Diodes Incorporated AP2127K-3.3TRG1

Overview

AP2127K-3.3TRG1 from Diodes Incorporated is a 300mA, 3.3V fixed-output CMOS low-dropout (LDO) regulator in SOT-23-5 package, featuring 170mV dropout at full load, ±2% output voltage accuracy, and 60μVRMS output noise. It delivers stable power to noise-sensitive analog circuitry in portable electronics with 60μA quiescent current and integrated thermal/overcurrent protection.

For engineers reviewing the AP2127K-3.3TRG1 datasheet, AP2127K-3.3TRG1 pinout, AP2127K-3.3TRG1 application, or AP2127K-3.3TRG1 equivalent, key selection criteria include low-noise regulation for RF/analog subsystems, fast 50μs soft-start for sequencing control, compatibility with 1μF ceramic input/output capacitors, and shutdown-enabled auto-discharge via 60Ω internal MOSFET.

Technical Context

The AP2127K-3.3TRG1 uses a PMOS pass transistor architecture enabling ultra-low dropout and high PSRR (68dB @ 1kHz). Its internal 0.8V reference feeds a precision error amplifier that maintains output regulation across line (2.5–6V input), load (1–300mA), and temperature (−40°C to +85°C) variations.

It integrates active shutdown logic with 1.5V high-threshold and 0.5V low-threshold inputs, enabling controlled power sequencing. The device includes an internal 60Ω discharge FET between VOUT and GND during shutdown, reducing residual output voltage decay time without external components.

Key Specifications

Pinout & Package

SOT-23-5 package with exposed thermal pad (connected to GND for optimal thermal performance); 5-pin surface-mount outline measuring 2.9mm × 1.6mm × 1.1mm (L×W×H).

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 AP2127K-3.3TRG1 uniquely combines 300mA capability, 60μA IQ, active shutdown with auto-discharge, and full thermal/overcurrent protection-making it optimal for sequenced, safety-aware, and noise-sensitive embedded systems.

Availability

AP2127K-3.3TRG1 is available at Aetrix Electronics and suitable for wireless sensor nodes, industrial PLC I/O modules, notebook subsystem power, and medical wearable front-ends requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for AP2127K-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 company specializing in discrete, analog, and mixed-signal solutions for power management, signal integrity, and connectivity applications.

The AP2127 series belongs to Diodes' high-performance LDO portfolio designed specifically for battery-powered and noise-sensitive electronics requiring ultra-low noise, low IQ, and robust protection features.

FAQ

What is the minimum input voltage required for AP2127K-3.3TRG1 to maintain regulation at 300mA load?

The minimum input voltage is 3.47V, calculated as VOUT + VDROP = 3.3V + 0.17V. This 170mV dropout enables operation from partially discharged single-cell Li-ion batteries (nominal 3.7V, end-of-discharge ~3.4V), making it suitable for portable equipment with tight input voltage margins.

Can AP2127K-3.3TRG1 be used with ceramic output capacitors smaller than 1μF?

No-stability is guaranteed only with ≥1μF X7R or X5R ceramic capacitors on the output. Using smaller values risks oscillation due to insufficient phase margin; the device's internal compensation is optimized for 1μF–10μF ESR ranges typical of these MLCC types.

How does the shutdown pin function, and what happens to VOUT when it is pulled low?

The shutdown pin is active-high with 1.5V threshold. When pulled below 0.5V, the pass transistor turns off and the internal 60Ω discharge MOSFET connects VOUT to GND, actively draining output capacitance. This ensures rapid VOUT decay (<1ms for 10μF load), critical for safe power sequencing in multi-rail systems.

Is the exposed thermal pad on the SOT-23-5 package electrically connected, and how should it be handled in PCB layout?

Yes-the exposed pad is internally connected to GND and must be soldered to a dedicated GND copper pour for thermal and electrical performance. Use ≥4 thermal vias (0.3mm diameter) connecting the pad to inner-layer GND planes to achieve θJA ≤ 250°C/W and prevent junction temperature exceedance under 300mA continuous load.