LM339AD - Quad Differential Comparator | Texas Instruments
MPN： LM339AD ✓ 啟用中LM339AD 概覽
A voltage comparator is an analog interface that compares two input voltages and changes its output state according to their relationship. The LM339 belongs to the comparator IC hierarchy within interface and signal-conditioning semiconductors. Unlike an operational amplifier used for closed-loop precision amplification, the LM339 provides open-loop decision making with relatively low output saturation voltage. Its four independent channels can monitor multiple thresholds, provide isolated sensing functions, or implement window and overvoltage detection.
Key benefits include compatibility with TTL, MOS, and CMOS output systems, a supply-current requirement of 200 μA per comparator, and a response time listed as 1.3 μs in the manufacturer product details. These characteristics make the device appropriate for industrial control, power-supply supervision, sensor conditioning, and discrete logic interfaces. The open-collector outputs require an external pull-up resistor whenever a logic-high output is required.
The LM339AD family is designed to operate from a single power supply over a wide voltage range. Its differential input rating of ±38 V and ground-inclusive common-mode capability provide useful margin in systems where the input signal can exceed the local logic supply. The A-grade designation distinguishes this version from the improved B family, whose enhanced specifications and operating current should be reviewed when designing a new design.
Typical uses include overvoltage and undervoltage protection, zero-cross detection, temperature or light threshold switching, relay-drive logic, and four-channel sensing in industrial equipment. The 14-pin SOIC package permits compact board layouts and standard surface-mount assembly.
For reliable implementation, place bypass capacitors near the supply pins and provide an appropriate pull-up resistor on every open-collector output. Confirm common-mode, differential, and output ratings against the actual signal range. Check input polarity and offset requirements when the decision threshold must remain accurate.
This page combines manufacturer specifications, same-package replacement guidance, comparative parameters, and practical application guidance to support component selection and PCB design.
直接替換替代品，適用於 LM339AD — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： LM339AD （相同外形與佔位） — 差異在於 Comparator Type, Output Type, Package.
LM339AM
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →LM239ADT
✅ 直接替換📋 參考替代品（不在目錄中）
LM339ADT
✅ 直接替換📋 參考替代品（不在目錄中）
LM139AD
✅ 直接替換📋 參考替代品（不在目錄中）
LM339AD 最大額定值與電氣特性
| Comparator Count | 4 |
| Comparator Type | General-purpose differential comparator |
| 輸出類型 | Open-collector |
| 封裝 | 14-pin SOIC |
| Maximum Rating | Up to 38 V |
| Differential Input Voltage | ±38 V |
| Common-Mode Input Voltage | Includes ground |
| Low Input Offset Voltage | 0.37 mV |
| LM339A Maximum Input Offset Voltage | 2 mV max |
| Low Input Bias Current | 3.5 nA |
| 供應電流 | 200 μA per comparator |
| Response Time | 1.3 μs |
| Output Compatibility | TTL, MOS, and CMOS |
| ESD Rating HBM | 2 kV |
| Supply Configuration | Single supply |
| 安裝類型 | Surface mount |
LM339AD 14-pin soic 腳位配置指南
LM339AD（14-pin soic 封裝）的腳位配置。 此類比元件具有輸入、輸出與電源腳位。偏移歸零、補償與致能腳位配置請參閱製造商資料表。適用於訊號調理與放大器電路。
無詳細腳位定義資料： LM339AD.
請參閱 資料表 以查看完整腳位配置。
典型應用
LM339AD 適用於 6 應用s: Power-Supply Overvoltage and Undervoltage Detection, Industrial Sensor Threshold Conditioning, Relay and Solenoid Drive Logic, Battery and Automotive Monitoring, Zero-Cross and Window Detection, Logic-Level Interface and System Reset.
Power-Supply Overvoltage and Undervoltage Detection
The LM339AD fits multi-rail protection because it combines four independent differential comparator channels with a common-mode input range that includes ground. Each channel can compare a divided feedback voltage against a reference and then control an enable, crowbar, or relay circuit. The 38 V maximum rating and ±38 V differential input capability provide useful range for industrial power systems, while 200 μA supply current per comparator limits the continuous burden. Open-collector outputs allow multiple fault signals to share a pull-up when appropriate. The trade-off is that external resistor-divider accuracy, reference stability, and propagation delay determine the final protection threshold, so these components should be evaluated rather than assumed ideal.
推薦
Industrial Sensor Threshold Conditioning
The LM339AD is useful for converting slow or noisy industrial sensor signals into discrete logic decisions. Its 0.37 mV low input offset voltage helps preserve threshold accuracy, while the 3.5 nA input bias current limits disturbance of high-impedance sensing nodes. Four channels allow independent monitoring of temperature, pressure, level, or proximity conditions in one device. The 1.3 μs response time is suitable for many control and alarm loops rather than high-speed signal processing. Engineers should place the comparator close to the sensor interface, maintain the input common-mode voltage within limits, and use a pull-up resistor that meets the next-stage logic requirements.
推薦
Relay and Solenoid Drive Logic
The LM339AD can produce the decision signal used to energize relays, solenoids, and discrete driver stages. Its open-collector output is compatible with TTL, MOS, and CMOS systems and can pull down a driver input or fault line while a pull-up establishes the inactive state. The device's wide common-mode capability allows monitoring of system rails that may exceed the local logic voltage. Each comparator channel can implement a different threshold, reducing the number of discrete decision components. A flyback diode, adequate driver current, and protection against inductive transients remain external design requirements because the LM339AD is a logic-output comparator rather than a power driver.
推薦
Battery and Automotive Monitoring
The LM339AD supports multi-point battery and vehicle monitoring by comparing scaled voltages against thresholds and generating open-collector status signals. Four channels can monitor battery pack, charger, ignition, or accessory conditions, while the input rating of up to 38 V provides margin for transients in suitable 12 V or 24 V systems. The low 200 μA-per-comparator supply demand is advantageous in continuously powered equipment. Automotive production use should be based on the appropriate qualified grade rather than this general-purpose ordering option, and the final design must include input clamping, transient protection, ground-offset analysis, and pull-up selection for the vehicle logic network.
推薦
Zero-Cross and Window Detection
The LM339AD can implement AC zero-cross detection or a voltage-window function when paired with suitable input scaling and reference circuitry. Its differential inputs allow one channel to detect a signal crossing a threshold and another to establish an upper or lower boundary. The 1.3 μs response time provides useful timing margin for control systems, while the open-collector output can trigger a timer, optocoupler, or digital input. For AC-coupled signals, engineers must include input bias compensation to limit threshold shifts and account for common-mode and differential input limits. Environmental noise filtering and hysteresis also help prevent repeated switching when the sensed waveform crosses the threshold repeatedly.
推薦
Logic-Level Interface and System Reset
The LM339AD is appropriate for compact discrete logic interfaces because four open-collector comparator channels can monitor several system conditions and pull shared buses or control lines to defined states. Applications include supply-good signaling, reset generation, polarity detection, and compatibility adaptation between open-collector and positive logic systems. The wide common-mode range is valuable in systems where the sensed voltage is not equal to the logic supply. A resistor network establishes thresholds, while pull-up resistors define bus-high behavior. Designers must verify output sink current, input offset, and common-mode behavior across temperature and supply, and should not use the comparator as a general-purpose precision amplifier.
推薦
推薦產品摘要
工程參考資料，適用於 LM339AD — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | LM339AM | LM239ADT | LM339ADT | LM139AD |
|---|---|---|---|---|---|
| Package | 14-pin SOIC | 14-pin SOIC | 14-pin PDSO | 14-pin PDSO | 14-pin PDSO |
| Brand | Texas Instruments | Texas Instruments | STMicroelectronics | STMicroelectronics | STMicroelectronics |
| Comparator Count | 4 | 4 | 4 | 4 | 4 |
| Output Type | Open-collector | Open-collector | Open-collector | Open-collector | Open-collector |
主要差異化特點
- Lower specified input offset than the identified STMicroelectronics alternatives (對比LM339ADT)
- Wide differential input capability (對比LM339ADT)
- Four-channel integration with open-collector outputs (對比LM239ADT)
- Logic compatibility with multiple output technologies (對比LM139AD)
設計說明
Place the supply bypass capacitor close to the LM339AD power pins and route the power connection with low inductance. The comparator must include a pull-up resistor on each open-collector output; place that resistor near the receiving logic device when possible to minimize trace capacitance and susceptibility to noise. Maintain a continuous ground return, and keep sensitive input traces away from relay, motor, and switching-node wiring.
Do not treat the 38 V figure as a recommended operating supply. Use the absolute-maximum ratings and recommended operating limits from the manufacturer datasheet when choosing resistor ratios, transient protection, and power-supply headroom. Likewise, confirm that the common-mode voltage includes the actual signal range and that input source current remains within its limit. Open-collector outputs also require an external pull-up and cannot source current.
Add hysteresis around the switching threshold when noise or slow input slopes could cause repeated output transitions. Positive feedback through a resistor network can create a controlled switching gap without changing the pinout. For high-impedance sensors, account for input bias current and leakage paths, and use guarding or guarding-layout techniques if the source impedance is sufficiently high for input bias error to affect the decision threshold.
Estimated: four operating comparators at 200 μA each require 800 μA from the supply before external pull-up loading. This estimate uses the manufacturer specification of 200 μA per comparator and four active channels. Add the pull-up resistor current, input current, and application-specific margin when sizing the supply. The estimate is not a substitute for the manufacturer operating-current conditions.
合規資訊
The available manufacturer and distributor information does not state RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals status. The ESD rating listed as 2 kV HBM is an electrical immunity rating rather than an environmental compliance declaration.