Diodes Incorporated AP7343D-28FS4-7B

Overview

AP7343D-28FS4-7B from Diodes Incorporated is a 300mA, 2.8V fixed-output low-dropout linear regulator with high PSRR (75dB at 1kHz), ultra-low output noise (60µVrms, 10Hz–100kHz), ±1% output voltage accuracy, and enable-controlled shutdown. Fabricated in CMOS, it delivers stable power to RF supplies and camera modules in space-constrained portable electronics using the X2-DFN1010-4 (Type B) package.

For engineers reviewing the AP7343D-28FS4-7B datasheet, AP7343D-28FS4-7B pinout, AP7343D-28FS4-7B application, or AP7343D-28FS4-7B equivalent, key selection criteria include dropout voltage at 300mA (0.35V typ. for 2.8V output), thermal resistance (θ_JA = 237°C/W), EN logic thresholds (V_IL ≤ 0.5V, V_IH ≥ 1.3V), and discharge functionality enabled by the "D" suffix.

Technical Context

The AP7343D integrates a precision voltage reference, error amplifier, current-limit circuit, and thermal shutdown protection. Its CMOS-based architecture enables low quiescent current (35µA typ.) and fast load transient response-critical for battery-powered RF and imaging subsystems where supply rail stability directly impacts signal integrity.

Unlike standard LDOs, the "D" variant includes an internal N-channel MOSFET (R_ON = 30Ω typ.) between VOUT and GND for active output discharge during shutdown, eliminating residual voltage hold-up and enabling clean power sequencing in multi-rail systems.

Key Specifications

Pinout & Package

X2-DFN1010-4 (Type B) package: 1.0mm × 1.0mm, 0.4mm pitch, exposed thermal pad (EP) - optimized for minimal PCB footprint and efficient heat dissipation in dense mobile layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP7343-28FS4-7B and XC6219B282MR-G, the AP7343D-28FS4-7B uniquely combines 300mA drive, 237°C/W thermal resistance in 1.0×1.0mm, and guaranteed active discharge-making it optimal for compact, multi-rail portable designs requiring deterministic power-down behavior.

Availability

AP7343D-28FS4-7B is available at Aetrix Electronics and suitable for RF power amplifier bias, CMOS image sensor core supply, wireless adapter PHY layer, and portable media player audio codec applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for AP7343D-28FS4-7B 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 for power management, signal integrity, and connectivity applications.

The AP7343 series targets portable and battery-powered electronics, delivering high-accuracy, low-noise, and low-quiescent-current regulation for RF, imaging, and audio subsystems where efficiency and signal purity are critical.

FAQ

What is the purpose of the exposed pad (EP) on the X2-DFN1010-4 (Type B) package?

The exposed pad is a thermal dissipation feature-not an electrical terminal. It must be soldered to a large copper area connected to GND to achieve the specified θ_JA = 237°C/W. Using it solely as a GND electrode without thermal connection degrades thermal performance and risks junction overheating under 300mA load.

How does the "D" suffix affect the AP7343D-28FS4-7B's shutdown behavior compared to non-D versions?

The "D" denotes integrated output discharge: when EN is pulled low, an internal 30Ω N-channel FET connects VOUT to GND, discharging the output capacitor to <0.1V within 100µs. Non-D versions leave VOUT floating, risking unintended operation of downstream circuitry during power sequencing.

Can AP7343D-28FS4-7B operate with input voltage below 2.8V?

Yes-the minimum input is 1.7V, but dropout voltage rises with load. At 300mA output, typical dropout is 0.35V; thus, VIN must be ≥3.15V to sustain 2.8V output. Below that, output collapses proportionally per the dropout curve in the datasheet (Fig. 7).

What output capacitor value and type are recommended for optimal transient response?

A 1µF X5R/X7R ceramic capacitor placed within 2mm of VOUT and GND pins is recommended. For loads with >100mA step changes, add a 4.7µF bulk capacitor in parallel. ESR must be ≤10mΩ to maintain stability across –40°C to +85°C, per the ESR vs. IOUT graph (Fig. 12).