Diodes Incorporated AP7343D-34FS4-7B

Overview

AP7343D-34FS4-7B from Diodes Incorporated is a 300mA, 3.4V fixed-output low-dropout (LDO) regulator in X2-DFN1010-4 (Type B) package, featuring ±1% output voltage accuracy, 75dB PSRR at 1kHz, 60µV_rms 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 portable wireless devices.

For engineers reviewing the AP7343D-34FS4-7B datasheet, AP7343D-34FS4-7B pinout, AP7343D-34FS4-7B application, or AP7343D-34FS4-7B equivalent, key selection criteria include dropout voltage at 300mA (0.22–0.29V for 3.4V output), EN logic thresholds (0–0.5V low, 1.3–5.25V high), thermal resistance (R_θJA = 237°C/W), and discharge functionality enabled by the "D" suffix.

Technical Context

The AP7343D employs a CMOS-based architecture with integrated voltage reference, error amplifier, current limit circuit, and thermal shutdown. Its enable input (EN) provides precise on/off control without floating-state risk, and the built-in auto-discharge path (enabled by "D") actively pulls VOUT to GND during shutdown to prevent back-powering of downstream circuitry.

This LDO delivers stable regulation across –40°C to +85°C ambient, supports input voltages from 1.7V to 5.25V, and maintains <±30ppm/°C output voltage drift. 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 but not used as sole GND electrode.

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 PCB ground plane for optimal thermal performance (R_θJB = 85.72°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1703T-3302E/MB and XC6210B342MR-G, AP7343D-34FS4-7B uniquely combines 3.4V precision, auto-discharge, ultra-low noise, and industry-leading 237°C/W thermal resistance in a 1.0mm² DFN-making it optimal for thermally constrained RF and imaging subsystems demanding both performance and safe shutdown behavior.

Availability

AP7343D-34FS4-7B is available at Aetrix Electronics and suitable for RF power amplifier bias, camera sensor core supply, wireless adapter modules, and portable media player audio codec applications requiring stable component supply, automotive-grade reliability (via AP7343Q variant), and long-term lifecycle support.

Supply support for AP7343D-34FS4-7B 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, designed specifically for noise-sensitive applications in portable communications equipment-including smartphones, tablets, and wireless infrastructure where supply rail cleanliness directly impacts RF performance and battery runtime.

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 large GND copper pour on the PCB to lower junction temperature. Diodes specifies R_θJB = 85.72°C/W when EP is properly connected; leaving it unconnected degrades thermal performance by >40°C under 300mA load.

Does AP7343D-34FS4-7B require an external pull-up resistor on the EN pin?

No external pull-up is required. The EN pin has internal weak pull-down (≤1µA leakage), so tying it directly to VIN or a GPIO suffices. However, if left floating, the regulator may behave unpredictably-always drive EN explicitly high or low per datasheet thresholds (V_IH ≥ 1.3V, V_IL ≤ 0.5V).

How does the auto-discharge feature affect system-level power sequencing?

The "D" suffix enables an internal 30Ω NMOS between VOUT and GND that activates within 1µs of EN going low. This discharges output capacitance in <100µs, preventing back-powering of upstream regulators or violating I/O voltage limits during controlled shutdown-critical for multi-rail SoC power sequencing.

Can AP7343D-34FS4-7B operate with only a 0.47µF input capacitor?

Yes-the datasheet specifies a minimum 0.47µF ceramic capacitor on VIN. For optimal transient response and noise rejection, place it within 2mm of VIN/GND pins using wide, low-inductance traces. Larger values (e.g., 1µF) further improve stability under fast load steps but are not mandatory.