STMicroelectronics LD1117V25C

Overview

LD1117V25C from STMicroelectronics is a fixed-output 2.5 V, low-dropout linear voltage regulator delivering up to 800 mA output current with 1.1 V typical dropout at 800 mA, ±1 % output voltage tolerance at 25 °C, and 75 dB supply voltage rejection at 120 Hz - used for post-regulation in industrial power supplies and embedded microcontroller core voltage stabilization.

For engineers reviewing the LD1117V25C datasheet, LD1117V25C pinout, LD1117V25C application, or LD1117V25C equivalent, key selection criteria include dropout voltage under full load, thermal resistance in SOT-223 package, output voltage accuracy across -40 to +125 °C, and minimum 10 µF output capacitor requirement for stability.

Technical Context

The LD1117V25C employs an NPN pass transistor architecture, enabling high efficiency by routing quiescent current primarily into the load rather than ground - unlike PNP-based regulators. Its internal bandgap reference and trimming circuitry achieve ±1 % initial output tolerance at 25 °C.

It integrates thermal shutdown and current limiting, operates with input voltages up to 15 V, and maintains regulation down to a 1.1 V dropout at 800 mA over the full -40 to +125 °C junction temperature range. Stability requires only a 10 µF aluminum or tantalum output capacitor.

Key Specifications

Pinout & Package

LD1117V25C is supplied in SOT-223 package (standard for this variant), with exposed tab electrically connected to VOUT for thermal conduction and mechanical anchoring.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-25CDCYR and MCP1703T-2502E/MB, the LD1117V25C uniquely balances 800 mA drive, 1.1 V dropout, ±1 % accuracy, and 75 dB PSRR in SOT-223 - making it optimal for industrial and automotive subsystems requiring robust mid-current regulation.

Availability

LD1117V25C is available at Aetrix Electronics and suitable for industrial PLCs, medical sensor modules, automotive body control units, and embedded MCU power rails requiring stable component supply with long-term lifecycle support.

Supply support for LD1117V25C 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, designing and manufacturing analog, power, microcontroller, and sensor solutions for industrial, automotive, and consumer markets.

The LD1117 series belongs to ST's legacy linear regulator product line, engineered specifically for cost-effective, thermally robust, and easy-to-use voltage regulation in space- and reliability-constrained embedded systems.

FAQ

What is the minimum output capacitor required for LD1117V25C stability?

The LD1117V25C requires a minimum 10 µF aluminum or tantalum capacitor on the output for guaranteed stability across all operating conditions. Ceramic capacitors may be used if ≥10 µF and ≥10 mΩ ESR is added externally; ST does not guarantee stability with low-ESR ceramics alone.

Can LD1117V25C operate with a 3.3 V input supply?

Yes - with a 3.3 V input, the LD1117V25C maintains regulation as long as the dropout condition is met: VIN ≥ (2.5 V + Vd). At 800 mA, Vd = 1.1 V, so 3.3 V input provides 0.7 V margin. Derating is recommended above 500 mA due to thermal limits in SOT-223 without heatsink.

Does LD1117V25C have reverse polarity or reverse current protection?

No - the LD1117V25C lacks internal reverse-voltage or reverse-current protection. If the output voltage exceeds the input (e.g., during shutdown or fault), current flows backward through the pass device, potentially damaging upstream circuitry. An external series diode or ideal diode controller is required for such scenarios.

How does the SOT-223 package affect thermal performance in continuous operation?

In SOT-223, the LD1117V25C has R_thJA = 110 °C/W. At 800 mA and 1.1 V dropout (0.88 W dissipation), junction temperature rise is ~97 °C above ambient - limiting continuous operation to ≤50 °C ambient without PCB copper thermal relief. Doubling copper area reduces R_thJA by ~25 %.