TPS61096A: Some question about the input voltage of Level shifter

Hi Lumina,

Thank you for reaching out.

Right, the level shifter input voltage must be higher than 0.8 × Vin to ensure the circuit could output correct output signal.

The level shifter circuit cannot output 100% correct signal if the input signal less than 0.8 x Vin. Suggest customer follow the datasheet recommendations. 

Hi,Zack Liu,

Our production are now using this incorrect circuit,can you kindly share this inverter's design to us to evaluate how much risks we are now takinig?

Hi Ding,

I'd like to help but unfortunately we don't have the data to comment the risk.

Hi,Zack Liu,

OK,thanks.

Another question about this circut.Vin=4V，Vout=21V, at very light load.

The pin 5 "ILIM" is tied to ground,but the inductor‘s peak current can be almost 400mA，I changed the inductor with 2.2uH/Irms 1.8A/Isat 2.1A,or 4.7uH//Irms 0.8A/Isat 0.28A,but the peak current is always approaching 400mA.

Is this waveform right or not?

...

Hi Ding,

250mA is the peak switch current limit typical spec. Considering variation, the peak switch current limit is 350mA max as written in datasheet.

When device peak switch current limit is triggered, the internal circuit would turn off the low-side FET and there is a delay time so actual peak current would be little bit higher due to the delay time.

How long is the "delay time"? I can't find this specification in the datasheet.

Hi Ding,

It is not a datasheet spec. It is not written in datasheet.

Is there any problem with the peak switching current limit function?

Hi,Zack Liu,

We want to use the inductor 4.7uH/Irms 0.8A/Isat 0.28A mentioned above，but the Isat is lower than the actual inductor peak current.

If we don't know the limit of the peak current,We have no choice,We can just choose a bigger Isat inductor.