Other Parts Discussed in Thread: TPS25831Q1EVM-062
Tool/software:
Hi!
I'm currently using TPS25833-Q1 for a USB charger design and making some tests with the TPS25831Q1EVM-062 Ev. board.
It is clear that the TPS2583X-Q1 family can work with or without external FET to manage current limit. The goal for our project is to not make use of external FET due to space limitations and cost limit
The desirable output range for current limit is from 3A to 3.6A, for this project. Considering the TPS2583X-Q1 family current tolerance of 10%, RILIMIT was calculated to a Iilimit of 3.3A (this way, with the tolerances, the range would be 3A to 3.6A).
For the tests, the following resistor values were set:
RILIMIT: 5.86kΩ
RSET: 300Ω
RSNS: 15mΩ
In the bench tests with external FET, when the output current reaches the calculated threshold (around 3.6A) the FET activates and the outpput is cutted off, as expected
In the bench tests without external FET, when the output current reaches the calculated threshold (around 3.6A), the TPS25831 assembled in the Ev. board maintain the current in the threshold limit (around 3.6A), but as the output load is increased, the voltage starts dropping, making the device work as a curent source where the current is maintained fixed (as much as the device can) and the voltage starts dropping
No output cuttof occurs, even with high load applied. The device keeps trying to maintain the current in the Iilimit caluclated, but voltage keeps dropping, adjusting the buck frequency to maintain power constant
Using the TPS2583X-Q1 family without external FET, is it possible to make it cuttoff the output when Ilimit is reached? Or it is just possible using external circuits to make the control using the Enable pin of TPS2583X-Q1?
Thanks,
