STMicroelectronics LD1117AD2MTR

Overview

LD1117AD2MTR from STMicroelectronics is a fixed-output 3.3 V low-dropout linear voltage regulator delivering up to 1 A output current with 1.15 V typical dropout at full load and ±2% output voltage tolerance at 25 °C. It features internal current and thermal limiting, requires only a 10 µF output capacitor for stability, and operates across 0 °C to 125 °C junction temperature - commonly used in post-regulation of DC-DC converter outputs in embedded power rails.

For engineers reviewing the LD1117AD2MTR datasheet, LD1117AD2MTR pinout, LD1117AD2MTR application, or LD1117AD2MTR equivalent, key selection criteria include dropout voltage at 1 A, quiescent current under no-load, supply voltage rejection at 120 Hz, thermal resistance (R_thJA = 100 °C/W in DPAK), and compatibility with standard 3.3 V logic supply domains requiring high PSRR and tight DC accuracy.

Technical Context

The LD1117AD2MTR uses an NPN pass transistor architecture to achieve low dropout while maintaining stable regulation under dynamic load steps. Its reference voltage is trimmed to 3.3 V with ±2% initial accuracy at 25 °C and 0.5% temperature stability over full operating range.

It integrates thermal shutdown and foldback current limiting to protect against sustained overload or ambient overheating. The device achieves 80 dB typical supply voltage rejection at 120 Hz with 1 V_PP ripple input and maintains <0.2 %/W thermal regulation drift during transient power dissipation events.

Key Specifications

Pinout & Package

LD1117AD2MTR is supplied in DPAK (TO-252) package with exposed thermal pad connected internally to V_OUT. The package provides optimized thermal performance for surface-mount applications requiring high current density and compact footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output LDO regulator applications.

Compared with TLV1117-33CDCR and MCP1700T-3302E/MB, LD1117AD2MTR uniquely balances 1 A capability, 1.15 V dropout, and DPAK thermal performance - making it the only drop-in solution for industrial 3.3 V rails requiring both high current and robust thermal management.

Availability

LD1117AD2MTR is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and automotive infotainment systems requiring stable component supply with guaranteed long-term manufacturability and traceable sourcing.

Supply support for LD1117AD2MTR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, power, microcontroller, and sensor solutions for industrial, automotive, and consumer markets.

LD1117AD2MTR belongs to ST's LD1117A family of low-dropout linear regulators engineered specifically for cost-sensitive, high-reliability industrial and embedded power management applications demanding tight DC accuracy and robust thermal behavior.

FAQ

What is the minimum input voltage required for LD1117AD2MTR to maintain 3.3 V regulation at 1 A?

The minimum input voltage is calculated as V_OUT + V_DROP = 3.3 V + 1.15 V = 4.45 V. At 1 A load and 25 °C, the typical dropout is 1.15 V; worst-case dropout is 1.30 V per datasheet Table 4, so 4.60 V ensures regulation across temperature and process variation. Input below this threshold causes output collapse.

Can LD1117AD2MTR be used with ceramic output capacitors?

Yes - the LD1117AD2MTR is stable with ceramic capacitors ≥10 µF and ESR as low as 10 mΩ. Unlike older LDOs, it does not require minimum ESR for phase margin; ceramic caps reduce size, cost, and ESL compared to electrolytics, and are recommended for high-frequency noise suppression.

Is the exposed thermal pad on the DPAK package electrically connected?

Yes - the exposed thermal pad is internally connected to the V_OUT pin. It must be soldered to a PCB copper pour tied to the 3.3 V output net to provide both thermal conduction and electrical continuity. Floating or grounding the pad will cause regulation failure or thermal runaway.

Does LD1117AD2MTR support reverse-voltage protection?

No - the device lacks integrated reverse-voltage protection. Applying reverse polarity to VIN or VOUT can damage the internal NPN pass transistor. External protection (e.g., series Schottky diode on input or back-to-back MOSFETs) is required in systems prone to accidental reverse connection or battery insertion errors.