LM317DCYR - 1.5A Adjustable Positive Regulator | Texas Instruments
料号： LM317DCYR ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $0.62 | $0.62 |
| 10 | $0.56 | $5.60 |
| 100 | $0.45 | $45.00 |
| 500 | $0.33 | $165.00 |
| 1,000 | $0.21 | $210.00 |
LM317DCYR 概述
A linear regulator maintains a constant output voltage by dissipating excess power as heat. The LM317 is an adjustable linear regulator whose output is programmed by a resistor divider, with a fixed 1.25V reference between the output and adjustment pins. Linear regulators belong to the broader power management IC family, alongside switching regulators and LDOs, and are preferred in noise-sensitive circuits for their low output noise and fast transient response.
Key features include typical line regulation of 0.01% and load regulation of 0.1%, plus internal short-circuit current limiting, thermal overload protection, and safe-area compensation. The device supports input voltages up to 40V, with a typical dropout voltage of about 2.5V at 1.5A load. The junction temperature range of 0C to 125C covers commercial and industrial requirements.
Architecturally, the LM317 uses a bandgap reference and error amplifier. The 1.25V reference across the programming resistor makes the device double as a precise constant-current source, useful for LED driving and battery charging. The SOT-223-4 package offers good thermal performance with a reasonable PCB copper area, and the tab is connected to the output pin for direct heatsinking to a copper pour.
Typical applications include adjustable bench power supplies, battery chargers, LED constant-current drivers, audio equipment, instrumentation, and industrial control systems where a stable adjustable rail is required.
Design tip: maintain at least a 3V input-output differential for regulation, size copper pour for thermal dissipation, and bypass the adjustment pin with a capacitor to improve ripple rejection.
直接替换替代料： LM317DCYR ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
本系列中的变体
可与以下型号直接替换的同系列型号： LM317DCYR （相同外形与封装尺寸） ——差异在于 Maximum Output Current, Output Type, Protection Features, Reference Voltage.
快速对比工具——选择替代料号进行并排对比：
LM317QDCYRQ1
✅ 直接替换✓ 有现货
$0.31 / 个
查看数据手册 →LM317MDT
⚡ 相同封装 ⚠️ 规格未核验📋 参考替代料（不在目录中）
LM317D2TR4G
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
LM317S-13
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
LM317DCY
✅ 直接替换📋 参考替代料（不在目录中）
LM317DCYR 最大额定值与电气特性
| 输出类型 | Adjustable positive |
| 输出电压范围 | 1.25 V to 37 V |
| 最大输出电流 | > 1.5 A |
| Maximum Input Voltage | 40 V |
| Line Regulation | 0.01% (typical) |
| Load Regulation | 0.1% (typical) |
| 基准电压 | 1.25 V (VOUT to ADJ) |
| 压差电压 | Approximately 2.5 V at 1.5 A load |
| Protection Features | Current limiting, thermal overload, safe-area compensation |
| 工作结温 | 0C to +125C |
| 封装 | SOT-223-4 (DCY) |
| 安装类型 | Surface Mount |
| Number of Terminals | 4 (3-terminal regulator + tab) |
| External Components | 2 resistors set output voltage |
| RoHS 状态 | Compliant |
LM317DCYR 引脚配置
| 引脚 1 | ADJ — Adjustment pin - 1.25V reference between this pin and output; connect resistor divider here |
| 引脚 2 | OUT — Regulated output voltage (also connected to tab for heatsinking) |
| 引脚 3 | VIN — Input supply voltage, up to 40V |
| 引脚 4 | TAB — Mechanical tab connected to OUT for thermal dissipation to copper pour or heatsink |
典型应用
LM317DCYR 适用于 6 应用s: Adjustable Bench Power Supplies, Battery Chargers, LED Constant-Current Drivers, Audio Equipment Power Rails, Industrial Control and Instrumentation, Post-Regulation After Switching Converters.
Adjustable Bench Power Supplies
The LM317DCYR is the classic core of DIY and lab adjustable bench supplies. Its 1.25V to 37V output range with a simple two-resistor programming network lets designers dial in any rail without firmware or external controllers. With 1.5A capability, 0.01% line regulation and 0.1% load regulation, output remains stable across line and load steps, while internal current limiting and thermal shutdown provide fault tolerance. A potentiometer in place of R2 gives continuous adjustment; the tab can be soldered to a copper area or heatsink for higher dissipation.
推荐
Battery Chargers
Per the TI datasheet typical applications, the LM317DCYR serves as a simple lead-acid or NiCd charger by programming a current-limited, voltage-regulated output with two resistors plus a series resistor for current limiting. The 1.25V reference between OUT and ADJ makes constant-current charging trivial: charging current equals 1.25V divided by the sense resistor. Input voltage up to 40V supports charging from automotive or unregulated adapter rails, while built-in thermal overload and safe-area compensation protect against fault conditions during long charge cycles.
推荐
LED Constant-Current Drivers
The LM317DCYR doubles as a linear constant-current LED driver because the fixed 1.25V across the ADJ-to-OUT resistor defines LED current: I = 1.25V / R. An 8.3 ohm resistor yields 150mA; a 1.25 ohm resistor yields 1A. This topology needs no inductors or controller ICs, costs pennies, and inherits the LM317's thermal shutdown and current limiting as intrinsic protection. Trade-off: efficiency is limited to roughly VLED/VIN, so it suits low- and medium-power indicator and accent lighting rather than high-efficiency luminaires.
推荐
Audio Equipment Power Rails
Linear regulation eliminates switching noise, and the LM317DCYR provides quiet analog rails for preamps, headphone amplifiers, and op-amp stages. Unlike buck converters, it injects no switching ripple, and adding a 10uF bypass capacitor on the ADJ pin raises ripple rejection further per the TI datasheet. With 0.01% line regulation, supply-induced hum and noise stay minimal. Place it downstream of a rectifier or preregulator with at least 3V headroom, and budget copper area for the (VIN - VOUT) x ILOAD dissipation at high listening currents.
推荐
Industrial Control and Instrumentation
In factory controllers, sensor front ends, and instrumentation, the LM317DCYR generates well-regulated intermediate or analog rails from 24V-class industrial supplies, thanks to its 40V input rating. Internal short-circuit current limiting, thermal overload protection, and safe-area compensation give robust behavior under fault and brownout conditions common in industrial environments. The surface-mount SOT-223-4 package withstands reflow assembly for automated production, and its two-resistor programming lets one PCB design support multiple rail voltages by changing a single resistor value.
推荐
Post-Regulation After Switching Converters
A common architecture pairs the LM317DCYR after a buck converter to strip switching ripple and tighten load regulation for sensitive analog loads. The buck handles the high-efficiency bulk step-down; the LM317 provides a clean final rail with 0.1% load regulation. Because the preregulator holds VIN-VOUT small, the linear stage dissipates little power, combining switching efficiency with linear-rail cleanliness. Keep at least 3V of headroom for LM317 regulation, and use 10uF input and output ceramics with an ADJ bypass capacitor for best transient and ripple performance.
推荐
推荐产品汇总
工程参考数据： LM317DCYR ——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 | LM317QDCYRQ1 | LM317D2TR4G | LM317S-13 |
|---|---|---|---|---|
| Package | SOT-223-4 (DCY) | SOT-223-4 (DCY) - same | SOT-223 - same footprint | SOT-223 - same footprint |
| Brand | Texas Instruments | Texas Instruments | onsemi | Diodes Incorporated |
| Output Voltage Range | 1.25 V to 37 V | 1.25 V to 37 V | 1.25 V to 37 V | 1.25 V to 37 V |
| Output Current | > 1.5 A | > 1.5 A | > 1.5 A | > 1.5 A |
| Automotive Grade (AEC-Q100) | No | Yes (Q1) | No | No |
关键差异点
- Automotive-qualified variant available on same footprint （对比 LM317QDCYRQ1)
- Wide 40V input and 37V output range （对比 LM317S-13)
- Only two external resistors for full adjustability （对比 Fixed-output LDOs (e.g., TPS7133QDR))
设计说明
Power dissipation is (VIN - VOUT) x ILOAD. At 12V in, 5V out, 1A load, the LM317DCYR dissipates 7W, far beyond what a bare SOT-223 can handle. Connect the output tab to a generous copper pour (1 square inch or more) or an external heatsink, and verify junction temperature stays below 125C. Keep at least 3V input-output differential for guaranteed regulation per the TI datasheet.
Place the programming resistors close to the ADJ pin to keep the sense path short and noise-free. Use 0.1uF ceramic input bypass if the regulator is more than a few inches from the input filter capacitor, and 1uF or 10uF tantalum/ceramic on the output for transient response. The tab (OUT) copper area serves double duty as electrical connection and heatsink.
Do not omit the output capacitor if the ADJ pin is bypassed - an output capacitor without proper diode protection can discharge into the regulator on input short, damaging it. Add a protection diode from OUT to IN if input shorts are possible and output capacitance exceeds about 10uF. Ensure the ADJ pin leakage path resistor (R1, typically 240 ohm) is always present or the output floats high.
合规信息
RoHS compliant per TI product page. AEC-Q100 qualification applies to the LM317QDCYRQ1 variant, not the standard LM317DCYR. REACH and halogen-free status not stated in provided data.
