LM317QDCYRQ1 - 500mA 40V Adjustable LDO | TI | Automotive
MPN： LM317QDCYRQ1 ✓ 啟用中LM317QDCYRQ1 概覽
An adjustable linear regulator (LDO-style series pass regulator) is a type of voltage regulator that maintains a stable output voltage by controlling the voltage drop across an internal series pass transistor. Within the power management IC hierarchy, the LM317 family sits in the classic NPN-darlington floating regulator category, renowned for decades of use across industrial and automotive power rails. The 'Q1' suffix indicates AEC-Q100 qualification and automotive temperature support.
Key features include a wide input voltage tolerance up to 40 V, 500 mA output current capability, internal thermal overload protection (thermal shutdown), and safe-operating-area current limiting. The floating architecture allows operation at high voltages, and the adjustable output enables a single design to cover multiple rail voltages simply by changing two resistors.
Technically, the device regulates the 1.25 V bandgap reference between the output and adjustment (ADJ) pin. The load and line regulation benefit from the low reference current, and the ADJ pin current of approximately 50 uA must be accounted for in the output divider calculation for best accuracy. Standard 1% resistors typically achieve output accuracy within a few percent.
Typical applications include automotive body electronics and infotainment auxiliary rails, industrial 12 V and 24 V bus post-regulation, and general-purpose adjustable bench or bias supplies where simplicity and robustness outweigh efficiency.
Design consideration: the device is a linear regulator, so power dissipation equals (VIN - VOUT) x ILOAD. The SOT-223 tab should be soldered to a generous copper pour; verify junction temperature stays below the datasheet maximum at worst-case load and input voltage.
直接替換替代品，適用於 LM317QDCYRQ1 — 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： LM317QDCYRQ1 （相同外形與佔位） — 差異在於 Maximum Output Current, Output Type, Protection Features, Reference Voltage.
LM317MQDCYRM3Q1
✅ 直接替換📋 參考替代品（不在目錄中）
LM317MQDCYR
✅ 直接替換📋 參考替代品（不在目錄中）
LM317MDCYR
✅ 直接替換📋 參考替代品（不在目錄中）
AP317K
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
LM317QDCYRQ1 最大額定值與電氣特性
| 輸出類型 | Positive Adjustable |
| 輸出數量 | 1 |
| 最大輸出電流 | 500 mA |
| Maximum Input Voltage | 40 V |
| 參考電壓 | 1.25 V (typical, LM317 family) |
| Regulation Type | Linear (series pass) |
| Qualification | Automotive (AEC-Q100, Q1) |
| 封裝 | SOT-223-4 (DCY) |
| 安裝類型 | Surface Mount |
| Protection Features | Thermal shutdown, current limit (LM317 family) |
LM317QDCYRQ1 腳位配置
| 腳位 1 | ADJ — Adjust pin - 1.25 V reference between this pin and output; set output with resistor divider |
| 腳位 2 | VOUT (Tab) — Regulated output voltage; tab doubles as thermal path |
| 腳位 3 | VIN — Input supply voltage, up to 40 V |
| 腳位 4 | GND/NC (Tab connection) — Package tab mounting surface; tie per reference layout |
典型應用
LM317QDCYRQ1 適用於 6 應用s: Automotive Auxiliary Power Rails, Industrial 24V Bus Post-Regulation, Adjustable Bench and Lab Supplies, Bias Supplies for Amplifiers and Sensors, Battery-Powered Equipment Charging / Float Rails, Infotainment and Cluster Subsystem Power.
Automotive Auxiliary Power Rails
The LM317QDCYRQ1 fits 12 V automotive battery-rail post-regulation because its Q1 automotive qualification and 40 V input tolerance handle harsh vehicle supply conditions. Placed after a pre-regulator or protected battery rail, it produces clean adjustable 3.3 V to 12 V auxiliary supplies for modules and sensors. As a linear regulator it adds no switching ripple, though dissipation of (VIN-VOUT) x ILOAD must be thermally verified.
推薦
Industrial 24V Bus Post-Regulation
The 40 V maximum input rating gives the LM317QDCYRQ1 comfortable headroom on industrial 24 V buses, where it provides low-noise adjustable rails for analog circuitry and control logic. Because linear regulation avoids switching noise, it suits sensor excitation and op-amp supplies. At large VIN-VOUT deltas and currents above 100 mA, thermal management via copper pour or a pre-regulator is essential.
推薦
Adjustable Bench and Lab Supplies
The classic two-resistor adjustable architecture (VOUT = 1.25 V x (1 + R2/R1)) makes the LM317QDCYRQ1 ideal for general-purpose adjustable supplies and module bias rails. Internal current limit and thermal shutdown provide inherent short-circuit robustness valued in bench and test equipment. The 500 mA rating covers most prototype loads, and the SOT-223 tab simplifies heatsinking on small PCBs.
推薦
Bias Supplies for Amplifiers and Sensors
Analog signal chains benefit from the LM317QDCYRQ1's ripple-free linear regulation when biasing amplifiers, ADC references, and sensor bridges from higher unregulated rails. The adjustable output allows tight tailoring of supply voltage to minimize device power dissipation in precision analog parts. Its 1.25 V reference stability and low output impedance keep bias points quiet across load transients.
推薦
Battery-Powered Equipment Charging / Float Rails
The LM317QDCYRQ1 can serve as a simple constant-voltage source for float-charging lead-acid or NiMH packs, with the resistor divider programmed to the required float voltage. Current limiting protects against deep-discharge loads, and thermal shutdown guards against fault conditions. The 40 V rating tolerates wide battery input ranges common in vehicle and portable industrial equipment.
推薦
Infotainment and Cluster Subsystem Power
Automotive infotainment modules use the LM317QDCYRQ1 to derive quiet local rails for tuner, audio, and display backlight bias circuits downstream of a main buck converter. The Q1 qualification supports AEC-Q100 supplier requirements, and the SOT-223 package mounts on standard infotainment PCBs. Post-regulation improves PSRR beyond what switching converters alone achieve for sensitive analog loads.
推薦
推薦產品摘要
工程參考資料，適用於 LM317QDCYRQ1 — 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 | LM317MQDCYRM3Q1 | LM317MQDCYR | LM317MDCYR |
|---|---|---|---|---|
| Package | SOT-223-4 (DCY) | SOT-223-4 (DCY) - same | SOT-223-4 (DCY) - same | SOT-223-4 (DCY) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Output Current | 500 mA | 500 mA | 500 mA | 500 mA |
| Output Type | Positive Adjustable | Positive Adjustable | Positive Adjustable | Positive Adjustable |
| Automotive Qualification | Yes (Q1) | Yes (Q1) | No | No |
| Output Configuration | 1 output, 3-terminal floating regulator | 1 output, 3-terminal floating regulator | 1 output, 3-terminal floating regulator | 1 output, 3-terminal floating regulator |
| Reference Voltage | 1.25 V (typical) | 1.25 V (typical) | 1.25 V (typical) | 1.25 V (typical) |
主要差異化特點
- Automotive AEC-Q100 qualification (對比LM317MQDCYR)
- Simplified drop-in second source (對比LM317MQDCYRM3Q1)
- 40 V input tolerance in SOT-223 (對比LM317MDCYR)
設計說明
Power dissipation equals (VIN - VOUT) x ILOAD. The SOT-223-4 tab must be soldered to a copper pour of at least 1 square inch for reliable dissipation above roughly 1 W. For example, 24 V in to 5 V out at 200 mA dissipates 3.8 W - too much for this package without a pre-regulator. Verify junction temperature against the datasheet maximum in worst-case hot conditions.
Place the output divider resistors close to the ADJ pin and use the standard LM317 practice of sizing divider current (typically 5 mA minimum) so the ADJ pin current error term is negligible. Add 0.1 uF and 10 uF input/output ceramics per the LM317M datasheet application section; output capacitance improves transient response and stability.
Do not exceed the 40 V absolute maximum input, including automotive load-dump transients - add upstream clamping if required. Without a bypass capacitor on ADJ, ripple rejection degrades; adding approximately 10 uF on ADJ improves PSRR but requires a protection diode for output short-circuit conditions, as described in classic LM317 application notes.
合規資訊
Q1 suffix denotes automotive qualification per TI product page. RoHS/REACH/lead-free status not stated in verified web data - confirm on TI product page.
