Texas Instruments LM1117IMP-ADJ

Overview

LM1117IMP-ADJ from Texas Instruments is an adjustable low-dropout linear regulator delivering up to 800 mA output current with 1.25 V reference voltage, 1.2 V dropout at 800 mA, ±1% output voltage accuracy, and thermal shutdown protection. It serves as a post-regulator for DC–DC converters in embedded power rails requiring stable 1.25–13.8 V outputs.

For engineers reviewing the LM1117IMP-ADJ datasheet, LM1117IMP-ADJ pinout, LM1117IMP-ADJ application, or LM1117IMP-ADJ equivalent, this page provides verified package mapping (SOT-223), confirmed adjustable-output circuit role, validated thermal protection behavior, and real-world ripple rejection performance data.

Technical Context

The LM1117IMP-ADJ uses a Zener-trimmed bandgap reference to maintain ±1% output voltage accuracy across 0°C to 125°C. Its internal current limiting and thermal shutdown activate at ≥1200 mA and ≥150°C junction temperature respectively.

It requires a minimum 10-µF tantalum output capacitor for stability and transient response. The ADJ pin draws only 60 µA typical, enabling precise resistor-divider-based output programming without significant load error.

Key Specifications

Pinout & Package

SOT-223 (MP) package: 4-pin thermally enhanced surface-mount package with exposed tab (pin 2/TAB) serving as VOUT and thermal path. Body size 6.50 mm × 3.50 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-ADJ, LM1117IMP-ADJ offers identical current and dropout but lacks extended temperature qualification; versus MCP1703T-ADJ, it delivers 3.2× higher output current in a larger but thermally superior package.

Availability

LM1117IMP-ADJ is available at Aetrix Electronics and suitable for post-regulation, battery charging, and portable instrumentation applications requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.

Supply support for LM1117IMP-ADJ 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 company specializing in analog and embedded processing technologies, with leadership in power management ICs since the 1980s.

The LM1117 product line was designed for cost-sensitive, thermally demanding linear regulation tasks in industrial, computing, and communications equipment where reliability and simplicity are prioritized over ultra-low quiescent current.

FAQ

What is the minimum output capacitor required for stable operation of the LM1117IMP-ADJ?

The LM1117IMP-ADJ requires a minimum 10-µF tantalum capacitor at the output for guaranteed stability and transient response. This value is specified in the TI SNOS412N datasheet Section 8.2.2.1.3. Ceramic capacitors may be used if their ESR falls within the 0.3 Ω to 22 Ω range; however, 10 µF tantalum remains the baseline validation condition for all LM1117IMP-ADJ production units.

Can the LM1117IMP-ADJ be used with an input voltage of 2.5 V to generate 1.8 V output?

No, the LM1117IMP-ADJ cannot regulate 1.8 V output from a 2.5 V input. Its dropout voltage is 1.2 V at 800 mA, meaning VIN must exceed VOUT by at least 1.2 V. For 1.8 V output, minimum valid VIN is 3.0 V. Attempting 2.5 V input will result in unregulated, input-following behavior and potential thermal stress on the LM1117IMP-ADJ.

What is the purpose of the ADJ pin on the LM1117IMP-ADJ, and how is it connected?

The ADJ pin on the LM1117IMP-ADJ serves as the reference node for the internal 1.25 V bandgap. It connects to the midpoint of an external resistor divider (R1 between VOUT and ADJ, R2 between ADJ and GND) to set output voltage as VOUT = 1.25 V × (1 + R2/R1). The ADJ pin draws only 60 µA, enabling high-value resistors that minimize divider current loss in the LM1117IMP-ADJ design.

Does the LM1117IMP-ADJ include reverse-voltage or reverse-current protection?

No, the LM1117IMP-ADJ does not include reverse-voltage or reverse-current protection. If the output voltage exceeds the input (e.g., during hot-swap or backup battery scenarios), current can flow backward through the internal body diode, potentially damaging upstream sources. External protection diodes or MOSFET-based OR-ing circuits must be added when reverse conditions are possible in the system using LM1117IMP-ADJ.

How does thermal shutdown operate in the LM1117IMP-ADJ, and what happens after activation?

The LM1117IMP-ADJ activates thermal shutdown when junction temperature reaches approximately 150°C, halting output conduction to prevent damage. Once the die cools by ~15°C (hysteresis), regulation automatically resumes. This cycle repeats under sustained overload, protecting the LM1117IMP-ADJ but causing output voltage interruption - proper heatsinking or derating is required for continuous operation.