**ADP7118ARDZ-5-R7: A Comprehensive Guide to the 5V, 200mA Low-Noise LDO Regulator**
In the world of precision electronics, clean and stable power is non-negotiable. Noise on a power supply rail can severely degrade the performance of sensitive components like analog-to-digital converters (ADCs), digital-to-analog converters (DACs), oscillators, and sensors. This is where low-dropout regulators (LDOs) like the **ADP7118ARDZ-5-R7** from Analog Devices become critical components. This article provides a comprehensive guide to this high-performance regulator, exploring its key features, applications, and design advantages.
The ADP7118ARDZ-5-R7 is a fixed 5V, 200mA low-noise LDO designed to deliver exceptionally clean power from a higher input voltage. Its primary role is to reject noise and ripple from the input source, providing a pristine, stable output voltage even when the input is only slightly higher than the output. The "-5-R7" suffix denotes the fixed 5.0V output version in a compact 8-lead SOIC package supplied on a 7-inch reel.
**Key Features and Technical Superiority**
What sets the ADP7118 apart from standard LDOs is its focus on ultra-low noise and high power supply rejection ratio (PSRR), achieved through an advanced architecture.
* **Ultra-Low Noise Performance:** The regulator boasts an incredibly **low output noise of just 9 μV√Hz** at 10 kHz. This is achieved through an innovative design that includes an internal error amplifier and a separate noise-filtered reference voltage. For even lower noise, an external bypass capacitor can be added to the `NR` (Noise Reduce) pin, further reducing noise to levels as low as 1.8 μV√Hz.
* **Exceptional Power Supply Rejection Ratio (PSRR):** The PSRR measures an LDO's ability to reject ripple and noise from its input. The ADP7118 excels here, offering a **PSRR greater than 70 dB at 10 kHz**. This means it effectively attenuates input noise, making it ideal for post-regulation after a switching regulator, which is a common source of high-frequency noise.
* **High Accuracy and Low Dropout Voltage:** The device features a **high output voltage accuracy of ±1.8%** over line, load, and temperature variations, ensuring reliable performance for precision circuits. With a typical dropout voltage of 240 mV at 200 mA load, it can maintain regulation even when the input voltage dips close to 5.24V, enhancing power efficiency and allowing for operation in low-headroom scenarios.
* **Wide Input Voltage Range and Protection:** With an input voltage range from **3.0 V to 5.5 V**, it is perfectly suited for regulating down from common 5V or 3.3V rails. The device also includes crucial protection features like current limiting and thermal shutdown, safeguarding both the regulator and the load under fault conditions.
**Typical Applications**
The combination of low noise and high PSRR makes the ADP7118ARDZ-5-R7 indispensable in a wide array of applications:
* **Precision Data Acquisition Systems:** Powering ADCs, DACs, and instrumentation amplifiers where supply noise directly impacts measurement accuracy and signal integrity.
* **RF and Communication Systems:** Providing clean power to voltage-controlled oscillators (VCOs), phase-locked loops (PLLs), and mixers to minimize phase noise and improve signal clarity.
* **Medical and Healthcare Equipment:** Used in sensitive monitoring and diagnostic devices where signal fidelity is paramount.
* **Post-Regulation for Switch-Mode Power Supplies (SMPS):** It is the perfect second-stage regulator to clean up the noisy output of a DC-DC switcher, combining the efficiency of switching regulators with the clean output of an LDO.
**Design Considerations**
Implementing the ADP7118 is straightforward. For stability, ceramic output capacitors with a value of **2.2 μF or greater** are recommended. The critical design step for optimal noise performance is the connection of a capacitor (typically 10 nF) from the `NR` pin to ground, which activates the ultra-low noise mode.
**ICGOODFIND**
In summary, the ADP7118ARDZ-5-R7 is a superior choice for designers who cannot compromise on power quality. Its exceptional blend of **ultra-low noise, high PSRR, and solid 200mA output current** makes it an essential component for elevating the performance of any noise-sensitive application. When your design demands the cleanest possible power rail, this LDO delivers.
**Keywords:**
1. **Low-Noise LDO Regulator**
2. **Power Supply Rejection Ratio (PSRR)**
3. **200mA Output Current**
4. **5V Fixed Output**
5. **Precision Analog Power**
