Diodes Incorporated AP7331-28WG-7

Overview

AP7331-28WG-7 from Diodes Incorporated is a fixed-output 2.8V, 300mA low-dropout linear regulator in SOT25 package with enable control, 65μA quiescent current, 300mV dropout at full load, and integrated thermal shutdown, current limit, and short-circuit protection. It powers battery-operated wireless LAN cards and XDSL routers requiring stable low-power voltage regulation.

For engineers reviewing the AP7331-28WG-7 datasheet, AP7331-28WG-7 pinout, AP7331-28WG-7 application, or AP7331-28WG-7 equivalent, key selection criteria include dropout voltage at 300mA, EN logic thresholds (VIH = 1.4V, VIL = 0.4V), PSRR of 65dB at 100Hz, stability with 1μF ceramic output capacitor, and -40°C to 85°C operating ambient range.

Technical Context

The AP7331-28WG-7 implements a PMOS pass transistor architecture enabling ultra-low quiescent current across load (55–85μA) and input voltage (2–6V) ranges. Its internal 0.4V bandgap reference feeds an error amplifier that drives the gate of the pass element to maintain regulated 2.8V output.

Protection circuitry includes foldback current limiting (400–600mA), short-circuit clamping (~100mA), and thermal shutdown activation at 140°C with 15°C hysteresis. The device achieves 80μs start-up time and fast transient response due to optimized internal compensation and low output impedance.

Key Specifications

Pinout & Package

SOT25 package (2.9mm × 2.8mm × 1.3mm), RoHS-compliant, green molding compound, lead-free finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-quiescent-current LDO applications.

Compared with MCP1700-2802E/TO and TPS7A0528PDBVR, the AP7331-28WG-7 uniquely balances 300mA drive, 65μA I_Q, EN control, and full fault protection in a cost-effective SOT25 footprint-making it optimal for mid-power portable infrastructure where reliability and feature completeness matter.

Availability

AP7331-28WG-7 is available at Aetrix Electronics and suitable for wireless LAN cards, XDSL routers, and battery-powered test equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for AP7331-28WG-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 semiconductor company specializing in discrete, analog, and mixed-signal solutions, with design centers across Asia, Europe, and the US.

The AP7331 belongs to Diodes' high-efficiency LDO portfolio targeting portable and battery-powered applications, emphasizing ultra-low quiescent current, fast transient response, and robust protection for space-constrained designs.

FAQ

What is the minimum input voltage required to maintain 2.8V output at 300mA?

The AP7331-28WG-7 requires a minimum input voltage of 3.1V to sustain 2.8V output at 300mA load, based on its typical 300mV dropout voltage specification. At higher temperatures or worst-case process corners, VIN should be ≥3.35V to guarantee regulation across all conditions.

Can the AP7331-28WG-7 operate without an output capacitor?

No. The AP7331-28WG-7 requires a minimum 1μF ceramic output capacitor connected between OUT and GND for stability and transient performance. Omitting it causes oscillation and potential damage; X7R or X5R dielectrics with 10–200mΩ ESR are recommended.

How does the EN pin behave during power-up sequencing?

The EN pin must be held low (<0.4V) until VIN reaches ≥2V to prevent premature turn-on and output overshoot. Once VIN stabilizes, pulling EN ≥1.4V initiates 80μs start-up; the device remains off if EN stays below 0.4V, drawing only 1μA shutdown current.

Is the AP7331-28WG-7 compatible with ceramic capacitors having ESR below 10mΩ?

Yes. The AP7331-28WG-7 is designed for low-ESR ceramics and remains stable with ESR as low as 10mΩ. Capacitors with ESR <10mΩ (e.g., some specialty MLCCs) may cause marginal phase margin; adding a 1–5Ω series resistor restores stability if needed.