Diodes Incorporated AP7343-18FS4-7B

Overview

AP7343-18FS4-7B from Diodes Incorporated is a 300mA, 1.8V fixed-output low-dropout linear regulator with ±1% output voltage accuracy, 75dB PSRR at 1kHz, and 60µV_rms output noise (10Hz–100kHz). Fabricated on a CMOS process, it features enable control, thermal shutdown, short-circuit protection, and operates from 1.7V to 5.25V input. It powers RF supply rails in compact portable devices requiring stable, low-noise bias.

For engineers reviewing the AP7343-18FS4-7B datasheet, AP7343-18FS4-7B pinout, AP7343-18FS4-7B application, or AP7343-18FS4-7B equivalent, key selection criteria include dropout voltage at 300mA (0.35V typ. for 1.8V output), quiescent current (35µA typ.), EN logic thresholds (0.5V low / 1.3V high), and thermal resistance (237°C/W θ_JA in X2-DFN1010-4).

Technical Context

The AP7343-18FS4-7B integrates a precision voltage reference, error amplifier, current-limit circuit, and NMOS pass transistor in a CMOS-based LDO architecture. Its enable input directly controls gate drive to the pass element, enabling fast turn-on/turn-off with no external discharge path required (non-discharge variant).

Designed for high PSRR and low noise, it uses internal compensation optimized for 1µF ceramic output capacitors. Thermal shutdown activates at +150°C with +20°C hysteresis, and short-circuit protection limits output current to ~55mA when V_OUT is shorted to GND.

Key Specifications

Pinout & Package

AP7343-18FS4-7B is housed in the X2-DFN1010-4 (Type B) package - a 1.0mm × 1.0mm, 0.4mm pitch, 4-terminal leadless package with an exposed thermal pad (EP). The EP must be connected to PCB ground plane for optimal thermal performance (θ_JB = 85.7°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700-1802E/TO and XC6210B182MR-G, AP7343-18FS4-7B delivers superior PSRR (75dB vs. ≤65dB), lower noise (60µV_rms vs. 45–75µV_rms), and smaller footprint (1.0×1.0mm vs. 2.9×1.6mm), making it optimal for space-constrained, noise-sensitive RF and imaging applications.

Availability

AP7343-18FS4-7B is available at Aetrix Electronics and suitable for RF power amplifier bias, mobile camera sensor core supply, wireless SoC I/O domain, and portable media player audio codec applications requiring stable component supply, consistent parametric performance, and long-term manufacturability.

Supply support for AP7343-18FS4-7B 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 ICs for power management, signal integrity, and connectivity solutions.

The AP7343 series belongs to Diodes' high-performance LDO portfolio, engineered specifically for low-noise, high-PSRR power delivery in battery-powered portable electronics and RF subsystems.

FAQ

What is the maximum allowable input voltage for AP7343-18FS4-7B?

The absolute maximum input voltage is 6.0V, but the recommended operating range is 1.7V to 5.25V. Exceeding 5.25V risks violating safe operating area limits and may trigger thermal shutdown or reduce reliability. Operation above 5.25V is not characterized and voids parametric guarantees.

Does AP7343-18FS4-7B include an output discharge function?

No. The "7B" suffix and absence of "D" in the part number indicate the non-discharge variant. When disabled via EN, the output remains floating and does not actively pull V_OUT to GND. An external discharge resistor or FET is required if rapid output discharge is needed.

Can AP7343-18FS4-7B operate with only a 0.47µF input capacitor?

Yes - a minimum 0.47µF ceramic capacitor between VIN and GND is specified for input decoupling. However, for systems with high di/dt load transients or noisy input sources, a 1µF capacitor is recommended to ensure stability and minimize input voltage droop during step-load events.

How does thermal performance differ between X2-DFN1010-4 and SOT25 packages?

The X2-DFN1010-4 (Type B) package has θ_JA = 237°C/W, while SOT25 is 179°C/W - meaning the SOT25 dissipates heat more effectively in standard JEDEC test boards. However, the DFN's smaller size (1.0×1.0mm vs. 2.9×1.6mm) enables denser layouts, and its exposed pad allows superior thermal conduction when properly soldered to a large GND copper area.