Diodes Incorporated AP2125N-3.3TRG1

Overview

AP2125N-3.3TRG1 from Diodes Incorporated is a 300mA, fixed 3.3V CMOS low-dropout (LDO) regulator in SOT-23-3 package, featuring 65mV dropout at 100mA, ±2% output voltage accuracy, and 50µVrms output noise. It integrates over-temperature shutdown, current limiting, and active-high enable control-designed for power-sensitive battery-powered systems requiring stable, ultra-low-noise 3.3V rail generation.

For engineers reviewing the AP2125N-3.3TRG1 datasheet, AP2125N-3.3TRG1 pinout, AP2125N-3.3TRG1 application, or AP2125N-3.3TRG1 equivalent, key selection criteria include dropout performance under 100mA load, standby current below 0.01µA, compatibility with ceramic output capacitors, and thermal shutdown behavior at +160°C junction temperature.

Technical Context

The AP2125N-3.3TRG1 employs a CMOS-based error amplifier architecture with internal voltage reference and resistor network to maintain precise 3.3V regulation across line (4.3V–6V input), load (1mA–300mA), and temperature (−40°C to +85°C) variations. Its high PSRR (65dB at 1kHz) suppresses switching noise from upstream DC/DC converters.

It features an active-high CE pin enabling full system-level power sequencing, with logic thresholds of 1.5V (high) and 0.4V (low), and supports automatic output discharge when disabled. The device operates without external compensation and is stable with 1µF ceramic capacitors on both input and output.

Key Specifications

Pinout & Package

SOT-23-3 package: 3-pin surface-mount, lead-free, RoHS-compliant, footprint compatible with industry-standard PCB land patterns. Thermal resistance θ_JA = 200°C/W (no heatsink).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700T-3302E/TT and XC6206P332MR-G, the AP2125N-3.3TRG1 uniquely balances 300mA drive, sub-100mV dropout, active enable, and 50µVrms noise-making it optimal for battery-powered systems needing both performance headroom and power-state control.

Availability

AP2125N-3.3TRG1 is available at Aetrix Electronics and suitable for CDMA/GSM handsets, handheld instruments, laptops, and PCMCIA cards requiring stable component supply with guaranteed green RoHS compliance and traceable lot history.

Supply support for AP2125N-3.3TRG1 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 manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability, energy-efficient components for consumer, industrial, and communications markets.

The AP2125 series belongs to Diodes' precision LDO portfolio, engineered specifically for ultra-low-noise, low-quiescent-power regulation in space-constrained, battery-operated equipment.

FAQ

What is the minimum input voltage required for regulation at 300mA load?

The AP2125N-3.3TRG1 requires VIN ≥ VOUT + VDROP. At 300mA, typical dropout is 200mV (max 300mV per datasheet), so minimum input is 3.5V. Operation below this causes output collapse; 4.3V nominal input ensures margin across temperature and process variation.

Can AP2125N-3.3TRG1 be used with a 0.47µF output capacitor?

No. The datasheet specifies stability with ≥1µF ceramic output capacitance. Using 0.47µF risks oscillation due to insufficient phase margin-confirmed by ESR vs. output current plots showing instability below 1µF. Always use 1µF or higher X5R/X7R ceramic.

Does the CE pin require a pull-up resistor when interfaced to a microcontroller GPIO?

No external pull-up is needed. The CE pin has no internal pull-up; however, the microcontroller GPIO must actively drive high (≥1.5V) to enable and low (≤0.4V) to disable. Leaving CE floating results in undefined output state-designs must ensure controlled logic levels during reset and sleep transitions.

Is thermal derating required for continuous 300mA operation in still air?

Yes. With θ_JA = 200°C/W and P_D = (VIN − VOUT) × IOUT = (4.3V − 3.3V) × 0.3A = 300mW, junction rise is 60°C above ambient. At 85°C ambient, T_J = 145°C-within 150°C limit but near thermal shutdown threshold. Derate to ≤250mA at 85°C ambient unless PCB copper area improves thermal dissipation.