**ADP151AUJZ-5-R7: A Comprehensive Technical Overview of the Low-Noise, 200 mA CMOS LDO Voltage Regulator**

In the realm of power management, the demand for clean, stable, and efficient voltage regulation is paramount, especially for noise-sensitive applications like RF transceivers, precision sensors, and high-fidelity audio equipment. The **ADP151AUJZ-5-R7** from Analog Devices stands out as a premier solution, engineered to meet these critical requirements. This article provides a detailed technical examination of this high-performance, low-dropout (LDO) voltage regulator.

**Core Architecture and Key Specifications**

The ADP151 is a CMOS LDO regulator capable of delivering a **maximum output current of 200 mA**. Its fixed output voltage version, the `-5-R7` suffix, is preset to **5.0 V**. The device is designed to operate with a very low dropout voltage—typically **85 mV at 200 mA load**—making it exceptionally efficient even when the input voltage is only marginally higher than the output level. This is crucial for battery-powered devices where extending operational life is a priority.

A defining characteristic of the ADP151 is its ultra-low noise performance. It incorporates a **silicon-based bandgap reference and an error amplifier** architecture specifically optimized for minimal inherent noise. Furthermore, it features an external `NR` (Noise Reduction) bypass capacitor pin. By connecting a small 10 nF ceramic capacitor to this pin, the output noise can be reduced to an impressively low **9 µV√Hz typ. at 10 kHz**. This active noise cancellation makes it a top choice for powering sensitive analog and RF circuitry, such as **VCOs (Voltage-Controlled Oscillators), PLLs (Phase-Locked Loops), and high-resolution ADCs/DACs**.

Beyond its low-noise prowess, the regulator excels in power supply rejection (PSRR). It offers an outstanding **PSRR of 70 dB at 1 kHz and 50 dB at 10 kHz**, effectively preventing ripples and noise from the input power source from propagating to the regulated output. This ensures a clean supply rail even in electrically noisy environments.

The device is housed in a compact, 5-lead **TSOT package**, ideal for space-constrained PCB designs. It incorporates essential protection features like **current limiting and thermal shutdown**, safeguarding both the regulator and the load under fault conditions. Its quiescent current is a modest 30 µA, contributing to high overall efficiency.

**Application Circuit and Usage**

Implementing the ADP151AUJZ-5-R7 is straightforward. The basic circuit requires only two external ceramic capacitors: a 1 µF (or larger) input capacitor (`CIN`) and a 1 µF output capacitor (`COUT`). For optimal noise performance, a 10 nF capacitor (`CNR`) must be connected from the `NR` pin to ground. The stability of the LDO is maintained with these low-ESR ceramic capacitors, simplifying the bill of materials and reducing board space.

**ICGOODFIND Summary**

The **ADP151AUJZ-5-R7** is a superior CMOS LDO voltage regulator that masterfully combines **ultra-low output noise, high PSRR, and low dropout voltage** in a miniature package. Its specialized design for noise-critical applications, ease of use, and robust protection features make it an indispensable component for designers striving to achieve the highest signal integrity and power purity in advanced electronic systems.

**Keywords:**

1. **Low-Noise LDO**

2. **200 mA Output Current**

3. **High PSRR**

4. **CMOS Voltage Regulator**

5. **Ultra-Low Dropout**