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Texas Instruments LMH6645MA
- Part No.:
- LMH6645MA
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LMH6645MA.pdf
- Description:
- IC VOLTAGE FEEDBACK 1 CIRC 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,720
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Product details
Overview
LMH6645MA 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 LMH6645MA datasheet, LMH6645MA pinout, LMH6645MA application, or LMH6645MA equivalent, key selection criteria include its rail-to-rail I/O swing (within 20 mV of rails), 17 nV/√Hz input voltage noise, shutdown capability (in LMH6647 variant), and stable operation across 2.5–12 V supply range with minimal parameter drift.
Technical Context
The LMH6645MA employs a proprietary VIP10 dielectrically isolated bipolar process, enabling high ft (~8 GHz) under low 2.7 V bias. 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 topology capable of sourcing/sinking ±20 mA within 0.5 V of rails, maintaining consistent bandwidth (55 MHz) and slew rate (22 V/μs) across 2.5–12 V supply voltages - a design choice that decouples critical AC performance from supply variation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| −3 dB Bandwidth | 55 MHz at AV = +1 - supports high-fidelity signal amplification up to video and medium-speed data acquisition frequencies. |
| Slew Rate | 22 V/μs - enables clean 10 VPP output at ≥2 MHz without slewing distortion in active filter or buffer stages. |
| Supply Current | 650 μA/channel at 2.7 V - allows integration into always-on sensor front-ends with multi-year battery life. |
| Input Voltage Noise | 17 nV/√Hz at 100 kHz - preserves SNR in low-level transducer amplification (e.g., strain gauge, thermopile). |
| Output Swing | Within 20 mV of V+ and V− rails - maximizes dynamic range in 3.3 V or lower single-supply systems. |
| Input Common-Mode Range | Extends 0.3 V beyond both rails - simplifies level-shifting and eliminates external bias networks in AC-coupled inputs. |
| CMRR | 77 dB min (25°C) - ensures rejection of supply- or ground-related interference in noisy industrial environments. |
Pinout & Package
SOT-23-5 package (2.90 mm × 1.60 mm body size) with exposed pad thermal enhancement; compact footprint ideal for space-constrained portable PCBs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - OUTPUT | Amplifier output | Delivers rail-to-rail voltage swing; drives 1 kΩ load to within 20 mV of rails at 2.7 V supply. |
| 2 - V− | Negative supply | Accepts ground (single-supply) or negative rail (split-supply); supports operation down to 0 V. |
| 3 - +IN | Non-inverting input | High-impedance node (3 MΩ RIN); accepts signals from 0.3 V below V− to 0.3 V above V+. |
| 4 - −IN | Inverting input | Differential pair input; matched to +IN for <3 mV offset and stable closed-loop gain accuracy. |
| 5 - V+ | Positive supply | Operates from 2.5 V to 12 V; PSRR >75 dB ensures immunity to supply ripple in mixed-signal systems. |
Key Features
| Feature | Design Value |
|---|---|
| Rail-to-rail input and output | Enables full-scale signal utilization in 2.7–3.3 V systems without external level-shifting or dual supplies. |
| Low 650 μA supply current | Reduces quiescent power to 1.755 mW at 2.7 V - critical for always-on IoT sensor nodes and wearable health monitors. |
| 55 MHz bandwidth at low supply | Maintains high-speed performance even at 2.7 V, unlike many competitors that degrade bandwidth below 5 V. |
| 17 nV/√Hz input voltage noise | Supports high-gain, low-noise amplification of microvolt-level sensor outputs without degrading system SNR. |
| Robust ±20 mA output drive | Drives ADC input buffers, coaxial cables, or multiple parallel loads without external gain boosting. |
Applications
| Active Filters | Current Sense Buffer |
|---|---|
Use Scenario: Second-order Sallen-Key low-pass filter in motor control feedback loop operating from 3.3 V supply. IC Role / Device Role / Timing Role: Voltage feedback op-amp implementing unity-gain stable filter transfer function with 55 MHz bandwidth margin. Use Value: Maintains phase linearity and group delay stability up to 10× cutoff frequency due to high GBW and low distortion. | Use Scenario: Bidirectional shunt-based current measurement in 12 V automotive body control module. IC Role / Device Role / Timing Role: Precision differential-to-single-ended buffer with rail-to-rail output driving 12-bit SAR ADC reference input. Use Value: 20 mV rail-to-rail swing captures full 0–100% shunt voltage range; 17 nV/√Hz noise avoids limiting 1% current measurement resolution. |
| High-Speed Portable Devices | High-Speed Transducer Amp |
Use Scenario: Front-end amplifier for ultrasound Doppler sensor in handheld medical probe powered by Li-ion cell (3.0–4.2 V). IC Role / Device Role / Timing Role: Low-noise, low-power gain stage amplifying 2–5 MHz acoustic echo signals before digitization. Use Value: 22 V/μs slew rate prevents pulse distortion; 650 μA current enables >10-hour battery runtime during continuous scanning. | Use Scenario: Signal conditioning for piezoelectric vibration sensor in predictive maintenance edge node (2.7 V coin cell supply). IC Role / Device Role / Timing Role: Charge-to-voltage converter interface with high-Z input and rail-to-rail output swing. Use Value: Input common-mode range extending 0.3 V beyond rails accommodates sensor bias offsets; 3 MΩ input resistance minimizes signal loading. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-speed, low-power op-amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| OPA355DBVR | Lower 200 μA supply current but reduced 200 MHz GBW and no rail-to-rail input; 11 nV/√Hz noise. | Better for ultra-low-power, lower-bandwidth (<10 MHz) sensing; unsuitable where input must swing to rail. | Select OPA355DBVR only when supply current is primary constraint and input common-mode range ≥0.5 V beyond rails is not required. |
| ADA4891-1ARJZ-R7 | Higher 3.5 mA supply current, 220 MHz GBW, rail-to-rail output only; 7 nV/√Hz noise. | Better for high-precision, higher-bandwidth applications where power budget allows >5× current draw. | Choose ADA4891-1ARJZ-R7 when system requires sub-10 nV/√Hz noise and >100 MHz bandwidth, accepting higher quiescent power. |
Compared with OPA355DBVR and ADA4891-1ARJZ-R7, LMH6645MA uniquely balances 55 MHz bandwidth, rail-to-rail input/output, and sub-1 mA supply current - making it optimal for portable instrumentation where dynamic range, speed, and battery life must coexist.
Availability
LMH6645MA is available at Aetrix Electronics and suitable for active filters, current sense buffers, high-speed portable devices, and high-speed transducer amplifiers requiring stable component supply across industrial temperature range (−40°C to +85°C) and long-term production continuity.
Supply support for LMH6645MA 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 high-performance op-amps, data converters, and power management ICs.
The LMH664x product line was designed specifically for low-voltage, high-speed signal conditioning in portable and battery-operated equipment - emphasizing rail-to-rail operation, micro-power efficiency, and robust AC performance across wide supply ranges.
FAQ
What is the maximum supply voltage for LMH6645MA?
The LMH6645MA supports a supply voltage range of 2.5 V to 12 V between V+ and V− terminals. Absolute maximum rating is 12.6 V; operation beyond 12 V risks permanent damage. At 12 V, supply current increases to ~1.6 mA/channel, and output swing remains within 50 mV of rails under 1 kΩ load - verified per Electrical Characteristics table in SNOS970D Rev D.
Does LMH6645MA have built-in shutdown functionality?
No, LMH6645MA does not include shutdown functionality. Shutdown is exclusive to the LMH6647 (SOT-23-6 and SOIC-8 variants), which features a dedicated SD pin. The LMH6645MA is a 5-pin device with no shutdown terminal; its quiescent current is fixed at 650 μA/channel under normal operation and cannot be reduced via external control.
What is the input offset voltage specification for LMH6645MA over temperature?
The LMH6645MA has a guaranteed input offset voltage of ±4 mV over the full operating temperature range (−40°C to +85°C), with typical value of ±1 mV at 25°C. Input offset drift is ±5 μV/°C, meaning total offset variation across temperature extremes remains within ±4 mV - confirmed in Section 7.5 of SNOS970D datasheet under "Electrical Characteristics 2.7 V".
Can LMH6645MA drive a 50 Ω load directly?
LMH6645MA is not optimized for direct 50 Ω driving. Its specified output current is ±20 mA into loads ≥500 Ω. Driving 50 Ω continuously risks exceeding safe junction temperature due to power dissipation (e.g., 1 V swing into 50 Ω draws 20 mA, dissipating ~20 mW extra). For 50 Ω transmission lines, use LMH6645MA into a series 45 Ω resistor (for 50 Ω match) or add a dedicated line driver stage.
Is LMH6645MA suitable for single-supply operation at 3.3 V?
Yes, LMH6645MA is fully specified for single-supply operation at 3.3 V. Its rail-to-rail input accepts common-mode voltages from −0.3 V to +3.6 V, and output swings within 20 mV of 0 V and 3.3 V under 1 kΩ load. All key parameters - including 55 MHz bandwidth, 22 V/μs slew rate, and 17 nV/√Hz noise - are characterized at 2.7 V and scale favorably to 3.3 V, making LMH6645MA ideal for modern low-voltage embedded systems.
LMH6645MA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Amplifier Type:
- Voltage Feedback
- Number of Circuits:
- 1
- Output Type:
- Push-Pull, Rail-to-Rail
- Slew Rate:
- 22V/µs
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 55 MHz
- Current - Input Bias:
- 650 nA
- Voltage - Input Offset:
- 1 mV
- Current - Supply:
- 725µA
- Current - Output / Channel:
- 20 mA
- Voltage - Supply Span (Min):
- 2.5 V
- Voltage - Supply Span (Max):
- 12 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
LMH6645MA FAQ
1.How can I place an order for LMH6645MA through Aetrix?
Please submit a Request for Quotation (RFQ) for LMH6645MA on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LMH6645MA reliable?
The price and inventory of LMH6645MA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LMH6645MA is usually 5 days.
3.What payment methods are accepted for LMH6645MA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LMH6645MA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LMH6645MA?
LMH6645MA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LMH6645MA order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LMH6645MA?
For technical support, including LMH6645MA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LMH6645MA requirements.
6.How does Aetrix verify that LMH6645MA is sourced from the original manufacturer or authorized distributors?
All LMH6645MA products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LMH6645MA meets industry standards.
7.What is the process for return or replacement of LMH6645MA?
All LMH6645MA units undergo pre-shipment inspection (PSI). If there is an issue with LMH6645MA, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LMH6645MA part is unused and in its original packaging.
Return procedure for LMH6645MA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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