onsemi NCP121AMX145TCG

Overview

NCP121AMX145TCG from onsemi is a fixed-output, 1.45 V, 150 mA very low dropout (VLDO) linear regulator with NMOS pass transistor and separate bias rail (VBIAS). It delivers ±1.0% output accuracy over line/load/temperature, 75 mV max dropout at full load, and ultra-low 80 µA typical bias current-designed for noise-sensitive, space-constrained portable applications such as smartphone core logic rails.

For engineers reviewing the NCP121AMX145TCG datasheet, pinout, applications, or equivalent options, key selection criteria include dual-rail operation (VIN/VBIAS), active output discharge capability, XDFN6 1.2 mm × 1.2 mm package constraints, and PSRR performance above 70 dB at 1 kHz.

Technical Context

The NCP121AMX145TCG implements a dual-supply NMOS-based VLDO architecture: VIN supplies the pass element while VBIAS powers internal control circuitry-including reference, error amplifier, and UVLO-with independent regulation paths. This decoupling enables stable operation down to 0.8 V input and supports monotonic startup with controlled inrush current.

It features integrated thermal shutdown (160°C trip), current limiting (200–600 mA), and logic-level enable with hysteresis. The device is optimized for ceramic output capacitors ≥1 µF and includes active output discharge only in "A"-suffix variants like NCP121AMX145TCG-enabling fast VOUT ramp-down during disable.

Key Specifications

Pinout & Package

XDFN6 package (Case 711AT), 1.2 mm × 1.2 mm × 0.4 mm, with exposed thermal pad soldered to GND plane for R_JA = 170°C/W. Pin 1 = OUT, Pin 2 = N/C, Pin 3 = EN, Pin 4 = BIAS, Pin 5 = GND, Pin 6 = IN.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout linear regulator applications.

Compared with NCP121AMX145TCG, the XC6210B145MR-G offers simpler biasing but sacrifices dropout performance and discharge control, while the RT9080-145GJ6 trades VBIAS independence for higher current capability-making NCP121AMX145TCG optimal for thermally constrained, noise-sensitive dual-rail systems demanding precision and fast sequencing.

Availability

NCP121AMX145TCG is available at Aetrix Electronics and suitable for smartphone core logic rails, tablet I/O interface power, wearable sensor hubs, and wireless camera modules requiring stable component supply, consistent marking (Y rotation), and Pb-free RoHS-compliant packaging.

Supply support for NCP121AMX145TCG 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient technologies for automotive, industrial, cloud, medical, and IoT applications.

The NCP121 product line delivers high-accuracy, ultra-low-IQ, dual-rail VLDO regulators specifically engineered for battery-powered portable electronics where size, noise, and efficiency are critical.

FAQ

What is the nominal output voltage of the NCP121AMX145TCG?

The NCP121AMX145TCG is a fixed-output linear regulator with a nominal output voltage of 1.45 V. This value is laser-trimmed during manufacturing and specified with ±1.0% accuracy across −40°C to +85°C. The "145" in the part number explicitly denotes the 1.45 V output, confirmed in the Ordering Information table on page 7 of the official datasheet.

Does the NCP121AMX145TCG support active output discharge, and how is it implemented?

Yes, the NCP121AMX145TCG includes integrated active output discharge. When the EN pin is driven low, an internal 150 Ω pull-down resistor connects the OUT pin to GND, discharging the output capacitor rapidly. This feature is exclusive to "A"-suffix variants (like NCP121AMX145TCG) and is documented in Figure 2's block diagram and the PIN FUNCTION DESCRIPTION table on page 2 of the datasheet.

What are the minimum and maximum allowable input and bias supply voltages for the NCP121AMX145TCG?

The NCP121AMX145TCG accepts VIN from 0.8 V to 5.5 V and VBIAS from 2.4 V to 5.5 V. The minimum VBIAS is further constrained to (VOUT + 1.35 V) per Electrical Characteristics-so for 1.45 V output, VBIAS must be ≥2.80 V. These ranges are specified in the Absolute Maximum Ratings and Electrical Characteristics tables on pages 2–3 of the datasheet.

Can the NCP121AMX145TCG operate with a 1 µF ceramic output capacitor, and why is effective capacitance emphasized?

Yes, the NCP121AMX145TCG is stable with a 1 µF ceramic output capacitor, provided its effective capacitance (accounting for DC bias, temperature, and tolerance derating) remains ≥1 µF. The datasheet stresses effective capacitance because high-K ceramics (e.g., X5R/X7R) lose significant capacitance under DC bias-especially at 1.45 V output-so nominal 2.2 µF or 4.7 µF parts may be required to ensure ≥1 µF effective value.

What thermal performance can be expected from the NCP121AMX145TCG in its XDFN6 package?

The NCP121AMX145TCG in XDFN6 (Case 711AT) has a junction-to-air thermal resistance (R_JA) of 170°C/W when the thermal pad is properly soldered to the PCB ground plane. Its thermal shutdown activates at 160°C and recovers at 140°C. These values are measured per JEDEC standards and published in the THERMAL CHARACTERISTICS table on page 3 of the datasheet.