Diodes Incorporated AP7343-32FS4-7B

Overview

AP7343-32FS4-7B from Diodes Incorporated is a 300mA, 3.2V fixed-output low-dropout linear regulator with ±1% output voltage accuracy, 75dB PSRR at 1kHz, and 60µV_rms output noise (10Hz–100kHz). Built on a CMOS process, it features enable control, thermal shutdown, and short-circuit protection, and is optimized for RF supply rails in compact portable electronics.

For engineers reviewing the AP7343-32FS4-7B datasheet, AP7343-32FS4-7B pinout, AP7343-32FS4-7B application, or AP7343-32FS4-7B equivalent, key selection criteria include its 1.7V–5.25V input range, 35µA quiescent current, X2-DFN1010-4 (Type B) package footprint, and guaranteed 300mA output under tight thermal constraints.

Technical Context

The AP7343-32FS4-7B integrates a precision voltage reference, error amplifier, current-limit circuit, and CMOS pass transistor-enabling stable 3.2V regulation with dropout as low as 0.22V at 300mA. Its enable input (EN) provides precise on/off control with defined logic thresholds (V_IL ≤ 0.5V, V_IH ≥ 1.3V), and internal thermal shutdown activates at +150°C with +20°C hysteresis.

Designed for noise-sensitive analog and RF subsystems, it delivers 75dB ripple rejection at 1kHz and maintains <±30ppm/°C output voltage drift across –40°C to +85°C ambient. The device operates without external compensation and remains stable with 1µF ceramic output capacitance.

Key Specifications

Pinout & Package

AP7343-32FS4-7B 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 dissipation (R_θJA = 237°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1703T-3202E/MB and XC6210B322MR-G, the AP7343-32FS4-7B offers best-in-class PSRR (75dB) and smallest footprint (1.0mm²), making it optimal for space-constrained RF and portable imaging designs where noise and size are co-critical.

Availability

AP7343-32FS4-7B is available at Aetrix Electronics and suitable for RF power amplifier supplies, portable camera sensor biasing, wearable MCU core regulation, and wireless audio codec power requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for AP7343-32FS4-7B 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 manufacturer of discrete semiconductors and analog ICs, specializing in high-performance 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 requiring ultra-small footprints and extended battery life.

FAQ

What is the minimum input voltage required for stable 3.2V output at 300mA?

The AP7343-32FS4-7B requires VIN ≥ 3.42V (3.2V + 0.22V dropout) to sustain 300mA output. At lower inputs, output voltage collapses per the dropout curve-e.g., at VIN = 3.3V, max load drops to ~220mA. This is verified in Electrical Characteristics Table (Dropout Voltage section) and Dropout vs. IOUT graphs on page 7 of DS37952 Rev. 12-2.

Can the EN pin be left unconnected if always-on operation is needed?

No-the EN pin must never float. For always-on use, tie EN directly to VIN. This ensures reliable activation above the 1.3V threshold and avoids unintended shutdown due to leakage or EMI. The datasheet explicitly states "must not be floating" and defines V_IH ≥ 1.3V for guaranteed enable (page 3, Pin Descriptions).

Is an output capacitor mandatory, and what value is recommended?

Yes-a minimum 1µF ceramic output capacitor is mandatory for stability and transient response. Diodes specifies stability with "very small ceramic capacitors" and recommends placing it adjacent to VOUT and GND pins. Larger values (e.g., 4.7µF) improve load-step response but are not required for basic operation (page 12, Application Information).

Does AP7343-32FS4-7B include output discharge functionality?

No-AP7343-32FS4-7B is the non-discharge variant. The "D" suffix (e.g., AP7343D-32FS4-7B) denotes built-in discharge. This part lacks the internal NMOS discharge path, so VOUT decays only through load current and COUT leakage-critical for systems requiring hold-up time or avoiding reverse current.