I see in the datasheet that the LT3010 is used to power INT_vcc. May I ask whether the GND of LT3010 is connected to SGND or PGND
The LTC4020 datasheet says the INTVCC capacitor connects to PGND, so that is where I would ground the LT3010.
I am glad you asked this question because the use of the INTVcc preregulator in datasheet figure 9, figure 10 and the application circuit on p. 39. will not work. Please use the following circuit instead…
thanks for your reply
I am glad you asked this question because the use of the INTVcc preregulator in datasheet figure 9, figure 10 and the application circuit on p. 39. will not work. Please use the following circuit instead. Note that I have connected the ground pin of the LT3012 to PGND.
I used the LT3012 which can supply 250mA; the LT3010 can supply 50mA.
Thanks for answering,I did not use PowerPathFET,So how should my FBG pin be connected?Is it better to use LT3010 or LT3012？
Following is more explanation on FBG and DC2044A schematic.
For CC/CV mode a powerpath FET is used to disconnect the battery after timeout. The voltage divider connected from the battery is returned to FBG. After timeout FBG is disconnected from ground (internal to LTC4020), so the voltage divider does not drain current from the battery. This is why the DC2044A uses the FBG connection instead of SGND for the voltage divider.
For Lead-Acid mode no powerpath FET is necessary because the charger operates continuously (trickle charge). It is OK to use SGND for the voltage divider return, because the charger operates continuously.