Diodes Incorporated AP7353-33FS4-7

Overview

AP7353-33FS4-7 from Diodes Incorporated is a 250mA low-dropout linear regulator with fixed 3.3V output, ±1% accuracy, 90dB PSRR at 1kHz, 10µV_rms output noise (10Hz–100kHz), and 18µA typical quiescent current. It operates from 2.0V to 5.5V input and delivers stable power to RF circuitry and portable media subsystems.

For engineers reviewing the AP7353-33FS4-7 datasheet, AP7353-33FS4-7 pinout, AP7353-33FS4-7 application, or AP7353-33FS4-7 equivalent, key selection criteria include dropout voltage at 250mA (65–138mV depending on V_OUT), enable control timing (180µs turn-on), thermal resistance (237°C/W for X2-DFN1010-4), and compatibility with 1µF ceramic output capacitors.

Technical Context

The AP7353-33FS4-7 implements a CMOS-based LDO architecture with integrated voltage reference, error amplifier, and current-limit protection. Its non-discharge configuration avoids automatic output discharge during shutdown, preserving downstream capacitor charge.

It features dual-package support-this variant uses the X2-DFN1010-4 (Type B) 1.0mm × 1.0mm 4-pin package with exposed pad-and supports fast load transient response (<20µs recovery for 1mA→250mA step) and robust line regulation (0.02%/V).

Key Specifications

Pinout & Package

X2-DFN1010-4 (Type B) is a 1.0mm × 1.0mm, 0.4mm pitch, 4-terminal surface-mount package with an exposed thermal pad (EP) for enhanced heat dissipation. Recommended PCB layout uses large copper area connected to GND under the EP.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP2204-3.3TRG1 and MCP1700T-3302E/TT, the AP7353-33FS4-7 uniquely balances ultra-low noise, high PSRR, and sub-20µA quiescent current in a 1.0mm² DFN, making it optimal for space-constrained RF and high-fidelity analog systems where all three parameters are simultaneously critical.

Availability

AP7353-33FS4-7 is available at Aetrix Electronics and suitable for smartphone RF supplies, portable camera modules, and wireless audio adaptors requiring stable component supply, long-term manufacturability, and AEC-Q200-aligned reliability.

Supply support for AP7353-33FS4-7 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 for consumer, computing, communications, industrial, and automotive markets.

The AP7353 series belongs to Diodes' high-performance LDO portfolio, designed specifically for noise-sensitive portable electronics requiring ultra-low quiescent current, high PSRR, and minimal board space.

FAQ

What is the maximum allowable input voltage for AP7353-33FS4-7?

The absolute maximum input voltage is 6.0V, but recommended operating range is 2.0V to 5.5V. Exceeding 5.5V risks permanent damage per Absolute Maximum Ratings. For 3.3V output, minimum functional input is 3.365V (accounting for worst-case 138mV dropout at 250mA), ensuring regulation across temperature and process variation.

Does AP7353-33FS4-7 include thermal shutdown protection?

Yes, it integrates thermal shutdown that activates at +125°C junction temperature. When triggered, the output is disabled until junction temperature falls below the hysteresis threshold (~15°C below trip point). This protects against sustained overload or poor PCB thermal design without requiring external circuitry.

Can AP7353-33FS4-7 be used with ceramic output capacitors smaller than 1µF?

The minimum effective capacitance is 0.7µF, accounting for DC bias, temperature, and tolerance derating of X5R/X7R ceramics. Using a 0.7µF–1µF capacitor is viable if its actual capacitance remains ≥0.7µF under operating bias and temperature-but 1µF is strongly recommended to ensure stability margin and optimal transient response across all conditions.

Is the exposed pad (EP) on AP7353-33FS4-7 electrically connected internally?

No, the exposed pad is thermally conductive only and not electrically connected to any internal node. Diodes' datasheet explicitly states it should be connected to GND for thermal performance but must not serve as the sole GND electrode-standard GND pins (Pin 2) must carry return current. Improper use may cause thermal stress or solder voiding without electrical benefit.