# Adafruit bq25185 USB / DC / Solar Charger with 3.3V Buck Board

## Overview

Danger: There is an unmodifiable 6 hour safety timeout on this chip. If the board is charging for 6 hours without any interruptions, charging will stop.

![](https://cdn-learn.adafruit.com/assets/assets/000/133/794/medium800/components_6092-06.jpg?1732305428)

We're always on the look out for better ways to make projects portable: being able to charge your battery in the most convenient manner will let projects run no matter what power is available. Then we added a power supply chip with it to let you run your project without a separate board. The result is the **Adafruit bq25185 USB / DC / Solar Charger with 3.3V Buck Board!**

![](https://cdn-learn.adafruit.com/assets/assets/000/133/795/medium800/components_6092-05.jpg?1732305458)

It uses the new [bq25185](https://www.ti.com/product/BQ25185) is a nifty charger chip with fairly high charge current, power path support, and the ability to charge from USB, DC or solar power. It's also a great value, so it's a good upgrade from [MCP73833](https://www.adafruit.com/product/259) or [MCP73831-based](https://www.adafruit.com/product/4410) charger boards. The buck converter is the [TPS62569](https://www.adafruit.com/product/4711), which will give a clean 1 Amp output with good efficiency, to squeeze the most power possible out of your battery.

![](https://cdn-learn.adafruit.com/assets/assets/000/133/796/medium800/components_6092-01.jpg?1732305518)

This board is meant to be everything you need to power your 3.3V electronics: simply connect a 500mAh or larger battery to the JST PH 2-pin port, then charge it when you can from USB or DC/solar. At the other end is a terminal block which will provide the power-path-load output from the bq25185 which will range from 3.0V (battery near-dead) to 4.5V (USB/DC/Solar is powering the board) at about 1 Amp max. Another terminal port will give 3.3V output, up to 1 A (this will also dip down to 3.0V when the battery is near-empty).

![](https://cdn-learn.adafruit.com/assets/assets/000/133/797/medium800/components_6092-02.jpg?1732305553)

- **USB Type C** connector with 5.1k CC resistors so it will work with any computer or power supply to get 5V and up to 1A. Data lines available if needed, on the bottom breakout.
- **Separate DC or Solar Input** - Two pads on the edge can be used to connect a 5 ~ 18V power supply, which can be used instead of USB. If the input is a solar panel, the charging chip will adjust the current draw so that the voltage does not dip below the battery, thus optimizing the solar power input. No large capacitor needed to stabilize it, and you get near-MPPT capability without the cost and complexity of MPPT.
- **Default charge rate of 1A** , but you can cut the jumper on the back to set the rate to 500mA
- **Power Path to Load** - If the 4.5V or 3.3V load connector is drawing current while the USB / DC/Solar power is attached, it will default to drawing current from the charger and any left over current will go to the battery. That keeps your battery from constantly charging/discharging which will reduce the battery life.
- **Regulated 4.5V-max Output** - no matter what voltage you have on the USB or DC / solar inputs, the 4.5V terminal block output port will never go above 4.5V due to an internal voltage regulator. Keep this in mind, though, when dealing with high currents and high DC voltages as the LDO will make the board start to overheat and throttle the current.
- **Regulated 3.3V-max Output** - a separate buck converter will take the load output from the bq25185 and switch it down to 3.3V at 1 Amp max load
- **Three Status LEDs** - Orange **C** harging LED, red **F** ault LED, and Green 3.3V output LED.
- **Enable pad -** to disable the 3.3V buck converter.
- Mounting holes!

![](https://cdn-learn.adafruit.com/assets/assets/000/133/798/medium800/components_6092-00.jpg?1732305814)

This board is pretty much plug-and-play. Change the charging jumper if you like, then connect your battery to the BATT port, and the 4.5V-max and 3.3V-max outputs go to your circuit. Don't forget the two outputs will never go above 4.5V or 3.3V, but it can go as low as 3.0V if the battery is nearly empty. You can monitor the voltage on the battery via the secondary pads on the bottom edge, if necessary.

![](https://cdn-learn.adafruit.com/assets/assets/000/133/799/medium800/components_6092-04.jpg?1732305851)

To use with solar, [pick up a 5~7V solar panel](https://www.adafruit.com/category/580) (using a higher voltage panel will only lose the extra voltage as heat so there's no benefit to going over 7V), and either cut the connector off to wire it directly, or [use a 2.1mm adapter cable](https://www.adafruit.com/product/2788) plus a [2.1mm terminal block](https://www.adafruit.com/product/368) to get two wires for the DC Input port.

If you need a board with higher charge current or a DC plug already on-board, [check out the bq24074 which has up to 1.5A charge rate and a on-board 2.1mm DC jack](https://www.adafruit.com/product/4755). It doesn't have a buck converter but you could wire up the [TPS62569](https://www.adafruit.com/product/4711) separately

# Adafruit bq25185 USB / DC / Solar Charger with 3.3V Buck Board

## Pinouts

Danger: There is an unmodifiable 6 hour safety timeout on this chip. If the board is charging for 6 hours without any interruptions, charging will stop.

![](https://cdn-learn.adafruit.com/assets/assets/000/133/909/medium800/components_double.jpg?1733257225)

## Power Inputs
- **USB Type C** - On the edge of the board is the  **USB Type C** connector. It has 5.1k CC resistors so it will work with any computer or power supply to get 5V and up to 1A.
- **VIN** - This is the solar panel or DC power input to the bq25185. Connect a 5 ~ 18V power supply. If the input is a solar panel, the charging chip will adjust the current draw so that the voltage does not dip below the battery, thus optimizing the solar power input. The /CE pin is tied to ground, so the safety timer cannot be reset except by removing and applying the supply voltage.
- **VU** - This is the power input from the USB connector. 
- **G** - common ground.

![power_components_6092-06.jpg](https://cdn-learn.adafruit.com/assets/assets/000/133/924/medium640/power_components_6092-06.jpg?1733325318)

## Battery Output
At the top of the board is the JST battery connector. By default, the output is 3.7V nominal / 4.2V max battery chemistry/voltage for all modern 1-cell LiPoly or LiIon batteries with a default charge rate of 1A.  
This output is available on the bottom of the board as well, labeled **BAT** on the board silk. You can use this secondary output to monitor the voltage on the battery with a multimeter.

![components_bat.jpg](https://cdn-learn.adafruit.com/assets/assets/000/133/919/medium640/components_bat.jpg?1733324928)

## Terminal Block Output
- **4.5V** - This is the load output, labeled  **4.5V** on the board silk. It provides a regulated 4.5V-max load output. No matter what voltage you have on the USB or DC / solar inputs, the load output port will never go above 4.5V due to an internal voltage regulator. Keep this in mind, though, when dealing with high currents and high DC voltages as the LDO will make the board start to overheat and throttle the current.  
- **-** - This is common ground.
- **3V** - This is the regulated 3.3V output from the separate buck converter. It takes the load output from the bq25185 and switches it down to 3.3V at 1 Amp max load. This output is available on the bottom of the board as well, labeled **3V** on the board silk.

![components_terminalBlock.jpg](https://cdn-learn.adafruit.com/assets/assets/000/133/920/medium640/components_terminalBlock.jpg?1733324982)

## USB Data Pins
- **D+** and **D-** - USB positive and negative data lines

![components_data.jpg](https://cdn-learn.adafruit.com/assets/assets/000/133/925/medium640/components_data.jpg?1733325401)

## Enable Pin
- **EN** - This is the enable pad for the 3.3V output from the buck converter. Bring this pin low to disable the 3.3V output.

![components_enable.jpg](https://cdn-learn.adafruit.com/assets/assets/000/133/921/medium640/components_enable.jpg?1733325030)

## Charge Rate Jumper
On the back of the board is the  **charge rate jumper**. You can cut this jumper to change the charge rate from 1A to 500mA.

![components_jumper.jpg](https://cdn-learn.adafruit.com/assets/assets/000/133/923/medium640/components_jumper.jpg?1733325206)

## Status LEDs
- **3.3V Output LED** - In the top right corner of the board is the 3.3V output LED. It is the green LED. It will be lit if the 3.3V output is enabled.
- **Charge LED** - In the top left corner of the board is the charge status LED. It is the orange LED. It is labeled C on the board silk. It will be lit while a battery is charging.
- **Fault LED** - Directly below the charge status LED is the fault status LED. It is the red LED. It is labeled F on the board silk. It will be lit if the board experiences a fault condition. The bq25185 has integrated fault protection for a few conditions:  

  - Input overvoltage protection
  - Battery undervoltage protection
  - Battery short protection
  - Battery overcurrent protection
  - Input current limit protection
  - Thermal regulation and thermal shutdown
  - Battery thermal fault protection
  - Safety timer fault
  - ISET and ILIM/VSET pin short/open protection.

![components_leds.jpg](https://cdn-learn.adafruit.com/assets/assets/000/133/922/medium640/components_leds.jpg?1733325101)

# Adafruit bq25185 USB / DC / Solar Charger with 3.3V Buck Board

## Downloads

Danger: There is an unmodifiable 6 hour safety timeout on this chip. If the board is charging for 6 hours without any interruptions, charging will stop.

## Files

- [bq25185 Datasheet](https://cdn-learn.adafruit.com/assets/assets/000/133/752/original/bq25185.pdf?1732204133)
- [EagleCAD PCB Files on GitHub](https://github.com/adafruit/Adafruit-bq25185-with-3.3V-Buck-PCB)
- [3D models on GitHub](https://github.com/adafruit/Adafruit_CAD_Parts/tree/main/6092%20BQ25185%203V%20Buck)
- [Fritzing object in the Adafruit Fritzing Library](https://github.com/adafruit/Fritzing-Library/blob/master/parts/Adafruit%20bq25185%20with%203.3V%20Output.fzpz)

## Schematic and Fab Print
![](https://cdn-learn.adafruit.com/assets/assets/000/133/800/medium800/components_schem.png?1732307024)

![](https://cdn-learn.adafruit.com/assets/assets/000/133/801/medium800/components_fab.png?1732307032 dimensions are in inches)

![](https://cdn-learn.adafruit.com/assets/assets/000/134/501/medium800/components_6092_BQ25185_3V_Buck.jpg?1737051627)


## Primary Products

### Adafruit bq25185 USB / DC / Solar Charger with 3.3V Buck Board

[Adafruit bq25185 USB / DC / Solar Charger with 3.3V Buck Board](https://www.adafruit.com/product/6092)
We're always on the look out for better ways to make projects portable: being able to charge your battery in the most convenient manner will let projects run no matter what power is available. Then we added a power supply chip with it to let you run your project without a separate board....

In Stock
[Buy Now](https://www.adafruit.com/product/6092)
[Related Guides to the Product](https://learn.adafruit.com/products/6092/guides)

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### 5V 5W Solar Panel - ETFE

[5V 5W Solar Panel - ETFE](https://www.adafruit.com/product/5367)
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### 3.8 / 1.3mm or 3.5 / 1.1mm to 5.5 / 2.1mm DC Jack Adapter Cable

[3.8 / 1.3mm or 3.5 / 1.1mm to 5.5 / 2.1mm DC Jack Adapter Cable](https://www.adafruit.com/product/2788)
This convenient **3.8mm/1.3mm or 3.5mm/1.1mm or 1.3mm DC to 2.1mm DC adapter cable ** lets you plug one of our [solar panels](https://www.adafruit.com/categories/67) into [our optimized Solar Lithium Ion/Polymer...](http://www.adafruit.com/products/390)

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### Female DC Power adapter - 2.1mm jack to screw terminal block

[Female DC Power adapter - 2.1mm jack to screw terminal block](https://www.adafruit.com/product/368)
If you need to connect a DC power wall wart to a board that doesn't have a DC jack - this adapter will come in very handy! There is a 2.1mm DC jack on one end, and a screw terminal block on the other. The terminals are labeled with positive/negative assuming a positive-tip configuration...

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As technology changes and adapts, so does Adafruit. This   **USB Type A to Type C** cable will help you with the transition to USB C, even if you're still totin' around a USB Type A hub, computer or laptop.

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