STMicroelectronics LDL1117S25R

Overview

LDL1117S25R from STMicroelectronics is a fixed 2.5 V, 1.2 A low-dropout linear voltage regulator in SOT-223 package, featuring 350 mV typical dropout at full load, 87 dB PSRR at 120 Hz, and ±2% output accuracy at 25°C - designed for post-regulation in DC-DC converters and point-of-load (PoL) supplies on industrial motherboards.

For engineers reviewing the LDL1117S25R datasheet, LDL1117S25R pinout, LDL1117S25R application, or LDL1117S25R equivalent, key selection criteria include dropout performance under 1.2 A load, thermal shutdown threshold (175°C), SOA-limited short-circuit current (1.5–2 A), and stability with 4.7 µF ceramic output capacitance.

Technical Context

The LDL1117S25R employs a PNP pass transistor architecture enabling low dropout and high PSRR across frequency - 87 dB at 120 Hz, 80 dB at 1 kHz, and 65 dB at 100 kHz - making it suitable for noise-sensitive analog rails downstream of switching regulators. Its internal SOA protection dynamically limits peak current based on VIN–VOUT differential to prevent thermal runaway.

Thermal management integrates dual protection: junction shutdown at 175°C (with 25°C hysteresis) and differential thermal sensing that disables both channels during rapid thermal gradients. The device operates across –40°C to +125°C ambient, supported by θ_J-A = 120°C/W and θ_J-C = 15°C/W.

Key Specifications

Pinout & Package

SOT-223 package with exposed thermal tab connected internally to V_OUT; requires PCB copper pour under tab for optimal thermal dissipation (θ_J-C = 15°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-25CDR and MCP1703T-2502E/MB, the LDL1117S25R delivers 50% higher output current, 27 dB better PSRR at line frequency, and integrated SOA/thermal-differential protection - critical for reliability in industrial PoL and automotive infotainment designs.

Availability

LDL1117S25R is available at Aetrix Electronics and suitable for industrial motor control, embedded networking, medical diagnostics, and automotive infotainment requiring stable component supply across extended temperature and high-reliability production cycles.

Supply support for LDL1117S25R 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 silicon solutions for automotive, industrial, and power management applications.

The LDL1117 series targets high-PSRR, high-current linear regulation in space-constrained industrial and computing systems - emphasizing thermal resilience, wide input range, and compatibility with ceramic capacitors to simplify layout and improve long-term reliability.

FAQ

What is the minimum input voltage required for stable 2.5 V output at 1.2 A?

The LDL1117S25R requires VIN ≥ VOUT + VDROP = 2.5 V + 0.6 V = 3.1 V (max dropout) to maintain regulation at 1.2 A across temperature. At 25°C, 350 mV dropout allows operation from 2.85 V, but design margin mandates ≥3.1 V for full-spec compliance per DS12022 Rev 7 Table 4.

Can the LDL1117S25R be used with aluminum polymer capacitors instead of ceramic?

No - the LDL1117S25R control loop is optimized for ceramic capacitors with ESR < 100 mΩ and capacitance ≥4.7 µF. Aluminum polymer caps typically exhibit higher ESR and capacitance drift over temperature, risking instability per Figure 20–21 in DS12022. X5R/X7R ceramics are mandatory for guaranteed phase margin.

How does the SOA protection affect short-circuit current versus input voltage?

SOA protection reduces short-circuit current as (VIN–VOUT) increases: at VOUT = 2.5 V, ISC drops from ~2 A at VIN = 3 V to ~1.5 A at VIN = 12 V (per Figure 16). This prevents destructive power dissipation by limiting I_SC × (V_IN–V_OUT) product, unlike fixed-current limiters.

Is the thermal pad (tab) electrically isolated in the SOT-223 package?

No - the exposed thermal tab is internally connected to VOUT (per DS12022 Table 1 and Figure 2). PCB layout must route the tab to the 2.5 V output net via thermal vias and copper pour; isolation would compromise thermal performance and violate internal connectivity.