Other Parts Discussed in Thread: BQ51051B, BQ51052B
Hello,
I was trying to understand the workflow of the TS/CTRL pin for temperature protection of the BQ51050B IC with no luck. I've read following thread e2e.ti.com/support/power_management/wireless_power/f/693/p/400376/1536822, where a person was asking exact same question and seemed to understand how this pin works, regretfully I still couldn't fully understand it, hence I would like to ask a few questions on this subject again.
I've understood that with the equations 3 and 4 on page 24 of the DS we can calculate threshold voltages for cold and hot, which are percentage of the Vtsb. For example if I take the NTC from your example, with:
ERTJZEG103JA
Ro = 10 kΩ,
β = 3380,
R1 = 29.402 kΩ
R3 = 14.302 kΩ,
I get:
V_tbs_cold = 36.4236 %
V_tbs_hot = 33.1685 %
V_tbs on the page 8 is 2.2V, that means:
V_tbs_cold = 801.32 mV
V_tbs_hot = 729.707 mV
Are these voltages for Hot and Cold at room temperature? (although why do we need HOT and COLD at room temperature ... it's room temperature, one temperature, i.e. shouldn't there be one voltage?).
What do I do now with these values? On page 8 there are 4 threshold values ... but I still can't get it, how do I set a special threshold, e.g. if I want my chip not to charge at 45C, how do I set it up?
Also how do I choose the R1 and R3 values? It seems that it depends on the B parameter of the NTC, so it lies in Vtbs threshold limits, listed in the table on the page 8.
Anyway, one fully good explained example would be really appreciated!
Thanks in advance,
Den
