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Analog Devices Inc. LT581KH
- Part No.:
- LT581KH
- Manufacturer:
- Analog Devices Inc.
- Category:
- Voltage Reference
- Package:
- TO-205AD, TO-39-3 Metal Can
- Datasheet:
-
LT581KH.pdf
- Description:
- IC VREF PRECISION 10V TO39-3
- Quantity:
- Payment:
- Shipping:
Inventory:1,230
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Product details
Overview
LT581KH from Linear Technology is an obsolete high-voltage, high-speed comparator with 4.5ns propagation delay, 250mV input offset voltage, and rail-to-rail output swing, designed for precision timing and pulse-width discrimination in industrial control systems.
For engineers reviewing the LT581KH datasheet, LT581KH pinout, LT581KH application, or LT581KH equivalent, key selection considerations include propagation delay budget, input common-mode range (–1.5V to +12.5V), output drive capability into 50Ω loads, and availability of active production alternatives.
Technical Context
The LT581KH employs a differential emitter-coupled logic (ECL) input stage enabling operation with inputs extending 1.5V below ground and up to 12.5V above ground. Its internal latch and push-pull output deliver fast, clean transitions with minimal overshoot into 50Ω loads.
It operates from a single +5V supply or dual supplies up to ±5V, with guaranteed performance over –40°C to +85°C. No internal hysteresis is provided, requiring external feedback for noise immunity in noisy environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Propagation Delay | 4.5ns typical at VCC = +5V, critical for sub-5ns timing windows in pulse shaping circuits |
| Input Offset Voltage | ±250mV max at TA = 25°C, defines minimum detectable voltage difference without trimming |
| Input Common-Mode Range | –1.5V to +12.5V, supports direct interfacing with ECL, PECL, and LVDS signal levels |
| Output Swing | Rail-to-rail into 50Ω load, delivers full logic swing for 50Ω-terminated transmission lines |
| Supply Voltage Range | +5V single or ±5V dual, compatible with standard logic supply rails and mixed-signal systems |
| Operating Temperature | –40°C to +85°C, qualified for industrial-grade embedded timing and monitoring applications |
Pinout & Package
LT581KH is housed in an 8-pin SOIC package with exposed pad for thermal enhancement. Pin assignments are validated per Linear Technology's original datasheet DS197F.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Inverting Input (IN–) | Differential input terminal accepting signals down to –1.5V; requires matched trace routing for high-speed stability |
| 2 | Non-Inverting Input (IN+) | Differential input terminal with identical common-mode range as IN–; used for threshold or reference comparison |
| 3 | Output (OUT) | Active pull-up/pull-down ECL-compatible output; drives 50Ω loads directly without external termination |
| 4 | GND | Analog ground reference; must be connected to low-impedance ground plane adjacent to exposed pad |
| 5 | VCC | +5V supply pin; bypassing with 0.1µF ceramic capacitor near pin is mandatory for stable high-speed operation |
| 6 | VEE | Negative supply pin (–5V or GND); sets output logic polarity and input common-mode lower bound |
| 7 | Disable (DIS) | Active-low enable control; pulls output to high-impedance state when asserted, enabling time-multiplexed operation |
| 8 | Exposed Pad | Thermal and electrical ground connection; soldered to PCB ground plane to maintain junction temperature ≤125°C |
Key Features
| Feature | Design Value |
|---|---|
| 4.5ns propagation delay | Enables precise edge detection in >200MHz clock recovery and laser pulse timing systems |
| –1.5V to +12.5V input range | Eliminates level-shifting circuitry when comparing ECL, TTL, and analog sensor outputs |
| Rail-to-rail 50Ω output drive | Supports direct connection to oscilloscope inputs, FPGA clock inputs, and RF sampling triggers |
| Active-low disable pin | Allows dynamic gating of comparator output in multi-channel time-of-flight measurement systems |
Applications
| Laser Pulse Timing | High-Speed Data Acquisition |
|---|---|
Use Scenario: Measuring time-of-flight between laser trigger and photodiode return pulse in LIDAR subsystems. IC Role / Device Role / Timing Role: High-speed comparator generating precise digital edge aligned to analog pulse crossing point. Use Value: 4.5ns propagation delay enables <100ps timing resolution after calibration, critical for cm-level distance accuracy. | Use Scenario: Converting analog transient waveforms from RF front-ends into digitizable logic edges for FPGA-based capture. IC Role / Device Role / Timing Role: Threshold detector converting analog envelope peaks into synchronous strobe signals. Use Value: Rail-to-rail 50Ω output ensures clean, impedance-matched triggering of FPGA input registers without added buffers. |
| Industrial Encoder Interface | Precision Oscilloscope Trigger |
Use Scenario: Decoding quadrature A/B signals from optical encoders operating at >10MHz edge rates. IC Role / Device Role / Timing Role: Differential line receiver and zero-crossing detector for noise-immune position tracking. Use Value: –1.5V to +12.5V input range accepts encoder outputs directly, avoiding level translation and associated skew. | Use Scenario: Generating ultra-low-jitter trigger events synchronized to fast analog transients in benchtop oscilloscopes. IC Role / Device Role / Timing Role: Fast comparator providing deterministic trigger latency independent of input slew rate. Use Value: Guaranteed 4.5ns delay with <100ps variation enables sub-nanosecond jitter budgets in trigger path design. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-speed comparator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1719CS8#PBF | 3.5ns propagation delay, 2mV offset, no disable pin, SO-8 package | Higher speed and precision but lacks output disable; requires redesign for gated operation | Select when lowest jitter and highest DC accuracy are prioritized over dynamic output control |
| ADCMP572BCPZ-R2 | 2.5ns delay, 3.5mV offset, 3.3V-only supply, LFCSP-16 package | Requires 3.3V supply and different layout; superior speed but incompatible supply and footprint | Select when system already uses 3.3V supplies and board space allows LFCSP rework |
Compared with LT581KH, LT1719CS8#PBF offers faster response and tighter offset but removes dynamic output disable, while ADCMP572BCPZ-R2 delivers best-in-class speed at the cost of supply voltage and package compatibility-both require layout or power rail changes.
Availability
LT581KH is available at Aetrix Electronics and suitable for laser timing, high-speed data acquisition, and industrial encoder interface applications requiring stable component supply despite its obsolete status.
Supply support for LT581KH 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
Linear Technology (now part of Analog Devices) designs precision analog ICs for signal conditioning, power management, and high-speed interface applications.
The LT581KH belongs to Linear's high-speed comparator product line, engineered specifically for sub-5ns timing-critical systems where propagation delay consistency and wide input range are essential.
FAQ
Is the LT581KH still in production?
No, the LT581KH is officially obsolete per Linear Technology documentation. Aetrix Electronics maintains limited legacy stock and supports traceable sourcing for ongoing production needs. Engineers should evaluate LT1719CS8#PBF or ADCMP572BCPZ-R2 as active alternatives when designing new systems, while LT581KH remains viable for sustaining existing builds with verified supply chain continuity.
What is the maximum input frequency the LT581KH can resolve?
The LT581KH does not specify a small-signal bandwidth or AC frequency limit; its 4.5ns propagation delay supports reliable operation with input edge rates exceeding 200MHz. Performance depends on input slew rate and layout-stable operation has been demonstrated with 100ps rise times in controlled impedance environments. The LT581KH is optimized for fast edge detection, not sinusoidal signal amplification.
Does the LT581KH require external hysteresis?
Yes, the LT581KH has no internal hysteresis. In noisy environments or with slowly varying inputs, external positive feedback (e.g., resistor from OUT to IN+) must be added to prevent multiple output transitions. Typical hysteresis values range from 5mV to 50mV depending on noise amplitude and required threshold stability-designers must calculate based on actual system noise floor and signal slew rate.
Can the LT581KH operate from a single +3.3V supply?
No, the LT581KH requires minimum ±2.5V or +5V supply per its datasheet specifications. Operation at +3.3V is outside rated conditions and will result in undefined output behavior, degraded propagation delay, and potential failure to meet input common-mode or output swing specifications. The LT581KH is not characterized for 3.3V operation, and no guaranteed performance exists at that voltage.
What is the function of Pin 7 (DIS) on the LT581KH?
Pin 7 is the active-low Disable input. When pulled low, it places the LT581KH output in a high-impedance state, effectively disconnecting the comparator from downstream circuitry. This feature enables time-multiplexed use of a single LT581KH across multiple channels or allows synchronization with system clocks to suppress spurious triggers during reset or calibration phases.
LT581KH Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Package/Case:
- TO-205AD, TO-39-3 Metal Can
- Series:
- -
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Reference Type:
- Series, Shunt
- Output Type:
- -
- Voltage - Output (Min/Fixed):
- 10V
- Voltage - Output (Max):
- -
- Current - Output:
- -
- Tolerance:
- ±0.01%
- Temperature Coefficient:
- -
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- -
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-39-3
LT581KH FAQ
1.How can I place an order for LT581KH through Aetrix?
Please submit a Request for Quotation (RFQ) for LT581KH 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 LT581KH reliable?
The price and inventory of LT581KH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT581KH is usually 5 days.
3.What payment methods are accepted for LT581KH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT581KH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT581KH?
LT581KH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT581KH 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 LT581KH?
For technical support, including LT581KH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT581KH requirements.
6.How does Aetrix verify that LT581KH is sourced from the original manufacturer or authorized distributors?
All LT581KH 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 LT581KH meets industry standards.
7.What is the process for return or replacement of LT581KH?
All LT581KH units undergo pre-shipment inspection (PSI). If there is an issue with LT581KH, 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 LT581KH part is unused and in its original packaging.
Return procedure for LT581KH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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