onsemi NCP1117DT18T5G

Overview

NCP1117DT18T5G from onsemi is a 1.8 V fixed-output, low-dropout linear voltage regulator in DPAK package, delivering up to 1.0 A output current with 1.2 V max dropout at 800 mA over temperature, ±1.0% output voltage accuracy, and integrated thermal shutdown, current limiting, and safe operating area protection. It is used for point-of-load regulation in industrial power supplies and hard drive controllers.

For engineers reviewing the NCP1117DT18T5G datasheet, pinout, applications, or equivalent options, key selection criteria include dropout voltage at full load, thermal performance in DPAK layout, line/load regulation specs (≤0.5% / ≤4.3 mV), ripple rejection (66 dB at 120 Hz), and compatibility with 10 µF input/output ceramic capacitors.

Technical Context

The NCP1117DT18T5G implements a bandgap-referenced error amplifier with internal trimming to maintain 1.8 V output within ±1.0% across temperature and load. Its dropout behavior is characterized by 1.07 V at 800 mA and 1.10 V at 800 mA over temperature, enabling stable operation with input as low as 2.9 V.

Protection circuitry includes foldback current limiting that activates before junction temperature reaches 175°C, and an internally compensated feedback loop requiring only 10 µF output capacitance with ESR between 33 mΩ and 2.2 Ω for stability - no external compensation needed.

Key Specifications

Pinout & Package

Package: DPAK (Case 369C), surface-mount, exposed metal tab connected to Pin 2 (Output) for thermal conduction to PCB copper.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV1117-18CDR and LD1117S18TR, the NCP1117DT18T5G delivers higher output current (1.0 A vs. 0.8 A), tighter initial accuracy (±1.0% vs. ±2%), and superior thermal dissipation via DPAK's exposed tab - making it preferred for industrial and storage applications demanding sustained load and reliability.

Availability

NCP1117DT18T5G is available at Aetrix Electronics and suitable for industrial embedded systems, hard drive controllers, and switching power supply post-regulation requiring stable component supply, long-term lifecycle support, and Pb-free compliance.

Supply support for NCP1117DT18T5G 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, sensor, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The NCP1117 series was designed for high-reliability point-of-load regulation in industrial and computing equipment, emphasizing low dropout, tight output tolerance, and robust thermal protection - directly addressing needs in hard drive controllers and embedded power subsystems.

FAQ

What is the maximum input voltage rating for the NCP1117DT18T5G?

The NCP1117DT18T5G supports a maximum input voltage of 20 V, as specified in its Absolute Maximum Ratings table. Operation above this level risks permanent damage. For reliable 1.8 V output, the minimum recommended input is 2.9 V to maintain regulation at full 1.0 A load, given its 1.10 V dropout at 800 mA over temperature. Always verify derating margins for ambient temperature and PCB thermal design.

Does the NCP1117DT18T5G require an external capacitor on the adjust pin?

No - the NCP1117DT18T5G is a fixed-output variant; it has no adjust pin. Only the adjustable versions (e.g., NCP1117DTAG) require C_adj for ripple rejection enhancement. The NCP1117DT18T5G requires only a 10 µF input capacitor and a 10 µF output capacitor (with ESR 33 mΩ–2.2 Ω) for stability and transient response, per the datasheet's Figure 23 and Applications Information section.

What thermal considerations apply to the NCP1117DT18T5G in DPAK package?

The NCP1117DT18T5G's DPAK package features an exposed metal tab electrically connected to Pin 2 (Output), which must be soldered to a large copper pour for effective heat dissipation. Per Figure 22, with 2 oz. copper and 10 mm PCB copper length, R_JA drops to ~67 °C/W. At 1.0 A and 1.1 V dropout, power dissipation is ~1.1 W - requiring careful thermal layout to keep junction temperature below 150°C, especially above 50°C ambient.

Is the NCP1117DT18T5G pin-compatible with the LM317?

Yes - the NCP1117DT18T5G shares the same 3-pin DPAK pinout (Input, Output, Ground) as the LM317, and the datasheet explicitly states "pin compatible with the older LM317". However, unlike the LM317, the NCP1117DT18T5G is fixed-output and does not require external resistors. This enables direct replacement in LM317-based designs where 1.8 V output is acceptable and no adjustment is needed.

What is the load regulation performance of the NCP1117DT18T5G across its full current range?

The NCP1117DT18T5G exhibits 4.3 mV load regulation from 0 mA to 800 mA (per Electrical Characteristics table), corresponding to 0.24% deviation relative to 1.8 V. At 1.0 A, regulation remains within specification due to internal current limiting and SOA compensation. This tight load regulation ensures consistent voltage delivery during dynamic load transients common in disk controller and FPGA I/O applications.