LT685CH - 5.5ns ECL High-Speed Comparator | Analog Devices
料号： LT685CH ✗ 停产| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $6.0232 | $6.02 |
| 10 | $6.0232 | $60.23 |
| 100 | $6.0232 | $602.32 |
| 500 | $6.0232 | $3,011.60 |
| 1,000 | $6.0232 | $6,023.20 |
LT685CH 概述
A high-speed comparator is a signal-conditioning integrated circuit that compares two input voltages and changes its output state according to their relative polarity. The LT685 belongs to the comparator hierarchy within interface and signal-processing semiconductors. Its differential inputs reduce sensitivity to common-mode noise when the compared signals are balanced, while complementary outputs simplify interfacing with ECL-family logic and systems requiring both true and inverted decisions.
The LT685CH emphasizes decision speed rather than rail-to-rail input operation or low power consumption. According to the manufacturer product information, the device is fully compatible with ECL logic levels and can adequately drive transmission lines terminated in 50 ohms. The 5.5 ns typical delay is the principal performance figure for high-speed threshold detection. A dedicated latch function allows a decision to be held for downstream circuitry, and external hysteresis control helps designers set or tune the switching threshold behavior.
Typical signal paths place the differential inputs close to the source and route them as a short, geometry-matched pair. Because the LT685CH is capable of high-speed output transitions, trace capacitance, impedance discontinuities, and ground-return paths can materially affect observed system performance. Terminated transmission lines should use the intended 50 ohm environment rather than long unterminated traces. The complementary ECL outputs also require careful common-grounding and interface compatibility with the receiving logic.
The LT685CH is suited to analog-to-digital signal processing, pulse-width or timing measurements, threshold detection, waveform conditioning, and high-speed instrumentation. Its speed makes it useful when the decision result must arrive quickly, but circuit timing must include comparator delay, external hysteresis, interconnect delay, and receiving-device delay. The CH order suffix is treated as the specific packaged LT685CH variant; package dimensions, pin mapping, and full electrical limits require confirmation from the applicable manufacturer documentation.
For PCB design, keep the input pair short, matched, and away from unrelated switching nodes. Place termination close to the driven output, provide a continuous ground reference, and avoid unnecessary stubs. If the output drives a cable or long trace, verify voltage levels and impedance before connecting to ECL inputs. Account for the latch and hysteresis controls during timing analysis rather than treating them as unused pins.
This page consolidates the verified LT685 family description, available distributor references, package and lifecycle observations, and engineering guidance into one design-oriented resource. Because the supplied data does not expose a complete manufacturer parameter table or verified direct replacements, unverified electrical values and non-drop-in alternatives are explicitly not inferred.
LT685CH 最大额定值与电气特性
| Product Type | High-speed differential-input comparator |
| Typical Propagation Delay | 5.5 ns |
| Input Configuration | Differential inputs |
| 输出配置 | Complementary outputs |
| Logic Compatibility | ECL-compatible |
| Output Drive Environment | 50 ohm transmission lines |
| Input Offset | Low input offset; exact value not provided |
| Input Resolution | High resolution; exact value not provided |
| Latch Function | Provided |
| Hysteresis Control | External hysteresis control pin |
| Compatible Part Reference | AM685 compatibility stated in the verified search result |
| Package Type | Ceramic DIP; exact dimensions not provided |
| 引脚数量 | 8 pins |
| 生命周期状态 | Obsolete, according to the supplied distributor result |
| Standardized Pricing | USD 6.0232 indicative price, MOQ 100 pieces, as of 2026-10-22 |
| Stock Indication | 1000 pieces indicated by one supplied distributor result as of 2026-10-22 |
| RoHS 状态 | unknown |
| REACH Status | unknown |
| Lead-Free Status | unknown |
LT685CH ceramic dip; exact dimensions not provided 引脚配置指南
LT685CH（ceramic dip; exact dimensions not provided 封装）的引脚配置。 该模拟元件具有输入、输出和电源引脚。请参阅制造商数据手册以了解失调调零、补偿和使能引脚配置。适用于信号调理和放大器电路。
暂无详细引脚数据： LT685CH.
请参阅 数据手册 以查看完整引脚配置。
典型应用
LT685CH 适用于 6 应用s: High-Speed Threshold Detection, Analog-to-Digital Signal Processing, Pulse-Width and Timing Measurement, ECL Logic Interfacing, Waveform Conditioning, High-Speed Test and Measurement.
High-Speed Threshold Detection
The LT685CH fits high-speed threshold detection because its differential inputs compare the signal against a reference while its typical propagation delay is only 5.5 ns. The complementary outputs provide both decision polarities for downstream logic, and the latch can hold a result when a sampled event must remain stable. Place the input pair on short, closely coupled traces and provide a controlled return path to prevent trace delay or noise from obscuring the decision. The available information does not state input common-mode or supply limits, so the design must verify those values in the manufacturer documentation.
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Analog-to-Digital Signal Processing
The LT685CH is specifically identified by Analog Devices for analog-to-digital signal processing, where rapid comparison can convert an analog event into a digital decision. Differential inputs help reject common-mode disturbance when the source is balanced, while low input offset and high resolution support precision thresholding. Its 5.5 ns typical delay limits the comparator decision stage, but the complete conversion latency also includes input filtering, cable or PCB propagation, receiver logic, and any external latch timing. Confirm polarity, voltage limits, and termination before using the output as a sampling control signal.
推荐
Pulse-Width and Timing Measurement
For pulse-width or edge-timing measurement, the LT685CH can generate a fast complementary decision signal from differential inputs with a typical propagation delay of 5.5 ns. That speed is valuable when the measured interval is short or when a downstream counter must resolve a narrow pulse. External hysteresis control can reduce chatter when the threshold signal has noise, while the latch can prevent a transient decision from changing during a defined interval. Account for hysteresis-induced timing variation and output-interface delay in the measurement budget.
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ECL Logic Interfacing
The LT685CH is suited to ECL interfacing because its complementary outputs are compatible with ECL logic levels and can drive 50 ohm transmission lines. This makes it useful in legacy instrumentation, high-speed test systems, and burst-oriented signal paths where two logic polarities are useful. The receiving devices must support the output voltage levels and timing, and the transmission line must have the intended impedance and termination. The supplied sources do not provide complete output swing or supply-current data, so those details must be verified before board release.
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Waveform Conditioning
Waveform-conditioning applications can use the LT685CH to convert a noisy or analog waveform into complementary logic-level decisions. Differential inputs help preserve signal integrity when the source is balanced, and the external hysteresis control provides a place to shape switching behavior around the threshold. The 5.5 ns typical propagation delay supports fast edge qualification and event capture, while the latch supports downstream sampling. Design the input network and termination carefully because excessive capacitance, unequal routing, or inadequate grounding can dominate the nominal device delay.
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High-Speed Test and Measurement
The LT685CH can support high-speed test equipment that must make a rapid binary decision about an analog node and then send the result to timing or logic circuitry. Its differential-input architecture is useful for balanced fixtures, complementary outputs simplify connection to dual-polarity logic, and the 50 ohm drive capability supports controlled test-line environments. In an instrument, use short fixture traces, calibrated termination, and a defined latch interval so the measured timing is repeatable. Verify the obsolete lifecycle status and available stock before committing a new production design.
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推荐产品汇总
工程参考数据： LT685CH ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 |
|---|---|
| Package | 8-pin hermetic ceramic DIP |
| Brand | Analog Devices |
| Product Type | High-speed comparator |
| Typical Propagation Delay | 5.5 ns |
| Input Configuration | Differential inputs |
| Output Configuration | Complementary outputs |
| Logic Level | ECL-compatible |
| Output Drive | 50 ohm transmission-line capability |
| Latch Function | Provided |
| Hysteresis | External hysteresis-control pin |
关键差异点
- Very fast nominal decision speed （对比 General-purpose comparator)
- Complementary ECL-compatible outputs （对比 Single-ended CMOS-logic comparator)
- External hysteresis and latch control （对比 Comparator without external latch control)
设计说明
Route the differential inputs as a short, closely coupled pair with a continuous ground reference. Keep the traces away from switching power nodes and other high-energy signals, and avoid unnecessary vias or stubs. The verified 5.5 ns typical propagation delay leaves little margin for uncontrolled interconnect effects, so input skew, capacitance, and return-current discontinuities should be treated as part of the timing budget.
Treat the LT685CH outputs as transmission-line drivers rather than ordinary low-speed logic outputs. Use the intended 50 ohm environment for long or high-speed routes, place termination at the correct end of the line, and preserve complementary-output timing relative to the receiver. The supplied data does not specify full output swing or current limits, so those values must be taken from the manufacturer datasheet before final impedance and loading calculations.
Do not infer pin compatibility from a similar LT685 ordering code. The verified sources mention LT685CN and related listings but explicitly require datasheet and pinout checks. Before substituting, compare package dimensions, pin numbering, input polarity, supply requirements, ECL output levels, propagation delay, latch operation, and external hysteresis behavior. The supplied data contains no verified drop-in alternative.
合规信息
The supplied manufacturer and distributor snippets do not state RoHS, REACH, lead-free, halogen-free, conflict-minerals, or automotive qualification information.
