About the role of Preload of LTC1733

Hi Yuya, 

The 2Ω resistor is used to sink current from the charger. Some power supply cannot sink current (no current input, just output). If the 2Ω is not connected, the LT1733 will try to output current to the power supply, and as the power supply cannot have current flowing in, the voltage on LT1733 BAT pin will increase until it reaches target battery charge voltage. With the 2Ω resistor, the current will flow through the resistor, and the BAT pin voltage will be controlled by the power supply. You will be able to measure the charge current correctly. 

If you are using a power supply with current sink capability (Bi-polar power supply), then this 2Ω resistor is not needed. 

Thanks,

Wenwei. 

Hi, Wenwei

Thank you for your answer.

I got a good understanding of the role of 2Ω resistors.

Best regards

Yuya