Hello,
I have a few questions about the BQ25504. Your answers are greatly appreciated:
1) On page 4 of the bq25504 data sheet (SLUSAH0 - October 2011),the Vbat accuracy says +/-5% when using 0.1% tolerance resistors for the UV, OV, and VBAT_OK settings. However, in the bq25504 EVM schematic/BOM, all resistors are 1% tolerance. Is the data sheet correct in saying 0.1% tolerance or is the EVM schematic/BOM correct showing 1%? I would like to maintain the +/-5% on the settings.
2) Is the +/-5% tolerance for each setting independently (UV, OV,VBAT_OK) or would they all shift together? If they are independent, does that mean I need to calculate worst case values for each setting and ensure that they do not overlap?
3) On the EVM schematic and Typical Application Circuit on page 6 of the bq25504 data sheet, the resistor values for UV, OV, and VBAT_OK have been calculated using a Vbias of 1.23V instead of the typical value of 1.25V shown on page 4 of the bq25504 data sheet. Do you know why this is? Which is the correct value to use for my calculations?
4) I don't see any mention of maximum allowable load/current output on VSTOR? Most of the time, my system will be operating at less than 1mA. But, I will be powering a small vibrating motor with a current draw of ~100mA for very short periods to alert the user. My battery can handle it easily, but not sure how the bq25504 will limit things or if I need to somehow run directly from VBAT instead. My system will be based on the EVM schematic (with changes to UV, OV, and VBAT_OK).
-David
