Diodes Incorporated AP7343-285FS4-7B

Overview

AP7343-285FS4-7B from Diodes Incorporated is a 300mA, 2.85V fixed-output low-dropout linear regulator (LDO) with high PSRR (75dB at 1kHz), ultra-low output noise (60µVrms, 10Hz–100kHz), and ±1% output voltage accuracy over temperature. Fabricated on a CMOS process, it features enable control, thermal shutdown, short-circuit protection, and operates from 1.7V to 5.25V input - optimized for RF supply rails in portable wireless devices.

For engineers reviewing the AP7343-285FS4-7B datasheet, AP7343-285FS4-7B pinout, AP7343-285FS4-7B application, or AP7343-285FS4-7B equivalent, key selection criteria include dropout voltage at 300mA (0.35V typ. for 2.85V output), quiescent current (35µA typ.), EN logic thresholds (0.5V low / 1.3V high), and X2-DFN1010-4 (Type B) thermal performance (RθJA = 237°C/W).

Technical Context

The AP7343-285FS4-7B integrates a precision voltage reference, error amplifier, current-limit circuit, and CMOS pass transistor - enabling stable regulation with fast load transient response and minimal external components. Its architecture supports both low-noise analog rail generation and high-PSRR filtering of noisy DC-DC outputs.

It delivers fixed 2.85V output without external feedback resistors, uses an active-high enable pin (EN) for system-level power sequencing, and includes built-in thermal shutdown (150°C trip) and fold-back short-circuit protection (~55mA limit). The non-discharge variant (indicated by absence of "D" in part number) retains output voltage during disable.

Key Specifications

Pinout & Package

AP7343-285FS4-7B 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). The EP must be connected to PCB ground plane for optimal thermal dissipation (R_θJB = 85.7°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP7343-285FS4-7B, AP7361-285SG-7 offers double current capacity at the cost of 3× footprint and reduced integration (no integrated thermal pad), while MCP1700-2802E/TO omits enable control, delivers 50mV lower voltage, and cannot support 300mA loads - making AP7343-285FS4-7B the sole fit for space-constrained, high-performance portable RF applications.

Availability

AP7343-285FS4-7B is available at Aetrix Electronics and suitable for RF power amplifier biasing, camera ISP core supplies, wireless audio codec references, and Bluetooth LE SoC subsystems requiring stable component supply, consistent parametric performance, and long-term production continuity.

Supply support for AP7343-285FS4-7B 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 ICs, with emphasis on power management, signal integrity, and connectivity 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 clean, efficient, and space-optimized voltage regulation is critical.

FAQ

What is the minimum input voltage required for AP7343-285FS4-7B to regulate 2.85V at 300mA?

The minimum input voltage is determined by dropout: at 300mA, typical dropout is 0.35V, so VIN(min) = 2.85V + 0.35V = 3.2V. Absolute minimum VIN per datasheet is 1.7V, but regulation fails below 3.2V under full load. For guaranteed 300mA operation, maintain VIN ≥ 3.25V with margin.

Does AP7343-285FS4-7B include output discharge functionality?

No. The "D" suffix denotes discharge variants (e.g., AP7343D-285FS4-7B). AP7343-285FS4-7B is the non-discharge version: when EN is pulled low, VOUT remains floating and retains its voltage until discharged by external load or leakage. This behavior is intentional for systems requiring hold-up or controlled power-down sequencing.

Can AP7343-285FS4-7B be used with ceramic output capacitors smaller than 1µF?

Yes - the device is stable with ≥0.47µF ceramic capacitors, per datasheet recommendations. However, 1µF is specified for optimal transient response and PSRR performance. Using <1µF may increase output voltage deviation during 100mA–300mA load steps and reduce high-frequency ripple rejection.

How does the exposed thermal pad (EP) affect thermal performance in AP7343-285FS4-7B?

The EP reduces junction-to-board thermal resistance to 85.7°C/W (vs. >300°C/W without it), enabling 30% higher power dissipation before thermal shutdown. It must be soldered to a ≥4mm² GND-connected copper pour; using it as sole GND connection violates pin function - GND pin (PIN2) remains mandatory for signal integrity.