8.4.7 High Accuracy Current Sense Amplifier

As an industry standard, high accuracy current sense amplifier (CSA) is used to monitor the input current or the charge current, selectable via SMBUS (ChargeOption() bit[5]=0 select the input current, bit[5]=1 select the charge current) by host. The CSA senses voltage across the sense resistor by a factor of 20 through the IOUT pin. Once VCC is above UVLO and ACDET is above 0.6V, CSA turns on and IOUT output becomes valid. To lower the voltage on current monitoring, a resistor divider from IOUT to GND can be used and accuracy over temperature can still be achieved.

A 100pF capacitor connected on the output is recommended for decoupling high-frequency noise. An additional RC filter is optional, if additional filtering is desired. Note that adding filtering also adds additional response delay.