onsemi NCP121AMX175TCG

Overview

NCP121AMX175TCG from onsemi is a fixed-output, high-accuracy, very low dropout (VLDO) linear voltage regulator with NMOS pass transistor and separate bias rail (VBIAS). It delivers 150 mA at 1.75 V output with ±1.0% accuracy over line/load/temperature, 75 mV max dropout at full load, and operates from 0.8 V to 5.5 V input while requiring 2.4–5.5 V bias supply - ideal for post-regulation in space-constrained, noise-sensitive portable electronics.

For engineers reviewing the NCP121AMX175TCG datasheet, pinout, applications, or equivalent options, key selection criteria include its dual-rail architecture (VIN + VBIAS), ultra-low bias current (80 µA typ), active output discharge capability, stability with 1 µF ceramic output capacitor, and XDFN6 1.2 mm × 1.2 mm package thermal performance.

Technical Context

The NCP121AMX175TCG uses an NMOS pass transistor powered by VBIAS, decoupling control circuitry from VIN to enable stable regulation at ultra-low input-to-output differentials. Its dual-rail design separates power delivery (VIN) from internal logic biasing (VBIAS), allowing operation even when VIN drops near VOUT - unlike PMOS-based LDOs.

It integrates undervoltage lockout on VBIAS (1.6 V threshold with 0.2 V hysteresis), thermal shutdown (160°C trip), current limiting (200–600 mA), and monotonic startup with controlled slew rate. The EN pin provides logic-level ON/OFF control, and the NCP121A variant includes active output discharge during disable mode.

Key Specifications

Pinout & Package

The NCP121AMX175TCG is housed in an XDFN6 (Case 711AT) package: 1.2 mm × 1.2 mm × 0.4 mm, with exposed thermal pad soldered to ground plane for 170°C/W junction-to-air thermal resistance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar very low dropout, fixed-output regulator applications.

Compared with Torex XC6210B175MR-G and Richtek RT9013-175GB, the NCP121AMX175TCG uniquely supports dual-rail operation with 75 mV dropout and active discharge - enabling tighter input voltage margins and robust power sequencing in advanced portable SoC designs.

Availability

NCP121AMX175TCG is available at Aetrix Electronics and suitable for smartphone core regulation, tablet I/O interface power, digital camera sensor bias, and STB memory interface applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for NCP121AMX175TCG 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The NCP121 series is part of onsemi's precision analog portfolio, designed specifically for ultra-low-noise, ultra-low-dropout regulation in space-constrained, battery-operated portable electronics with demanding accuracy and thermal requirements.

FAQ

What is the output voltage tolerance of the NCP121AMX175TCG over temperature and load?

The NCP121AMX175TCG guarantees ±1.0% output voltage accuracy across −40°C to +85°C junction temperature, full 1–150 mA load range, and input voltage from V_OUT+V_DO to 5.0 V. At 25°C only, accuracy tightens to ±0.2%. This is confirmed in the Electrical Characteristics table of the official datasheet (Rev. 1, October 2019), where V_OUT min/max values are explicitly specified under those conditions.

Does the NCP121AMX175TCG require an external bias supply, and what voltage range is acceptable?

Yes, the NCP121AMX175TCG requires a separate VBIAS supply connected to Pin 4. The acceptable range is 2.4 V to 5.5 V - or (V_OUT + 1.35 V), whichever is greater. For the 1.75 V output, minimum VBIAS is therefore 3.1 V. This bias rail powers internal control circuitry independently of VIN, enabling stable operation even when VIN approaches VOUT.

Is active output discharge supported on the NCP121AMX175TCG, and how does it function?

Yes, active output discharge is supported because the "A" suffix in NCP121AMX175TCG denotes the NCP121A variant, which includes this feature. When EN is driven low, an internal pull-down switch connects OUT to GND, discharging the output capacitor rapidly. This is confirmed in Figure 2 (block diagram footnote) and the PIN FUNCTION DESCRIPTION section of the datasheet.

What is the maximum dropout voltage of the NCP121AMX175TCG at 150 mA load?

The maximum dropout voltage of the NCP121AMX175TCG at 150 mA is 75 mV, defined as the (VIN − VOUT) differential at which VOUT drops 3% below nominal. This value is specified in the ELECTRICAL CHARACTERISTICS table under "VIN Dropout Voltage" and is validated across temperature and process corners per the datasheet test conditions.

Can the NCP121AMX175TCG operate with a 1 µF ceramic output capacitor, and why is that significant?

Yes, the NCP121AMX175TCG is stable with a minimum 1 µF ceramic output capacitor - verified in the APPLICATIONS INFORMATION section and Typical Characteristics plots. This eliminates need for larger, more expensive, or less reliable capacitors, reducing PCB area and BOM cost while supporting miniaturized designs like smartphones and wearables.