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Texas Instruments LM317MQKTPR
- Part No.:
- LM317MQKTPR
- Manufacturer:
- Texas Instruments
- Package:
- TO-252-3, DPAK (2 Leads + Tab), SC-63
- Datasheet:
-
LM317MQKTPR.pdf
- Description:
- IC REG LIN POS ADJ 500MA TO252-3
- Quantity:
- Payment:
- Shipping:
Inventory:1,621
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Product details
Overview
LM317MQKTPR from Texas Instruments is a 3-terminal adjustable positive-voltage linear regulator delivering ≥500 mA output current, with programmable output voltage from 1.25 V to 37 V, input-to-output differential up to 40 V, and integrated thermal-overload and short-circuit protection. It serves as a floating regulator in power supply circuits for industrial instrumentation and embedded control systems.
For engineers reviewing the LM317MQKTPR datasheet, LM317MQKTPR pinout, LM317MQKTPR application, or LM317MQKTPR equivalent, key selection criteria include its PFM (KTP) package thermal performance, 1.25-V internal reference accuracy, ≤1.5% load regulation across temperature, ADJUST terminal current of 50–100 µA, and compatibility with ceramic or electrolytic output capacitors for transient response tuning.
Technical Context
The LM317MQKTPR implements a floating NPN Darlington pass element architecture with feedback referenced to the OUTPUT terminal-not ground-enabling high-precision voltage or current regulation without a device ground pin. Its 1.25-V bandgap reference feeds an error amplifier that controls the pass transistor to maintain VO = VREF × (1 + R2/R1) + IADJ × R2.
Operation requires ≥2.5-V headroom (VI – VO) for regulation; below this, dropout occurs. Internal safe-area compensation prevents thermal runaway during overload, while quiescent current flows entirely to the OUTPUT terminal-eliminating wasted ground current and supporting high-efficiency light-load operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | 1.25 V to 37 V - set by two external resistors; enables flexible rail generation without multiple fixed regulators |
| Max Output Current | 500 mA - sufficient for mid-power analog subsystems and sensor signal chains |
| Input-Output Differential | 2.5 V to 40 V - supports wide-input applications including unregulated DC supplies and battery-powered systems |
| Reference Voltage | 1.25 V ±0.05 V - stable internal reference enabling <1% output voltage tolerance with precision resistors |
| Load Regulation | ≤1.5% - ensures minimal output deviation across 10 mA to 500 mA load changes |
| Ripple Rejection | 65–80 dB - suppresses AC ripple at 120 Hz; improves with 10-µF capacitor on ADJUST terminal |
| Thermal Shutdown Threshold | 125 °C - protects against sustained overloads or insufficient heatsinking |
Pinout & Package
LM317MQKTPR uses the KTP (PFM) surface-mount package: 6.04 mm × 6.15 mm body, 3-pin configuration with exposed thermal pad, JEDEC TO-252-3 compatible footprint, and RoHS-compliant NiPdAu lead finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| INPUT | Unregulated input supply connection | Accepts 2.5–40 V above OUTPUT; must be bypassed with ≥0.1-µF capacitor if >6 inches from bulk filter |
| OUTPUT | Regulated output voltage node | Sources up to 500 mA; bias current flows here-must be consumed by load or feedback network to maintain regulation |
| ADJUST | Feedback reference input | Connected to resistor divider; 50–100 µA current flows into this pin, contributing to output voltage error if not accounted for in R2 selection |
Key Features
| Feature | Design Value |
|---|---|
| Floating regulator topology | Enables output voltages hundreds of volts above ground-only limited by VI–VO ≤40 V-ideal for high-side current sources and floating supplies |
| Internal safe-area compensation | Prevents thermal runaway under simultaneous high voltage and high current stress without external components |
| Adjust terminal bypass capability | Adding capacitor from ADJUST to ground improves ripple rejection by 10–15 dB and reduces noise sensitivity in sensitive analog rails |
| Thermal-overload and short-circuit protection | Self-resetting shutdown maintains reliability in fault conditions; no latch-up or manual reset required |
| No ground pin requirement | Eliminates ground loop errors and simplifies PCB layout in isolated or multi-rail systems |
Applications
| Industrial Process Transmitters | Programmable Bench Power Supplies |
|---|---|
Use Scenario: 4–20 mA loop-powered sensor transmitter requiring stable 5 V or 12 V local rail from variable loop voltage. IC Role / Device Role / Timing Role: Adjustable linear regulator providing isolated, low-noise bias for op-amps and ADCs within the transmitter. Use Value: Floating architecture allows direct derivation of regulated rail from loop voltage without auxiliary winding or isolation DC/DC-reducing BOM count and board area. | Use Scenario: Lab-grade bench supply with digitally controlled output voltage between 1.25 V and 30 V at up to 500 mA. IC Role / Device Role / Timing Role: Core voltage-setting element in analog control path, paired with DAC-driven resistor network. Use Value: 1.25-V reference stability and low load regulation (<1.5%) enable precise, repeatable voltage setting across full range without calibration drift. |
| Medical Patient Monitoring Front-Ends | Appliance Motor Control Logic Rails |
Use Scenario: Low-noise analog front-end for ECG or pulse oximetry modules requiring clean 3.3 V or 5 V supply. IC Role / Device Role / Timing Role: Post-regulator after switching supply, filtering switching noise and providing quiet bias for instrumentation amplifiers. Use Value: 65–80 dB ripple rejection with ADJUST bypass capacitor suppresses switching artifacts, meeting IEC 60601-1 EMC requirements for clinical devices. | Use Scenario: Powering microcontroller, gate driver logic, and sensor interfaces in washing machine or HVAC control boards. IC Role / Device Role / Timing Role: Main 5 V or 12 V system rail generator from unregulated DC bus derived from rectified AC line. Use Value: Integrated thermal and short-circuit protection ensures robustness against motor stall faults and relay contact arcing-no external crowbar needed. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable linear regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM317KTPR | Same electrical specs but standard-grade (non-automotive) qualification; TJ rating 0–125°C vs −40–125°C | Lacks AEC-Q100 qualification; unsuitable for automotive under-hood or safety-critical industrial use | Select LM317MQKTPR when extended temperature range and automotive-grade reliability are mandatory |
| TLV1117-33CDCYR | Fixed 3.3 V output, 800 mA max, lower dropout (1.2 V), no ADJUST pin-requires different circuit topology | Not adjustable; cannot replace LM317MQKTPR in variable-voltage or current-source designs | Choose only for cost-sensitive, fixed-rail applications where adjustability is unnecessary |
Compared with LM317KTPR, LM317MQKTPR adds automotive-grade temperature range and qualification-critical for harsh environments-while TLV1117-33CDCYR trades adjustability for higher current and lower dropout in fixed-rail roles, making it incompatible for reconfigurable power architectures.
Availability
LM317MQKTPR is available at Aetrix Electronics and suitable for industrial process transmitters, medical patient monitors, programmable lab power supplies, and appliance motor control systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LM317MQKTPR 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 designing analog ICs, embedded processors, and digital signal solutions for industrial, automotive, and consumer markets.
The LM317M product line delivers rugged, easy-to-use adjustable linear regulators optimized for reliability in harsh environments-including automotive, instrumentation, and white goods-where thermal resilience and long-term stability are essential.
FAQ
What is the maximum input-to-output voltage differential supported by LM317MQKTPR?
The LM317MQKTPR supports a maximum input-to-output differential voltage of 40 V under absolute maximum ratings. For reliable continuous operation, TI specifies 2.5 V to 37 V as the recommended operating range. Exceeding 40 V risks permanent damage-even momentarily-due to internal junction breakdown. Always ensure VI – VO remains within limits across all operating conditions, including startup surges and load transients, when using LM317MQKTPR in your design.
Does LM317MQKTPR require an output capacitor for stability?
No, LM317MQKTPR does not require an output capacitor for basic stability-unlike many LDOs. However, adding a 1–10 µF ceramic or tantalum capacitor at the OUTPUT terminal significantly improves transient response during load steps. Without it, output voltage may dip or overshoot under rapid current changes. TI confirms stability is maintained with or without CO, but design best practice strongly recommends one for dynamic loads. This behavior is intrinsic to the LM317MQKTPR's internal compensation and floating architecture.
How does the ADJUST terminal current affect output voltage accuracy in LM317MQKTPR?
The ADJUST terminal draws 50–100 µA (typical 75 µA), which flows through the lower feedback resistor R2 and introduces a voltage error term: ΔVO = IADJ × R2. For example, with R2 = 2.4 kΩ, this adds ~0.18 V error-exceeding typical 1% tolerance. To minimize impact, keep R2 ≤ 1 kΩ or use the standard 240-Ω R1 with R2 scaled accordingly. This current is a defined, measurable parameter of LM317MQKTPR-not parasitic-and must be included in precision output voltage calculations per Equation 2 in the datasheet.
Can LM317MQKTPR be used as a constant-current source?
Yes, LM317MQKTPR can be configured as a precision constant-current source by connecting a single resistor R between OUTPUT and ADJUST terminals, with the load returned to ground. Output current is IO = 1.25 V / R, leveraging the device's stable 1.25-V internal reference. This works because the regulator forces 1.25 V across R, making current independent of input voltage (within VI–VO limits) and load impedance. TI validates this mode in Section 7.3.3 and Figure 7 of the LM317MQKTPR datasheet, confirming ≤5% current accuracy with proper heatsinking.
What thermal considerations apply to LM317MQKTPR in the KTP (PFM) package?
LM317MQKTPR in the KTP (PFM) package has a junction-to-board thermal resistance (RθJB) of 9.4°C/W and requires a properly sized copper thermal pad per TI's KVU0003A layout guidelines. Without adequate board copper, junction temperature can exceed 125°C at full 500 mA load with 10 V drop-triggering thermal shutdown. TI recommends ≥1 in² of 2-oz copper connected to the exposed pad via ≥4 thermal vias. Derate output current linearly above 25°C ambient; at 85°C, max continuous current drops to ~350 mA for safe operation of LM317MQKTPR.
LM317MQKTPR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- TO-252-3, DPAK (2 Leads + Tab), SC-63
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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:
- TO-252-3
LM317MQKTPR FAQ
1.How can I place an order for LM317MQKTPR through Aetrix?
Please submit a Request for Quotation (RFQ) for LM317MQKTPR 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 LM317MQKTPR reliable?
The price and inventory of LM317MQKTPR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM317MQKTPR is usually 5 days.
3.What payment methods are accepted for LM317MQKTPR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM317MQKTPR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM317MQKTPR?
LM317MQKTPR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM317MQKTPR 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 LM317MQKTPR?
For technical support, including LM317MQKTPR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM317MQKTPR requirements.
6.How does Aetrix verify that LM317MQKTPR is sourced from the original manufacturer or authorized distributors?
All LM317MQKTPR 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 LM317MQKTPR meets industry standards.
7.What is the process for return or replacement of LM317MQKTPR?
All LM317MQKTPR units undergo pre-shipment inspection (PSI). If there is an issue with LM317MQKTPR, 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 LM317MQKTPR part is unused and in its original packaging.
Return procedure for LM317MQKTPR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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