LinearPi Pro

A. Introduction

LinearPi Pro is a top-quality high current ultra-low noise audiophile grade linear power supply. It can deliver up to 5A continuous output current at extremely low-noise level, which is much suitable for Raspberry Pi 5 and other high current noise sensitive applications. It could be one of the best linear power supply solutions for both digital and analog audio applications. Multiple LinearPi Pros can be grouped into a big power supply system. LinearPi Pro can also be upgraded to an 5V/3.3V ultra capacitor power supply by integrating with UcConditioner/Pro.

B. Specifications and Highlighted Features

• 0.8uV Ultra-low noise level.
• Built-in ON/OFF control logic with on-board or possible external ON/OFF control switch.
• Multiple LinearPi Pros can be grouped into a big power supply system by making use of the built-in isolated master/slave on-off control signal chain.
• Seamlessly integrates with UcConditioner/Pro to be upgraded to an ultracapacitor power supply.
• Optimized for continuous AC input mode to get best possible sound quality.
• Deals with MLCC piezoelectric effect noise.
• Available in 5V, 3.3V, and 12V configurations.
• Two stages ultra-low noise soft start up feature, great for both digital and analog application.
• Fully SMT high-quality heavy-duty design.

C. LinearPi Pro New Features

• 5A high continuous output current.
• 2.5 mOhm ultra-low output impedance.
• New parallel power output stages architecture.
• 4 layers double copper thickness PCB for higher current density and additional shield layers.
• 29080 uF total filtering capacitance.
• Enhanced optional Kelvin sense input to lower the output impedance and improve performance.
• Actual noise level superior to LinearPi because of the parallel architecture and the new shield layers.
• New low drop high speed high current soft recovery Schottky rectifiers.
• Bigger size heat sink.

D. PCB Layout

Please download DXF files for the Dimensions.

LinearPi Pro Solo PCB Layout: Depicts a single circuit board with input terminals (J6 AC/DC Input), output terminals (J5 4-pin 5.0mm terminal, J7 USB-C Output), control connectors (J1, J3, J4), onboard switch (S1), jumpers (S2, S3), fuses (F1, F2), inductors (L1, L2), and capacitors. The layout highlights the component placement and connection points.

LinearPi Pro Dual or +/- 5V or 5V+3.3V PCB Layout: Shows two identical circuit boards side-by-side, illustrating configurations for dual output or specific voltage combinations (e.g., +/- 5V, 5V+3.3V). The layout is similar to the Solo version, indicating component placement and connection points for multiple units.

E. Order Information

1. #38A LinearPi Pro Dual (default 5V, settable for 3.3V or 12V)
2. #38B LinearPi Pro Solo (default 5V, settable for 3.3V or 12V)
3. #38C LinearPi Pro Dual 5V + 3.3V
4. #38D LinearPi Pro Dual +/- 12V

F. Getting Started

1. Ensure jumpers S2 and S3 (on the back of the PCB) are configured correctly for the desired output voltage: 3.3V, 5V (default), or 12V.
2. Connect an AC power supply to J6 as per the transformer recommendation chart. Power up the AC supply; Input LED D3 should illuminate.
3. Turn the on-board ON/OFF control switch S1 to the ON position. Power LED D6 should illuminate. Verify the output voltage between V+ and V- at output terminal block J5 is correct. Ensure screws are tightened for secure connections.
4. Turn S1 to the OFF position. Connect the V+ and V- terminals of J5 to your device using high-quality power wires (18 AWG or bigger).

LinearPi Pro is now ready to work.

G. Connectors

J6: AC/DC Input (2-pin barrier terminal block)

An AC or DC power input must be connected to J6 to operate. A 5A or higher current rating is recommended.

Transformer Recommendation Chart

For lower current applications, the input voltage can be slightly higher than the listed values for more headroom, but ensure the temperature at the heat sink does not exceed 80°C. AC input must come from an independent coil of a power transformer; never share a coil with other power supplies or modules.

DC Power Input Suggestions

DC power input is also acceptable, non-polarity, but must be totally isolated from all other circuits. Never share DC input ground with other power supplies.

• 3.3V configuration: DC5V
• 5V configuration: DC9V
• 12V configuration: DC15V

J5: Output (4-pin 5.0mm terminal)

• V+ and V-: Output, 5V, 3.3V, or 12V according to jumper settings.
• S+ and S-: Optional Kelvin sensing inputs. For normal applications, S+ and S- can be left unconnected.

LinearPi Pro is equipped with an enhanced Kelvin sensing circuit. If the power cable is longer than 5 inches, or if you want to improve power supply performance, use this optional Kelvin sense input to maintain ultra-low output impedance and good regulation performance.

J7: Output in USB-C connector

Internally connected to the V+ and V- of J5. The output voltage will follow the jumper settings and not always be 5V.

J3: External ON/OFF control switch connector (2-pin PH2.0, at bottom side of the PCB)

The external ON/OFF control switch is functionally equivalent to the on-board switch S1. To use the external switch, the on-board switch S1 must be in the OFF position. The external ON/OFF switch is not included in the package.

J4: Slave ON/OFF control input (2-pin PH2.0, isolated)

LinearPi Pro can be controlled remotely via this slave control input. LinearPi Pro will turn on when a 3V-12V control voltage is applied to this input. The control signal is non-polarity and optically isolated from LinearPi Pro. To use the remote ON/OFF control, the on-board switch S1 must be in the OFF position.

J1: Master ON/OFF Control Output (2-pin PH2.0)

1: Control signal -

2: Control signal +

To set up a control chain of a power supply group, connect J1 of the first LinearPi Pro to the slave input J4 of the following LinearPi Pro using the supplied control cable. This also applies to other power supplies with a slave control input.

H. Switch and Jumper

S1: ON-board ON/OFF switch

• ON position: LinearPi Pro is enabled, and output voltage is applied to the output connectors.
• OFF position: LinearPi Pro is disabled, and there will be no output at J5 or J7.

S1 must be in the OFF position if an external ON/OFF switch or slave control input is used.

S2, S3: Output voltage setting jumper

I. LED Indicators

• D3: Power input indicator. Illuminates when the power input is applied.
• D6: Power on indicator. Illuminates when the LinearPi Pro is turned on and output voltage is applied to J5.

J. Fuse

The fuse is a standard 5*20mm fast-action glass fuse. The default fuse is Littelfuse 0235005.MXP.

The fuse can be sourced here: iancanada.ca/products/fuses.

K. Load Transient Response Measurement

LinearPi Pro exhibits excellent load transient response performance. The output voltage drop is only 10mV at ultra-low noise levels when the output current changes over large steps between 1A and 5A. The measured dynamic output impedance is as low as 2.5mOhm (@1kHz), potentially offering the best performance among low-noise linear power supplies on the market. Performance can be further enhanced with Kelvin sensing input.

Measured Load Transient Response Waveform: A description of the oscilloscope trace shows the output voltage dipping slightly and recovering during current steps from 1A to 5A. Testing conditions included: Load current steps: 1A to 5A, Output voltage: 5V, Frequency: 1kHz, Duty cycle: 50%, Probe: 1:1, 1 mOhm, 10mV/DIV.

L. Application Notes

1. Two Stages Soft Start Up Feature

• 0V-3.0V: Fast startup stage designed to meet the reset timing requirements of digital circuits like FifoPi Ma.
• After 3.0V: Slow startup stage to maintain ultra-low noise performance for both analog and digital circuits.

2. Upgrade to Ultra Capacitor Power Supply with UcConditioner/Pro

Upgrading a LinearPi Pro with a UcConditioner/Pro can further improve low-noise performance.

Upgrade Steps:

1. Mount a UcConditioner/Pro (same voltage) on top of the LinearPi Pro using 35mm LinearPi Pro screw/standoff sets (sold separately).
2. Connect V+ and V- from the LinearPi Pro output J5 to the + and - of input J2 of the UcConditioner/Pro using 18 AWG or bigger power wires.
3. (Optional) Connect S+ and S- from the LinearPi Pro Kelvin sensing input J5 to the + and - of the output J6 of the UcConditioner/Pro using high-quality wires.
4. Connect the UcConditioner/Pro output J6 to the device requiring power.

Note:

• Ensure the UcConditioner/Pro 5V is used for the 5V LinearPi Pro, and UcConditioner/Pro 3.3V for the 3.3V LinearPi Pro configuration.
• Using the enhanced Kelvin sensing function with UcConditioner/Pro is highly recommended to further reduce output impedance. Without sensing connections, fewer active components are involved in the final output. A real listening test is suggested for preference.

UcConditioner/Pro Module Image: A photograph displays the UcConditioner/Pro module, a compact board featuring large capacitors and connected via wires to screw terminals. It is designed to enhance the low-noise performance of the LinearPi Pro.

3. Recommend the Continuous AC Input Mode

While the LinearPi Pro can be turned on/off using AC power and the ON/OFF switch S1 (which must be at the ON position), it is highly recommended to use the continuous AC input mode for the best sound quality. This involves keeping the AC input continuously powered and using the ON/OFF control switch/logic to manage the LinearPi Pro's state. In this mode, filtering capacitors are continuously charged, aiding their break-in, with no additional power consumption when the unit is off.

4. How to Group LinearPi Pro Power Supplies Using Control Chains

For LinearPi Pro Dual configurations, connect the Master control output J1 of the first unit to the Slave control input J4 of the second LinearPi Pro using the supplied control cable. To create larger groups, connect the Master control output J1 to the Slave control input J4 of subsequent LinearPi Pros in a chain. The ON/OFF switch/logic of the master LinearPi Pro will control the entire power supply group.

M. Pictures

1. LinearPi Pro Solo

Image Description: A photograph of the LinearPi Pro Solo board, showcasing its compact design with large heatsinks, multiple yellow capacitors, and green terminal blocks for input and output connections. The "0.8uV Ultra low-noise PSU" label is visible.

2. LinearPi Pro Dual, or LinearPi Pro 5V +3.3V, or LinearPi +/- 15V

Image Description: A photograph featuring two LinearPi Pro boards arranged side-by-side, illustrating dual configurations such as 5V +3.3V or +/- 15V outputs. The boards are presented against a dark, reflective background.

3. As a great linear low-noise power supply for RaspberryPi 5

Image Description: A photograph demonstrating the integration of the LinearPi Pro with a Raspberry Pi 5. The LinearPi Pro is shown powering the Raspberry Pi 5, highlighting its suitability for high-performance single-board computers.

N. History of Revising

© 2024 IanCanada. The firmware code embedded in the LinearPi Pro is the property of Ian Jin. You are granted a non-exclusive, non-transferable, non-sublicenseable, royalty-free right to use the LinearPi Pro solely for your own, non-commercial purposes. You may not distribute, sell, lease, transfer, modify, adapt, translate, reverse engineer, prepare derivative works of, decompile, or disassemble the software provided. All rights reserved.