN, VCC). This allows direct substitution in existing layouts when gain, bandwidth, or full-scale sense voltage requirements change. However, FB must be configured per device: left open for MAX9919 variants, and actively driven for MAX9918/MAX9920 gain adjustment.