Diodes Incorporated AP7343D-22FS4-7B

Overview

AP7343D-22FS4-7B from Diodes Incorporated is a 300mA low-dropout linear regulator with fixed 2.2V output, ±1% accuracy, 75dB PSRR at 1kHz, 60µV_rms output noise (10Hz–100kHz), and 35µA quiescent current - designed for RF supply rails in compact portable electronics using the X2-DFN1010-4 (Type B) package.

For engineers reviewing the AP7343D-22FS4-7B datasheet, AP7343D-22FS4-7B pinout, AP7343D-22FS4-7B application, or AP7343D-22FS4-7B equivalent, key selection criteria include dropout voltage under 300mA load (0.35V typ. at V_OUT = 2.2V), enable-controlled shutdown (EN threshold: 0–0.5V low, 1.3–5.25V high), thermal shutdown at +150°C, and compatibility with 1µF ceramic input/output capacitors.

Technical Context

The AP7343D-22FS4-7B implements a CMOS-based LDO 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 discharge function actively pulls V_OUT to GND during shutdown - critical for sequencing-sensitive systems.

It operates across 1.7V–5.25V input range and maintains regulation down to 0.35V dropout at 300mA (V_OUT = 2.2V). The X2-DFN1010-4 (Type B) package features an exposed pad optimized for thermal dissipation (R_θJA = 237°C/W, R_θJC(bot) = 16.2°C/W), supporting stable operation up to +85°C ambient.

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 via large copper area for optimal thermal performance; not used as functional ground electrode.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP7343-22FS4-7B, the D-suffix variant adds critical auto-discharge for safe power-down sequencing, while the Torex alternative trades current capability and package size for slightly lower noise - making AP7343D-22FS4-7B optimal for compact, high-current, sequenced RF and imaging systems.

Availability

AP7343D-22FS4-7B is available at Aetrix Electronics and suitable for RF power amplifier biasing, CMOS image sensor core supplies, wireless adapter SoC I/O rails, and portable media player audio codec supplies requiring stable component supply and long-term production continuity.

Supply support for AP7343D-22FS4-7B 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 belongs to Diodes' high-PSRR, low-noise LDO product line, engineered specifically for noise-sensitive portable electronics where battery efficiency, small form factor, and reliable power sequencing are critical design constraints.

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. It must be soldered to a ≥25mm² GND copper pour to achieve the specified R_θJA = 237°C/W. While connected to GND for thermal conduction, it must not serve as the sole GND return path - dedicated PIN2 connection remains essential for signal integrity and stability.

Does AP7343D-22FS4-7B require an external discharge resistor?

No. The "D" suffix denotes integrated auto-discharge functionality: when EN is pulled low, an internal 30Ω NMOS switch connects V_OUT to GND, actively discharging output capacitance. This eliminates need for external resistors and ensures predictable power-down timing in multi-rail systems.

Can AP7343D-22FS4-7B operate with input voltage below 1.7V?

No. Absolute minimum input voltage is 1.7V per datasheet specifications. Below this, regulation fails and output collapses. For sub-1.7V operation (e.g., single NiMH cell), consider Diodes' AP2204K-22W5-7 or similar ultra-low-V_IN LDOs - AP7343D-22FS4-7B is optimized for 1.7V–5.25V systems like Li-ion or 3.3V logic rails.

How does load transient response vary between 1µF and 4.7µF output capacitors?

With 1µF ceramic C_OUT, load step recovery (1mA ↔ 300mA) shows ~40mV undershoot/overshoot and settles in <100µs. Using 4.7µF reduces peak deviation to ~25mV and improves settling time to <60µs - critical for RF PA bias where rapid current surges demand tighter voltage control.