In the previous article we have seen the main hardware features of Guard18650.

In this article I want to show you some screens taken from an oscilloscope that explain what happen when an event activate a protection

these screens represent the COUT and DOUT state when a protection occur:

  • COUT is the red signal
  • DOUT is the yellow signal

the time division is 20 µS and for both channels, the voltage division is 2V

Over Voltage Protection

Protection occur when battery voltage reach the value of 4.24V (4.275V from datasheet), COUT drops in about 34 µS (measured from 10% to 90%  voltage of transition)

Under Voltage Protection

Protection occur when battery voltage reach the value of 2.78V (2.8V from datasheet), DOUT drops in about 9µS (measured from 10% to 90%  voltage of transition)

Over Current Charge Protection

This is not shown with a graphic rappresentation on an oscilloscope due to a difficulty to charge the battery at more than 4A (that is the current that I expect the protection to start), however according to the voltage drop between V- and VSS pin (that is 100mV), protection will activate at about 4.2A

Over Current Discharge Protection

Protection occur when battery source a current above 4.2A, DOUT drops in about 9µS (measured from 10% to 90%  voltage of transition)

Short Circuit Protection

Protection occur when VBAT+ and VBAT-  are shorted together, both COUT and DOUT have the same drop