TINA/Spice/TPS22945: minimum current limit accuracy

Hi Nikos,

Are you sure you are not using the TPS22941/3 model (lower current limit)? If not, would it be possible to measure the VOUT-VIN voltage difference in the simulation when the current limit becomes active? Figure 11 in the datasheet shows the potential for a lower current limit if the voltage drop is small enough.

Thanks,

Alek Kaknevicius

Hi,

thanks for the quick reply.I am positive that I have the right model. The voltage drop is indeed very low 33mV approximately but that is to be expected by 5V input and 60Ohm load . What i don't understand is this. Does the voltage drop have to be greater than 0.2V(see figure 11) in order for the switch to allow 100ma up until the 150ma limit? If so this doesn't make much sense. Can I not use the switch up until 100ma(50 Ohm load at 5V) like a normal closed switch without entering an overcurrent condition? From the simulation it seems not. I need a switch that allows current of at least 100ma before it limits. Is the TPS22941 not that?

Best regards,
Nikos

Edit from last post
I mean the TPS22945 and NOT TPS22941.
Best regards Nikos

Hi Nikos,

This does seem like odd behavior since the device should be able to be used to pass loads below 100mA. I'm looping in the modeling team to see how this behavior is programmed into the model.

Thanks,

Alek Kaknevicius

Hi Nikos,

Can you please share your simulation setup so we can look into this?

Hi, 

I am using the Pspice model for the TPS22945  from your website with the following modifications.

1)Vin=5V instead of 1.62V(originally)

2)Rload=60Ohms instead of 500Ohms

3)The pulse width of V2=300ms(so that the ON pin remains active long enough)

4)I created a new simulation profile that runs for 0.5 seconds

What I see is that the OC pin is being pulled low(overcurrent condition)  and the output cycles from 5V to 0V according to the spec for the overcurrent condition(i.e If condition lasts for 10ms the output goes to 0V and the switch restarts after 80ms when that shouldn't happen by 60 Ohms since the current is 83mamps.

Hi Nikos,

Apologies for the delayed response. We have identified the issue and are in the process to fix this. We should have this out to you shortly.

Hi Nikos,

I am following up on this issue. The model has been approved internally and is very close to being released. We should have it out by later this week.