Little Nugget v1 - 1.8/3.3/5V 2A

Little Nugget v1 - 1.8/3.3/5V 2A

$25.00 Sale

Sorry, this product is discontinued!
About
I designed this power supply for small projects, prototyping, Arduino, IoT, and wireless embedded applications.  An ATtiny45 provides the ideal balance between features and efficiency.  When on, efficiencies go as high as 92%.  When off, it consumes just 2μA!  It uses two LEDs, red and green, to provide simple information about the charging and power of the device.

This power supply has protection for input overcurrent, output short circuit, output disconnect, battery disconnect, battery overvoltage, and battery undervoltage.

It's difficult to find a power supply to convert a Lithium-Ion battery to a 1.8V, 3.3V, or 5V with high current output, high efficiency, and safety features.  This board uses the Texas Instruments TPS63020, which is capable of this task.

This power supply uses a single cell Lithium-Ion battery.  The battery is charged at a maximum of 500mA using the Microchip MCP73831.  A battery is required to use this power supply.


Specs
  • 3.3VDC output
  • 4A peak output (100ms max)
  • 2A continuous output
  • 90%+ efficiency
  • 2μA sleep current
  • Micro USB charge input
  • Micro JST Connector for Single Cell Li-Ion
  • 500mA max charge rate
  • Minimum recommended battery capacity - 500mAh

 

 LED  Status
Green ON
Green and Slow Blinking Red ON, battery low (<30%)
Green and Fast Blinking Red ON, battery critical (<10%)
Glowing Green ON, charging
Glowing Red OFF, charging
Red OFF, fully charged

 

Efficiency (LEDs off, Vbat = 3.6V) Output Current
 85% 1mA
91% 10mA
92% 100mA
91% 1A
85% 2A

 

This project is Open Source and Open Hardware under the CC BY-SA license

 

1.8V Design Files

 

3.3V Design Files

 

5V Design Files

 

FAQ

Do I need a battery to use this power supply?

Yes.  Although the power supply will work without one, the max output is limited to 500mA and does not respond well to changes in load current.

What does the LED switch do?

This switch is for disabling the LEDs.  The LEDs draw a maximum of 1.67mA each.  In some low power applications, disabling the LEDs may increase battery life significantly.

Can I charge with something besides microUSB?

Yes, if you want to add another source, you can directly solder any source between 3.75VDC to 7VDC.  See the schematic for where to make solder connections.

Can I change the max charge current?

Yes.  You'll have to remove replace resistor R5.  The charge current can be anywhere from 0mA to 500mA.  The formula for R5 is Max Charge Current (mA) = 1000 / R.  The standard value for R5 is 2kΩ.

Why won't my power supply turn on?

First, see if the LED switch is on.  The power supply may be on even though the LEDs are disabled.

Second, check the battery voltage.  If the battery voltage is below 3.3V, the power supply will not turn on.

Will the battery charge while the power supply is off?

Yes.  The power switch will disable the output, but still allow the battery to charge.

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