Diodes Incorporated AP7351D-28FS4-7B

Overview

AP7351D-28FS4-7B from Diodes Incorporated is a 2.8V fixed-output, 150mA ultra-low quiescent current LDO regulator in X2-DFN1010-4 (Type B) package, featuring ±1% output voltage accuracy at +25°C, 0.5µA quiescent current, and 0.19V dropout at 150mA - designed for power management in compact, battery-constrained wearable and IoT sensor modules.

For engineers reviewing the AP7351D-28FS4-7B datasheet, AP7351D-28FS4-7B pinout, AP7351D-28FS4-7B application, or AP7351D-28FS4-7B equivalent, key selection criteria include its 1.4V–5.5V input range, active output discharge function, EN-controlled shutdown with 0.02µA standby current, and compatibility with 0.1µF ceramic input/output capacitors.

Technical Context

The AP7351D-28FS4-7B integrates a precision voltage reference, error amplifier, current-limit circuit, and enable-controlled pass transistor to deliver stable 2.8V output across –40°C to +85°C ambient. Its internal resistor network fixes the output, eliminating external feedback components.

It features active output discharge via an internal 35Ω NMOS switch when EN is low, ensuring rapid VOUT decay during shutdown. Thermal shutdown activates at +160°C with +20°C hysteresis, and PSRR reaches 60dB at 1kHz for noise-sensitive analog rails.

Key Specifications

Pinout & Package

X2-DFN1010-4 (Type B) is a 1.0mm × 1.0mm, 0.4mm pitch, 4-terminal surface-mount package with exposed thermal pad. It offers low profile (0.39mm max height) and optimized thermal performance for high-density portable PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700T-2802E/TT and XC6210B282MR-G, the AP7351D-28FS4-7B uniquely combines ultra-low 0.5µA quiescent current, integrated active discharge, and X2-DFN1010-4's thermal efficiency - making it optimal for space- and battery-limited wearable and medical edge nodes where rail sequencing and leakage matter.

Availability

AP7351D-28FS4-7B is available at Aetrix Electronics and suitable for wearable electronics, IoT sensor nodes, wireless camera modules, and medical patch monitors requiring stable component supply with long-term lifecycle assurance.

Supply support for AP7351D-28FS4-7B 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 ICs for power management, signal integrity, and connectivity applications.

The AP7351D belongs to Diodes' ultra-low-IQ LDO family, engineered specifically for extended battery life in portable and energy-harvesting systems where micropower operation and small form factor are critical.

FAQ

What is the minimum input voltage required for AP7351D-28FS4-7B to maintain regulation at 150mA load?

The minimum input voltage is calculated as VOUT + dropout = 2.8V + 0.19V = 2.99V. At 150mA and +25°C, the device sustains regulation down to 2.99V input. Below this, output voltage drops nonlinearly per the 2% nominal specification. Input must remain ≥1.4V for basic functionality, but regulation requires ≥2.99V under full load.

Does AP7351D-28FS4-7B require an external pull-up on the EN pin?

No external pull-up is required. The EN pin has no internal pull-up or pull-down; it must be actively driven high (≥1.0V) to enable or low (≤0.4V) to disable. If unused, Diodes recommends tying EN directly to VIN to ensure permanent operation - floating EN causes undefined behavior and potential instability.

Can AP7351D-28FS4-7B be used with ceramic capacitors smaller than 0.1µF?

No. The datasheet specifies stability with ≥0.1µF ceramic capacitors on both input and output. Using smaller values risks oscillation or poor transient response due to insufficient phase margin. X5R/X7R dielectrics are recommended for stable capacitance and ESR across temperature.

Is the exposed pad (EP) of the X2-DFN1010-4 package electrically connected to GND internally?

No - the exposed pad is thermally conductive but not electrically connected to any internal node. It must be soldered to a PCB copper area tied to GND for thermal performance, but it serves no electrical function as a GND terminal. Relying on it as the sole GND path violates the pinout definition and compromises reliability.