Diodes Incorporated AP7343D-21FS4-7B

Overview

AP7343D-21FS4-7B from Diodes Incorporated is a 300mA, 2.1V fixed-output low-dropout (LDO) regulator in X2-DFN1010-4 (Type B) package, featuring ±1% output voltage accuracy, 75dB PSRR at 1kHz, 60µV_rms output noise (10Hz–100kHz), 35µA quiescent current, and integrated enable control. It delivers stable power to RF supplies and portable media subsystems under wide input range (1.7V–5.25V) with fast load transient response.

For engineers reviewing the AP7343D-21FS4-7B datasheet, AP7343D-21FS4-7B pinout, AP7343D-21FS4-7B application, or AP7343D-21FS4-7B equivalent, key selection criteria include dropout voltage at 300mA (0.30V typ. for 2.1V output), thermal shutdown threshold (+150°C), EN logic thresholds (0.5V low / 1.3V high), and discharge functionality enabled by the "D" suffix.

Technical Context

The AP7343D employs a CMOS-based architecture with integrated voltage reference, error amplifier, current limit, and thermal shutdown circuitry. Its enable input controls NMOS pass transistor conduction, while the built-in auto-discharge path (enabled by "D" variant) actively pulls VOUT to GND during shutdown via a 30Ω internal N-channel switch.

Designed for low-noise analog and RF supply rails, it achieves 75dB ripple rejection at 1kHz and maintains stability with ≥1µF ceramic output capacitors. The X2-DFN1010-4 (Type B) package provides 237°C/W junction-to-ambient thermal resistance and requires exposed pad connection to GND for optimal thermal dissipation.

Key Specifications

Pinout & Package

X2-DFN1010-4 (Type B) package: 1.0mm × 1.0mm, 0.4mm pitch, exposed thermal pad (EP). Requires soldering EP to GND plane for thermal performance (R_θJB = 85.7°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP7343D-21FS4-7B, AP7361D-21YG-7 offers higher current headroom and easier assembly but larger footprint, while XC6210B212MR-G sacrifices discharge, PSRR, and dropout performance for lower unit cost in non-critical applications.

Availability

AP7343D-21FS4-7B is available at Aetrix Electronics and suitable for RF power amplifier biasing, camera ISP power delivery, portable media player audio codec supply, and wireless adapter baseband IC regulation requiring stable component supply across automotive-grade temperature ranges (-40°C to +85°C).

Supply support for AP7343D-21FS4-7B 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 belongs to Diodes' high-PSRR, low-noise LDO product line, engineered specifically for noise-sensitive portable and wireless communication equipment requiring ultra-low quiescent current and fast transient response.

FAQ

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

The exposed pad serves as the primary thermal dissipation path, not an electrical terminal. It must be soldered to a large PCB copper area connected to GND to achieve the specified R_θJB = 85.7°C/W. Leaving it unconnected degrades thermal performance by >50%, risking thermal shutdown under 300mA load.

Does AP7343D-21FS4-7B require an external discharge resistor?

No. The "D" suffix denotes integrated auto-discharge functionality: when EN is pulled low, a 30Ω internal N-channel MOSFET actively discharges the output capacitor. This eliminates the need for external bleed resistors, reducing BOM count and PCB area while ensuring controlled power-down sequencing.

Can AP7343D-21FS4-7B operate with a 1.7V input while delivering 2.1V output?

No. With a 2.1V nominal output, the minimum input voltage is V_OUT + V_DROP. At 300mA, typical dropout is 0.30V, so minimum valid input is 2.4V. Operation below 2.4V results in dropout mode and unregulated output; the 1.7V–5.25V range applies only to versions with V_OUT ≤ 1.7V.

How does the AP7343D's PSRR performance vary with load current?

PSRR remains stable across load conditions: 75dB at 1kHz is specified at I_OUT = 30mA, and typical curves show <3dB degradation up to 300mA. This consistency stems from its CMOS error amplifier design and internal compensation, making it suitable for dynamically loaded RF and digital subsystems without PSRR derating.