Share this project

Done

Share this project

Done
High-performance Easy-to-use Mini Power Modules for Makers. Innovative circuitry enables positive/negative supply in one module.
High-performance Easy-to-use Mini Power Modules for Makers. Innovative circuitry enables positive/negative supply in one module.
528 backers pledged $18,453 to help bring this project to life.
Last updated

About

PNMini - Positive/Negative Power Supply Module for Makers project video thumbnail
Replay with sound
Play with
sound

PNMini - Positive/Negative Power Supply Module for Makers

$18,453

528

Update #5: Manufacturing starts today!!

PNMini backers are all around the world!

 (This map doesn't show all exact locations, because your information is kept private by Kickstarter and I am not able to see your location until May 7th. For those of you who don't see your country or city on the map and would like me to add a pin, just let me know in which city you live. I am more than happy to mark it on the map!! :P Great thanks to your support from all around the globe! :P )

PNMini will be available on 

PNMini story is on

Update #3: Kicktraq Technology Hot List #1 & possible free PCB give out for backers

Updated FAQ: Why negative output?

What is PNMini?

PNMini is a family of high performance, easy-to-use DC/DC Power Modules for DIY electronics.

PNMini can be used as positive supply or negative supply. If both positive and negative supply rail are needed, just connect two PNMini modules together. No hardware changes are required.

PNMini is available in a small PCB package that enhances thermal performance and allows for hand soldering or plugin use. It provides +3.3V/-3.3V, +5V/-5V, or +12V/-12V output directly to your circuits requiring no external components.

PNMini family has two output current options to meet your system needs:

  • PNMini-500mA: supports up to 500mA output current
  • PNMini-2A: supports up to 2A output current

Find the DATASHEET!

In case the link above doesn't work, try this one: https://drive.google.com/file/d/0B0aPceJUD-kdSUVuLXQxZHlqcHM/edit?usp=sharing

Shown in the figure below is a PNMini-2A module. All the application instructions given below use PNMini-2A as an example. The PNMini-500mA version is similar in terms of how to use. Detailed specifications and test data of PNMini-500mA will be available after the final test is done.

Top view of PNMini-2A version
Top view of PNMini-2A version
PNMini blank PCB
PNMini blank PCB

How do I use it?

Supply Rail Configuration

PNMini is extremely easy to use. There is no external component required. The three terminals of PNMini are input voltage VIN, output voltage VOUT, and ground connection GND. The VIN pin is always fixed as Pin 3. Depending on the system requirements, Pin 1 can be positive output VOUT(+) or GND; Pin 2 can be GND or negative output VOUT(-).

Input Range

The input range of the PNMini family is very wide to cover more DIY electronics applications. For PNMini-2A, the input range for positive output is 3.5V to 27V. The input range for negative output is 2.7V to 27V.

Output Programming

The output voltage is programmable through three feedback resistors connected from VOUT terminal to GND terminal.

Application Examples

PNMini can be used in all kinds of DIY electronics projects. Below are two application examples:

1. Arduino drone with longer battery life

PNMini can be used to power your Arduino drone. A miniature Arduino board is usually powered by 3.3V. The motors and sensors are usually 5V. You can use 3 li-ion battery stack and two PNMini to get the voltage you want! It's more efficient than LDO. PNMini provides up to 92% efficiency while LDOs can hardly achieve more than 50% efficiency. That's a 40% longer battery life for your design!

2. A simple ECG amplifier

Another application example is a simple ECG amplifier which can display your ECG waveform on a oscilloscope. For sensor or amplifier applications, dual supply is often preferred. Positive supplies are everywhere, but sometimes it's difficult to find a negative power supply. PNMini solves the problem by generating both positive and negative supply from a single source.

How does it work?

PNMini combines positive and negative supply capability into one module. The positive supply is a buck converter; the negative supply is a inverting buck-boost converter. Some buck converter controller ICs can be used as inverting buck-boost converter controllers. A Texas Instruments application note has one such application.

The figure below shows that if you switch the diode and the inductor in a buck converter, it becomes a buck-boost converter. And this is how PNMini works.

What about the technical details?

More key features of PNMini-2A module are:

  • High efficiency at light loads: 85% efficiency at Vin=7V
  • Typical 5uA shutdown quiescent current
  • Slow start limits inrush currents
  • Under voltage lock out (UVLO) protection
  • Over voltage transient protection
  • Thermal shutdown protection
  • Cycle-by-cycle current limit enables short circuit protection

How efficient is it? Shown below are some test data:

Efficiency plots of PNMini-2A
Efficiency plots of PNMini-2A

How does the efficiency compare with 7805/7905? PNMini is a DC/DC switching regulator, which can easily achieve more than 90% efficiency; 7805/7905 are linear regulators, the efficiency is usually below 50%, depending on the input and output voltages, and the quiescent current of the regulator. The efficiency of a linear regulator can be estimated by Efficiency = Vout/Vin * 100%, if the quiescent current is very small. From the equation, at a certain Vout, the higher the input voltage is, the lower the efficiency is. Below is a comparison of PNMini vs. LM7805.

Efficiency - PNMini vs. LM7805
Efficiency - PNMini vs. LM7805

How does it achieve high efficiency at light load? At light load, the switching noise become significant. Instead of always switching, PNMini enters a mode called "Burst Mode", meaning that it switches for a certain amount of time, and then stops switching. When the output voltage drops below a certain level, it switches again. In this way, the switching loss is reduced at light load, thus the efficiency is improved.

What kind of protections does PNMini have? PNMini is a very robust design, it has over voltage protection, thermal shutdown protection, and short circuit protection. The way it protects itself from damage from a short circuit is by a technique called "cycle-by-cycle current limiting" - if the current exceeds a certain level, PNMini will cut the PWM waveform of the current cycle thus limits the current from growing.

What about the other specifications such as line regulation, load regulation, start up, transient response, and output voltage ripple? Don't worry! The PNMini solution is FULLY tested. It's not something you get from eBay and get nothing but a board. You get comprehensive test data on each of the specification!! 

PNMini lab test:

 project video thumbnail
Replay with sound
Play with
sound
PNMini Thermal Image at Vin=12V, Vout=3.3V, Iout=2A, front
PNMini Thermal Image at Vin=12V, Vout=3.3V, Iout=2A, front
PNMini Thermal Image at Vin=12V, Vout=3.3V, Iout=2A, back
PNMini Thermal Image at Vin=12V, Vout=3.3V, Iout=2A, back

How did you make it and what are the next steps?

I'm a maker and I love electronics. For every electronic circuit I built, I need a power supply for it. Power supply design is usually not the interesting part of the circuit, but you have to do it and make it a robust design. It's an annoying fact that you have to design a power supply circuit over and over again. So I design to make it modular. 

There are many good positive dc-dc modules you can get from eBay, you can hardly find a negative power supply. And even for the positive supply, the problem is, what you get from eBay is a black box. You get very limited information of the board. When you test it yourself in lab, you may find that at light load the efficiency is really poor, or the ripple voltage does not meet the requirement of your system. So I want to make a high performance dc-dc module that I know everything of it, and I want it to support both positive and negative supply.

This is the first PNMini prototype soldered by hand, and it's intended for a MSP430 controlled weight sensor application.

PNMini first prototype
PNMini first prototype

After the first prototype, I made a 2A PNMini, as shown in the first section. I tested intensively in lab and generated the PNMini-2A datasheet. Then I made a 500mA version of PNMini. Shown below is a small USB charger using PNMini-500mA prototype v1:

PNMini based DIY USB charger
PNMini based DIY USB charger
PNMini-500mA
PNMini-500mA
PNMini-500mA
PNMini-500mA

Two PNMinis are planned - 500mA version and 2A version. This covers very wide applications for DIY electronics. The PCBs for PNMini family are in line and ready for production. Shown in the figure below are PNMini-2A and PNMini-500mA new PCB with optimized routing:

New PNMini-2A and PNMini-500mA 3D view
New PNMini-2A and PNMini-500mA 3D view
PNMini-2A v1 vs. PNMini-2A v2
PNMini-2A v1 vs. PNMini-2A v2

The prototype is fully tested and functioning well. Production will start immediately after successfully funded. The unit cost is inversely proportional to the amount. The cost consists:

  • PCB board cost. The PCB board cost is very high if the volume is low. Above is a PCB cost estimation from an online quote comparison tool. It is calculated by assuming that we'll order 300 boards at a time. From the quote, the total PCB cost of 300 boards with 2 layers and silkscreen is around $300, and it'll be a one week turn.
  • Component cost. Assuming 300 units, the total cost of all the components on board is around $3 per unit, including integrated circuits, diodes, inductors, capacitors, resistors, and pin headers.
  • Assembly and test cost. If the amount is below 300 units, we will be forced to solder all units by hand because of the cost, and I will testing all the units by myself in my lab - which is very time consuming. If the we get more than 300 units, we'll be able to use soldering machine service and the test service provided by the factory.
  • Package and shipping cost. We'll use USPS standard service inside US. Additional cost will be added for international shipping.

We plan to begin manufacturing after successfully funded. But we can start manufacturing immediately if the number of orders reaches 300 units.

Stretch Goal

If we get more than enough funding, we plan to add a color package to PNMini family. The package will be heat dissipation and provides insulation for the internal components. PNMini logo and pin names will be printed on the package. Color package will be available in the retail version after kickstarter funding period ends, if we get enough funding.

Below are several sample package we made:

Power supply modules are like nails to your furniture. You will need a power supply circuit for each of your design. PNMini will accelerate your design process, and leave the most interesting part of the design to you. I hope this idea is beneficial to the makers community.The cost of new PCB production is very high. What I need is your support. With your help, PNMini will be made open source and get into your hand.

Thank you for your time and support!!! 

Risks and challenges

The design itself is very robust. As a power supply design professional, I guarantee that it is high quality, and I will test every module and make sure it works before I send it to you (if you choose a starter kit and want to solder it yourself, I will provide a very detailed assemble guide, and a user's manual to make sure that you can power it up).

The biggest risk at this point is being able to meet demand. I set the funding at the level that I estimated to be enough for manufacturing. If the demand is high, it may at first take a little longer to fill orders than I would like. I have plans to expand production if needed to accommodate higher order volumes. If the demand does not meet, I won’t be able to kick off the fabrication.

This is my very first project on Kickstarter, please help me on make it a reality, and help me share this great idea to more makers!

Learn about accountability on Kickstarter
Questions about this project? Check out the FAQ

Support

  1. Select this reward

    Pledge US$ 2 or more About US$ 2

    Thank you very much for your support! You'll get a thank you post card from us! With your help, the great idea will become popular in the open hardware community, and make DIY electronics easier and more enjoyable.

    Less
    Estimated delivery
    Ships to Anywhere in the world
    6 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  2. Select this reward

    Pledge US$ 10 or more About US$ 10

    PNMini - DIY, This is a 500mA version of PNMini kit for you to solder together yourself. Shipped with PNMini schematic, layout, BOM, assemble guide, and user's guide.

    Less
    Estimated delivery
    Ships to Anywhere in the world
    Limited 29 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  3. Select this reward

    Pledge US$ 16 or more About US$ 16

    PNMini-500mA assembled version - This is the assembled PNMini-500mA. This comes assembled ready to use. Shipped with PNMini schematic, layout, BOM, and user's guide.

    Less
    Estimated delivery
    Ships to Anywhere in the world
    Limited 10 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  4. Select this reward

    Pledge US$ 28 or more About US$ 28

    Get 2 PNMini-500mA assembled version for dual supply use - This is the assembled PNMini-500mA. This comes assembled ready to use. Shipped with PNMini schematic, layout, BOM, and user's guide.

    Less
    Estimated delivery
    Ships to Anywhere in the world
    20 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  5. Select this reward

    Pledge US$ 30 or more About US$ 30

    Get both PNMini-500mA and PNMini-2A assembled version. Shipped with PNMini schematic, layout, Gerber file, BOM, and user's guide.

    Less
    Estimated delivery
    Ships to Anywhere in the world
    81 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  6. Select this reward

    Pledge US$ 34 or more About US$ 34

    Get 2 PNMini-2A assembled version for dual supply use - This is the assembled PNMini-2A. This comes assembled ready to use. Shipped with PNMini schematic, layout, BOM, and user's guide.

    Less
    Estimated delivery
    Ships to Anywhere in the world
    114 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  7. Select this reward

    Pledge US$ 60 or more About US$ 60

    Get 2 PNMini-500mA and 2 PNMini-2A assembled version for dual supply use. Shipped with PNMini schematic, layout, Gerber file, BOM, and user's guide.

    Less
    Estimated delivery
    Ships to Anywhere in the world
    97 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  8. Select this reward

    Pledge US$ 60 or more About US$ 60

    CHOOSE YOUR OWN!! You can choose your own PNMinis. Price for each assembled PNMini-500mA is $14, assembled PNMini-2A is $16. Minimum pledge is $60. Maximum allowed No. of each is 10. Add $3 for international shipping.

    Less
    Estimated delivery
    Ships to Anywhere in the world
    24 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  9. Select this reward

    Pledge US$ 100 or more About US$ 100

    Custom PNMini - Get PNMini-500mA or PNMini-2A in custom shape and color or get it designed in on your PCB. Supplied with PNMini schematic, layout, Gerber file, BOM, and user's guide.

    Less
    Estimated delivery
    Ships to Anywhere in the world
    Limited 1 backer
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  10. Select this reward

    Pledge US$ 300 or more About US$ 300

    Custom power supply design - Get custom power supply design service from me, a power electronics professional. I will provide up to 100W AC-DC or DC-DC power design service to power up your project.

    Less
    Estimated delivery
    Ships to Anywhere in the world
    Limited 0 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  11. Reward no longer available

    Pledge US$ 1 or more About US$ 1

    Claim your FREE PNMini today! Post PNMini kickstarter page on your Facebook and get 50+ shares! Claim your free assembled PNMini by sending the screen shot of the facebook share to billy.docxwolf@gmail.com. Please mention which one you'd like to get as well (PNMini-2A or PNMini-500mA)You'll get a confirmation email from Billy after you claim your free PNMini.

    I was going to put $0.01 for this reward, but the minimum reward allowed on kickstarter is $1. Select this reward to enter your shipping address. Only 20 free PNMini for the first 20! Free shipping worldwide!

    Less
    Estimated delivery
    Ships to Anywhere in the world
    Reward no longer available 20 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  12. Reward no longer available

    Pledge US$ 7 or more About US$ 7

    PNMini-500mA early bird price! You will get an assembled PNMini-500mA from our first batch for less than retail price. Only 30 available!

    Less
    Estimated delivery
    Ships to Anywhere in the world
    Reward no longer available 30 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  13. Reward no longer available

    Pledge US$ 8 or more About US$ 8

    PNMini-2A early bird price!
    You will get an assembled PNMini-2A from our first batch for less than retail price. US shipping only. Only 30 available!

    Less
    Estimated delivery
    Ships to Anywhere in the world
    Reward no longer available 30 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  14. Reward no longer available

    Pledge US$ 15 or more About US$ 15

    PNMini - DIY, This is a 2A version of PNMini kit for you to solder together yourself. Shipped with PNMini schematic, layout, BOM, assemble guide, and user's guide.

    Less
    Estimated delivery
    Ships to Anywhere in the world
    Reward no longer available 30 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  15. Reward no longer available

    Pledge US$ 18 or more About US$ 18

    PNMini-2A assembled version - This is the assembled PNMini-2A. This comes assembled ready to use. Shipped with PNMini schematic, layout, BOM, and user's guide.

    Less
    Estimated delivery
    Ships to Anywhere in the world
    Reward no longer available 30 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.

Funding period

- (50 days)