Diodes Incorporated AP7343D-185FS4-7B

Overview

AP7343D-185FS4-7B from Diodes Incorporated is a 300mA, 1.85V fixed-output low-dropout regulator with high PSRR (75dB at 1kHz), ultra-low output noise (60µVrms), and ±1% output voltage accuracy over temperature. Packaged in X2-DFN1010-4 (Type B), it features enable control, thermal shutdown, short-circuit protection, and operates from 1.7V to 5.25V input-optimized for RF supply rails in compact portable devices.

For engineers reviewing the AP7343D-185FS4-7B datasheet, AP7343D-185FS4-7B pinout, AP7343D-185FS4-7B application, or AP7343D-185FS4-7B equivalent, key selection criteria include dropout voltage at 300mA (0.35V typ), quiescent current (35µA), EN logic thresholds (0.5V low / 1.3V high), and thermal resistance (θ_JA = 237°C/W) for thermally constrained PCB layouts.

Technical Context

The AP7343D-185FS4-7B integrates a CMOS-based LDO architecture with internal voltage reference, error amplifier, current limit circuit, and thermal shutdown. Its discharge function (indicated by "D" suffix) actively pulls VOUT to GND when EN is low, eliminating residual voltage on downstream loads.

It supports fast load transient response (≤100µs recovery with 1µF C_OUT) and maintains stability with ceramic capacitors as low as 1µF. The X2-DFN1010-4 (Type B) package includes an exposed pad (EP) for enhanced thermal dissipation-recommended to connect to GND via large copper area.

Key Specifications

Pinout & Package

X2-DFN1010-4 (Type B) package: 1.0mm × 1.0mm, 0.4mm pitch, 4 active terminals + exposed thermal pad (EP). EP must be connected to GND 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 AP7343-185FS4-7B, the D-suffix version adds critical discharge functionality for systems requiring zero-VOUT holdoff, while versus XC6210B185MR-G, it delivers superior noise and PSRR performance essential for RF and precision analog loads.

Availability

AP7343D-185FS4-7B is available at Aetrix Electronics and suitable for RF power amplifier bias, mobile camera sensor core supply, wireless adapter baseband ICs, and portable media player audio codec applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for AP7343D-185FS4-7B 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-reliability power management, signal integrity, and protection solutions for consumer, industrial, and automotive markets.

The AP7343 series belongs to Diodes' high-PSRR, low-noise LDO product line-designed specifically for noise-sensitive applications in portable communications equipment where space, 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 interface-not an electrical terminal-and must be soldered to a GND-connected copper pour to reduce junction-to-board thermal resistance (θ_JB = 85.7°C/W). It improves power dissipation capability by up to 40% versus omitting the pad, but must never be used as the sole GND connection point for the device.

Does AP7343D-185FS4-7B require an external pull-up resistor on the EN pin?

No external pull-up is required. The EN pin has no internal pull-up; it must be driven actively high (>1.3V) to enable or low (<0.5V) to disable. Leaving it floating violates absolute maximum ratings and may cause erratic regulation. If unused, tie EN directly to VIN to maintain continuous operation.

Can AP7343D-185FS4-7B operate with only a 1µF output capacitor?

Yes-this LDO is optimized for stability with 1µF ceramic capacitors (X5R/X7R, 0402 or larger). The datasheet confirms stability across temperature and load with 1µF C_OUT, provided ESR remains below 100mΩ. Larger bulk capacitance (e.g., 4.7µF) further improves load transient response but is not mandatory.

How does the discharge function behave during EN deactivation?

When EN transitions from high to low, an internal 30Ω NMOS switch connects VOUT to GND, discharging the output capacitor within 200µs (typical). This prevents residual voltage from powering downstream circuits unintentionally-critical for systems requiring strict power-domain isolation during sleep states.