LIR2450 USB Charger v1.2
author: chrislabs
2 layer board of 1.45 x 1.87 inches (36.9 x 47.6 mm)
Uploaded:
February 10, 2015
Shared:
February 10, 2015
Total Price:
$13.60
Github Repo: github.com/cgrossde/LIR2450-USB-Charger
Based on MCP73831. Beware not tested (yet).
There are two charge modes:
- fast (45mA)
- slow (25mA)
Max charge current for a coin cell is usually between 80% and two third of it’s capacity. So you could charge a 100mA coin cell with 80mA. I wanted to increase the lifetime of my coin cells and reduced the charge current. If you want to have different currents here is the equation to calculate R_SLOW/R_FAST:
mA = 1000 / R in kΩ
Example: 1000/20kΩ = 50mA
BOM:
- MCP73831 SOT-23-5
- 0603 LED Green (~3.1V voltage drop)
- 0603 LED Orange (~2V voltage drop)
- 0805 Resistor 200Ω
- 0805 Resistor 320Ω
- 0805 Resistor 40kΩ
- 0805 Resistor 22kΩ
- 0805 Capacitor 4.7uF
- CR/LIR2450 Coin cell holder (20mm diameter, 5mm height)
- (optional) male pin header, jst pin header
Github Repo: github.com/cgrossde/LIR2450-USB-Charger
Based on MCP73831. Beware not tested (yet).
There are two charge modes:
- fast (45mA)
- slow (25mA)
Max charge current for a coin cell is usually between 80% and two third of it’s capacity. So you could charge a 100mA coin cell with 80mA. I wanted to increase the lifetime of my coin cells and reduced the charge current. If you want to have different currents here is the equation to calculate R_SLOW/R_FAST:
mA = 1000 / R in kΩ
Example: 1000/20kΩ = 50mA
BOM:
- MCP73831 SOT-23-5
- 0603 LED Green (~3.1V voltage drop)
- 0603 LED Orange (~2V voltage drop)
- 0805 Resistor 200Ω
- 0805 Resistor 320Ω
- 0805 Resistor 40kΩ
- 0805 Resistor 22kΩ
- 0805 Capacitor 4.7uF
- CR/LIR2450 Coin cell holder (20mm diameter, 5mm height)
- (optional) male pin header, jst pin header
