Diodes Incorporated AP7351D-27FS4-7B

Overview

AP7351D-27FS4-7B from Diodes Incorporated is a 2.7V 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 typical quiescent current, and 0.2V dropout at 150mA for VOUT=2.7V. It delivers stable power to wearable electronics and IoT sensor modules requiring extended battery life.

For engineers reviewing the AP7351D-27FS4-7B datasheet, AP7351D-27FS4-7B pinout, AP7351D-27FS4-7B application, or AP7351D-27FS4-7B equivalent, key selection criteria include guaranteed 150mA output under 1.4V–5.5V input, active output discharge, thermal shutdown at +160°C, and compatibility with 0.1µF ceramic input/output capacitors.

Technical Context

The AP7351D-27FS4-7B integrates a precision voltage reference, error amplifier, current-limit circuit, and enable control logic. Its internal resistor network fixes the output at 2.7V, eliminating external feedback components.

It features active output discharge via a 35Ω internal FET when EN is low, ensuring rapid VOUT decay during shutdown. Thermal protection includes +160°C shutdown threshold with +20°C hysteresis, and it operates across –40°C to +85°C ambient temperature.

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 θ_JA = 237°C/W and supports high-density layout in space-constrained wearables.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700T-2702E/TT and XC6210B272MR-G, the AP7351D-27FS4-7B uniquely combines ultra-low 0.5µA IQ, active discharge, thermal shutdown, and EN control in a 1.0mm² DFN - making it optimal for compact, safety-aware, battery-critical designs.

Availability

AP7351D-27FS4-7B is available at Aetrix Electronics and suitable for wearable electronics, IoT sensor nodes, medical patches, and industrial wireless monitors requiring stable component supply and long-term lifecycle support.

Supply support for AP7351D-27FS4-7B 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 devices, with manufacturing certified to IATF 16949 and product qualification per AEC-Q100 for automotive use.

The AP7351D belongs to Diodes' ultra-low-IQ LDO family, designed specifically for energy-constrained battery-powered applications where extended runtime and precise voltage regulation are essential.

FAQ

What is the minimum input voltage required for AP7351D-27FS4-7B to maintain regulation at full 150mA load?

The minimum input voltage is calculated as VOUT + dropout voltage. At 150mA and +25°C, dropout is 0.2V for 2.7V output, so VIN(min) = 2.9V. At –40°C, dropout increases slightly; datasheet specifies 0.25V max over temperature, requiring VIN ≥ 2.95V for guaranteed regulation at full load across the full operating range.

Does AP7351D-27FS4-7B require an external pull-up on the EN pin for reliable startup?

No external pull-up is required. The EN pin has no internal pull-up; however, it must never float. For always-on operation, tie EN directly to VIN. If controlled by a microcontroller GPIO, ensure the driver meets V_EN(H) ≥ 1.0V and V_EN(L) ≤ 0.4V thresholds - no additional resistors needed if the MCU IO meets these specs.

Can AP7351D-27FS4-7B be used with tantalum output capacitors instead of ceramic?

No. The AP7351D is optimized for ceramic capacitors with ESR < 100mΩ. Tantalum capacitors typically have higher ESR (500mΩ–2Ω), which can cause instability and oscillation. The datasheet explicitly recommends X5R/X7R ceramics and warns against high-ESR types; using tantalum voids stability guarantees.

Is the exposed pad (EP) on the X2-DFN1010-4 (Type B) package electrically connected internally?

No. The exposed pad is thermally conductive only and has no electrical connection to any internal circuit. It must be soldered to a PCB copper pour tied to GND for thermal performance, but it must not be used as a functional GND terminal - all GND current flows through PIN2. Using EP as sole GND path risks thermal overstress and regulation drift.