STMicroelectronics LD1117DT25CTR

Overview

LD1117DT25CTR from STMicroelectronics is a fixed-output 2.5 V, 800 mA low-dropout linear voltage regulator in SOT-223 package, featuring 1.0 V typical dropout at 100 mA, ±1 % output voltage tolerance at 25 °C, and 75 dB supply voltage rejection. It serves as a primary post-regulator in embedded power rails for microcontrollers, sensors, and analog circuitry requiring stable 2.5 V bias.

For engineers reviewing the LD1117DT25CTR datasheet, LD1117DT25CTR pinout, LD1117DT25CTR application, or LD1117DT25CTR equivalent, this page delivers verified electrical specs, thermal performance data, real-world use cases, and validated alternative options for industrial and automotive-grade power management designs.

Technical Context

The LD1117DT25CTR uses an NPN pass transistor architecture to minimize quiescent current consumption-most of which flows into the load rather than ground-enabling high efficiency at light loads. Its internal bandgap reference and trimming circuitry achieve ±1 % initial accuracy over temperature and time.

Stability requires only a 10 µF ceramic or tantalum output capacitor; no input capacitor is mandatory. Thermal shutdown and current limiting are integrated, with junction-to-case thermal resistance of 15 °C/W enabling 800 mA operation without forced airflow in SOT-223 mounting on ≥1 cm² copper area.

Key Specifications

Pinout & Package

SOT-223 package with exposed thermal tab electrically connected to V_OUT; compact footprint (6.5 × 3.5 mm) optimized for space-constrained PCBs while delivering superior thermal performance vs. SO-8 or DPAK in same power class.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-25CDCYR and AP2112K-2.5TRG1, the LD1117DT25CTR offers tighter initial accuracy, lower thermal resistance, and higher guaranteed current-making it the preferred choice for thermally demanding, precision-critical 2.5 V rails.

Availability

LD1117DT25CTR is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and medical wearable device production requiring stable component supply, long-lifecycle support, and traceable sourcing.

Supply support for LD1117DT25CTR 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, specializing in power management, microcontrollers, and automotive ICs with ISO/TS 16949-certified manufacturing.

The LD1117 product line delivers robust, cost-effective LDO regulators targeting industrial control, automotive subsystems, and consumer electronics where reliability and thermal resilience are essential.

FAQ

What is the minimum input voltage required for stable 2.5 V output at 800 mA?

The LD1117DT25CTR requires VIN ≥ VO + Vd, where Vd is 1.15 V max at 500 mA and 1.2 V max at 800 mA per datasheet Table 5. Thus, minimum input is 3.7 V for full 800 mA load. Below that, output drops or current limits activate. Derating is recommended above 85 °C ambient.

Can LD1117DT25CTR replace adjustable LD1117 variants in existing designs?

No-LD1117DT25CTR is a fixed 2.5 V version with only three pins (VIN, GND, VOUT); adjustable versions require four pins including ADJ. Pinout, feedback network, and internal reference differ fundamentally. Board redesign is necessary for substitution.

Is an input capacitor required for stability?

No input capacitor is mandatory per ST's datasheet (Section 4, Figure 4). However, a 1 µF ceramic capacitor placed near VIN improves transient response and reduces high-frequency noise coupling. Output capacitor (≥10 µF) is mandatory and must be low-ESR.

How does thermal performance compare between SOT-223 and DPAK packages?

SOT-223 has R_thJC = 15 °C/W and R_thJA = 110 °C/W; DPAK (TO-252) has R_thJC = 8 °C/W and R_thJA = 100 °C/W. DPAK offers better junction-to-case conduction but requires larger PCB area. SOT-223 achieves comparable board-level cooling with proper copper pour and is preferred for density-critical layouts.