Diodes Incorporated AP7343-135FS4-7B

Overview

AP7343-135FS4-7B from Diodes Incorporated is a 300mA low-dropout linear regulator with fixed 1.35V 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.

For engineers reviewing the AP7343-135FS4-7B datasheet, AP7343-135FS4-7B pinout, AP7343-135FS4-7B application, or AP7343-135FS4-7B equivalent, key selection criteria include dropout voltage at 300mA (0.39V typ. for 1.35V_OUT), enable threshold compatibility (EN high ≥1.3V), thermal resistance (θ_JA = 237°C/W in X2-DFN1010-4), and discharge option absence (non-discharge variant).

Technical Context

The AP7343-135FS4-7B integrates a CMOS-based error amplifier, precision voltage reference, current-limit circuit, and thermal shutdown protection. Its architecture delivers stable regulation across 1.7V–5.25V input while maintaining tight load/line regulation (≤30mV load shift, ≤0.1%/V line shift) under dynamic conditions.

It operates without external compensation, supports fast transient response (≤100µs recovery for 1mA↔300mA load steps with 1µF C_OUT), and features an enable input with defined logic thresholds (V_EN(H) ≥1.3V, V_EN(L) ≤0.5V) and leakage <±1.0µA - enabling precise power sequencing in multi-rail systems.

Key Specifications

Pinout & Package

AP7343-135FS4-7B uses the X2-DFN1010-4 (Type B) 1.0mm × 1.0mm, 0.4mm pitch, 4-pin package with exposed thermal pad (EP). The EP must be connected to GND via large copper area for optimal thermal performance (θ_JB = 85.7°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1703T-135I/OT and XC6210B135MR-G, the AP7343-135FS4-7B uniquely balances 300mA drive, 60µV_rms noise, and 237°C/W thermal resistance in a 1.0mm² footprint - making it optimal for space-constrained, noise-sensitive, high-current portable RF designs.

Availability

AP7343-135FS4-7B is available at Aetrix Electronics and suitable for RF power amplifier bias, camera image signal processor supply, wireless SoC core regulation, and portable media player audio codec applications requiring stable component supply, long-lifecycle support, and RoHS-compliant sourcing.

Supply support for AP7343-135FS4-7B 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-critical portable electronics where RF performance, battery life, and miniaturization are primary design constraints.

FAQ

What is the maximum input voltage rating for AP7343-135FS4-7B?

The absolute maximum input voltage is 6.0V, but the recommended operating range is 1.7V to 5.25V. Exceeding 5.25V risks violating safe operating area limits and may trigger thermal shutdown or degrade long-term reliability, even if below the 6.0V absolute maximum.

Does AP7343-135FS4-7B include output auto-discharge functionality?

No. The "-7B" suffix indicates the non-discharge variant. When disabled via EN pin, the output remains floating and retains charge on the output capacitor until naturally discharged through the load. For active discharge, select AP7343D-135FS4-7B instead.

Can AP7343-135FS4-7B operate with only a 0.47µF input capacitor?

Yes - a minimum 0.47µF ceramic capacitor between VIN and GND is specified for input decoupling. However, for systems with high di/dt load transients, adding a 1–2.2µF bulk capacitor in parallel improves immunity to input rail collapse and reduces conducted EMI.

What is the thermal performance difference between X2-DFN1010-4 and SOT25 packages?

X2-DFN1010-4 has θ_JA = 237°C/W and θ_JC(bot) = 16.2°C/W; SOT25 has θ_JA = 179°C/W and θ_JC(bot) = 58.4°C/W. The DFN's lower junction-to-case resistance enables better heat transfer to the PCB ground plane, but its higher junction-to-ambient value means it relies more heavily on proper thermal pad layout.