Texas Instruments LMH6645MAX

Overview

LMH6645MAX from Texas Instruments is a single-channel, rail-to-rail input and output voltage feedback operational amplifier optimized for low-voltage, low-power, high-speed applications. It delivers 55 MHz −3 dB bandwidth, 22 V/μs slew rate, and ±20 mA linear output current while consuming only 650 μA per channel at 2.7 V supply - enabling precision signal conditioning in battery-powered portable instrumentation and sensor interfaces.

For engineers reviewing the LMH6645MAX datasheet, LMH6645MAX pinout, LMH6645MAX application, or LMH6645MAX equivalent, key selection criteria include its rail-to-rail I/O swing (within 20 mV of rails), 17 nV/√Hz input voltage noise at 100 kHz, shutdown capability (in LMH6647 variant), and stable operation across 2.5–12 V supply range with minimal parameter drift.

Technical Context

The LMH6645MAX 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 extends common-mode range 0.3 V beyond either supply rail, while the Class A-B "turn-around" input stage reduces power and improves offset/noise performance versus conventional high-speed op-amps.

The output stage uses a common-emitter push-pull configuration delivering ±20 mA into loads while maintaining rail-to-rail swing down to 20 mV from V+ or V− at light loads. Critical parameters - bandwidth, slew rate, and output current - remain stable across 2.5–12 V supply and −40°C to +85°C temperature range due to process and architecture co-optimization.

Key Specifications

Pinout & Package

SOT-23-5 package (2.90 mm × 1.60 mm body size) with exposed pad for thermal enhancement. Pin 1 = OUTPUT, Pin 2 = V−, Pin 3 = +IN, Pin 4 = −IN, Pin 5 = V+.

Key Features

Applications

Equivalent & Alternatives

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

Compared with OPA355DBVR and ADA4891-1ARJZ-R7, LMH6645MAX uniquely balances 55 MHz bandwidth, 22 V/μs slew, and 650 μA quiescent current - making it the only option for battery-powered instruments requiring both speed and micro-power operation without sacrificing rail-to-rail swing or noise performance.

Availability

LMH6645MAX is available at Aetrix Electronics and suitable for portable medical sensors, active anti-aliasing filters, current sense amplifiers, and high-speed transducer interfaces requiring stable component supply across production lifecycles.

Supply support for LMH6645MAX 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 and embedded processing technologies, with decades of expertise in high-performance op-amps and precision signal chains.

The LMH664x family was designed specifically for portable, low-voltage instrumentation demanding rail-to-rail operation, micro-power consumption, and high-speed fidelity - targeting medical, test equipment, and industrial sensor markets.

FAQ

What is the maximum supply voltage for LMH6645MAX?

The LMH6645MAX supports a recommended operating supply voltage range of 2.5 V to 12 V (V+ – V−). Absolute maximum rating is 12.6 V. Operation above 12 V risks permanent damage. At 12 V, supply current rises to ~1.4 mA per channel, and output swing remains within 40 mV of rails at RL = 1 kΩ - confirming robustness across the full specified range. LMH6645MAX maintains consistent 55 MHz bandwidth and 22 V/μs slew rate from 2.7 V to 10 V.

Does LMH6645MAX include a shutdown function?

No, LMH6645MAX does not include a shutdown pin. Shutdown functionality is exclusive to the LMH6647 variant (SOT-23-6 and SOIC-8 packages). The LMH6645MAX is a single-channel amplifier in SOT-23-5 and SOIC-8 packages with pins dedicated to power, input, and output only. If system-level power gating is required, external enable circuitry must be implemented - but LMH6645MAX's 650 μA quiescent current at 2.7 V often eliminates the need for shutdown in always-on portable applications.

What is the input common-mode voltage range of LMH6645MAX?

The LMH6645MAX features rail-to-rail input with an input common-mode voltage range extending 0.3 V beyond either supply rail - i.e., from (V− − 0.3 V) to (V+ + 0.3 V) at 25°C. This is confirmed across −40°C to +85°C, with minimum guaranteed range of (V− − 0.1 V) to (V+ + 0.1 V) over temperature. This capability eliminates external bias resistors in AC-coupled configurations and enables direct interfacing with sensors operating near ground or supply rails.

Can LMH6645MAX drive a 50 Ω load directly?

Yes, LMH6645MAX can drive a 50 Ω load directly, delivering ±20 mA linear output current - sufficient for 1 VPP into 50 Ω (20 mA peak). However, output swing compresses to within ~150 mV of rails under this load at 2.7 V supply. For full rail-to-rail swing, use RL ≥ 1 kΩ. Driving 50 Ω continuously increases junction temperature; thermal design must ensure RθJA ≤ 265°C/W (SOT-23) is respected. Layout best practices include short traces, ground plane under device, and local 0.1 μF V+ bypass.

What is the typical input offset voltage drift of LMH6645MAX?

The LMH6645MAX has a typical input offset voltage drift of ±5 μV/°C over −40°C to +85°C, as specified in the Electrical Characteristics table. Measured offset voltage changes linearly with temperature, with worst-case drift bounded by ±5 μV/°C across the full operating range. At 25°C, typical VOS is ±1 mV; at −40°C and +85°C, measured values fall within ±4 mV limits. This low drift supports stable DC-coupled gain in precision sensor signal chains without periodic auto-zeroing.