Diodes Incorporated AP7351D-33FS4-7B

Overview

AP7351D-33FS4-7B from Diodes Incorporated is a fixed 3.3V, 150mA ultra-low quiescent current LDO regulator in X2-DFN1010-4 (Type B) package with enable control, ±1% output voltage accuracy at +25°C, 0.5µA quiescent current, and 60dB PSRR at 1kHz - designed for power management in battery-constrained wearable sensors and IoT edge nodes.

For engineers reviewing the AP7351D-33FS4-7B datasheet, AP7351D-33FS4-7B pinout, AP7351D-33FS4-7B application, or AP7351D-33FS4-7B equivalent, key selection criteria include dropout voltage at 150mA (0.16–0.35V), active output discharge capability, thermal shutdown threshold (+160°C), and compatibility with 0.1µF ceramic input/output capacitors.

Technical Context

The AP7351D-33FS4-7B integrates a precision voltage reference, error amplifier, current-limit circuit, and active output discharge path. Its enable input (EN) accepts logic-level control (VIH ≥ 1.0V, VIL ≤ 0.4V) to switch between active regulation and <0.2µA standby current mode.

It operates across 1.4V–5.5V input range with guaranteed 150mA output into loads requiring stable 3.3V supply. The device features internal thermal shutdown (+160°C trigger, +20°C hysteresis) and short-circuit protection (60mA limit), and remains stable with minimal 0.1µF ceramic CIN/COUT.

Key Specifications

Pinout & Package

X2-DFN1010-4 (Type B) package: 1.0mm × 1.0mm, 0.65mm pitch, exposed thermal pad (EP) - requires PCB copper area connected to GND for optimal thermal dissipation (θ_JA = 237°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700-3302E/TO and XC6210B332MR-G, the AP7351D-33FS4-7B delivers superior battery life (0.5µA vs. ≥1.0µA), integrated power sequencing (active discharge), and smaller footprint - making it optimal for space- and energy-constrained edge nodes.

Availability

AP7351D-33FS4-7B is available at Aetrix Electronics and suitable for wearable electronics, IoT sensor modules, and wireless communication devices requiring stable component supply with long-term manufacturability and RoHS/Green compliance.

Supply support for AP7351D-33FS4-7B 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-I_Q LDO family targeting battery-powered portable and industrial edge devices where extended runtime and small form factor are essential design constraints.

FAQ

What is the minimum input voltage required for AP7351D-33FS4-7B to maintain regulation at 150mA?

The minimum input voltage is determined by dropout voltage: at 150mA and 3.3V output, typical dropout is 0.16V, so VIN must be ≥ 3.46V. Absolute maximum dropout is 0.35V, requiring VIN ≥ 3.65V under worst-case conditions. Below 1.4V input, the device ceases regulation entirely per datasheet limits.

Does AP7351D-33FS4-7B require an external pull-up on the EN pin for default-on operation?

No external pull-up is required. To enable the regulator by default, connect EN directly to VIN. The EN pin has no internal pull-up; leaving it unconnected risks floating state and unpredictable behavior. Driving EN to VIN ensures reliable activation across all operating voltages (1.4–5.5V).

Can AP7351D-33FS4-7B be used with tantalum output capacitors instead of ceramic?

No - the AP7351D-33FS4-7B is optimized for ceramic capacitors with ESR < 100mΩ. Tantalum capacitors typically exhibit higher ESR and risk instability or oscillation. The datasheet explicitly recommends X5R/X7R ceramics and provides ESR vs. IOUT stability boundaries; using tantalum violates validated design conditions.

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

No, the exposed pad is not internally connected to any pin. It serves solely as a thermal and mechanical interface. Per datasheet layout guidance, it should be soldered to a PCB copper area tied to GND for heat dissipation - but must not be used as the sole GND connection point, as it lacks electrical bonding to PIN2 (GND).