Diodes Incorporated AP7315D-12FS4-7B

Overview

AP7315D-12FS4-7B from Diodes Incorporated is a 150mA low-dropout linear regulator with fixed 1.2V output, ±1% accuracy, 75dB PSRR at 1kHz, 60µV_rms output noise (10Hz–100kHz), and 35µA quiescent current - designed for RF supply rails in space-constrained portable devices using the X2-DFN1010-4 package.

For engineers reviewing the AP7315D-12FS4-7B datasheet, AP7315D-12FS4-7B pinout, AP7315D-12FS4-7B application, or AP7315D-12FS4-7B equivalent, key selection criteria include dropout voltage at 150mA (max 0.50V for 1.1V ≤ V_OUT < 1.5V), enable threshold compatibility (V_EN(H) ≥ 1.3V), thermal pad layout guidance, and discharge functionality versus non-discharge variants.

Technical Context

The AP7315D-12FS4-7B integrates a CMOS-based error amplifier, precision voltage reference, current-limit circuit, and active pull-down transistor for fast output discharge during shutdown. Its architecture supports stable operation with 0.47µF ceramic input/output capacitors and delivers regulated 1.2V from input voltages as low as 1.7V.

Unlike standard AP7315 variants, the "D" suffix denotes built-in auto-discharge functionality: when EN is pulled low, an internal 30Ω N-channel MOSFET connects VOUT to GND, discharging external capacitance within microseconds - critical for sequencing-sensitive systems requiring rapid rail collapse.

Key Specifications

Pinout & Package

X2-DFN1010-4 (1.0mm × 1.0mm, 0.4mm pitch) with exposed thermal pad - requires PCB copper pour connected to GND for optimal thermal performance (θ_JA ≈ 220°C/W on JEDEC High-K board).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP7315-12FS4-7B, the "D" variant adds essential discharge control for sequenced systems, while MCP1700T trades PSRR and noise performance for lower quiescent current - making AP7315D-12FS4-7B optimal for noise-sensitive, sequenced 1.2V analog/RF rails.

Availability

AP7315D-12FS4-7B is available at Aetrix Electronics and suitable for RF transceiver power, portable camera modules, wearable biometric front-ends, and low-power sensor nodes requiring stable component supply across high-mix production runs.

Supply support for AP7315D-12FS4-7B 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 company specializing in discrete, analog, and mixed-signal solutions for power management, signal integrity, and connectivity applications.

The AP7315 series belongs to Diodes' high-PSRR, low-noise LDO portfolio engineered specifically for noise-sensitive analog and RF subsystems in portable and wireless equipment.

FAQ

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

The thermal pad on AP7315D-12FS4-7B is a mechanical and thermal interface-not an electrical terminal. It must be soldered to a PCB copper pour connected to GND to dissipate heat effectively; leaving it unconnected reduces thermal performance by >40%, risking thermal shutdown under 150mA load at 85°C ambient.

Does the AP7315D-12FS4-7B require an external pull-up on the EN pin?

No external pull-up is required, but the EN pin must never float. It can be tied directly to VIN for always-on operation, or driven by a GPIO with logic-high ≥1.3V and logic-low ≤0.5V. Floating EN causes unpredictable enable/disable behavior due to lack of internal pull-up/down.

How does the auto-discharge feature affect PCB layout?

The internal 30Ω discharge FET activates only when EN = low, sinking VOUT to GND. Layout must avoid placing large capacitance (>10µF) directly on VOUT unless discharge timing is verified - excessive capacitance slows collapse rate and may interfere with downstream power-good signaling.

Can AP7315D-12FS4-7B replace AP7315-12FS4-7B without circuit changes?

Yes, pin-to-pin and functionally compatible - the "D" variant adds discharge capability without altering input/output behavior during regulation. However, if downstream circuitry relies on VOUT remaining high after EN deactivation, the discharge action may require timing analysis or isolation diodes.