Diodes Incorporated AP2125KC-3.3TRG1

Overview

AP2125KC-3.3TRG1 from Diodes Incorporated is a 300mA, fixed-output 3.3V CMOS low-dropout (LDO) regulator in SC-70-5 package, featuring 65mV dropout at 100mA, ±2% output voltage accuracy, 50µVrms output noise, and 0.01µA standby current. It integrates over-temperature shutdown, current limiting, and enable control-designed for power-sensitive portable electronics requiring stable, ultra-low-noise bias.

For engineers reviewing the AP2125KC-3.3TRG1 datasheet, AP2125KC-3.3TRG1 pinout, AP2125KC-3.3TRG1 application, or AP2125KC-3.3TRG1 equivalent, key selection criteria include dropout performance under 100mA load, RMS noise budget below 60µV, thermal shutdown threshold at +160°C, and compatibility with 1µF ceramic output capacitors without external compensation.

Technical Context

The AP2125KC-3.3TRG1 employs a CMOS pass transistor architecture with internal voltage reference and error amplifier feedback loop, enabling high PSRR (65dB typical at 1kHz) and excellent line/load regulation (≤15mV). Its enable input (CE) provides active-high logic control with 1.5V high-threshold and 0.4V low-threshold, supporting system-level power sequencing.

Thermal protection uses a dedicated OTSD circuit triggering at +160°C with +25°C hysteresis, while current limiting activates at 50mA during short-circuit conditions. The device operates across –40°C to +85°C ambient and supports input voltages from (VOUT + 0.5V) up to 6V.

Key Specifications

Pinout & Package

AP2125KC-3.3TRG1 is housed in a 5-pin SC-70-5 package (2.0mm × 1.25mm × 0.9mm), optimized for space-constrained portable designs. Pinout is validated per Diodes DS38144 Rev. 2–2, top-view configuration.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP2125KC-3.3TRG1, the AP2125K-3.3TRG1 offers superior thermal handling in compact systems, while the MCP1700T-3302E/TT trades current capacity and noise performance for broader vendor availability - making the original optimal for space- and noise-critical 300mA applications.

Availability

AP2125KC-3.3TRG1 is available at Aetrix Electronics and suitable for CDMA/GSM handsets, handheld instruments, PCMCIA cards, and laptop standby power requiring stable component supply, consistent parametric performance, and RoHS-compliant green packaging.

Supply support for AP2125KC-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.

The AP2125 series belongs to Diodes' high-performance LDO portfolio, engineered specifically for battery-powered portable electronics demanding ultra-low noise, minimal dropout, and nanoscale quiescent current.

FAQ

What is the minimum input voltage required for stable 3.3V output?

The AP2125KC-3.3TRG1 requires VIN ≥ VOUT + 0.5V = 3.8V for guaranteed regulation across all operating conditions. At 100mA load, dropout is 65mV, so 3.365V input sustains regulation-but Diodes specifies 3.8V minimum to ensure performance across temperature, process variation, and line/load regulation limits.

Can this LDO operate with a 1µF ceramic output capacitor only?

Yes. The AP2125KC-3.3TRG1 is explicitly designed for stability with 1µF ceramic capacitors (ESR < 1Ω), as confirmed in DS38144 Section 15 ("ESR vs. Output Current"). No additional series resistance or parallel capacitance is needed, simplifying layout and reducing BOM count.

How does the CE pin behave during power-up and brown-out conditions?

The CE pin has no internal pull-up or pull-down; it must be actively driven. During power-up, CE should be held low until VIN reaches ≥3.8V, then asserted high. Under brown-out (VIN dropping below UVLO threshold), the regulator disables automatically if CE remains high-but sustained low CE forces shutdown regardless of VIN level.

Is the NC pin (Pin 4) safe to connect to ground?

Yes. Pin 4 is internally unconnected and may be left floating or tied to GND without affecting regulation, noise, or thermal performance. Diodes recommends grounding NC pins in SC-70 packages to improve mechanical reliability and reduce potential for parasitic coupling in high-density layouts.