Diodes Incorporated AP2128K-2.8TRG1

Overview

AP2128K-2.8TRG1 from BCD Semiconductor is a fixed-output 2.8V, 300mA CMOS low-dropout regulator in SOT-23-5 package, featuring 170mV dropout at 300mA, ±2% output voltage accuracy, and 60µV_rms output noise. It delivers stable power to noise-sensitive analog circuitry in portable systems with input range 2.5V–6V and integrated thermal/overcurrent protection.

For engineers reviewing the AP2128K-2.8TRG1 datasheet, AP2128K-2.8TRG1 pinout, AP2128K-2.8TRG1 application, or AP2128K-2.8TRG1 equivalent, key selection criteria include dropout performance at 300mA load, PSRR (68dB @1kHz), soft-start timing (50µs), shutdown logic thresholds (0–0.4V low / 1.5–6V high), and compatibility with 1µF ceramic input/output capacitors.

Technical Context

The AP2128K-2.8TRG1 implements a CMOS-based LDO architecture with P-channel pass transistor, enabling low quiescent current (60µA typical) and minimal dropout voltage across its operating range. Its internal reference (0.8V) and error amplifier regulate output via direct sensing of VOUT-no external feedback resistors required for fixed versions.

It integrates active shutdown control with internal pull-down (3MΩ) and VOUT discharge MOSFET (R_DS(ON) = 60Ω), plus thermal shutdown (165°C) with 30°C hysteresis and short-circuit limiting (50mA). The 50µs soft-start prevents inrush current during enable transitions.

Key Specifications

Pinout & Package

SOT-23-5 package: 2.82mm × 2.65mm × 1.30mm body, 0.95mm lead pitch, gull-wing leads, RoHS-compliant green finish (G1 suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6206P282MR and RT9193-28GB, AP2128K-2.8TRG1 uniquely combines ultra-low dropout (170mV), integrated soft-start (50µs), and VOUT discharge (60Ω) in a single SOT-23-5 package-enabling simpler, more robust power sequencing and noise management in compact battery-powered systems.

Availability

AP2128K-2.8TRG1 is available at Aetrix Electronics and suitable for portable medical sensors, notebook subsystem power, industrial IoT edge nodes, and wearable health monitors requiring stable component supply, long-term lifecycle support, and RoHS-compliant green packaging.

Supply support for AP2128K-2.8TRG1 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

BCD Semiconductor Manufacturing Limited is a Shanghai-based analog and power IC designer specializing in high-performance, cost-effective power management solutions for consumer, industrial, and communications markets.

The AP2128 series targets battery-powered portable electronics, emphasizing ultra-low noise, fast transient response, and minimal external component count-enabling compact, reliable power delivery in space-constrained designs.

FAQ

What is the minimum input voltage required for AP2128K-2.8TRG1 to maintain regulation at full 300mA load?

The AP2128K-2.8TRG1 requires VIN ≥ 2.97V to sustain 2.8V output at 300mA, based on its 170mV dropout specification (2.8V + 0.17V = 2.97V). Operation below this threshold results in unregulated output and potential system reset or brownout conditions.

Can AP2128K-2.8TRG1 be used with ceramic capacitors smaller than 1µF?

No-BCD's datasheet specifies 1µF minimum for both CIN and COUT to ensure stability, transient response, and PSRR performance. Using smaller ceramics risks oscillation, increased output ripple, and degraded load regulation, especially under dynamic current steps.

Does the SHUTDOWN pin require an external pull-up resistor?

No-AP2128K-2.8TRG1 includes an internal 3MΩ pull-down resistor on the SHUTDOWN pin, ensuring default-disabled state at power-up. An external pull-up is unnecessary unless active-high enable timing must override the internal pull-down during specific sequencing phases.

How does the VOUT discharge function operate during shutdown?

When SHUTDOWN is driven low (<0.4V), the internal 60Ω MOSFET connects VOUT to GND, discharging output capacitance within milliseconds. This prevents floating or slow-decay voltages that could cause latch-up or false wake-up in downstream logic, critical for multi-rail power sequencing.