TPS7A4701 Low Noise Power Supply for Audio

This compact positive LDO regulator module is based on the TPS7A4701 from Texas Instruments. It was designed for audio, analog and other sensitive applications where very clean and stable power is required.

The TPS7A4701 is a very low-noise regulator with only 4 uVrms output noise, making this module a very good choice for powering op-amps, DACs, ADCs, analog filters, clock-related circuits and other precision stages that benefit from low ripple and low noise supply rails.

Main features:

• based on the TPS7A4701 positive low-noise LDO regulator,
• very low output noise: 4 uVrms,
• adjustable output voltage set by two resistors: R1 and R2,
• compact PCB size of about 23.9 x 10.4 mm,
• simple 3-pin connection: OUT / GND / IN,
• designed for output current up to about 0.5 A,
• well suited for audio and precision analog power rails.

Simple and practical circuit

The schematic uses a clean and minimal adjustable configuration. The regulator is enabled directly from the input supply, the output voltage is set with R1 and R2, and the board includes an output capacitor and an NR capacitor for low-noise operation.

On this board the main supporting parts are:

• R1 and R2 for output voltage adjustment,
• C1 = 10 uF / 25 V output capacitor,
• C12 = 10 nF capacitor on the NR pin.

Panelized design for lower PCB cost

The project also includes a separate panel version with 21 modules on one PCB. This helps reduce manufacturing cost compared with ordering many separate small boards. After production, the individual power supply modules can be separated from the panel, which is convenient for prototyping and small batch builds.

Output voltage setting

The output voltage is defined by the resistor divider made of R1 and R2. This makes the same PCB very flexible, because different output voltages can be obtained by selecting different resistor values.

Suggested resistor values from the TPS7A4701 datasheet:

• 1.8 V: R1 = 2.8 kΩ, R2 = 9.76 kΩ
• 3.3 V: R1 = 13.3 kΩ, R2 = 9.76 kΩ
• 5 V: R1 = 25.5 kΩ, R2 = 10 kΩ
• 12 V: R1 = 76.8 kΩ, R2 = 10.2 kΩ
• 15 V: R1 = 102 kΩ, R2 = 10.5 kΩ
• 18 V: R1 = 118 kΩ, R2 = 10 kΩ
• 24 V: R1 = 165 kΩ, R2 = 10.2 kΩ

Applications:

• audio analog supply rails,
• local power supply for DAC / ADC / op-amp circuits,
• post-regulation after DC/DC converters,
• measurement, RF and laboratory projects,
• DIY audio and precision analog electronics.

Summary

This is a compact and practical positive low-noise power supply module for demanding analog applications. Its main advantages are very low noise, adjustable output voltage, small size and the availability of a 21-piece panel version that helps reduce PCB manufacturing cost when multiple modules are needed.