Diodes Incorporated AP2125K-3.3TRG1

Overview

AP2125K-3.3TRG1 from Diodes Incorporated is a 300mA, fixed-output 3.3V CMOS low-dropout (LDO) regulator in SOT-23-5 package, featuring 65mV dropout at 100mA, ±2% output voltage accuracy, 50µV_rms output noise, and active-high enable control. It delivers stable power to noise-sensitive analog circuitry in portable battery-powered systems.

For engineers reviewing the AP2125K-3.3TRG1 datasheet, AP2125K-3.3TRG1 pinout, AP2125K-3.3TRG1 application, or AP2125K-3.3TRG1 equivalent, key selection criteria include ultra-low noise performance, sub-100mV dropout under load, 0.01µA shutdown current, compatibility with ceramic output capacitors, and thermal shutdown protection at +160°C.

Technical Context

The AP2125K-3.3TRG1 integrates a precision voltage reference, error amplifier, resistor feedback network, CE-controlled enable logic, overcurrent limiting, and overtemperature shutdown (OTSD) circuitry - all fabricated in CMOS process for low quiescent current. Its architecture supports fast transient response and stable operation with 1µF ceramic capacitors on input and output.

It operates across -40°C to +85°C ambient, accepts input voltages from (V_OUT + 0.5)V up to 6V, and maintains regulation under 300mA load while rejecting supply ripple up to 65dB at 1kHz. The CE pin enables full system-level power sequencing with 1.5V logic-high threshold and 0.4V logic-low threshold.

Key Specifications

Pinout & Package

SOT-23-5 package: 2.9mm × 1.6mm × 1.1mm body, surface-mount, RoHS-compliant, halogen-free "Green" construction.

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 AP2125K-3.3TRG1 uniquely combines 300mA capability, 65mV dropout, integrated thermal shutdown, and 50µV_rms noise in a standard SOT-23-5 - making it optimal for thermally demanding, noise-critical, and sequenced power architectures.

Availability

AP2125K-3.3TRG1 is available at Aetrix Electronics and suitable for CDMA/GSM handsets, handheld test instruments, notebook computers, and PCMCIA peripheral cards requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for AP2125K-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 semiconductor manufacturer specializing in discrete, analog, and mixed-signal solutions, with emphasis on power management, signal integrity, and protection devices for industrial, computing, and consumer markets.

The AP2125 series belongs to Diodes' high-performance LDO portfolio, designed specifically for battery-powered portable electronics where ultra-low noise, low dropout, and minimal quiescent current are essential for runtime and signal fidelity.

FAQ

What is the minimum input voltage required for AP2125K-3.3TRG1 to maintain regulation?

The AP2125K-3.3TRG1 requires VIN ≥ (VOUT + 0.5V) = 3.8V to guarantee regulation across temperature and load. At 100mA output, its 65mV dropout means it sustains 3.3V output down to 3.365V input; however, the 0.5V headroom ensures stability under line/load transients and worst-case process corners per datasheet specification.

Can AP2125K-3.3TRG1 operate with a 1µF ceramic output capacitor only?

Yes - the AP2125K-3.3TRG1 is explicitly characterized and guaranteed stable with a 1µF X5R/X7R ceramic capacitor (ESR < 100mΩ) on VOUT, as confirmed in DS38144 Rev. 2-2 Section 15 (ESR vs. Output Current plot) and Typical Application Circuit. No series resistance or secondary capacitor is required.

Does AP2125K-3.3TRG1 support reverse-voltage protection?

The AP2125K-3.3TRG1 includes inherent reverse-input protection: when VIN < GND, the internal PMOS pass device remains off, limiting reverse current to <1µA (per Absolute Maximum Ratings table). This prevents damage during board rework or miswiring but does not protect against reverse output voltage.

How does the CE pin behave during power-up and power-down sequencing?

The CE pin has no internal pull-up/down; it must be actively driven. During power-up, CE must rise above 1.5V after VIN reaches ≥3.8V to avoid brown-out activation. During power-down, CE must fall below 0.4V before VIN drops below 3.3V to ensure clean shutdown - external RC timing or dedicated sequencer is recommended for deterministic behavior.