Diodes Incorporated AP7343D-09FS4-7B

Overview

AP7343D-09FS4-7B from Diodes Incorporated is a 300mA, 0.9V fixed-output low-dropout (LDO) regulator in X2-DFN1010-4 (Type B) package, featuring ±1% output voltage accuracy, 75dB PSRR at 1kHz, 60µVrms output noise (10Hz–100kHz), and 35µA quiescent current. It integrates enable control, thermal shutdown, and short-circuit protection, and is optimized for RF supply rails in compact portable electronics.

For engineers reviewing the AP7343D-09FS4-7B datasheet, AP7343D-09FS4-7B pinout, AP7343D-09FS4-7B application, or AP7343D-09FS4-7B equivalent, key selection criteria include dropout voltage at 300mA (0.51V typ. for 0.9V VOUT), EN logic thresholds (0.5V low / 1.3V high), thermal resistance (θJA = 237°C/W), and discharge functionality enabled by the "D" suffix.

Technical Context

The AP7343D-09FS4-7B uses a CMOS-based LDO architecture with integrated voltage reference, error amplifier, current limit, and thermal shutdown circuitry. Its enable input (EN) provides precise on/off control, and the built-in auto-discharge path (enabled by "D" variant) actively pulls VOUT to GND during shutdown, preventing floating rail issues in multi-rail systems.

Designed for ultra-low-noise operation, it achieves 60µVrms output noise across 10Hz–100kHz and maintains 75dB ripple rejection at 1kHz - critical for powering sensitive RF front-ends and analog signal chains. The device operates across 1.7V–5.25V input range and guarantees stable regulation down to 0.9V output with ≤2% dropout at full 300mA load.

Key Specifications

Pinout & Package

AP7343D-09FS4-7B is housed in the X2-DFN1010-4 (Type B) package - a 1.0mm × 1.0mm, 0.4mm pitch, 4-terminal surface-mount package with exposed thermal pad (EP). This footprint minimizes PCB area while enabling efficient heat dissipation via EP-to-GND copper pour.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1804T-0902E/MB and XC6210B092MR-G, the AP7343D-09FS4-7B uniquely combines 300mA drive, 35µA IQ, and integrated discharge in a 1.0×1.0mm footprint - making it optimal for space-constrained, multi-rail portable designs requiring clean, sequenced power.

Availability

AP7343D-09FS4-7B is available at Aetrix Electronics and suitable for RF power amplifier biasing, mobile camera ISP core supplies, Bluetooth LE SoC I/O domains, and wearable sensor hub core rails requiring stable component supply, consistent parametric performance, and automotive-grade reliability validation.

Supply support for AP7343D-09FS4-7B 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-performance LDO portfolio, engineered specifically for noise-sensitive, battery-powered portable electronics where ultra-low IQ, high PSRR, and precise low-voltage regulation are mandatory.

FAQ

What is the purpose of the exposed pad (EP) on the AP7343D-09FS4-7B?

The exposed pad is a thermal interface-not an electrical terminal-and must be soldered to a dedicated GND copper pour on the PCB. Doing so lowers junction-to-ambient thermal resistance from 237°C/W to near the datasheet's specified value, enabling safe 300mA operation at ambient temperatures up to +85°C without derating.

Does the "D" in AP7343D-09FS4-7B affect electrical specifications beyond discharge functionality?

No. The "D" suffix solely indicates inclusion of the internal NMOS discharge transistor (R_ON ≈ 30Ω); all other parameters-including output accuracy, PSRR, noise, dropout, and quiescent current-are identical to the non-D variant. The discharge path activates only when EN is driven low.

Can AP7343D-09FS4-7B operate with input voltage below 1.7V?

No. The absolute minimum input voltage is 1.7V per datasheet specifications. Below this, regulation fails and output collapses. For sub-1.7V inputs (e.g., deeply discharged batteries), a buck-boost pre-regulator is required before the AP7343D-09FS4-7B input stage.

Is a minimum output capacitance required for stability, and what type is recommended?

Yes: a minimum 1µF ceramic capacitor (X5R/X7R, ≤100mΩ ESR) is required between VOUT and GND, placed within 2mm of the pins. Larger values (e.g., 4.7µF) improve load transient response but do not compromise stability - unlike electrolytic or high-ESR capacitors, which risk oscillation.