Diodes Incorporated AP131-28WL-7

Overview

AP131-28WL-7 from Diodes Incorporated is a 300mA fixed-output low-dropout linear regulator with 2.8V output, 400mV dropout at full load, 50µA quiescent current, and active-low enable control. It integrates current limiting, thermal shutdown, and bandgap reference in a SOT25 package, designed for battery-powered portable electronics requiring stable low-noise voltage regulation.

For engineers reviewing the AP131-28WL-7 datasheet, AP131-28WL-7 pinout, AP131-28WL-7 application, or AP131-28WL-7 equivalent, key selection criteria include dropout performance at 300mA, EN pin logic polarity, BP pin noise-filtering capability, ±2% output accuracy over temperature, and SOT25 thermal resistance (163°C/W).

Technical Context

The AP131-28WL-7 uses a PMOS pass element with 1.5Ω on-resistance, enabling low dropout and zero base-drive current. Its error amplifier compares feedback from an internal 1.08V bandgap reference to regulate output precisely across line (0.1%/V) and load (30mV) variations.

Enable functionality is implemented via a dedicated EN pin with 0–0.8V logic-low disable threshold and 1.5–VIN logic-high enable range. The BP pin provides access to the internal bandgap node, allowing external capacitor filtering to reduce output noise-critical for RF and audio subsystems.

Key Specifications

Pinout & Package

SOT25 (5-pin, lead-free, RoHS-compliant surface-mount package with 163°C/W junction-to-ambient thermal resistance; footprint matches JEDEC MO-178AA standard).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP7343-28W5-7 and MCP1700-2802E/TO, the AP131-28WL-7 uniquely balances 300mA capability, 50µA IQ, BP-based noise reduction, and SOT25 thermal performance-making it optimal for space-constrained, noise-sensitive, battery-operated systems requiring precise 2.8V regulation.

Availability

AP131-28WL-7 is available at Aetrix Electronics and suitable for battery-powered wearables, wireless sensor nodes, PC peripheral cards, and optical drive logic supplies requiring stable component supply, consistent parametric performance, and long-term manufacturability.

Supply support for AP131-28WL-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, manufacturing, and sales operations across Asia, Europe, and North America.

The AP131 series belongs to Diodes' precision LDO portfolio, engineered specifically for portable and energy-constrained applications demanding low dropout, ultra-low quiescent current, and robust fault protection in miniature packages.

FAQ

What is the minimum input voltage required for AP131-28WL-7 to maintain regulation at 300mA load?

The minimum input voltage is calculated as V_OUT + V_DROP = 2.8V + 0.4V = 3.2V. At 300mA load and 25°C, regulation is maintained down to 3.2V input; below that, output voltage drops linearly with input. Operation below 2.7V input is outside recommended conditions and may cause instability or shutdown.

Can the BP pin be left unconnected, or is an external capacitor mandatory?

The BP pin may be left unconnected for basic operation, but doing so forfeits the noise-reduction benefit. A 0.1µF ceramic capacitor to ground improves PSRR by up to 15dB and reduces output voltage noise-especially critical in RF, audio, or precision ADC applications. Diodes recommends using the capacitor unless board space or cost strictly prohibits it.

Does AP131-28WL-7 support reverse-voltage or reverse-current protection?

No. The AP131-28WL-7 does not include reverse-voltage or reverse-current protection circuitry. If the output voltage exceeds the input (e.g., during hot-swap or backup battery scenarios), current can flow backward through the PMOS pass device, potentially damaging upstream circuitry. External protection diodes or MOSFET-based OR-ing circuits are required in such configurations.

How does thermal shutdown behave during continuous overload, and can it be manually reset?

Thermal shutdown activates at junction temperature ≥125°C, disabling the output until T_J falls below ~110°C (typical hysteresis). No manual reset is needed-the device automatically resumes regulation once cooled. During sustained overload, this results in thermal cycling (hiccup mode), protecting both the IC and PCB. Continuous operation above 85°C ambient requires careful thermal pad layout per Diodes' SOT25 recommendations.