Diodes Incorporated AP1117T50L-U

Overview

AP1117T50L-U from Diodes Incorporated is a 1A low-dropout linear voltage regulator in fixed 5.0V output mode, housed in a TO220-3L package with lead-free finish and RoHS compliance. It delivers stable regulation with ≤1.4V dropout at full load, supports input voltages from 6.5V to 18V, and features built-in thermal shutdown and current limiting. It is designed for high-speed bus termination and low-current 3.3V/5V logic supplies in PC peripherals and VGA cards.

For engineers reviewing the AP1117T50L-U datasheet, AP1117T50L-U pinout, AP1117T50L-U application, or AP1117T50L-U equivalent, key selection considerations include dropout voltage under 1A load, thermal resistance (θ_JA = 78°C/W), minimum load current requirement (5–10mA), and stability with 10µF output capacitor (ESR 0.15–20Ω).

Technical Context

The AP1117T50L-U operates as a fixed-output LDO regulator using an internal bandgap reference (1.25V nominal) and error amplifier driving a PNP pass transistor. Its architecture enables fast transient response due to low output impedance and integrated compensation.

It requires no external feedback resistors for 5.0V operation, simplifies PCB layout, and maintains regulation only when VIN exceeds VOUT by ≥1.3V. Thermal shutdown activates at ~150°C junction temperature, cycling output until die cools.

Key Specifications

Pinout & Package

AP1117T50L-U uses the TO220-3L package: 3-terminal through-hole package with metal tab electrically connected to VOUT, enabling direct heatsinking. Tab must be isolated from chassis ground unless VOUT is system ground.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2940CT-5.0/NOPB and MCP1703T-5002E/MB, AP1117T50L-U uniquely balances 1A output, 1.4V dropout, TO220 thermal performance, and cost-effective fixed 5V delivery - making it irreplaceable in mid-power industrial and PC peripheral designs where both current and thermal headroom are essential.

Availability

AP1117T50L-U is available at Aetrix Electronics and suitable for PC peripheral power, VGA card logic supply, industrial control I/O, and embedded network interface applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant through-hole assembly.

Supply support for AP1117T50L-U 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design and manufacturing operations across Asia and the Americas.

The AP1117 product line targets cost-sensitive, high-reliability linear regulation in computing, communications, and industrial equipment - emphasizing robust thermal behavior, low dropout, and compatibility with standard PCB assembly processes.

FAQ

What is the minimum input voltage required for AP1117T50L-U to maintain regulation?

The device requires VIN ≥ VOUT + 1.3V to regulate properly, so minimum input is 6.3V. However, datasheet testing specifies 6.5V minimum for guaranteed 5.0V output across temperature and load. Below this, dropout occurs - output drops linearly with input, losing regulation.

Can AP1117T50L-U be used with ceramic output capacitors?

No - the datasheet mandates a minimum ESR of 0.15Ω for stability, and standard ceramic capacitors have near-zero ESR. A 10µF tantalum or aluminum electrolytic capacitor (0.15–20Ω ESR) is required. If ceramics must be used, a 1Ω damping resistor in series is needed, degrading transient response.

Is the metal tab on AP1117T50L-U electrically connected, and to which pin?

Yes - the metal tab is internally connected to Pin 2 (VOUT). It must be electrically isolated from chassis ground unless the 5V output rail is referenced to system ground. When heatsinking, use insulating hardware (e.g., mica washer + nylon screw) if tab isolation is required.

Does AP1117T50L-U require an input capacitor, and what value is recommended?

While not strictly mandatory for stability, a 10µF aluminum or tantalum input capacitor (low-ESR) is strongly recommended to prevent input voltage sag during load transients. Without it, VIN may dip below dropout threshold during 1A step changes, causing temporary regulation loss.