Texas Instruments LM359MX

Overview

LM359MX from Texas Instruments is a dual, high-speed, programmable current-mode (Norton) amplifier IC designed for wideband video, active filter, and photodiode amplification applications. It delivers 400 MHz gain-bandwidth product at AV = 10–100, 60 V/μs slew rate, and operates from a single 5–22 V supply with inverting output swing from 2 mV to VCC −2 V.

For engineers reviewing the LM359MX datasheet, LM359MX pinout, LM359MX application, or LM359MX equivalent, key selection considerations include user-programmable ISET(IN)/ISET(OUT) for gain-bandwidth/slew-rate trade-offs, current-differencing inputs enabling >VCC common-mode input voltage, and decompensated architecture requiring external compensation below inverting gain of 10.

Technical Context

The LM359MX implements two independent cascode-based current-differencing amplifiers optimized for high-frequency stability and programmability. Each amplifier uses external ISET(IN) to control input-stage current (≈3×ISET(IN)), directly setting slew rate, open-loop dominant pole frequency, and inverting-input bias current; ISET(OUT) sets Darlington emitter-follower output stage bias, governing sink current capability and total supply current.

Its decompensated design provides unity-gain bandwidth up to 30 MHz and 400 MHz GBW at AV = 10–100, but requires external lead compensation (1–5 pF) for inverting gains <10 or all non-inverting configurations. Input common-mode range extends beyond VCC, and output swing reaches within 2 mV of ground and 2 V below VCC under 600 Ω load.

Key Specifications

Pinout & Package

LM359MX is housed in a 14-pin SOIC (Small Outline Integrated Circuit) package, designated NFF0014A by Texas Instruments, with 1.27 mm pitch and surface-mount compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM359MX, LM3900DR offers lower cost and higher channel count but lacks programmability and bandwidth; THS3091D delivers superior speed and linearity but requires dual supplies and sacrifices current-mode advantages like rail-exceeding inputs and simplified DC biasing.

Availability

LM359MX is available at Aetrix Electronics and suitable for video signal conditioning, high-frequency active filtering, and photodiode amplification requiring stable component supply across industrial and broadcast design cycles.

Supply support for LM359MX 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and high-reliability silicon solutions for industrial, automotive, and communications markets.

The LM359MX belongs to TI's legacy high-speed current-mode amplifier product line, engineered specifically for broadband video, precision photodiode interfacing, and wideband active filter design where traditional op-amps fall short in speed or input-range capability.

FAQ

What is the maximum operating supply voltage for the LM359MX?

The LM359MX supports a maximum supply voltage of 22 VDC (or ±11 VDC in split-supply configurations). Exceeding this absolute maximum rating risks permanent device damage. At 12 V operation-common in video and instrumentation designs-the LM359MX delivers optimal gain-bandwidth and slew rate performance while staying within its 750 mW SOIC package power dissipation limit.

How does ISET(IN) programming affect LM359MX performance?

ISET(IN) directly controls the LM359MX's input-stage current, which determines slew rate, gain-bandwidth product, inverting-input bias current, and open-loop dominant pole frequency. For example, setting ISET(IN) = 0.5 mA yields 60 V/μs slew rate and 400 MHz GBW at AV = 10–100; reducing it to 0.1 mA lowers slew rate to ~12 V/μs and GBW to ~80 MHz-enabling power/performance trade-offs in battery-powered or thermally constrained designs.

Can the LM359MX drive capacitive loads without oscillation?

The LM359MX can directly drive capacitive loads up to 100 pF while maintaining stability. Loads exceeding 100 pF require isolation-such as a series resistor (e.g., 10–50 Ω) between the LM359MX output and the capacitance-or over-compensation via increased C_comp. This limitation stems from the decompensated architecture; proper layout (short traces, ground plane) and external compensation at COMP pins are essential for robust high-frequency operation with reactive loads.

What is the purpose of the NC pins (5 and 14) on the LM359MX?

Pins 5 and 14 on the LM359MX are No Connect (NC) terminals-internally unconnected and electrically isolated from all circuitry. TI specifies these pins must remain floating (unbonded and unconnected) on PCBs to prevent parasitic coupling, unintended current paths, or thermal stress that could degrade amplifier matching or noise performance. Soldering or routing traces to these pins violates the SOIC NFF0014A mechanical and electrical design specification.

Why does the LM359MX require external compensation for non-inverting configurations?

The LM359MX is internally compensated only for stable closed-loop inverting operation at gains ≥10. In non-inverting mode-or inverting gains <10-the feedback topology introduces additional phase lag from stray capacitance at the inverting input and feedback network, risking instability. External lead compensation (1–5 pF capacitor across the feedback resistor) restores phase margin without sacrificing slew rate, unlike over-compensation via C_comp, which reduces GBW and slew rate.