High Output-Current 3A LDO Provides Low-Noise and High-PSRR Power Supply for Noise-Sensitive Applications
By Meijin Chen, LDO Product Marketing Manager
In high-performance and high-speed applications, such as communications infrastructure, there are many power-noise-sensitive components that require power supplies with low noise and a high power-supply rejection ratio (PSRR), including high-performance SerDes, processors, data converters (ADCs and DACs), and various RF components. The low-noise, high-PSRR power is necessary to maintain signal integrity and accuracy, especially when a high output current is applied.
For digital loads that require low input-voltage and low output-voltage operation, designers can use ultra-low-dropout (LDO) linear regulators. LDO regulators feature smaller differences between input and output voltages; for example, to supply an output of 1.2V from an input of 0.9V. The difference between the input and output is called the “dropout voltage”, which in this example is 0.3V, or 300mV.
Diodes Incorporated has responded to the demand for low-noise LDO regulators with the AP7179D. The device is a high-current (3A), high-accuracy (1%), low-noise (4.4μVRMS), high-PSRR (40dB at 500kHz) LDO voltage regulator with a 180mV maximum dropout at 3A. These capabilities enable the AP7179D to power many noise-sensitive components, such as in high-speed communications and video, medical, or test/measurement applications. In particular, the AP7179D is well suited to power macro remote radio units (RRU) and active antenna systems (AAS).
The device has a single input with a wide input voltage range that supports operation as low as 1.1V and up to 6.5V. It includes a low-noise reference and error amplifier, ensuring minimal noise during operation. The high PSRR (40dB at 500kHz) minimizes coupling of the input supply noise to the output, thus reducing the effects of any noise from the power supply input. The combination of a low noise floor and high PSRR ensures that the device provides a clean supply to the application.
Overall, the AP7179D‘s 1% tolerance and low 4.4μVRMS noise offers a simple, compact solution for noise-sensitive power-conversion applications.
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