Texas Instruments LM317MKTPRG3

Overview

LM317MKTPRG3 from Texas Instruments is a 3-terminal adjustable positive linear voltage regulator in PFM (Power Flat Module) package, delivering ≥500 mA output current with 1.25-V to 37-V programmable output range, ±1% reference voltage accuracy, and integrated thermal-overload and short-circuit protection. It serves as a precision floating regulator in lab power supplies, industrial control rails, and embedded bias generation where input-to-output differential up to 40 V is required.

For engineers reviewing the LM317MKTPRG3 datasheet, LM317MKTPRG3 pinout, LM317MKTPRG3 application, or LM317MKTPRG3 equivalent, key selection criteria include guaranteed 500-mA output current at 125°C junction temperature, 0.07% load regulation over full temperature range, ADJUST terminal current ≤100 μA, and compatibility with ceramic, tantalum, or electrolytic output capacitors for transient response optimization.

Technical Context

The LM317MKTPRG3 implements a floating NPN Darlington pass element architecture referenced to the OUTPUT terminal-not ground-enabling high line regulation (0.07%/V max) and load regulation (1.5%VO max). Its internal 1.25-V bandgap reference feeds an error amplifier that controls the pass transistor via feedback from the ADJUST terminal.

Operation requires minimum 2.5-V headroom (VI–VO) for regulation, with safe-area compensation preventing thermal runaway during overload. The ADJUST terminal draws only 50–100 μA, flowing into the load or feedback network, eliminating ground-referenced quiescent current waste.

Key Specifications

Pinout & Package

LM317MKTPRG3 uses the KTP (PFM) 3-pin surface-mount package (6.04 mm × 6.15 mm), featuring an exposed thermal pad for enhanced heat dissipation. The package is RoHS-compliant, green, and moisture-sensitivity level (MSL) 3 rated for 168-hour floor life at 260°C peak reflow.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable linear regulator applications.

Compared with LM317LDG4 and TLV1117LV33DCYR, LM317MKTPRG3 uniquely delivers field-programmable output voltage up to 37 V with 500-mA capability in a thermally robust PFM package-making it irreplaceable for applications requiring both wide-range adjustability and sustained high-current delivery under thermal stress.

Availability

LM317MKTPRG3 is available at Aetrix Electronics and suitable for industrial control systems, medical instrumentation, programmable power supplies, and white goods motor control requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for LM317MKTPRG3 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, embedded processing, and power management technologies, with decades of heritage in precision linear regulators.

The LM317 product line was engineered for high-reliability analog power management in industrial, medical, and test equipment-emphasizing wide input-output differential tolerance, intrinsic protection, and minimal external component count.

FAQ

What is the maximum input-to-output voltage differential supported by LM317MKTPRG3?

The LM317MKTPRG3 supports a maximum input-to-output differential voltage (VI–VO) of 40 V under absolute maximum ratings. For reliable continuous operation, TI specifies 37 V as the upper limit within recommended conditions. Exceeding 40 V risks permanent damage, even momentarily. This rating enables use in high-headroom applications such as unregulated 48-V bus step-down to 12-V rails, provided thermal design accommodates the resulting power dissipation in the LM317MKTPRG3.

Can LM317MKTPRG3 be used as a constant-current source?

Yes, LM317MKTPRG3 can function as a precision constant-current source by connecting a single resistor between OUTPUT and ADJUST terminals. The output current equals 1.25 V divided by the resistor value (IOUT = 1.25 V / R). For example, a 2.5-Ω resistor sets 500 mA. The LM317MKTPRG3's low ADJUST current drift (±5 μA over temperature) and stable 1.25-V reference ensure ±1% current accuracy. No additional components are required beyond the resistor and input/output capacitors.

What package type does LM317MKTPRG3 use, and what are its thermal characteristics?

LM317MKTPRG3 uses the KTP (PFM) package-a 3-pin surface-mount variant with an exposed thermal pad measuring 6.04 mm × 6.15 mm. Its junction-to-board thermal resistance (RθJB) is 9.4°C/W, enabling effective heat transfer to the PCB copper. Unlike TO-220 or TO-252, the PFM package integrates thermal performance into a compact footprint ideal for space-constrained industrial modules. Reflow profile must comply with MSL-3 requirements (260°C peak, 168-hour floor life).

Does LM317MKTPRG3 require input or output capacitors for basic operation?

No, LM317MKTPRG3 is stable without input or output capacitors under typical conditions. An input bypass capacitor (0.1 µF ceramic) is recommended only if the device is located >15 cm from bulk input filter capacitors. An output capacitor improves transient response but is not required for stability. A 10-µF electrolytic or tantalum capacitor at the ADJUST terminal significantly enhances ripple rejection-especially above 6 V output-though it necessitates a protection diode from ADJUST to OUTPUT per TI design guidelines.

How does the ADJUST terminal current affect output voltage accuracy in LM317MKTPRG3 designs?

The ADJUST terminal draws 50–100 μA, which flows through the R2 feedback resistor and introduces a voltage error term (IADJ × R2) in the output equation VO = 1.25 V × (1 + R2/R1) + IADJ × R2. For example, with R2 = 2.4 kΩ, this adds up to 240 mV of potential error. To minimize impact, keep R2 ≤ 1 kΩ or use a low-value R1 (e.g., 240 Ω) so R2 remains small. In high-accuracy applications, this error must be included in resistor tolerance and temperature coefficient budgeting for the LM317MKTPRG3.