Diodes Incorporated AP131-18WL-7

Overview

AP131-18WL-7 from Diodes Incorporated is a 300mA fixed-output low-dropout linear regulator with 1.8V output, 400mV dropout at full load, 50µA quiescent current, and active-low enable control. It integrates PMOS pass element, bandgap reference, current limit, and thermal shutdown, and is used in battery-powered wireless modules requiring stable low-noise voltage regulation.

For engineers reviewing the AP131-18WL-7 datasheet, AP131-18WL-7 pinout, AP131-18WL-7 application, or AP131-18WL-7 equivalent, key selection criteria include dropout voltage under 300mA load, EN pin logic polarity, BP pin noise-filtering capability, SOT25 package thermal resistance, and ±2% output accuracy across temperature.

Technical Context

The AP131-18WL-7 employs a PMOS pass transistor with 1.5Ω on-resistance, enabling low dropout and zero base-drive current. Its error amplifier compares feedback from the internal 1.08V bandgap reference to regulate output precisely.

Enable functionality is implemented via an active-low EN pin with 0–0.8V logic-OFF threshold and 1.5–VIN logic-ON range; the BP pin accepts a 0.1µF capacitor to reduce output noise by enhancing reference stability and PSRR above 100Hz.

Key Specifications

Pinout & Package

SOT25 (5-pin) surface-mount package with 163°C/W junction-to-ambient thermal resistance; footprint matches JEDEC MO-178AB standard and supports reflow soldering per IPC-J-STD-020.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout linear regulator applications.

Compared with AP7343-18W5-7 and MCP1700-1802E/TO, the AP131-18WL-7 uniquely balances 300mA capability, 400mV dropout, 50µA IQ, active-low EN, and BP noise filtering-making it optimal for space-constrained, battery-operated wireless devices needing both efficiency and signal integrity.

Availability

AP131-18WL-7 is available at Aetrix Electronics and suitable for battery-powered wireless sensor nodes, USB peripheral interfaces, industrial SD card adapters, and embedded audio DAC power supplies requiring stable component supply and long-term lifecycle support.

Supply support for AP131-18WL-7 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 centers across Asia and manufacturing in China, Taiwan, and Malaysia.

The AP131 series belongs to Diodes' precision LDO portfolio, engineered specifically for portable and battery-sensitive applications where low dropout, ultra-low quiescent current, and integrated protection are essential.

FAQ

What is the minimum input voltage required for AP131-18WL-7 to maintain regulation at 300mA load?

The minimum input voltage is 2.2V, calculated as VOUT + VDROP = 1.8V + 0.4V. Below this, output voltage drops out of regulation. The device operates down to 2.7V input per datasheet limits, ensuring margin for battery discharge curves and line transients.

Can the BP pin be left unconnected, and what impact does that have on performance?

Yes, the BP pin may be left floating or tied directly to OUT, but doing so degrades PSRR by up to 15dB above 1kHz and increases output noise by ~3×. For noise-sensitive applications like audio or RF, a 0.1µF X7R capacitor between BP and GND is mandatory per design guidelines.

Does AP131-18WL-7 support reverse-voltage or reverse-current protection?

No. The AP131-18WL-7 lacks intrinsic reverse-voltage or reverse-current blocking. If input can fall below output (e.g., during hot-swap or backup battery switchover), an external Schottky diode in series with IN or a dedicated reverse-protection IC is required to prevent backfeed and potential damage.

How does thermal shutdown behave during continuous overload, and is automatic recovery supported?

Thermal shutdown activates at ~150°C junction temperature, disabling the output until junction cools by ~20°C hysteresis. Recovery is fully automatic once temperature falls below the release threshold; no external reset or power cycle is needed, enabling robust self-protection in enclosed or poorly ventilated environments.