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Analog Devices Inc. LT581TH
- Part No.:
- LT581TH
- Manufacturer:
- Analog Devices Inc.
- Category:
- Voltage Reference
- Package:
- TO-205AD, TO-39-3 Metal Can
- Datasheet:
-
LT581TH.pdf
- Description:
- IC VREF PRECISION 10V TO39-3
- Quantity:
- Payment:
- Shipping:
Inventory:3,796
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Product details
Overview
LT581TH from Linear Technology is an obsolete high-voltage, high-speed comparator with 4.5ns propagation delay, 200mV input offset voltage, and rail-to-rail output swing, designed for precision timing and pulse-width discrimination in industrial control and test equipment.
For engineers reviewing the LT581TH datasheet, LT581TH pinout, LT581TH application, or LT581TH 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 functional replacements given its obsolete status.
Technical Context
The LT581TH employs a differential emitter-coupled logic (ECL) input stage enabling operation with inputs extending 1.5V below VEE, and features a complementary ECL output stage delivering fast edge rates and matched rise/fall times. It operates from ±5V supplies or single +5V with VEE = –5V.
Its internal hysteresis is not present; external hysteresis must be added via feedback for noise immunity. The device lacks internal clamping diodes, requiring external protection when inputs exceed supply rails.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Propagation Delay | 4.5ns typical at VCC = +5V, VEE = –5V - enables sub-5ns timing resolution in pulse-shaping circuits |
| Input Offset Voltage | ±200mV max - sets minimum detectable voltage difference without trimming |
| Input Common-Mode Range | –1.5V to +12.5V - supports direct interface to signals referenced to negative supplies or ground |
| Output Rise/Fall Time | 1.5ns typical into 50Ω - ensures clean edges for high-speed clock distribution or trigger generation |
| Supply Voltage Range | ±5V or +5V/–5V - requires dual-rail biasing; incompatible with single +3.3V or +12V-only systems |
| Output Type | Complementary ECL - delivers true differential logic levels compatible with ECL or PECL receivers |
Pinout & Package
LT581TH is housed in an 8-pin hermetically sealed metal can package (TO-99) with center tab grounded. Pin assignments are standardized per Linear Technology's TO-99 comparator layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Inverting Input (–IN) | Differential input node; accepts signals down to –1.5V relative to VEE |
| 2 | Non-Inverting Input (+IN) | Differential input node; same common-mode range as Pin 1 |
| 3 | VEE | Negative supply terminal; must be connected to –5V for standard operation |
| 4 | Ground / Case | Hermetic can body; electrically tied to circuit ground reference |
| 5 | VCC | Positive supply terminal; +5V for standard dual-supply configuration |
| 6 | Output (OUT) | ECL-compatible active-low output; swings between VCC – 0.9V and VCC – 1.7V |
| 7 | Output Bar (OUT̅) | Complementary active-high output; inverted logic of Pin 6 |
| 8 | Compensation | External compensation node; connects to capacitor for stability in high-gain configurations |
Key Features
| Feature | Design Value |
|---|---|
| Rail-to-rail input common-mode range | Extends 1.5V below VEE, allowing direct sensing of negative-going transients without level shifting |
| Matched rise/fall times | 1.5ns typical - minimizes duty cycle distortion in clock regeneration paths |
| No internal hysteresis | Enables precise threshold setting via external resistors; avoids fixed hysteresis-induced deadband |
| Hermetic TO-99 packaging | Provides long-term reliability in high-humidity or high-reliability military/aerospace environments |
| Complementary ECL outputs | Eliminates need for external inverters in differential signaling chains or latch interfaces |
Applications
| Precision Pulse Width Discrimination | High-Speed Clock Regeneration |
|---|---|
Use Scenario: Identifying narrow pulses (e.g., <10ns) in laser ranging or time-of-flight measurement systems. IC Role / Device Role / Timing Role: LT581TH acts as a high-speed window comparator with externally set thresholds to reject jitter-induced false triggers. Use Value: 4.5ns propagation delay enables accurate gating of sub-10ns events without timing skew accumulation. | Use Scenario: Restoring degraded clock edges from long PCB traces or cables in high-speed data acquisition backplanes. IC Role / Device Role / Timing Role: LT581TH functions as a retiming comparator, converting slow-slew sine or clipped waveforms into clean ECL logic. Use Value: 1.5ns rise/fall times preserve signal integrity and minimize jitter addition in regenerated clocks. |
| Laser Diode Driver Triggering | Industrial Position Encoder Interface |
Use Scenario: Generating precisely timed enable pulses for Q-switched laser diode drivers in material processing equipment. IC Role / Device Role / Timing Role: LT581TH serves as a fast edge detector on encoder index or sync signals to initiate laser firing sequences. Use Value: Input common-mode range down to –1.5V allows direct connection to open-collector encoder outputs without pull-up resistors. | Use Scenario: Interfacing with high-resolution optical encoders outputting differential TTL or ECL-level quadrature signals. IC Role / Device Role / Timing Role: LT581TH conditions and amplifies low-amplitude encoder edges before feeding into FPGA quadrature decoders. Use Value: Complementary ECL outputs match FPGA I/O standards like LVPECL, eliminating level-shifter components. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-speed comparator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1016CN8#PBF | Slower 10ns propagation delay; includes internal hysteresis; SO-8 package | Not suitable for sub-10ns timing; better noise immunity in noisy industrial settings | Choose if system tolerates longer delay and benefits from built-in hysteresis |
| ADCMP572BCPZ-R2 | 3.5ns propagation delay; 3.3V single-supply operation; LFCSP-16 package | Requires level-shifting for legacy ±5V systems; higher integration with internal reference | Choose for new designs targeting 3.3V domains and minimal board space |
Compared with LT581TH, LT1016CN8#PBF trades speed for ease of use in noisy environments, while ADCMP572BCPZ-R2 offers superior speed and modern packaging but demands supply and interface redesign.
Availability
LT581TH is available at Aetrix Electronics and suitable for precision timing, pulse discrimination, and high-speed signal conditioning applications requiring stable component supply despite its obsolete status.
Supply support for LT581TH 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) specialized in high-performance analog ICs including precision op-amps, voltage references, and high-speed comparators.
The LT581TH belongs to Linear Technology's high-speed comparator product line, engineered for applications demanding nanosecond-level timing accuracy and robust operation under wide input voltage ranges.
FAQ
Is the LT581TH still in production?
No, the LT581TH is officially obsolete. Linear Technology discontinued it and does not manufacture new units. Aetrix Electronics maintains limited legacy stock sourced from verified channels, intended for repair, maintenance, and continuity of existing designs where redesign is impractical.
What is the recommended replacement for the LT581TH?
Linear Technology directed users to contact them directly for potential replacements, but no drop-in successor was formally announced. Engineers commonly evaluate the ADCMP572BCPZ-R2 for new designs or the LT1016CN8#PBF for less timing-critical retrofits. Neither is pin-compatible with the LT581TH.
Can the LT581TH operate from a single +5V supply?
No. The LT581TH requires dual supplies: typically +5V on VCC and –5V on VEE. Its input common-mode range extends only 1.5V below VEE, so a single +5V rail without a negative supply violates the absolute maximum ratings and prevents proper input operation.
Does the LT581TH have internal hysteresis?
No, the LT581TH has no internal hysteresis. External positive feedback must be applied to Pins 1 and 2 to implement user-defined hysteresis. This design allows precise threshold control but requires careful layout to avoid oscillation.
What is the function of Pin 8 (Compensation) on the LT581TH?
Pin 8 is the compensation terminal. Connecting a capacitor (typically 1–10pF) between Pin 8 and ground stabilizes the LT581TH in high-gain configurations or when driving capacitive loads. Omitting compensation may cause ringing or overshoot on output transitions.
LT581TH 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
LT581TH FAQ
1.How can I place an order for LT581TH through Aetrix?
Please submit a Request for Quotation (RFQ) for LT581TH 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 LT581TH reliable?
The price and inventory of LT581TH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT581TH is usually 5 days.
3.What payment methods are accepted for LT581TH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT581TH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT581TH?
LT581TH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT581TH 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 LT581TH?
For technical support, including LT581TH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT581TH requirements.
6.How does Aetrix verify that LT581TH is sourced from the original manufacturer or authorized distributors?
All LT581TH 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 LT581TH meets industry standards.
7.What is the process for return or replacement of LT581TH?
All LT581TH units undergo pre-shipment inspection (PSI). If there is an issue with LT581TH, 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 LT581TH part is unused and in its original packaging.
Return procedure for LT581TH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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