Diodes Incorporated AP7343D-30FS4-7B

Overview

AP7343D-30FS4-7B from Diodes Incorporated is a 300mA, 3.0V fixed-output low-dropout linear regulator with high PSRR (75dB at 1kHz), ultra-low output noise (60µV_rms, 10Hz–100kHz), ±1% output voltage accuracy, and enable-controlled shutdown. Fabricated on a CMOS process, it delivers stable power to noise-sensitive RF and digital circuitry in space-constrained portable devices. Its X2-DFN1010-4 (Type B) package supports dense PCB layouts.

For engineers reviewing the AP7343D-30FS4-7B datasheet, AP7343D-30FS4-7B pinout, AP7343D-30FS4-7B application, or AP7343D-30FS4-7B equivalent, key selection criteria include dropout voltage at 300mA (0.22–0.29V for 3.0V output), quiescent current (35µA typ.), thermal shutdown threshold (+150°C), and EN input logic thresholds (0.5V max low, 1.3V min high).

Technical Context

The AP7343D-30FS4-7B integrates a precision voltage reference, error amplifier, current-limit circuit, and thermal shutdown protection. Its CMOS-based architecture enables low quiescent current and fast load transient response-critical for battery-powered systems with dynamic current demands.

Unlike standard LDOs, this variant includes an internal discharge FET (enabled by the "D" suffix) that actively pulls VOUT to GND during shutdown, preventing floating outputs and enabling rapid power-down sequencing in multi-rail systems.

Key Specifications

Pinout & Package

AP7343D-30FS4-7B uses the X2-DFN1010-4 (Type B) 1.0mm × 1.0mm, 0.4mm pitch, 4-pin package with exposed thermal pad (EP). The EP must be connected to GND via large copper area for optimal thermal performance (R_θJA = 237°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP7343D-30FS4-7B, AP7361D-30YG-7 trades miniaturization for higher current and thermal headroom, while MCP1703T-3002E/MB sacrifices discharge capability and accuracy for sub-µA quiescent current-making each optimal for distinct subsystem-level trade-offs.

Availability

AP7343D-30FS4-7B is available at Aetrix Electronics and suitable for smartphone baseband power, RF transceiver bias, camera sensor core supply, and portable media player audio codec applications requiring stable component supply, automotive-grade traceability, and long-term production continuity.

Supply support for AP7343D-30FS4-7B 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 manufacturer of discrete semiconductors and analog ICs, specializing in high-performance power management, signal integrity, and protection solutions for consumer, industrial, and automotive markets.

The AP7343 series targets portable electronics requiring ultra-low-noise, high-PSRR LDOs with compact packaging and integrated discharge-designed specifically for next-generation smartphones, tablets, and wireless edge devices.

FAQ

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

The exposed pad serves exclusively as a thermal dissipation path-not a functional electrical terminal. It must be soldered to a minimum 25mm² GND copper pour to achieve the specified R_θJB = 85.7°C/W. Using it solely as a GND connection without adequate copper area degrades thermal performance and risks junction overheating above 125°C under 300mA load.

How does the discharge function operate, and when is it activated?

The discharge FET activates only when the EN pin is driven below 0.5V (logic low), pulling VOUT to GND through a 30Ω typical on-resistance. This occurs during system shutdown or deep-sleep mode. When EN is high, the FET is off and has no effect on normal regulation. The function eliminates residual charge on output capacitors, preventing unintended wake-up or latch-up in downstream circuitry.

Can AP7343D-30FS4-7B be used with input voltages below 1.7V?

No. The absolute minimum input voltage is 1.7V per datasheet specifications. Operation below this threshold causes loss of regulation, increased dropout, and potential instability. For sub-1.7V applications (e.g., coin-cell powered sensors), consider Diodes' AP2204K-30 or similar ultra-low-VIN LDOs-AP7343D-30FS4-7B is not rated or characterized for such conditions.

What is the recommended output capacitor value and type for optimal stability?

A 1.0µF X5R/X7R ceramic capacitor with ≤100mΩ ESR, placed within 2mm of VOUT and GND pins, is recommended for all operating conditions. Larger values (e.g., 4.7µF) improve load transient response but require verification against ESR vs. IOUT stability curves in the datasheet. Tantalum or aluminum electrolytic capacitors are not recommended due to higher ESR and aging effects.