Diodes Incorporated AP7315D-31FS4-7B

Overview

AP7315D-31FS4-7B from Diodes Incorporated is a 3.1V fixed-output, 150mA low-dropout linear regulator with enable control, ±1% output voltage accuracy, 75dB PSRR at 1kHz, and 60µV_rms output noise (10Hz–100kHz). It features CMOS-based architecture, 35µA quiescent current, and operates from 1.7V to 5.25V input - optimized for RF supply rails in portable wireless devices.

For engineers reviewing the AP7315D-31FS4-7B datasheet, AP7315D-31FS4-7B pinout, AP7315D-31FS4-7B application, or AP7315D-31FS4-7B equivalent, key selection criteria include dropout voltage at 150mA (max 290mV for 3.1V output), EN pin logic thresholds (0.5V low / 1.3V high), thermal performance in X2-DFN1010-4, and discharge functionality for fast VOUT decay during shutdown.

Technical Context

The AP7315D variant integrates an internal NMOS pass transistor with auto-discharge capability: when EN is pulled low, a 30Ω on-resistance path actively discharges the output capacitor to GND. Its error amplifier uses a precision bandgap reference and achieves ±1% initial accuracy over temperature (±30ppm/°C drift) and load (0–150mA).

Designed for noise-sensitive analog and RF subsystems, it delivers 75dB ripple rejection at 1kHz and maintains stability with 0.47µF ceramic output capacitors. The regulator's low 60µV_rms noise floor and 35µA quiescent current support battery-powered applications requiring extended runtime and clean power delivery.

Key Specifications

Pinout & Package

X2-DFN1010-4 package: 1.0mm × 1.0mm, 0.4mm pitch, thermally enhanced with exposed pad (not electrically connected to GND by default; recommended to tie to GND plane for thermal relief).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP7315-31FS4-7B, the D-version adds critical discharge control for sequencing-critical systems; versus MCP1700, it trades slightly higher IQ for significantly better noise/PSRR performance essential in RF and high-fidelity analog designs.

Availability

AP7315D-31FS4-7B is available at Aetrix Electronics and suitable for RF power amplifier bias, camera sensor core supply, and wireless adapter SoC I/O rails requiring stable component supply, tight voltage accuracy, and fast shutdown discharge behavior.

Supply support for AP7315D-31FS4-7B 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 power management, signal integrity, and protection solutions for consumer, industrial, and automotive markets.

The AP7315 series belongs to Diodes' high-PSRR, low-noise LDO product line, engineered specifically for noise-sensitive RF and imaging subsystems in portable electronics where clean, sequenced power delivery is mandatory.

FAQ

What is the purpose of the thermal pad on the X2-DFN1010-4 package?

The thermal pad is a non-electrical copper land beneath the die used solely for heat dissipation. It must be soldered to a large PCB copper area connected to GND (or left floating) - never used as the sole GND connection. Proper thermal pad layout reduces junction-to-ambient thermal resistance by up to 30°C/W, preventing thermal shutdown at 150mA continuous load.

Does AP7315D-31FS4-7B require an external discharge resistor?

No. The "D" suffix denotes integrated auto-discharge functionality: an internal 30Ω NMOS FET connects VOUT to GND when EN is low. This eliminates need for external resistors, reduces BOM count, and ensures consistent 100µs discharge time regardless of output capacitance value - critical for reliable power sequencing.

Can AP7315D-31FS4-7B operate with input voltage below 3.1V?

No. With 3.1V nominal output, minimum input is 3.39V (3.1V + 290mV dropout) to maintain regulation at 150mA. At lighter loads, dropout decreases (e.g., 210mV at 50mA), allowing operation down to ~3.31V. Below that, output drops linearly with input - not suitable for sub-3.3V battery operation without pre-regulation.

How does the EN pin behave during power-up and power-down sequences?

The EN pin has hysteresis-free TTL-compatible thresholds: regulator enables when EN rises above 1.3V and disables when EN falls below 0.5V. During power-up, VIN must stabilize before EN is asserted; during shutdown, pulling EN low immediately activates discharge FET. No external pull-up is required - internal 100nA leakage ensures defined state if left unconnected.