Diodes Incorporated AP2127N-4.75TRG1

Overview

AP2127N-4.75TRG1 from Diodes Incorporated is a 300mA, 4.75V fixed-output CMOS low-dropout (LDO) regulator in SOT-23 package, featuring 140mV dropout at full load, ±2% output voltage accuracy, and 60μVRMS ultra-low noise. It operates from 2.5V to 6V input, supports ceramic capacitors as small as 1μF, and delivers stable power for noise-sensitive analog rails in portable electronics.

For engineers reviewing the AP2127N-4.75TRG1 datasheet, AP2127N-4.75TRG1 pinout, AP2127N-4.75TRG1 application, or AP2127N-4.75TRG1 equivalent, key selection criteria include dropout performance at 300mA, thermal behavior in SOT-23, shutdown-controlled auto-discharge (60Ω), and PSRR of 63dB @ 1kHz for RF/ADC supply filtering.

Technical Context

This LDO employs a PMOS pass transistor architecture enabling low dropout and fast transient response. Its internal 0.8V reference feeds a precision error amplifier that regulates output via feedback from VOUT to GND-no external resistors required for the fixed 4.75V version.

The device integrates active shutdown logic with 0.1μA standby current, thermal shutdown at +165°C with +30°C hysteresis, and short-circuit protection limiting output to 50mA. Soft-start time is fixed at 50μs, and the integrated discharge MOSFET (R_DS(ON) = 60Ω) ensures rapid VOUT decay during disable.

Key Specifications

Pinout & Package

SOT-23 package (3-pin, lead-free, RoHS-compliant) with 1.3mm × 2.9mm footprint and 1.0mm height; optimized for space-constrained PCB layouts and reflow assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700T-4702E/TT and XC6206P472MR-G, AP2127N-4.75TRG1 uniquely combines 4.75V precision, integrated shutdown with 0.1μA standby, and 60Ω auto-discharge-making it optimal for systems requiring exact USB-compliant voltage, power-state coordination, and rapid rail collapse.

Availability

AP2127N-4.75TRG1 is available at Aetrix Electronics and suitable for portable medical sensors, USB-C power delivery receivers, notebook subsystem rails, and industrial IoT edge nodes requiring stable component supply with guaranteed long-term availability.

Supply support for AP2127N-4.75TRG1 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 power management, signal integrity, and protection solutions for industrial, computing, and consumer markets.

The AP2127 series belongs to Diodes' high-speed, low-noise LDO product line, engineered specifically for battery-powered and noise-sensitive applications where precision regulation, minimal quiescent current, and ceramic-capacitor compatibility are mandatory.

FAQ

What is the minimum input voltage required for AP2127N-4.75TRG1 to maintain regulation at 300mA?

The minimum input voltage is calculated as V_OUT + V_DROP = 4.75V + 0.14V = 4.89V. This value is confirmed by the datasheet's electrical characteristics table, which specifies 140mV dropout at 300mA for the 4.75V version. Operation below 4.89V results in loss of regulation and output droop.

Can AP2127N-4.75TRG1 be used with aluminum polymer capacitors instead of ceramic?

No-aluminum polymer capacitors are not recommended. The AP2127N-4.75TRG1 is explicitly characterized and stabilized for use with low-ESR ceramic capacitors ≥1μF (X5R/X7R). Aluminum polymer types exhibit higher ESR and different frequency response, risking instability, oscillation, or degraded transient performance per the datasheet's "Output Capacitor" section.

Does the shutdown pin require a pull-up resistor to operate correctly?

No external pull-up is needed. The shutdown pin has an internal 3MΩ pull-down resistor, and the datasheet specifies a logic-high threshold of 1.5V minimum and logic-low threshold of 0.5V maximum. Driving the pin directly with a GPIO (0V for OFF, >1.5V for ON) ensures reliable control without additional components.

How does the auto-discharge function behave during normal operation versus shutdown?

The 60Ω discharge MOSFET is active only when the shutdown pin is driven low. During normal operation (shutdown pin high), the MOSFET is fully off and introduces no load. When disabled, it provides a controlled 4.75V/60Ω ≈ 79mA discharge path, collapsing VOUT within milliseconds-critical for meeting system reset timing and avoiding back-powering of upstream circuitry.