Texas Instruments LMH6646 MDC

Overview

LMH6646 from Texas Instruments is a dual, rail-to-rail input and output voltage feedback amplifier optimized for low-voltage, high-speed signal conditioning. It delivers 55 MHz −3 dB bandwidth, 22 V/μs slew rate, and ±20 mA linear output current per channel at 650 μA supply current per channel, operating from 2.5 V to 12 V supplies. It is used in active filters and current sense buffers where wide dynamic range and low quiescent power are critical.

For engineers reviewing the LMH6646 datasheet, LMH6646 pinout, LMH6646 application, or LMH6646 equivalent, key selection considerations include its dual-channel rail-to-rail I/O capability, 55 MHz bandwidth at AV = +1, 20 mV output swing from rails, −40°C to +85°C industrial temperature range, and SOIC-8/VSSOP-8 package compatibility.

Technical Context

The LMH6646 employs a proprietary VIP10 dielectrically isolated bipolar process enabling high ft (~8 GHz) under low supply (2.7 V) and low bias current. Its rail-to-rail input stage supports common-mode voltage beyond either supply rail by 0.3 V, while the class A-B "turn-around" input stage reduces noise and offset versus comparable speed amplifiers.

The output stage uses a common-emitter push-pull topology delivering ±20 mA into loads while maintaining output swing within 20 mV of V+ or V− at light loads. Key performance parameters-including bandwidth, slew rate, and output current-exhibit minimal variation across 2.5 V to 12 V supply range due to architecture-level supply independence.

Key Specifications

Pinout & Package

LMH6646 is available in SOIC-8 (D08A) and VSSOP-8 (DGK08A) packages, both measuring 4.90 mm × 3.91 mm (SOIC) or 3.00 mm × 3.00 mm (VSSOP). These thermally enhanced 8-pin surface-mount packages support standard reflow profiles and provide adequate thermal resistance (R_θJA = 190°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual high-speed rail-to-rail amplifier applications.

Compared with LMH6646, LMH6643MDE offers identical AC performance in half the channels and smaller size, while OPA2350UA trades bandwidth and power efficiency for DC accuracy-making LMH6646 optimal for dual-channel, medium-speed, low-power signal chains.

Availability

LMH6646 is available at Aetrix Electronics and suitable for active filters, current sense buffers, high-speed portable devices, and multiplexing applications requiring stable component supply, long-term industrial lifecycle support, and consistent parametric performance across temperature.

Supply support for LMH6646 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 designing analog ICs, embedded processors, and digital signal solutions for industrial, automotive, and communications markets.

The LMH6646 belongs to TI's LMH664x family of rail-to-rail I/O amplifiers engineered for low-voltage, high-speed signal conditioning in portable instrumentation, sensor interfaces, and precision analog front-ends.

FAQ

What is the maximum supply voltage range supported by the LMH6646?

The LMH6646 supports a supply voltage range of 2.5 V to 12 V between V+ and V− terminals. This includes single-supply operation (e.g., V− = 0 V, V+ = 3.3 V or 5 V) and split-supply configurations (e.g., ±2.5 V or ±5 V). Absolute maximum rating is 12.6 V, and operation outside the 2.5–12 V recommended range may compromise specifications or reliability. The LMH6646 maintains consistent 55 MHz bandwidth and 22 V/μs slew rate across this full range.

Does the LMH6646 include a shutdown function?

No, the LMH6646 does not include a shutdown function. Shutdown capability is exclusive to the LMH6647 (single-channel variant) in the LMH664x family. The LMH6646 has no SD (shutdown) pin and draws 650 μA per channel continuously in normal operation. For power-gated dual-channel operation, external enable circuitry or discrete FET control of the V+ rail would be required. The LMH6646 pinout omits SD and includes two independent output pins (OUT A and OUT B) instead.

What is the typical output swing capability of the LMH6646 at 3.3 V supply?

At V+ = 3.3 V and V− = 0 V, the LMH6646 delivers typical output swing within 20 mV of each rail - i.e., from ~20 mV to ~3.28 V - when driving a 1 kΩ load to V+/2. This rail-to-rail output performance is confirmed across temperature (−40°C to +85°C) and remains stable with supply variations. The LMH6646 achieves this using a common-emitter push-pull output stage, enabling full utilization of 3.3 V ADC references or DAC outputs without headroom loss.

How does crosstalk performance impact dual-channel use of the LMH6646?

The LMH6646 provides 47 dB crosstalk rejection at 5 MHz between its two amplifier channels, measured with receiver configured at AV = +2 and Rf = Rg = 510 Ω. This means a 1 VPP signal on Channel A induces less than 4.5 mVPP interference on Channel B at that frequency - sufficient for most dual-sensor, stereo, or MUX-driven applications. Crosstalk improves at lower frequencies and degrades above 5 MHz; layout best practices (separate ground returns, guard traces) further enhance isolation. The LMH6646's monolithic dual design ensures matched AC response without inter-device skew.

What package options are available for the LMH6646 and how do they differ thermally?

The LMH6646 is offered in SOIC-8 (D08A, 4.90 mm × 3.91 mm) and VSSOP-8 (DGK08A, 3.00 mm × 3.00 mm) packages. Both have identical pinout and electrical specs. Thermally, SOIC-8 exhibits R_θJA = 190°C/W and VSSOP-8 also has R_θJA = 190°C/W per TI's SNOS970D datasheet - meaning junction-to-ambient rise is equivalent under identical PCB copper area. VSSOP-8 offers 45% smaller footprint and improved high-frequency layout density, while SOIC-8 provides greater mechanical robustness and easier hand-soldering. Neither package includes an exposed thermal pad.