- on Power Supplies
- Published in issue 7/2014 on page 102
Current Boost for USB Lithium Charger
A TL431 shunt regulator can be used to ensure that a lithium cell cannot be charged to more than 4.2 V, meaning: when the cell has reached its maximum voltage, the TL431 must shunt all of the current flowing through the limiting resistor. A resistor with a value of around 10 ohms then limits the current to within what the TL431 can safely shunt.