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Analog Devices Inc. LT1994HDD#PBF
- Part No.:
- LT1994HDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LT1994HDD#PBF.pdf
- Description:
- IC OPAMP DIFF 1 CIRCUIT 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,680
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Product details
Overview
LT1994HDD#PBF from Analog Devices (formerly Linear Technology) is a fully differential input/output amplifier optimized for single-supply ADC driving, featuring rail-to-rail output swing, adjustable output common-mode voltage via VOCM pin, 3nV/√Hz input voltage noise, –94dBc distortion at 1MHz/2VP-P, and operation down to 2.375V supply. It enables precise single-ended-to-differential conversion with level shifting in low-voltage data acquisition systems.
For engineers reviewing the LT1994HDD#PBF datasheet, LT1994HDD#PBF pinout, LT1994HDD#PBF application, or LT1994HDD#PBF equivalent, key selection criteria include its –40°C to 125°C operating range, 85mA output drive capability, 70MHz gain-bandwidth product, VOCM-controlled common-mode translation, and DFN-8 package thermal performance for high-reliability industrial signal conditioning.
Technical Context
The LT1994HDD#PBF employs an internal common-mode feedback path that actively balances OUT+ and OUT– phases, reducing even-order harmonics and enabling accurate differential output centering around the VOCM-set voltage-regardless of input common-mode level. Its dual-output architecture supports both single-ended-to-differential and differential-to-differential configurations with unity-gain stability.
It integrates hardware shutdown (SHDN pin), delivering 225μA quiescent current in sleep mode while maintaining open-collector-like outputs with steering diodes. Input protection includes back-to-back diodes limiting differential overvoltage to 1V and ±10mA input current rating, with VOCM and SHDN pins similarly protected against supply rail excursions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2.375V to 12.6V - supports ultra-low-voltage 2.5V systems and higher-voltage industrial rails without redesign. |
| Differential Input Noise | 3nV/√Hz at 50kHz - enables high-resolution signal amplification before ADC sampling with minimal SNR degradation. |
| THD @ 1MHz, 2VP-P | –94dBc (2nd/3rd harmonic) - meets demanding spectral purity requirements for 12–16-bit ADC front-ends. |
| Output Drive Current | ±85mA per output - drives 100Ω loads directly and sustains rail-to-rail swing under heavy capacitive or resistive loading. |
| Gain-Bandwidth Product | 70MHz - ensures stable closed-loop operation up to ~10MHz with gain ≥7, suitable for wideband sensor interfaces. |
| DC Voltage Offset | <2mV max (input-referred) - minimizes baseline error in precision DC-coupled measurement paths. |
| Shutdown Current | 225μA at 3V - enables power-gating in battery-powered or thermally constrained embedded systems. |
Pinout & Package
LT1994HDD#PBF is housed in an 8-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 9) soldered to V– for thermal and electrical grounding. The package supports θJA = 43°C/W and operates up to 125°C junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN– (Pin 1) | Inverting input | Accepts differential or single-ended signals; requires matched layout to IN+ to preserve CMRR and balance. |
| VOCM (Pin 2) | Output common-mode reference | Sets average of OUT+ and OUT–; internal 40kΩ Thevenin resistance; must be bypassed with ≥0.1μF ceramic capacitor. |
| V+ (Pin 3) | Positive supply | Connect to clean, low-impedance source; bypass with 1μF + 0.1μF ceramics close to pin for stability. |
| OUT+ (Pin 4) | Positive differential output | Rail-to-rail capable; sources/sinks up to 85mA; rated for ≤25pF load to ground (12.5pF differential). |
| OUT– (Pin 5) | Negative differential output | Complementary to OUT+; phase-balanced by internal CMFB loop to suppress even-order harmonics. |
| V– (Pin 6) | Negative supply / ground | Must connect exposed pad (Pin 9) directly to this node; serves as primary thermal and reference path. |
| SHDN (Pin 7) | Shutdown control | Pull ≥2.1V below V+ to enter low-power mode; internal 55kΩ pull-up ensures active state when floating. |
| IN+ (Pin 8) | Noninverting input | Paired with IN–; input bias current ≤–3μA (typ); protected by steering diodes to V+/V– rails. |
Key Features
| Feature | Design Value |
|---|---|
| Fully differential I/O architecture | Enables true differential signaling with inherent common-mode noise rejection and 2× voltage swing vs. single-ended amps. |
| Adjustable output common-mode voltage | VOCM pin allows precise alignment of differential output midpoint to ADC input common-mode range (e.g., 1.5V for 3V ADCs). |
| Internal common-mode feedback (CMFB) | Actively corrects output phase imbalance, achieving –71dB balance (differential input) and suppressing 2nd-harmonic distortion. |
| Rail-to-rail output swing | Delivers full dynamic range across 2.375V–12.6V supplies, maximizing SNR in low-voltage, single-supply data acquisition. |
| Hardware shutdown with fast toggle | 1μs turn-on/off timing and 225μA shutdown current enable rapid power cycling in portable or thermally managed systems. |
| Robust input protection | Back-to-back diodes limit differential input overvoltage to 1V; steering diodes clamp IN+, IN–, VOCM, SHDN to rails (±10mA max). |
Applications
| Industrial Process Monitoring | Medical Instrumentation |
|---|---|
Use Scenario: Amplifying low-level bridge sensor outputs (e.g., strain gauges, RTDs) in PLC analog input modules operating from 3.3V supplies. IC Role / Device Role / Timing Role: Single-ended sensor signal → differential output driver with VOCM set to 1.65V to match SAR ADC common-mode requirement. Use Value: 3nV/√Hz noise and <2mV offset preserve microvolt-level resolution; rail-to-rail swing maximizes 16-bit ADC utilization. |
Use Scenario: Driving 14-bit, 2.8Msps differential-input ADCs (e.g., LTC1403A-1) in portable ECG front-ends powered from 3V coin cells. IC Role / Device Role / Timing Role: Converts single-ended biopotential signals to balanced differential outputs while translating common-mode to mid-supply. Use Value: –94dBc distortion at 1MHz ensures clean FFT-based arrhythmia detection; 13.3mA supply current extends battery life. |
| Automotive Battery Management | Test & Measurement Equipment |
Use Scenario: Level-shifting isolated cell voltage measurements (0–5V) to differential format for isolated ΣΔ ADCs in BMS stacks operating at –40°C to 125°C. IC Role / Device Role / Timing Role: Differential amplifier with VOCM referenced to isolated ADC's common-mode rail; operates across full H-grade temperature range. Use Value: Guaranteed –40°C to 125°C performance and 85mA drive support long trace routing and RC filtering without signal degradation. |
Use Scenario: Front-end driver for high-speed digitizers requiring >10MHz bandwidth, low THD, and programmable common-mode offset. IC Role / Device Role / Timing Role: Configured as unity-gain differential buffer with VOCM controlled by DAC to adjust output DC level dynamically. Use Value: 70MHz GBW and 65V/μs slew rate support fast transient response; 0.01% settling in 120ns enables accurate waveform capture. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fully differential amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADA4940-1ACPZ-R7 | Lower noise (2.9nV/√Hz), wider GBW (800MHz), but higher supply current (18.5mA) and no hardware shutdown. | Better for RF/IF signal chains; less suitable for low-power or thermally constrained industrial designs. | Choose ADA4940-1 when bandwidth >100MHz is required and power budget allows >18mA continuous draw. |
| THS4561IRGET | Higher output current (115mA), lower distortion (–105dBc), but only rated to 85°C and lacks VOCM flexibility (fixed 1.25V). | Optimized for high-fidelity audio and video; not qualified for extended-temperature automotive or industrial use. | Choose THS4561 when driving heavy loads at ambient ≤85°C and fixed common-mode is acceptable. |
Compared with ADA4940-1 and THS4561, the LT1994HDD#PBF uniquely combines extended temperature operation (–40°C to 125°C), integrated shutdown, VOCM adjustability, and sub-14mA quiescent current-making it optimal for ruggedized, power-aware, and ADC-coupled embedded systems.
Availability
LT1994HDD#PBF is available at Aetrix Electronics and suitable for industrial process monitoring, medical instrumentation, automotive battery management, and test & measurement equipment requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT1994HDD#PBF 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
Analog Devices, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets with precision signal chain solutions.
The LT1994HDD#PBF belongs to ADI's legacy Linear Technology precision amplifier portfolio, designed specifically for high-fidelity, low-noise, single-supply differential signal conditioning in data acquisition and sensor interface applications.
FAQ
What is the maximum operating temperature range for the LT1994HDD#PBF?
The LT1994HDD#PBF is specified for operation from –40°C to +125°C, with guaranteed performance across this full range. This H-grade qualification makes it suitable for under-hood automotive, industrial motor control, and high-ambient-temperature embedded systems where standard commercial or industrial grade amplifiers would fail.
How does the VOCM pin function in the LT1994HDD#PBF?
The VOCM pin on the LT1994HDD#PBF sets the average voltage of the differential outputs (VOUTCM = (VOUT+ + VOUT–)/2). It features a 40kΩ Thevenin-equivalent resistance and defaults to mid-supply when left open. Applying an external voltage (e.g., 1.5V for a 3V system) precisely aligns the output common-mode level to match the ADC's input requirement, enabling seamless interfacing without external level-shifting circuitry.
Can the LT1994HDD#PBF drive a 50Ω load differentially?
The LT1994HDD#PBF is rated to drive 100Ω loads to ground per output (i.e., 200Ω differentially), with short-circuit current up to ±85mA. Driving a true 50Ω differential load (25Ω per side) exceeds its safe operating area and risks thermal overload. For such loads, add series 25Ω resistors at each output to isolate capacitance and limit current while preserving signal integrity.
What is the typical supply current of the LT1994HDD#PBF at 3V operation?
The LT1994HDD#PBF draws 13.3mA of supply current at 3V operation under typical conditions. In shutdown mode (SHDN pulled ≥2.1V below V+), supply current drops to 225μA-reducing power consumption by over 98% while retaining fast wake-up capability (<1μs turn-on time).
Does the LT1994HDD#PBF require external compensation components?
No, the LT1994HDD#PBF is unity-gain stable and requires no external compensation. Its internal architecture is optimized for stable operation with standard resistor feedback networks (e.g., 499Ω) and typical PCB layouts. Stability is maintained across supply voltages from 2.375V to 12.6V and temperatures from –40°C to 125°C without added capacitors or network tuning.
LT1994HDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Amplifier Type:
- Differential
- Number of Circuits:
- 1
- Output Type:
- Rail-to-Rail
- Slew Rate:
- 65V/µs
- Gain Bandwidth Product:
- 70 MHz
- -3db Bandwidth:
- -
- Current - Input Bias:
- 18 µA
- Voltage - Input Offset:
- 3 mV
- Current - Supply:
- 14.8mA
- Current - Output / Channel:
- -
- Voltage - Supply Span (Min):
- 2.375 V
- Voltage - Supply Span (Max):
- 12.6 V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (3x3)
LT1994HDD#PBF FAQ
1.How can I place an order for LT1994HDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1994HDD#PBF 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 LT1994HDD#PBF reliable?
The price and inventory of LT1994HDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1994HDD#PBF is usually 5 days.
3.What payment methods are accepted for LT1994HDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1994HDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1994HDD#PBF?
LT1994HDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1994HDD#PBF 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 LT1994HDD#PBF?
For technical support, including LT1994HDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1994HDD#PBF requirements.
6.How does Aetrix verify that LT1994HDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT1994HDD#PBF 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 LT1994HDD#PBF meets industry standards.
7.What is the process for return or replacement of LT1994HDD#PBF?
All LT1994HDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1994HDD#PBF, 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 LT1994HDD#PBF part is unused and in its original packaging.
Return procedure for LT1994HDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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