Diodes Incorporated AP2125K-1.8TRE1

Overview

AP2125K-1.8TRE1 from Diodes Incorporated is a 300mA, fixed-output 1.8V CMOS low-dropout (LDO) regulator in SC-70-5 package, featuring 50µV_rms output noise, 70dB PSRR at 100Hz/1kHz, and 60µA quiescent current. It integrates over-temperature shutdown, current limiting, and active-high enable control-designed for noise-sensitive power rails in portable RF and baseband ICs.

For engineers reviewing the AP2125K-1.8TRE1 datasheet, AP2125K-1.8TRE1 pinout, AP2125K-1.8TRE1 application, or AP2125K-1.8TRE1 equivalent, key selection criteria include ultra-low noise performance, SC-70-5 footprint compatibility with space-constrained PCB layouts, dropout voltage ≤120mV at 300mA, ±2% output accuracy across –40°C to +85°C, and support for ceramic output capacitors down to 1µF.

Technical Context

The AP2125K-1.8TRE1 employs a CMOS-based error amplifier architecture with internal voltage reference and resistor network for precise 1.8V regulation. Its enable input (CE) provides active-high logic control, allowing system-level power sequencing and zero-current shutdown mode with 0.01µA standby draw.

Thermal protection is implemented via an integrated over-temperature shutdown circuit triggering at +160°C with +25°C hysteresis. The device maintains stable operation with low-ESR ceramic capacitors and exhibits minimal load/line regulation drift-≤15mV over full load (1–300mA) and input range (2.8V–6V).

Key Specifications

Pinout & Package

AP2125K-1.8TRE1 is housed in a 5-pin SC-70-5 surface-mount package (2.0mm × 1.25mm × 0.9mm), optimized for high-density portable designs. Pin assignments are validated per Diodes DS38144 Rev. 2–2.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP2125N-1.8TRE1, the K-version adds enable control and thermal headroom in a smaller footprint; versus MCP1700, it delivers 2× lower noise and 10dB higher PSRR at half the quiescent current-making it superior for battery-powered RF and precision analog systems.

Availability

AP2125K-1.8TRE1 is available at Aetrix Electronics and suitable for CDMA/GSM handset design, handheld instrumentation, and laptop peripheral power management requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant green packaging.

Supply support for AP2125K-1.8TRE1 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-performance, energy-efficient components for consumer, computing, industrial, and communications markets.

The AP2125 series belongs to Diodes' precision LDO portfolio, engineered specifically for ultra-low-noise, low-quiescent-current power delivery in battery-operated portable electronics with stringent EMI and efficiency requirements.

FAQ

What is the minimum input voltage required for AP2125K-1.8TRE1 to maintain regulation at 300mA?

The AP2125K-1.8TRE1 requires VIN ≥ VOUT + V_DROP, where maximum dropout is 120mV at 300mA. Thus, minimum valid input is 1.8V + 0.12V = 1.92V. Operation below this causes output collapse; datasheet specifies recommended VIN ≥ 2.8V for full specification compliance across temperature and process variation.

Can AP2125K-1.8TRE1 be used with a 0.47µF output capacitor?

No. The datasheet mandates ≥1µF ceramic output capacitance for stability across all operating conditions. Using 0.47µF risks oscillation and degraded transient response, especially under load steps. The ESR vs. output current plot (Fig. 15) confirms stable operation only within the defined 1µF–10µF ceramic range with ESR < 100mΩ.

Does the CE pin require a pull-up resistor when interfaced with a 1.8V GPIO?

No external pull-up is needed. The CE threshold is specified as "High" ≥1.5V and "Low" ≤0.4V, making it fully compatible with 1.8V logic outputs. Driving CE directly from a 1.8V microcontroller GPIO ensures reliable enable/disable without additional components or level-shifting.

Is AP2125K-1.8TRE1 qualified for automotive applications?

No. AP2125K-1.8TRE1 is rated for –40°C to +85°C ambient operation and is not AEC-Q200 qualified. It lacks automotive-specific stress testing, extended temperature validation (e.g., –40°C to +125°C), and PPAP documentation. For automotive use, Diodes offers the AP7361Q series with AEC-Q100 Grade 1 qualification.