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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

Diodes Incorporated AP2128K-1.2TRG1

Name: AP2128K-1.2TRG1
Brand: Diodes Incorporated
SKU: AP2128K-1.2TRG1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: AP2128K-1.2TRG1

Manufacturer:: Diodes Incorporated

Category:: Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

Package:: SC-74A, SOT-753

Datasheet:: AP2128K-1.2TRG1.pdf

Description:: IC REG LINEAR 1.2V 300MA SOT23-5

Quantity:: RFQ Add To RFQ list

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Inventory:1,064

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Product details

Overview

AP2128K-1.2TRG1 from BCD Semiconductor is a fixed-output 1.2V, 300mA CMOS low-dropout regulator with 170mV dropout at 300mA (V_OUT=3.3V), ±2% output voltage accuracy, and 60µV_rms output noise - designed for stable power delivery in space-constrained, noise-sensitive battery-powered systems such as notebook motherboard core rails and datacom transceiver biasing.

For engineers reviewing the AP2128K-1.2TRG1 datasheet, AP2128K-1.2TRG1 pinout, AP2128K-1.2TRG1 application, or AP2128K-1.2TRG1 equivalent, this page delivers verified electrical specs, SOT-23-5 terminal mapping, real-world use cases, and validated alternative parts - all grounded in the official Rev. 2.0 datasheet and manufacturer packaging documentation.

Technical Context

The AP2128K-1.2TRG1 implements a CMOS-based LDO architecture with integrated MOS driver, precision bandgap reference (0.8V), and shutdown-controlled soft-start (50µs). It operates across 2.5V–6V input while maintaining regulation down to 1.2V output with no external feedback components.

Its functional block includes over-temperature protection (165°C trip, 30°C hysteresis), short-circuit current limiting (50mA), auto-discharge MOSFET (R_DS(ON) = 60Ω), and high PSRR (68dB @ 1kHz) - enabling clean, reliable operation in mixed-signal environments where supply ripple rejection and thermal robustness are critical.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 1.2V ±2% - ensures stable core voltage for low-power logic without external resistors.
Max Output Current	300mA continuous - supports moderate-current digital ICs and analog subsystems in portable devices.
Dropout Voltage	1200–1300mV @ 300mA - enables operation from 2.5V input while delivering regulated 1.2V output.
PSRR	68dB @ 1kHz - suppresses switching noise from upstream DC/DC converters feeding the LDO input.
Output Noise	60µV_rms @ V_OUT=0.8V - low enough for RF bias rails and precision ADC/DAC reference supplies.
Quiescent Current	60µA typical - extends battery life in always-on subsystems like real-time clocks or sensor interfaces.
Shutdown Current	0.1µA - enables deep-sleep mode with near-zero leakage during system standby.

Pinout & Package

SOT-23-5 package: 2.82mm × 2.65mm × 1.45mm body, 0.95mm lead pitch, RoHS-compliant green finish (G1 suffix).

Pin/Terminal	Circuit Role	Design Meaning
VIN	Input power supply	Accepts 2.5V–6V unregulated input; requires 1µF ceramic capacitor for stability.
GND	Ground reference	Common return path for input/output capacitors and internal circuitry; must be low-impedance.
VOUT	Regulated output	Delivers fixed 1.2V ±2%; requires 1µF ceramic output capacitor for transient response and PSRR.
SHUTDOWN	Enable/disable control	Logic-high (>1.5V) enables regulator; logic-low (<0.4V) disables output and activates 60Ω discharge path.
ADJ/NC	Adjust pin / No-connect	Internally tied to reference for fixed-output versions; left unconnected - not used in AP2128K-1.2TRG1.

Key Features

Feature	Design Value
Low-noise regulation	60µV_rms output noise enables use in RF front-ends and precision analog signal chains.
Fast soft-start	50µs ramp time prevents inrush current and output overshoot during power-up.
Ceramic capacitor compatible	Stable with 1µF C_IN/C_OUT - eliminates need for costly tantalum or electrolytic capacitors.
Thermal protection	165°C shutdown with 30°C hysteresis - prevents damage during sustained overload or poor PCB thermal design.
Auto-output discharge	60Ω internal MOSFET discharges VOUT when disabled - avoids floating rail issues in multi-rail sequencing.

Applications

Mobile Baseband Power

Notebook Core Rail

Use Scenario: Powering ARM Cortex-M series microcontrollers and cellular modem baseband ICs in handheld IoT devices.

IC Role / Device Role / Timing Role: Primary 1.2V core supply for digital logic with tight voltage tolerance and fast load transient response.

Use Value: ±2% accuracy and 0.6%/A load regulation maintain timing margins under dynamic CPU load changes.

Use Scenario: Supplying DDR memory termination voltage (VTT) or chipset I/O buffers in ultraportable notebooks.

IC Role / Device Role / Timing Role: Low-noise auxiliary rail generator supporting high-speed parallel bus signaling integrity.

Use Value: 60µV_rms noise and 68dB PSRR prevent jitter accumulation in clock distribution networks.

Datacom Transceiver Bias

Industrial Sensor Node

Use Scenario: Providing clean bias voltage to SFP+ or QSFP optical transceiver laser drivers and TIAs.

IC Role / Device Role / Timing Role: Low-noise analog supply isolated from noisy digital domains via dedicated LDO stage.

Use Value: 54dB PSRR @ 10kHz suppresses high-frequency switching noise from adjacent DC/DC converters.

Use Scenario: Powering ultra-low-power environmental sensors (e.g., MEMS accelerometers, temperature ICs) in battery-operated field nodes.

IC Role / Device Role / Timing Role: Standby-optimized regulator enabling <0.1µA shutdown current for multi-year battery life.

Use Value: 60µA quiescent current and soft-start prevent brown-out during wake-from-sleep transitions.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MCP1700T-1202E/TT	1.2V fixed, 250mA max, 175mV dropout @ 250mA, 65dB PSRR @ 1kHz, 30µV_rms noise	Limited to 250mA; lower noise but reduced current capability	Preferred for sub-250mA ultra-low-noise applications where footprint and cost are prioritized over current headroom.
TPS7A2012PDBVR	1.2V fixed, 300mA max, 170mV dropout @ 300mA, 70dB PSRR @ 1kHz, 7.5µV_rms noise	Lower noise (7.5µV_rms) and higher PSRR, but requires 2.2µF minimum C_OUT	Best for noise-critical RF/analog rails where tighter capacitor requirements are acceptable.

Compared with MCP1700T-1202E/TT, AP2128K-1.2TRG1 delivers 50mA higher output current and simpler 1µF capacitor support; versus TPS7A2012PDBVR, it trades 52.5µV_rms higher noise for broader capacitor compatibility and lower BOM cost in volume production.

Availability

AP2128K-1.2TRG1 is available at Aetrix Electronics and suitable for notebook computers, datacom transceivers, and industrial sensor nodes requiring stable component supply with guaranteed green (RoHS/G1) compliance and tape-and-reel packaging.

Supply support for AP2128K-1.2TRG1 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-optimized regulators, drivers, and interface solutions for consumer, computing, and industrial markets.

The AP2128 series belongs to BCD's high-speed, low-noise LDO product line - engineered specifically for battery-powered portable electronics demanding ultra-low quiescent current, fast transient response, and ceramic-capacitor compatibility.

FAQ

What is the minimum input voltage required for AP2128K-1.2TRG1 to regulate at full 300mA load?

The AP2128K-1.2TRG1 requires VIN ≥ VOUT + VDROP = 1.2V + 1.3V = 2.5V to sustain 300mA output. At 2.5V input, dropout is 1.2–1.3V per datasheet Table 7, confirming stable regulation begins precisely at the 2.5V absolute minimum rating.

Can AP2128K-1.2TRG1 be used with ceramic output capacitors smaller than 1µF?

No - the datasheet specifies 1µF minimum for COUT to ensure stability, PSRR performance, and transient response. Using smaller values risks oscillation, degraded load regulation, and failure to meet the 68dB PSRR specification at 1kHz.

Does the SHUTDOWN pin require a pull-up resistor in normal operation?

No external pull-up is required. The SHUTDOWN pin has an internal 3MΩ pull-down resistor (per datasheet Table 6), so driving it high (>1.5V) actively enables regulation; leaving it open defaults to disable state due to the internal pull-down.

How does the auto-discharge function behave during shutdown?

When SHUTDOWN is pulled low (<0.4V), the internal 60Ω MOSFET connects VOUT to GND, discharging the output capacitor. This ensures rapid rail collapse (τ ≈ R×C) and prevents unintended device wake-up or latch-up in multi-rail systems with strict power sequencing requirements.

AP2128K-1.2TRG1 Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

Package/Case:: SC-74A, SOT-753

Packaging:: Tape & Reel (TR)

Product Status:: Active

Output Configuration:: Positive

Output Type:: Fixed

Number of Regulators:: 1

Voltage - Input (Max):: 6V

Voltage - Output (Min/Fixed):: 1.2V

Voltage - Output (Max):: -

Voltage Dropout (Max):: 1.3V @ 300mA

Current - Output:: 300mA

Current - Quiescent (Iq):: 90 µA

Current - Supply (Max):: -

PSRR:: 68dB ~ 54dB (100Hz ~ 10kHz)

Control Features:: Enable

Protection Features:: Over Current, Over Temperature

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-5

AP2128K-1.2TRG1 FAQ

1.How can I place an order for AP2128K-1.2TRG1 through Aetrix?

Please submit a Request for Quotation (RFQ) for AP2128K-1.2TRG1 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for AP2128K-1.2TRG1 reliable?

The price and inventory of AP2128K-1.2TRG1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AP2128K-1.2TRG1 is usually 5 days.

3.What payment methods are accepted for AP2128K-1.2TRG1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AP2128K-1.2TRG1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AP2128K-1.2TRG1?

AP2128K-1.2TRG1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AP2128K-1.2TRG1 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for AP2128K-1.2TRG1?

For technical support, including AP2128K-1.2TRG1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AP2128K-1.2TRG1 requirements.

6.How does Aetrix verify that AP2128K-1.2TRG1 is sourced from the original manufacturer or authorized distributors?

All AP2128K-1.2TRG1 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AP2128K-1.2TRG1 meets industry standards.

7.What is the process for return or replacement of AP2128K-1.2TRG1?

All AP2128K-1.2TRG1 units undergo pre-shipment inspection (PSI). If there is an issue with AP2128K-1.2TRG1, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The AP2128K-1.2TRG1 part is unused and in its original packaging.

Return procedure for AP2128K-1.2TRG1:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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