Analog Devices Inc./Maxim Integrated MAX9919FASA/V+T

Overview

The MAX9919FASA/V+T from Maxim Integrated is a fixed-gain, AEC-Q100 qualified current-sense amplifier optimized for high-accuracy bidirectional or unidirectional sensing of inductive load currents. It features a -20V to +75V input common-mode range, 45V/V fixed gain, ±0.45% max gain error over -40°C to +125°C, and rail-to-rail output - enabling precise motor/solenoid current monitoring in automotive H-bridge and battery management systems.

For engineers reviewing the MAX9919FASA/V+T datasheet, MAX9919FASA/V+T pinout, MAX9919FASA/V+T application, or MAX9919FASA/V+T equivalent, key selection criteria include its 45V/V fixed gain, 50mV full-scale sense voltage, SOIC-8 EP package with exposed pad, AEC-Q100 qualification, and support for both unidirectional (REFIN = GND) and bidirectional (REFIN = VCC/2) operation in harsh automotive environments.

Technical Context

The MAX9919FASA/V+T employs dual-level-shifting input architecture to maintain precision across its extended -20V to +75V common-mode range: one stage handles +2V to +75V, another handles -20V to +2V. Its laser-trimmed internal resistors fix gain at 45V/V, eliminating external gain-setting components and reducing layout sensitivity.

It operates as a unidirectional amplifier when REFIN is grounded (output referenced to GND), or as a bidirectional amplifier when REFIN is set to VCC/2 (output centered at VCC/2). The rail-to-rail output stage supports direct interfacing with 5V ADCs while maintaining ≥100mV headroom from supply rails for rated accuracy.

Key Specifications

Pinout & Package

Package: 8-pin SOIC with exposed pad (SO-EP), RoHS-compliant, lead(Pb)-free, automotive qualified (/V+). Exposed pad must be connected to solid ground for thermal and electrical performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX9919NASA/V+, the MAX9919FASA/V+T provides half the gain for improved noise immunity at higher sense voltages; compared with INA240A1QDRQ1, it offers configurable unidirectional/bidirectional operation and tighter gain accuracy at the cost of lower PSRR and narrower CMR below -4V.

Availability

MAX9919FASA/V+T is available at Aetrix Electronics and suitable for automotive motor control, solenoid actuation, supercapacitor energy management, and high-voltage battery monitoring requiring stable component supply across extended temperature and lifecycle requirements.

Supply support for MAX9919FASA/V+T 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 applications, with emphasis on high-reliability, high-performance signal conditioning.

The MAX9918/MAX9919/MAX9920 product line delivers high-accuracy current sensing for demanding automotive systems - specifically engineered to replace discrete op-amp solutions in motor, solenoid, and battery current monitoring with integrated level-shifting, gain, and AEC-Q100 compliance.

FAQ

What is the maximum common-mode voltage the MAX9919FASA/V+T can handle?

The MAX9919FASA/V+T supports an input common-mode voltage range of -20V to +75V. This allows reliable operation during inductive kickback events (e.g., motor turn-off) and reverse-battery conditions in automotive systems. Absolute maximum ratings specify RS+/RS- to GND as -30V to +80V at VCC = 5V, but functional operation is guaranteed only within the -20V to +75V range.

Does the MAX9919FASA/V+T support bidirectional current sensing?

Yes, the MAX9919FASA/V+T supports bidirectional current sensing when REFIN is set to VCC/2 (typically 2.5V on a 5V supply). In this mode, the output voltage (OUT) is centered at VCC/2 and swings positively for current in one direction and negatively for the opposite direction. For unidirectional sensing, tie REFIN to GND - then OUT ranges from near GND to near VCC.

What is the purpose of the FB pin on the MAX9919FASA/V+T?

The FB (feedback) pin is unused in the MAX9919FASA/V+T. It is reserved for the adjustable-gain variants MAX9918 and MAX9920, where external resistors R1/R2 set gain. In the MAX9919FASA/V+T, gain is fixed at 45V/V by internal laser-trimmed resistors, so FB must be left unconnected (floating) for proper operation and stability.

Is the MAX9919FASA/V+T pin-compatible with other devices in the MAX9918/MAX9919/MAX9920 family?

Yes, the MAX9919FASA/V+T shares identical pinout and SOIC-8 EP package with MAX9918ASA/V+, MAX9919NASA/V+, and MAX9920ASA/V+. All variants use the same RS+, RS-, SHDN, GND, OUT, FB, REFIN, and VCC pin assignments. However, functional differences exist: FB is unused in MAX9919 variants, and REFIN voltage range differs slightly between MAX9919 and MAX9920.

What thermal considerations apply to the MAX9919FASA/V+T's exposed pad?

For optimal thermal and electrical performance, the exposed pad (EP) of the MAX9919FASA/V+T must be soldered to a large-area, contiguous ground plane. Thermal resistance is θJC = 7°C/W (junction-to-case) and θJA = 41°C/W (junction-to-ambient, four-layer board). Do not rely solely on the EP as the ground connection - the Pin 4 (GND) connection remains essential for signal integrity and low-impedance return paths.