**ADP7185ACPZN3-R7: A Comprehensive Technical Overview of the -3V, Ultra-Low-Noise Linear Regulator**
In the realm of precision analog and RF systems, power supply integrity is paramount. Voltage fluctuations and noise can severely degrade the performance of sensitive components such as high-resolution ADCs, DACs, PLLs, and VCOs. Addressing this critical need, the **ADP7185ACPZN3-R7** stands out as a high-performance, negative-voltage linear regulator designed to deliver exceptionally clean and stable power. This article provides a deep technical dive into its architecture, key features, and ideal applications.
The ADP7185 is part of Analog Devices' acclaimed portfolio of linear regulators, with the specific part number "ACPZN3-R7" denoting the -3V output voltage version in a compact 4 mm × 4 mm LFCSP package supplied on a 7-inch reel. Its primary function is to regulate a negative input voltage (as low as -3.3V) to a precise -3.0V output, with a maximum output current of 500 mA.
One of the most defining characteristics of the ADP7185 is its **ultra-low output noise performance**. It achieves a remarkably low noise level of **9 μV√Hz (typical) at 10 kHz**, and its integrated bypass capacitor further reduces wideband noise to just **1.8 μVrms from 10 Hz to 100 kHz**. This is crucial for powering noise-sensitive circuitry without introducing additional phase noise or signal degradation.
Complementing its low-noise performance is an outstanding **power supply rejection ratio (PSRR)**. The regulator maintains a high PSRR of **70 dB at 10 kHz**, effectively attenuating ripple and noise originating from the preceding power stage (like a switching regulator). This allows designers to use a noisy but efficient switcher for initial voltage conversion, followed by the ADP7185 as a "clean-up" regulator, achieving both high efficiency and signal purity.
The device is engineered for robustness and stability. It operates over a wide input voltage range from -3.3 V to -30 V, offering significant design flexibility. **Stable with small, low-ESR ceramic output capacitors** as low as 2.2 μF, it simplifies the bill of materials and saves board space. Key protection features include internal current limiting and thermal shutdown, safeguarding the regulator and the load under fault conditions.
Housed in a space-efficient 8-lead LFCSP package, the ADP7185 is ideal for densely populated PCBs found in modern communication infrastructure, test and measurement equipment, medical imaging systems, and aerospace instrumentation. Its ability to provide a pristine negative supply makes it particularly suited for biasing GaN amplifiers and powering high-speed data converters.
**ICGOOODFIND**: The ADP7185ACPZN3-R7 is an exceptional ultra-low-noise linear regulator that sets a high bar for negative rail performance. Its combination of **minimal output noise, superior PSRR, and robust integration** makes it an indispensable component for engineers striving to maximize the performance of their most sensitive analog and RF systems.
**Keywords**:
* **Ultra-Low Noise**
* **Negative Voltage Regulator**
* **High PSRR**
* **RF/Analog Power Management**
* **LFCSP Package**
