BqChamps,
I'm trying to design my BQ27742 to protect over current at 800mA.
According to the datasheet this is set by the OCD register as follows.
Note. OCD0 is mentioned twice, this appears to be an error in the datasheet, please confirm.
As far as I know the Vocd is the voltage across the sense resistor. In the evaluation board the sense resistor is 5 mOhm. So for the default 34mV is equivalent to 34/5=6.8A which is extremely high, The lowest setting of 14mV is equivalent to 2.8A which is still very high.
If I change the sense resistor to 10 mOhm the lowest overcurrent detect current is 14 mV/10 mOhm = 1.4A which is still quite high.
In order to protect overcurrent at 800mA, then the sense resistor has to be at least 14 mV/800mA = 17.5 mOhm.
The higher the sense resistor value the higher the overall power wasted. Is there a better way to do this?