Texas Instruments LM1117DTX-2.85/NOPB

Overview

LM1117DTX-2.85/NOPB from Texas Instruments is a fixed-output, low-dropout linear voltage regulator delivering 2.85 V at up to 800 mA with 1.2 V dropout at full load, ±1% output voltage accuracy over 0°C to 125°C, and integrated thermal shutdown and current limiting - used in post-regulation stages of DC–DC converters and portable instrumentation power rails.

For engineers reviewing the LM1117DTX-2.85/NOPB datasheet, LM1117DTX-2.85/NOPB pinout, LM1117DTX-2.85/NOPB application, or LM1117DTX-2.85/NOPB equivalent, key selection criteria include dropout voltage at 800 mA, load regulation (≤10 mV), thermal resistance (R_θJA = 45.1°C/W in TO-252), minimum output capacitance (10 µF tantalum), and compatibility with fixed-voltage system rails requiring stable 2.85 V supply.

Technical Context

The LM1117DTX-2.85/NOPB implements a bandgap-referenced error amplifier driving a PNP pass transistor, enabling low dropout operation without external compensation. Its internal Zener-trimmed reference ensures ±1% initial output tolerance and 0.5% temperature stability across 0°C to 125°C.

It operates with a fixed 2.85 V output set by on-die resistor networks, eliminating external feedback components. Protection circuitry includes foldback current limiting (800–1500 mA trip range) and thermal shutdown triggered at 150°C junction temperature, with recovery upon cooldown.

Key Specifications

Pinout & Package

LM1117DTX-2.85/NOPB uses the TO-252 (DPAK) surface-mount package, 6.58 mm × 6.10 mm body, with exposed thermal pad for PCB heat sinking.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout linear regulator applications.

Compared with TLV1117-285CDR and LD1117S285TR, LM1117DTX-2.85/NOPB offers superior thermal performance in TO-252 (45.1°C/W), tighter ±1% output accuracy, and guaranteed 800 mA delivery across full temperature range - making it optimal for thermally constrained, precision 2.85 V applications.

Availability

LM1117DTX-2.85/NOPB is available at Aetrix Electronics and suitable for portable instrumentation, battery chargers, and post-regulation DC–DC converter applications requiring stable component supply, long-term lifecycle continuity, and traceable sourcing.

Supply support for LM1117DTX-2.85/NOPB 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 and high-reliability linear regulators.

The LM1117 product line was designed for cost-effective, robust low-dropout regulation in space-constrained and thermally demanding applications - targeting post-regulation, battery-powered, and industrial embedded systems.

FAQ

What is the minimum input voltage required for LM1117DTX-2.85/NOPB to maintain regulation at 800 mA?

The LM1117DTX-2.85/NOPB requires a minimum input voltage of 4.05 V to maintain regulation at 800 mA load, based on its maximum dropout voltage of 1.2 V (2.85 V + 1.2 V). Operation below this headroom causes output voltage collapse and loss of regulation. The datasheet specifies 3.2 V minimum input, but that applies only at lighter loads where dropout is lower.

Can LM1117DTX-2.85/NOPB be used with ceramic output capacitors?

Yes, LM1117DTX-2.85/NOPB supports ceramic output capacitors, but only if their equivalent series resistance (ESR) falls within the 0.3 Ω to 22 Ω range specified in the datasheet. Standard X7R/X5R ceramics often have ESR < 0.1 Ω and may cause instability; adding a 1–2 Ω series resistor or selecting specialty high-ESR ceramics ensures loop stability.

Does LM1117DTX-2.85/NOPB require an input capacitor?

Yes, LM1117DTX-2.85/NOPB requires an input bypass capacitor - typically 10 µF tantalum - to suppress high-frequency noise and prevent oscillation due to source impedance. Without it, line transients or PCB trace inductance can destabilize regulation, especially when sourced from switching converters or long cables.

What is the purpose of the exposed thermal tab on LM1117DTX-2.85/NOPB?

The exposed thermal tab on LM1117DTX-2.85/NOPB is electrically connected to Pin 1 (GND) and serves as the primary heat conduction path from the silicon die to the PCB. Soldering it to a copper thermal pad is mandatory to achieve the rated R_θJA of 45.1°C/W; omitting this connection raises junction temperature by >30°C at 800 mA, risking thermal shutdown.

How does LM1117DTX-2.85/NOPB handle short-circuit conditions?

LM1117DTX-2.85/NOPB employs foldback current limiting: under short-circuit, output current drops to ~300–500 mA (well below 800 mA nominal) to reduce power dissipation and prevent thermal runaway. Combined with thermal shutdown at 150°C, this dual protection enables safe indefinite short-circuit survival without damage when properly heatsunk.