Texas Instruments LMH6647MFX

Overview

LMH6647MFX from Texas Instruments is a single-channel, rail-to-rail input and output voltage feedback amplifier with shutdown control, operating from 2.5 V to 12 V supply, delivering 55 MHz −3 dB bandwidth, 22 V/μs slew rate, and ±20 mA linear output current at 650 μA supply current per channel. It enables high-speed multiplexing and power-sensitive portable instrumentation.

For engineers reviewing the LMH6647MFX datasheet, LMH6647MFX pinout, LMH6647MFX application, or LMH6647MFX equivalent, key selection criteria include shutdown threshold voltage (2.30 V typ at 2.7 V supply), turn-on/turn-off timing (250 ns / 560 ns), rail-to-rail input common-mode range (0.3 V beyond rails), and SOT-23-6 package compatibility with space-constrained PCB layouts.

Technical Context

The LMH6647MFX uses a proprietary VIP10 dielectrically isolated bipolar process enabling stable 55 MHz bandwidth and 22 V/μs slew rate across 2.7–12 V supply range. Its rail-to-rail input stage supports common-mode voltages extending 0.3 V beyond either supply rail, while the Class A-B "turn-around" input stage reduces offset drift and noise.

The shutdown function is controlled via a dedicated SD pin with TTL-compatible threshold (1.95–2.30 V at 2.7 V supply); during shutdown, supply current drops to ≤50 μA while maintaining well-behaved turn-on/off transitions and minimal output disturbance-critical for time-multiplexed signal paths.

Key Specifications

Pinout & Package

SOT-23-6 package (2.92 mm × 1.60 mm body), thermally enhanced for continuous operation at ambient temperatures up to +85°C with RθJA = 235°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed, low-power amplifier applications.

Compared with LMH6645MFX, LMH6647MFX adds critical shutdown control at minimal quiescent cost; versus OPA355DBVR, it trades raw bandwidth for ultra-low power and true rail-to-rail input-making it optimal for portable, battery-limited, DC-accurate signal chains.

Availability

LMH6647MFX is available at Aetrix Electronics and suitable for portable medical devices, multiplexed sensor systems, current sense amplifiers, and active filter drivers requiring stable component supply across extended production lifecycles.

Supply support for LMH6647MFX 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 company specializing in analog and embedded processing technologies, with leadership in precision amplifiers, data converters, and power management ICs.

The LMH664x product line was designed for high-speed, low-voltage, low-power signal conditioning in portable and space-constrained applications-emphasizing rail-to-rail operation, micro-power shutdown, and consistent AC performance across wide supply ranges.

FAQ

What is the shutdown threshold voltage for LMH6647MFX at 2.7 V supply?

The LMH6647MFX shutdown threshold voltage is specified as 1.95 V (min) to 2.30 V (typ) when operating at 2.7 V supply. This TTL-compatible range allows direct interfacing with 2.7 V or 3.3 V GPIO outputs without external level-shifting circuitry. The threshold remains stable over temperature (−40°C to +85°C), ensuring reliable enable/disable behavior in battery-powered portable equipment where supply voltage may sag.

Does LMH6647MFX support rail-to-rail input common-mode voltage?

Yes, LMH6647MFX supports rail-to-rail input common-mode voltage, with specification stating input common-mode range extends 0.3 V beyond either supply rail (e.g., −0.3 V to 3.0 V at 2.7 V single supply). This is enabled by its proprietary VIP10 bipolar process and complementary input stage design. It allows direct connection to sensors or shunt resistors operating at supply extremes-critical for high-side current sensing and DC-coupled biomedical front-ends where offset rejection matters.

What is the typical output swing of LMH6647MFX at 2.7 V supply?

At 2.7 V supply and RL = 1 kΩ to V+/2, LMH6647MFX delivers typical output swing of 2.55 V (high) and 40 mV (low), i.e., within 20 mV of each rail. This rail-to-rail output capability maximizes usable dynamic range in low-voltage systems-enabling full-scale utilization of 12-bit ADCs without gain compression or clipping. Performance holds across −40°C to +85°C, with worst-case swing degrading to 2.2 V high and 150 mV low under temperature extremes.

Can LMH6647MFX drive a 50 Ω load directly?

LMH6647MFX is not optimized for continuous 50 Ω driving: its linear output current is rated at ±20 mA into loads ≥1 kΩ, and short-circuit current is 42–43 mA (sinking/sourcing). Driving 50 Ω continuously would require ~54 mA at 2.7 V swing, exceeding safe linear operation and risking thermal overload or distortion. For 50 Ω interface, use an external buffer stage or select a purpose-built line driver like THS3201. LMH6647MFX excels at driving 1 kΩ+ loads such as ADC inputs, active filters, or capacitive cables up to 100 pF.

How does LMH6647MFX compare to LMH6646 in terms of pin compatibility?

LMH6647MFX (SOT-23-6) is not pin-compatible with LMH6646 (dual-channel, SOIC-8 or VSSOP-8). They differ in channel count, package type, pin count, and pin functions: LMH6647MFX has dedicated SD and N/C pins in SOT-23-6, while LMH6646 provides two independent amplifiers with separate IN/OUT pairs in 8-pin packages. No shared pin mapping exists. Migration from LMH6646 to LMH6647MFX requires PCB redesign, though both share identical AC performance specs (55 MHz BW, 22 V/μs SR) and shutdown architecture-making LMH6647MFX the single-channel counterpart for space-constrained implementations.