Tool/software: WEBENCH® Design Tools
Hello,
We are going to use BQ25890 or BQ25890H.
Under the section “Power Up REGN Regulation (LDO)”, one of the conditions to enable the REGN is:
VBUS above VBAT + VSLEEPZ in buck mode.
VBAT= 4.208V + 5% accuracy = 4.4184V
VSLEEPZ has minimum 0.13V and maximum 0.37V.
That means to enable the REGN, a minimum of 4.4184+0.37=4.7884V at the VBUS input is needed (worth case).
I use the WEBENCH to design the circuit with the following parameters:
Vinmin=4.27V
Vinmax=4.4V
Temperature=40 (It also works from temperatures -20 to 76C. Above these temperatures, WEBENCH asks for higher input).
Charge voltage=4.208V
Charge current=1.088A
Input current limit=1.2A
Here is the link for my design:
https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=D2B61A35606972C7
The question is if the WEBENCH works correctly, because the minimum and maximum Vin to WEBENCH is lower than the minimum input calculated from the datasheet (4.7884V).
Are WEBENCH calculations done in worth case?
Can the above circuit work with the mentioned parameters? We are working from 0 to 40C.
Best Regards,
Ramin
