STMicroelectronics LDL1117S15R

Overview

LDL1117S15R from STMicroelectronics is a fixed 1.5 V, 1.2 A low-dropout linear voltage regulator in SOT223 package, featuring 350 mV dropout at full load, 87 dB PSRR at 120 Hz, and operation from 2.5 V to 18 V input. It delivers stable post-regulation for DC-DC converters and motherboard point-of-load (P.O.L.) rails in industrial and consumer systems.

For engineers reviewing the LDL1117S15R datasheet, LDL1117S15R pinout, LDL1117S15R application, or LDL1117S15R equivalent, key selection criteria include guaranteed 1.2 A output current, thermal shutdown at 175 °C, ±2% output accuracy over temperature, and compatibility with ceramic input/output capacitors (1 μF/4.7 μF).

Technical Context

The LDL1117S15R employs a PMOS 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. Its internal current limiting (typ. 2 A) and SOA protection dynamically constrain power dissipation based on VIN–VOUT differential.

Thermal management integrates junction-to-case resistance of 15 °C/W and junction-to-ambient resistance of 120 °C/W, with automatic shutdown at 175 °C and restart at ~150 °C. The device requires no external compensation and is optimized for stability with X5R/X7R ceramic capacitors.

Key Specifications

Pinout & Package

SOT223 package with exposed thermal tab electrically connected to VOUT; footprint matches JEDEC MO-178AB standard; thermal resistance θ_J-C = 15 °C/W enables efficient heatsinking via PCB copper pour.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-15CDCYR and MCP1703T-1502E/MB, the LDL1117S15R uniquely supports 1.2 A at ≤350 mV dropout from 2.5 V input while delivering 87 dB PSRR - making it the sole option among the three for high-current, low-headroom, noise-critical P.O.L. use cases.

Availability

LDL1117S15R is available at Aetrix Electronics and suitable for industrial motor control, consumer multimedia devices, and SMPS post-regulation applications requiring stable component supply, long-lifecycle support, and traceable sourcing.

Supply support for LDL1117S15R 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The LDL1117 series belongs to ST's high-PSRR, high-current LDO portfolio, engineered specifically for demanding point-of-load regulation in noisy switch-mode power systems and thermally constrained embedded platforms.

FAQ

What is the minimum input voltage required for stable 1.5 V output regulation?

The LDL1117S15R requires VIN ≥ 2.6 V (or VOUT + 1 V, whichever is greater) for guaranteed regulation per datasheet test conditions. At 1.5 V output, this means a minimum of 2.6 V input is needed - below which the device may drop out or fail to regulate accurately.

Can the LDL1117S15R be used with aluminum polymer capacitors instead of ceramic?

No - the LDL1117S15R control loop is optimized exclusively for ceramic capacitors with X5R/X7R dielectrics. Aluminum polymer capacitors exhibit higher ESR and capacitance drift over temperature, risking instability, overshoot, or oscillation as confirmed in Figure 20 and Figure 21 of DS12022.

Does the thermal tab require electrical isolation from PCB ground planes?

Yes - the SOT223 thermal tab is internally connected to VOUT (per Table 1 and Figure 2), so any copper pour or heatsink attached to the tab must be routed to the 1.5 V output net, not GND. Improper isolation causes short-circuit failure or regulation loss.

Is the 350 mV dropout specification valid for the 1.5 V output version?

No - datasheet footnote 2 explicitly states the 350 mV dropout value applies only to nominal outputs ≥ 2.5 V. For LDL1117S15R (1.5 V), dropout is not characterized in the Electrical Characteristics table; actual dropout must be verified experimentally or via simulation under load.