STMicroelectronics LD1117ADT25TR

Overview

LD1117ADT25TR from STMicroelectronics is a fixed-output 2.5 V low-dropout linear voltage regulator delivering up to 1 A output current in DPAK (TO-252) package, featuring 1.15 V typical dropout at 1 A, ±2% output voltage tolerance at 25 °C, and 80 dB supply voltage rejection at 120 Hz - used for post-regulation of 3.3 V or 5 V rails in embedded power management.

For engineers reviewing the LD1117ADT25TR datasheet, LD1117ADT25TR pinout, LD1117ADT25TR application, or LD1117ADT25TR equivalent, key selection criteria include dropout voltage at full load, thermal resistance (R_thJA = 100 °C/W), minimum 10 µF output capacitance requirement, and internal current/thermal protection - all critical for stable 2.5 V supply in space-constrained industrial PCBs.

Technical Context

The LD1117ADT25TR employs an NPN pass transistor architecture enabling low dropout while maintaining high PSRR and thermal stability. Its reference voltage is internally trimmed to achieve ±2% accuracy at 25 °C and 0.5% temperature stability across 0–125 °C operating range.

It integrates internal current limiting and thermal shutdown with automatic recovery, and requires only a single 10 µF aluminum or tantalum capacitor on the output for stability - no external compensation needed. Quiescent current remains at 5 mA typ. across input voltages up to 10 V.

Key Specifications

Pinout & Package

DPAK (TO-252) package with exposed thermal pad connected to V_OUT; compact surface-mount footprint (6.0 × 6.6 mm) optimized for thermal performance and board area efficiency.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LD1117DT25TR, the LD1117ADT25TR offers tighter initial accuracy critical for analog references; versus TLV1117-25CDR, it delivers superior thermal performance in DPAK and higher PSRR - making it optimal for industrial 2.5 V power where stability and ruggedness are prioritized.

Availability

LD1117ADT25TR is available at Aetrix Electronics and suitable for industrial automation, telecom infrastructure, and test equipment requiring stable component supply with guaranteed long-term manufacturability and consistent parametric performance.

Supply support for LD1117ADT25TR 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, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The LD1117A series is part of ST's high-reliability linear regulator product line, engineered specifically for industrial-grade power integrity - emphasizing thermal robustness, wide-temperature operation, and minimal external component count.

FAQ

What is the minimum input voltage required for LD1117ADT25TR to maintain regulation at 1 A load?

The minimum input voltage is calculated as V_OUT + V_DROP = 2.5 V + 1.30 V (max dropout @ 1 A) = 3.8 V. At 25 °C, typical dropout is 1.15 V, so 3.65 V suffices. Operation below 3.8 V risks dropout under worst-case conditions including high temperature and process variation.

Can LD1117ADT25TR be used with ceramic output capacitors?

Yes, but only if a 1 Ω damping resistor is placed in series with the ceramic capacitor. The datasheet specifies stability with ≥10 µF aluminum/tantalum capacitors; ceramic types have near-zero ESR and may cause oscillation without added resistance per ST application note AN2819.

Is the thermal pad of the DPAK package electrically connected, and how should it be handled on the PCB?

Yes, the exposed thermal pad is internally connected to V_OUT. It must be soldered to a dedicated copper pour tied directly to the 2.5 V net - not left floating or grounded. This connection reduces R_thJA by up to 30 °C/W and is mandatory for safe 1 A operation at elevated ambient temperatures.

Does LD1117ADT25TR support reverse-voltage protection?

No. The device lacks intrinsic reverse-battery or reverse-polarity protection. Applying reverse voltage (e.g., V_OUT > V_VIN) can cause destructive current flow through the internal substrate diode. An external series Schottky diode is required in applications prone to back-driving or hot-swap events.