LT8602 and LTspice

Hi all.

I'm simulating the LT8602 with LTspiceXVII.

The four outputs are: OUT1=5V, OUT2=3.3V, OUT3=1V and OUT4=1.8V

I'd like to have the follow startup sequence: OUT1 -> OUT3 -> OUT4 -> OUT2 

For OUT1, OUT3 and OUT4 there are not problems but I do not understand the OUT2 trace because it is about 0.5V before 2.4ms and after it goes immediately to 3.3V without the soft-start.

The green trace (V(n009)) is the voltage in the TRKSS2 input.

Where am I doing wrong?

Thank you.

Nicola

  • Hi Nick11,

    Thank you for your interest in this part.

    Please refer to the datasheet that, with TRKSS low, it does not guarantee the channel stop switching.  Before the channel 4 OUT4 reached to the set voltage, the PG is pulled low by an internal switch. But the TRKSS voltage is divided from the VOUT1, according to your schematic.  The internal loop try to set the output according to the voltage at TRKSS.  

    If you have further questions, please contact our local FAE, and we would like to know more about your applications, the specifications, and they will give you assistance as well.  Thanks.

  • Hi Josh

    Thank you for the answer.

    So, I understand that it is not possible to keep channel 2 switch-off after that channel 1 is started.

    Anyway, I replace OUT1 with OUT4 and I increase the R4 value (now is 200k). In this case the channel 2 voltage remain under 81mV.

    Excuse me but what is FAE?

    Nicola

  • Hi Nick11,

    We have local field applications engineer (FAE) in your area.  You might contact him/her for more assistance.