Diodes Incorporated AP7343D-32FS4-7B

Overview

AP7343D-32FS4-7B from Diodes Incorporated is a 300mA, 3.2V fixed-output low-dropout linear regulator with high PSRR (75dB at 1kHz), ultra-low output noise (60µV_rms, 10Hz–100kHz), ±1% output voltage accuracy, and enable-controlled shutdown. Fabricated in CMOS, it delivers stable power to RF supplies and camera modules in space-constrained portable electronics using the X2-DFN1010-4 (Type B) package.

For engineers reviewing the AP7343D-32FS4-7B datasheet, AP7343D-32FS4-7B pinout, AP7343D-32FS4-7B application, or AP7343D-32FS4-7B equivalent, key selection criteria include dropout voltage at 300mA (0.22–0.29V for 3.2V output), thermal resistance (θ_JA = 237°C/W), EN logic thresholds (V_IL ≤ 0.5V, V_IH ≥ 1.3V), and discharge functionality enabled by the 'D' suffix.

Technical Context

The AP7343D integrates a precision voltage reference, error amplifier, current-limit circuit, and thermal shutdown protection. Its CMOS-based architecture enables low quiescent current (35µA typ.) and fast load transient response-critical for battery-powered RF and imaging subsystems.

Unlike standard LDOs, the 'D' variant includes an internal N-channel MOSFET (R_ON = 30Ω typ.) between VOUT and GND for active output discharge during shutdown, eliminating residual voltage hold-up and enabling precise sequencing in multi-rail systems.

Key Specifications

Pinout & Package

AP7343D-32FS4-7B uses the X2-DFN1010-4 (Type B) 1.0mm × 1.0mm, 0.4mm pitch, 4-pin package with exposed pad (EP) for thermal dissipation. The EP must be connected to GND via large copper area but not used as sole GND electrode.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP7343-32FS4-7B, the 'D' variant adds critical discharge functionality for sequencing-sensitive designs, while the XC6210B322MR-G offers alternative sourcing but requires external design effort to match discharge behavior and consumes significantly more quiescent current in standby.

Availability

AP7343D-32FS4-7B is available at Aetrix Electronics and suitable for smartphone camera modules, RF front-end biasing, portable media player audio codecs, and wireless adapter baseband circuits requiring stable component supply, automotive-grade traceability, and long-term production continuity.

Supply support for AP7343D-32FS4-7B 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 manufacturer 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 low-noise, high-PSRR power delivery in battery-powered portable and wireless communication equipment.

FAQ

What is the purpose of the 'D' suffix in AP7343D-32FS4-7B?

The 'D' denotes integrated output discharge functionality: when the EN pin is pulled low, an internal 30Ω N-channel MOSFET connects VOUT to GND, actively discharging the output capacitor to <0.1V within 100µs. This enables precise power sequencing in multi-rail systems and prevents unintended device wake-up due to residual voltage.

Can AP7343D-32FS4-7B operate from a single-cell Li-ion battery?

Yes. With a minimum input voltage of 1.7V and a 3.2V output, the device requires ≥3.42V input to maintain regulation at 300mA (max dropout = 0.29V). It operates reliably across the usable range of a single-cell Li-ion (3.4V–4.2V), including end-of-discharge conditions, provided layout minimizes trace resistance.

What is the recommended output capacitor for optimal stability?

A 1µF X5R/X7R ceramic capacitor placed within 2mm of VOUT and GND pins is recommended. The AP7343D is stable with low-ESR ceramics; avoid high-ESR electrolytics. For high-transient loads, parallel with a 4.7µF ceramic to improve dynamic response without compromising stability.

How does thermal performance differ between X2-DFN1010-4 and SOT25 packages?

The X2-DFN1010-4 (θ_JA = 237°C/W) offers superior thermal performance over SOT25 (θ_JA = 179°C/W) due to its exposed pad and smaller footprint. In practice, the DFN package achieves lower junction temperature under identical 300mA load and PCB copper area, enabling higher reliability in thermally dense layouts.