Tag Archives: Charger

High Voltage Capacitor Charger for Photo-Flash Using LT3751

The project is built for professional photo flash systems. Circuit generates high voltage from low voltage battery to operate a photo-flash tube. The project can also be used in other applications like high voltage capacitor charger, emergency strobe, high voltage power supply, security, detonators etc. LT3751 is the heart of the project.

The LT3751 is a high voltage input flyback controller designed to rapidly charge a large capacitor to a user-adjustable high target voltage set by the transformer turns ratio and three external resistors. Optionally, a feedback pin can be used to provide a low noise high voltage regulated output. The LT3751 has an integrated rail-to-rail MOSFET gate driver that allows for efficient operation down to 4.75V.

High Voltage Capacitor Charger for Photo-Flash Using LT3751 – [Link]

Versatile And Open Source LiPo bBattery Breadboard Power Supply

Orlando Hoilett from Calvary Engineering LLC designed a  versatile Li-Po battery breadboard power supply and wrote an Instructables on it. This power supply outputs 3.3V to the breadboard and takes input from a single-cell LiPo battery. The breadboard power supply also has the ability to charge the battery without needing to separate it from the circuit board. More importantly, this project is licensed under Open Source Hardware which means anyone can modify, distribute, make, and sell this design.

LiPo bread board power supply
LiPo breadboard power supply

Key Components

The complete BOM is available at the GitHub repository.

  • JST connector
    This connector connects directly to the LiPo battery.
  • 3.3V regulator, AP2210K
    3.3V logic is getting increasingly popular among electronics hobbyists and engineers. Also, boosting 3.7V of a LiPo battery to 5V can induce quite a bit of switching noise on the power supply. Linearly converting 3.7V to 3.3V is the best way to avoid this problem.
  • Battery Charger, MCP73831T
    This power supply has a charger built into the board so you can charge the battery without removing it from the power supply.
  • Voltage Selection Jumper
    The voltage selection headers are 3 pin male headers and they are labeled as 3.3V (or VReg) and VRAW (or LiPo). Connect the center pin to 3.3V to get power from the regulator. Connect the center pin to VRAW to get power directly from the LiPo battery.
  • DPDT Switch
    This switch lets you power down the board without removing the battery.
  • LED indicators
    LEDs are used to indicate the current status of the board.


This board breaks out the LiPo battery to the breadboard power rails on both sides. It has a DPDT switch to power down the board. The AP2210K IC has an ENABLE pin which is pulled down to the ground using the DPDT switch in order to enter the low power mode. In low power mode, the regulator and all the LEDs get disabled and draws almost no current from the LiPo. More about the AP2210K regulator IC is on this datasheet.

LiPo breadboard power supply schematic
LiPo breadboard power supply schematic

Another great feature of this breadboard power supply as mentioned earlier is, it incorporates an MCP73831T LiPo battery charger IC. It is a widely used PMIC (power management integrated circuit) for charging LiPo batteries. The LiPo battery should be connected to pin 3 (VBAT) and 5V should be applied to pin 4 (VDD).

The chip starts charging as soon as it detects 5V input and stops charging when the battery is full. Charging current is limited to USB standard i.e. 100mA by connecting a 10.2K resistor between pin 5 (PROG) and ground. So, it’s completely safe to charge the battery from your laptops USB port. Other host microcontrollers can check the battery status using pin 1 (status pin) of MCP73831T.

Solar Power Module v2

Chip McClelland @ hackster.io published his solar li-po battery charger based on MCP73871 to manage the solar and DC charging of the LiPo battery, TPS63020 Buck-Boost Converter and Maxim 74043 LiPo Fuel Gauge. He writes:

I build connected sensor which are often deployed in local parks where there is no access to utility power. Over the past couple years, I have been refining and testing my solar power modules and have arrived at this compact integrated design. I have a number of these deployed and they have been in continuous service for up to two years. I wanted to share this design in case it might be helpful for your projects. I would also greatly appreciate any input or suggestions on this design so v3 will be even better.

Solar Power Module v2 – [Link]

MPPT solar charger

Lukas Fässler from Soldernerd has been working on revised version of his MPPT Solar charger project:

Over the last few weeks I have been quite busy with my MPPT Solar Charger project. I’ve built up a first board and started writing firmware for it. Since the last version was not too different in terms of hardware I was able to re-use most of that code. But I hadn’t even touched on the whole USB stuff back then so there was still a lot of work to do. While the project is still far from being complete I am happy to say that I’ve made quite some progress. Most importantly, the new design seems to work well and so far I haven’t found any mistakes in the board layout. But let’s go through this step by step.

MPPT solar charger – [Link]

BQ25504 Solar Cell LiPo Charger

by Pesky Products @ tindie.com:

This is a small (0.5 x 0.5 inch) breakout board for Texas Instrument’s BQ25504 Ultra Low Power Boost Converter with Battery Management for Energy Harvesting Applications.

BQ25504 Solar Cell LiPo Charger – [Link]


New PWM controller IC By Microchip Charges Batteries of Any Chemistry

Battery technologies of all chemistry are experiencing revolutionary changes nowadays. Nanotechnology is leading this revolution by yielding new battery technologies including but not limited to Tiny Supercapacitors and Li-ion batteries that never explode at any condition. But, it’s bothersome to make different chargers for different types of batteries. So, Microchip solved this problem by introducing a new hybrid PWM controller, MCP19124/5, that charges batteries of any chemistry.

MCP19124 PWM Controller - 24 Pin QFN Package
MCP19124 PWM Controller – 24 Pin QFN Package

The power of this charging device lies in the combination of an 8-bit PIC microcontroller and an analog PWM controller in one package. This mixed signal low-side PWM controller features individual analog PWM control loops for both current regulation and voltage regulation. It can be configured with separate feedback networks and reference voltages. Any voltage, current, temperature, or duration can be used to trigger a transition to a different charging profile.

Various types of batteries require different charging profile. So, the only way to charge all kinds of batteries with a single device is to simulate all the charging profiles. A user can set his/her desired profile with the help of two independent current and voltage control loops, along with variable reference voltage. Now let’s get to know more details about this versatile PWM controller IC.

MCP19124/5 : 

The MCP19124/5 is a mid-voltage (4.5-42V) analog-based PWM controller with an integrated 8-bit PIC Microcontroller. There are two devices, the MCP19124 and MCP19125, where the last one has four I/O pins more than the first one. MPC19124 and MPC19125 are packaged in 24-lead QFN package and 28-lead QFN package respectively. It has following features:

  • Smooth, dynamic transitions from constant-current to constant-voltage operation
  • Dynamically adjustable output current and output voltage over a wide operating range
  • Wide operating voltage range: 4.5-42V
  • Analog peak-current mode Pulse-Width Modulation (PWM) control
  • Available fixed frequency (31 kHz to 2 MHz)
  • I2C communication interface
  • 9 GPIO for MCP 19124 and 12 GPIO for MCP19125
  • Integrated high voltage linear regulator, with external output
  • Integrated temperatures sense diode
  • Integrated 10 bit A/D converter
  • Minimal external components needed
  • Custom algorithm support
  • Topologies supported include Boost, SEPIC, Flyback, and Cuk

In fact, the above list is just a brief overview. The controller is so complicated that user must read all 236 pages of the datasheet to gain sufficient knowledge.

Now, the question is, how can we use this IC to design an efficient battery charger?

To find the answer, one must read the datasheet thoroughly. At the same time, in-depth knowledge about the target battery is also required. However, Microchip provided a few schematics (as references) in the datasheet based on different applications. The circuit on battery charger is given below:

Battery Charger Circuit Using MCP19124 ICBattery Charger Circuit Using MCP19124 IC
Battery Charger Circuit Using MCP19124 IC

This ultimate powerful dual-loop PWM controller is going to be a game changer and part of the battery technology revolution. It possesses lots of possibilities. To learn more about this fantastic hybrid controller, study the datasheet carefully.

MPPT solar charger


Lukas Fässler show us his progress on the MPPT solar charger:

One of my main goals with this design is to achieve very low standby current, somewhere in the tens of microamps. The basis for this is a low-power buck on the basis of a Texas TPS62120 where the microcontroller can switch the output voltage between 2.2 and 3.3 volts nominally. This works as intended. With no load and the output voltage low, the supply consumes 12.9 microamps at 12V input voltage. With the high output voltage the idle current goes up to 14.3uA. Quite a bit of that current is due to the voltage divider that sets the output voltage. The regulator itself consumes about 9uA in both cases.

MPPT solar charger – [Link]

A very simple DIY solar-powered USB charger


Raj @ embedded-lab.com tipped us with his latest project. It’s a simple, but useful USB Solar powered charger able to charge a power bank or your smartphone.

Yesterday, I built a very simple DIY solar-powered USB charger for my TP-link 10400mAh USB Power Bank. All I needed was a 6V/3.5W solar panel and the TD1410-based 5V buck converter module. I bought both of them on Aliexpress for less than $8.

A very simple DIY solar-powered USB charger – [Link]

SunDuino – Run your C application using solar power


SunDuino is a Single Board Computer with integrated Battery Charger, Voltage Regulators, I2C, Digital and Analog IO. It’s main benefit is that it can run a compiled C app for years on a small battery or forever using built in solar charger. A background RTOS provides SLEEP functions for reducing operating current to 100ua while providing 125ms periodic wakeups. Sunduino comes in 25W and 10W versions to better suit your application. Take a look at the manual and Datashseet. Also the schematic and PCB layout is available for free.

Key benefits of SunDuino:

  1. Battery charging logic is optimized for long battery life using temperature monitor. The SunDuino is a software defined charger, it supports many battery chemistries and sizes.
  2. Low current operation provides long battery life and runtime. An internal RTOS keeps battery monitoring, power event monitoring, user C Application and SLEEP mode all operating on a 100ua drain. Small batteries can run for years.
  3. Regulated output voltages of +5. +3.3 and +/-12 for the powering of external hardware. Radios, other processors, relays and LEDs are examples of external hardware which requires regulated voltages.
  4. Runs compiled C Applications and various library function for complete user control of power operation. Greatly simplifies system integration.

SunDuino – Run your C application using solar power – [Link]


iPhone Battery Charger / Tester


mozzwald.com has designed an iphone battery charger /tester.

I have seen technicians often replace batteries when they may not necessarily need to be or ignore the fact that they could be the cause of the issue at hand. To remedy this I designed a basic iPhone battery charging breakout board system. The system can charge a battery, has the option for expansion to support newer/other batteries and breaks out the battery status pins which can be read from a microcontroller or some other means. It consists of 6 battery connector boards (iPhone 4, 4S, 5, 5S/C, 6, 6+) and a main charging board.

iPhone Battery Charger / Tester – [Link]