Diodes Incorporated AP7351D-185FS4-7B

Overview

AP7351D-185FS4-7B from Diodes Incorporated is a 150mA ultra-low quiescent current LDO regulator with fixed 1.85V output, ±1% accuracy at +25°C, 0.5µA quiescent current, and X2-DFN1010-4 (Type B) package. It integrates enable control, active output discharge, and thermal shutdown, targeting power management in compact, battery-constrained systems such as wearable sensors and IoT edge nodes.

For engineers reviewing the AP7351D-185FS4-7B datasheet, AP7351D-185FS4-7B pinout, AP7351D-185FS4-7B application, or AP7351D-185FS4-7B equivalent, key selection criteria include dropout voltage at 150mA (0.32V typ), standby current (0.02µA), EN logic thresholds (1.0V high / 0.4V low), and thermal resistance (237°C/W).

Technical Context

The AP7351D-185FS4-7B employs a PMOS pass transistor architecture enabling ultra-low dropout (0.32V at 150mA for 1.85V output) and sub-µA quiescent operation. Its internal voltage reference and error amplifier maintain ±1% output accuracy across -40°C to +85°C ambient temperature.

Enable functionality supports precise system-level power sequencing: EN ≥1.0V activates regulation; EN ≤0.4V forces shutdown with 0.02µA standby current. Integrated active output discharge (35Ω typical) ensures rapid VOUT decay during disable, preventing floating rail conditions in multi-rail systems.

Key Specifications

Pinout & Package

X2-DFN1010-4 (Type B) package: 1.0mm × 1.0mm footprint, 0.4mm pitch, exposed thermal pad (EP) - optimized for minimal board area and enhanced thermal dissipation in ultra-thin devices.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700T-1802E/TT and XC6210B182MR-G, the AP7351D-185FS4-7B uniquely combines ultra-low 0.5µA quiescent current, integrated EN control, and active output discharge in a 1.0mm² DFN - making it optimal for energy-harvesting and duty-cycled IoT endpoints where rail control and leakage minimization are co-critical.

Availability

AP7351D-185FS4-7B is available at Aetrix Electronics and suitable for wearable electronics, IoT sensor modules, and wireless communication devices requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for AP7351D-185FS4-7B 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 manufacturer specializing in discrete, analog, and mixed-signal solutions for power management, signal integrity, and connectivity applications.

The AP7351D belongs to Diodes' ultra-low-IQ LDO family, designed specifically for extended-battery-life portable and wireless systems where micropower efficiency and small-footprint integration are mandatory.

FAQ

What is the minimum input voltage required for AP7351D-185FS4-7B to regulate 1.85V at 150mA?

The minimum input voltage is determined by dropout: 1.85V + 0.32V = 2.17V (typical). At worst-case 0.58V dropout (per datasheet), VIN must be ≥2.43V. Below 1.4V, the device cannot operate - this limit is set by internal reference and bias circuitry, not dropout alone.

Does AP7351D-185FS4-7B require an external pull-up on the EN pin for default-on operation?

No external pull-up is required. The EN pin has no internal pull-up; it must be actively driven. For default-on behavior, tie EN directly to VIN. Floating EN is prohibited - it may cause erratic enable/disable cycling due to noise susceptibility and undefined logic state.

Can the exposed pad (EP) of AP7351D-185FS4-7B be left unconnected?

No. The EP must be soldered to a PCB copper area connected to GND. Leaving it unconnected degrades thermal performance (θ_JA rises from 237°C/W to >300°C/W) and risks reliability failure under 150mA load. It is not electrically isolated and serves as both thermal conduit and supplementary GND path.

Is AP7351D-185FS4-7B qualified for automotive applications?

No. While Diodes offers AEC-Q100-qualified variants in the AP73xx family, AP7351D-185FS4-7B is rated for industrial temperature range (−40°C to +85°C) only and lacks PPAP documentation or IATF 16949 manufacturing certification. Automotive use requires explicit qualification confirmation from Diodes.