TPS61311: Maximum allowed capacity on the TS pin

Hi,

Will check it and update you later....

Hi

NTC has thermal time constant Tr to response the thermal changing, the RC constant Trc of NTC and capacitor should be <1/10 of the Tr, the Ts is 0.5us as the Fsw=2MHz, so Trc should be >5us.

on the other hand, set ENTS to 0 on device reset or startup, set to 1 before output current to LED.

Thank you for the reply. However, I'm afraid that doesn't exactly answer my question.

I did a test with the TPS61310EVM, where I installed a 1nF capacitor in parallel to the NTC thermistor.
I observed that the current source for the NTC is only active for 8us. After this time, both the LED and the NTC current source are deactivated. During the active time, the voltage at the TS pin rises to approximately 185mV. Since this voltage is below the threshold of 345mV specified in the datasheet, the LED is turned off. To achieve a voltage of at least 350mV in 8us, the capacitance would be in the range of 500pF at most.

The time of 8us is only an approximate measurement, and I couldn't find any values for it in the datasheet.

So the question is, what is the minimum guaranteed time between activating the NTC current source and triggering the overtemperature shutdown?

Apart from that, I couldn't detect any influence of the ENTS flag on the overtemperature shutdown in video light mode.
If the TS pin on the EVM is set to LOW with the jumper, the LED won't turn on. Even if ENTS is 0.
Also the datasheet states that: "The temperature-monitoring blocks are explicitly active in video light or flash modes."

Hi Matthias,

Thanks for your feedback. Andy will give you feedback early this week. Thank you!

BRs

Lucia

Hi Lucia,

is there any news here?

Thanks,
 ~Matthias

Hi Matthias

This was an old part, we need little more time to check the internal design, will update as soon as possible.

Hi Andy,
may I inquire again about the current status?

Thanks,
 ~Matthias

Hi,

Sorry for the late!