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Texas Instruments LM317MQDCYRG4
- Part No.:
- LM317MQDCYRG4
- Manufacturer:
- Texas Instruments
- Package:
- TO-261-4, TO-261AA
- Datasheet:
-
LM317MQDCYRG4.pdf
- Description:
- IC REG LIN POS ADJ 500MA SOT223
- Quantity:
- Payment:
- Shipping:
Inventory:2,370
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Product details
Overview
LM317MQDCYRG4 from Texas Instruments is a 3-terminal adjustable positive linear voltage regulator in SOT-223 package, delivering up to 500 mA output current with 1.25 V to 37 V programmable output range, ±1.5% load regulation, and 1.25 V internal reference voltage. It serves as a precision floating regulator in power supplies for medical instrumentation, point-of-sale terminals, and appliance control boards.
For engineers reviewing the LM317MQDCYRG4 datasheet, LM317MQDCYRG4 pinout, LM317MQDCYRG4 application, or LM317MQDCYRG4 equivalent, this page delivers verified technical context, thermal performance data, real-world transient response behavior, and validated alternative options for industrial-grade analog power design.
Technical Context
The LM317MQDCYRG4 implements a floating NPN Darlington pass element architecture with feedback referenced to the OUTPUT terminal-not ground-enabling high-voltage operation (up to 40 V input-to-output differential) and use as a current source. Its 1.25 V bandgap reference is stable across −40°C to +125°C operating junction temperature.
Internal protection includes thermal shutdown, safe-area compensation, and short-circuit current limiting that remains active even if the ADJUST terminal is disconnected. Quiescent current flows to the load rather than ground, improving efficiency in low-power configurations.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 500 mA max - supports mid-power analog rails without external boost transistors |
| Output Voltage Range | 1.25 V to 37 V - set by two external resistors; enables flexible system-level voltage scaling |
| Reference Voltage | 1.25 V ±0.05 V - stable bandgap reference enabling <±1% output accuracy with proper resistor tolerance |
| Line Regulation | 0.07 %/V max - ensures minimal output drift under input supply variation (e.g., unregulated wall adapters) |
| Ripple Rejection | 66 dB at 120 Hz - suppresses AC line ripple without requiring large input capacitors |
| Thermal Resistance θJA | 60.2 °C/W - requires heatsinking above ~1.5 W dissipation in still-air SOT-223 layout |
| Adjust Terminal Current | 50–100 μA - must be accounted for in R1/R2 divider design to avoid output voltage error |
Pinout & Package
SOT-223 (DCY) 4-pin thermally enhanced plastic package with exposed thermal pad; 6.5 mm × 3.5 mm footprint; 1.8 mm typical height; RoHS-compliant NiPdAu lead finish; MSL Level-2-260°C-1 year.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Tab/Exposed Pad) | Thermal Ground / Electrical GND | Internally connected to OUTPUT; must be soldered to PCB copper pour for thermal management and EMI control |
| 2 (OUTPUT) | Regulated Output Terminal | Delivers stabilized voltage; bias current flows here; connects to load and R1 of feedback divider |
| 3 (INPUT) | Unregulated Input Terminal | Accepts 2.5 V to 40 V above OUTPUT; requires ≥2.5 V headroom for regulation |
| 4 (ADJUST) | Feedback Reference Terminal | Senses 1.25 V below OUTPUT; sets output via R1–R2 divider; bypass capacitor improves ripple rejection |
Key Features
| Feature | Design Value |
|---|---|
| Floating regulator topology | Enables output voltages >100 V when referenced to ground-no device ground pin required |
| Internal safe-area compensation | Prevents thermal runaway during overload by dynamically limiting power dissipation in the pass transistor |
| Adjust terminal bypass support | Capacitor on ADJUST pin boosts ripple rejection beyond 60 dB without destabilizing loop response |
| Load current delivery to OUTPUT | Quiescent current flows into load instead of ground-reduces wasted power in battery-powered systems |
| Automotive-grade qualification | Qualified per AEC-Q100 Grade 3 (−40°C to +125°C); suitable for automotive body electronics and infotainment power rails |
Applications
| Medical Instrumentation | Point-of-Sale Terminals |
|---|---|
Use Scenario: Precision analog front-end power for ECG signal conditioning circuits requiring ultra-low noise and stable 3.3 V or 5 V rails. IC Role / Device Role / Timing Role: Adjustable linear regulator providing clean, ripple-free bias for op-amps and ADC references. Use Value: 0.003% RMS output noise and 66 dB ripple rejection maintain SNR integrity in sub-microvolt signal paths. |
Use Scenario: Compact 12 V → 5 V conversion for embedded payment processors and display backlight drivers in retail kiosks. IC Role / Device Role / Timing Role: Primary DC-DC stage delivering regulated bus voltage to microcontroller and interface ICs. Use Value: SOT-223 thermal pad enables 500 mA continuous output without external heatsink in space-constrained enclosures. |
| Home Appliance Control | Set-Top Box Power Management |
Use Scenario: Low-cost, robust 3.3 V supply for MCU and sensor interfaces in washing machine main control boards. IC Role / Device Role / Timing Role: Main system regulator handling wide input variations from rectified AC mains (12–36 V). Use Value: 40 V max input-to-output differential tolerates brownouts and surge events common in white goods environments. |
Use Scenario: Secondary 1.8 V or 2.5 V rail generation for SoC I/O domains in cable/satellite receivers. IC Role / Device Role / Timing Role: Post-regulator stabilizing switched-mode supply outputs against load transients. Use Value: 100 μA adjust current and tight line/load regulation preserve voltage margins during HDMI hot-plug events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable linear regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM317MDCYRG4 | Same SOT-223 package and electrical specs; differs only in lead finish (Sn vs NiPdAu) and MSL rating (Level-2 vs Level-2) | No functional difference; identical thermal and electrical performance in production PCBs | Select LM317MDCYRG4 for standard Sn-finish compatibility with legacy reflow profiles |
| LM317LDG | SOIC-8 package; lower 100 mA output; tighter 1% reference voltage tolerance; no exposed thermal pad | Not suitable for >200 mA loads or high-temperature ambient designs due to higher θJA (120 °C/W) | Choose LM317LDG only for low-current, space-constrained logic-supply applications where thermal margin is ample |
Compared with LM317MQDCYRG4, LM317MDCYRG4 offers identical performance with Sn finish for broader process compatibility, while LM317LDG trades output capability and thermal performance for smaller footprint-making LM317MQDCYRG4 optimal for mid-power industrial analog rails demanding reliability and thermal headroom.
Availability
LM317MQDCYRG4 is available at Aetrix Electronics and suitable for medical instrumentation, point-of-sale terminals, and home appliance control systems requiring stable component supply, long-term lifecycle assurance, and automotive-grade reliability.
Supply support for LM317MQDCYRG4 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
Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with over 90 years of innovation in power management, signal chain, and industrial ICs.
The LM317M series was designed for rugged, cost-sensitive linear regulation in industrial, medical, and consumer equipment-emphasizing simplicity, fault resilience, and wide operating voltage range without external compensation.
FAQ
What is the maximum input-to-output voltage differential for LM317MQDCYRG4?
The absolute maximum input-to-output differential voltage for LM317MQDCYRG4 is 40 V, as specified in the Absolute Maximum Ratings table. Operation beyond this limit risks permanent damage. For reliable continuous operation, TI recommends staying within 37 V differential under recommended conditions, especially at elevated temperatures.
Does LM317MQDCYRG4 require an input bypass capacitor?
LM317MQDCYRG4 does not require an input bypass capacitor for stability, but TI strongly recommends a 0.1 µF ceramic capacitor placed close to the INPUT and OUTPUT pins if the device is located more than six inches from the bulk input filter capacitor. This prevents oscillation and improves transient immunity in noisy power environments.
How is output voltage calculated for LM317MQDCYRG4?
LM317MQDCYRG4 output voltage is calculated using VO = 1.25 V × (1 + R2/R1) + IADJ × R2, where R1 connects OUTPUT to ADJUST, R2 connects ADJUST to ground, and IADJ is typically 50–100 µA. For most designs, the IADJ × R2 term is negligible if R2 ≤ 10 kΩ, simplifying to VO ≈ 1.25 V × (1 + R2/R1).
Can LM317MQDCYRG4 be used as a constant-current source?
Yes, LM317MQDCYRG4 can function as a precision constant-current source by connecting a single resistor R between OUTPUT and LOAD, with LOAD returned to ADJUST. The current is IOUT = 1.25 V / R. This configuration leverages the fixed 1.25 V reference and eliminates dependency on input voltage variation.
What thermal considerations apply to LM317MQDCYRG4 in SOT-223 package?
LM317MQDCYRG4 in SOT-223 has θJA = 60.2 °C/W. With 1 W dissipation, junction temperature rise is ~60°C above ambient. To stay within the 125°C max operating junction temperature, keep ambient ≤65°C when dissipating 1 W-or reduce power, improve PCB copper area, or add airflow. The exposed thermal pad must be soldered to ≥1 cm² of inner-layer copper for effective heat transfer.
LM317MQDCYRG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- TO-261-4, TO-261AA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Output Configuration:
- Positive
- Output Type:
- Adjustable
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.25V
- Voltage - Output (Max):
- 37V
- Voltage Dropout (Max):
- -
- Current - Output:
- 500mA
- Current - Quiescent (Iq):
- 10 mA
- Current - Supply (Max):
- -
- PSRR:
- 80dB ~ 65dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Current, Over Temperature, Short Circuit
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-223-4
LM317MQDCYRG4 FAQ
1.How can I place an order for LM317MQDCYRG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM317MQDCYRG4 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 LM317MQDCYRG4 reliable?
The price and inventory of LM317MQDCYRG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM317MQDCYRG4 is usually 5 days.
3.What payment methods are accepted for LM317MQDCYRG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM317MQDCYRG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM317MQDCYRG4?
LM317MQDCYRG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM317MQDCYRG4 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 LM317MQDCYRG4?
For technical support, including LM317MQDCYRG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM317MQDCYRG4 requirements.
6.How does Aetrix verify that LM317MQDCYRG4 is sourced from the original manufacturer or authorized distributors?
All LM317MQDCYRG4 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 LM317MQDCYRG4 meets industry standards.
7.What is the process for return or replacement of LM317MQDCYRG4?
All LM317MQDCYRG4 units undergo pre-shipment inspection (PSI). If there is an issue with LM317MQDCYRG4, 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 LM317MQDCYRG4 part is unused and in its original packaging.
Return procedure for LM317MQDCYRG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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