onsemi NCP1117LPST15T3G

Overview

NCP1117LPST15T3G from onsemi is a 1.5 V fixed-output, low-dropout linear voltage regulator delivering up to 1.0 A output current with 1.3 V dropout at full load, quiescent current of 550–700 µA, and thermal shutdown at 165 °C - used for post-regulation in consumer power supplies and embedded system core rails.

For engineers reviewing the NCP1117LPST15T3G datasheet, pinout, applications, or equivalent options, this page delivers verified electrical specs, SOT-223 package layout, thermal design guidance, and real-world substitution options for high-volume consumer electronics designs.

Technical Context

The NCP1117LPST15T3G implements a PNP-based LDO architecture with internal reference (1.25 V), current-limit protection (1.1 A typical), and thermal foldback. Its 1.3 V dropout at 1 A enables operation from 2.8 V input when regulating 1.5 V - critical for battery-adjacent or switching supply post-regulation stages.

It requires no minimum load for regulation, supports 10 µF output capacitance (20 mΩ–20 Ω ESR), and achieves 60 dB ripple rejection at 120 Hz. The device operates across 0–125 °C ambient and tolerates up to 18 V DC input, with built-in ESD protection (2 kV HBM).

Key Specifications

Pinout & Package

SOT-223 package (Case 318H) with exposed metal tab thermally connected to Pin 2 (Vout); heatsink tab must be soldered to PCB copper pour for thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700T-1502E/MB and TLV1117-15CDCYR, the NCP1117LPST15T3G uniquely balances 1 A capability, 1.3 V dropout, sub-mA quiescent current, and SOT-223 thermal efficiency - making it optimal for cost-sensitive, high-volume 1.5 V consumer power rails where both current and efficiency matter.

Availability

NCP1117LPST15T3G is available at Aetrix Electronics and suitable for TV power rails, set-top box core logic, and hard drive controller boards requiring stable component supply, RoHS compliance, and high-volume tape-and-reel delivery.

Supply support for NCP1117LPST15T3G 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, and consumer markets.

The NCP1117LP series was designed specifically for high-volume consumer electronics requiring low-cost, reliable, low-dropout regulation - emphasizing quiescent current reduction, thermal robustness, and Pb-free manufacturability.

FAQ

What is the maximum input voltage rating for the NCP1117LPST15T3G?

The NCP1117LPST15T3G has a maximum DC input voltage rating of 18 V, as specified in Table 2 of the official datasheet. This allows safe operation with common 12 V adapter inputs and transient-tolerant designs. Exceeding 18 V may cause permanent damage, and operation below −0.3 V is also prohibited. The device maintains regulation only when Vin remains at least 1.3 V above the 1.5 V output.

Does the NCP1117LPST15T3G require an external output capacitor, and what are the specifications?

Yes, the NCP1117LPST15T3G requires a minimum 4.7 µF output capacitor with ESR between 20 mΩ and 20 Ω for stability - 10 µF tantalum or ceramic is recommended per Figures 33 and 34. The capacitor must be placed directly at the Vout and GND pins. Using values outside this ESR range risks oscillation, especially under load transients, as confirmed in Figure 13's stability region plot.

Is the NCP1117LPST15T3G pin-compatible with the standard NCP1117 family?

Yes, the NCP1117LPST15T3G is pin-compatible with the legacy NCP1117 series in the same SOT-223 package, as explicitly stated in the Applications Information section (page 10). Pin 1 is GND, Pin 2 is Vout, and Pin 3 is Vin - identical layout and footprint. However, its reduced quiescent current and optimized thermal shutdown threshold differentiate its behavior under light-load and fault conditions.

What thermal performance can be expected from the NCP1117LPST15T3G in SOT-223 package?

In a standard 1 oz copper PCB layout, the NCP1117LPST15T3G exhibits a junction-to-ambient thermal resistance (R_JA) of 108 °C/W (Table 2), enabling ~0.9 W max continuous dissipation at 25 °C ambient. With enhanced copper pours (e.g., 2 oz, 100 mm²), R_JA drops to ~60 °C/W (Figure 32), supporting >1.5 W. The exposed tab (connected to Pin 2) must be soldered to PCB copper for rated performance.

How does the NCP1117LPST15T3G handle short-circuit conditions?

The NCP1117LPST15T3G responds to output shorts with foldback current limiting and thermal shutdown. Per Table 3, its current limit is 1.1 A typical at 7 V input. If sustained, junction temperature rises to 165 °C (±5 °C), triggering shutdown with 10 °C hysteresis - causing cyclical on/off behavior until fault removal. This protects the die without requiring external current-sense circuitry.