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TINA - Capacitor No Hold Up time - Transient Simulation

Jason Yow
Prodigy 80 points

Greeting,

I am new to the SPICE simulation.

Created a simple circuit with a voltage generator (toggle from 0 to 5V in 100Hz), connect through 4 parallel capacitor (4mF), and to the constant 0.1A current generator (to simulate constant current draw).

 

I am trying to simulate how long will the capacitor sustain the Vout (before Vout drop below 2.4V).
My lab result shown it can last >6ms, but my simulation result shown 0 hold up time.

I am using Transient Analysis.

Is there something I miss out? Or setting is wrong?

 

holdup.zip
  • 0
    TI__Mastermind 37790 points

    Jason,

    You are trying to discharge a 4mF capacitor with a constant current,  to get a 2.6V drop, you need to move 0.0104c of charge, which takes 104ms at 0.1A, not 6ms.

    There are two issues in the schematic. First, your VOUT is directly connected to the voltage generator, so basically you are measuing the waveform you set for the voltage generator. To observe the discharging, you need to "remove" the voltage generator. A diode or a switch can do the job.

    Second, 4mF capacitor and 250Ohm resistor gives you a time constant of 1second, which means the capacitors won't get charged to 5V in 500us. 3 seconds or more will be better, or use smaller resistors.

    However, you don't have to charge the capacitors with the voltage generator to observe the behavior, see this circuit and simulation result, a 2.6V drop in 104ms:

    The resistors have no effect since you are draining a constant current.

     -JC

  • 0 in reply to JC Zhu
    Prodigy 80 points

    Hi Zhu,

    Can you share the .TSC files mention above?

    Thanks.

  • 0 in reply to JC Zhu
    Prodigy 80 points

    Failed to simulate how long the VTANT discharge time from 5V down to 2.4V.

    TINA spice schematic attached.

    Application flow  as below:
    1. VCTANT charge the VTANT to ~5. VTANT should be fully charge
    2. VCTANT start loose power.
    3. VTANT should slowly discharge. We start trying to simulate how long will the VTANT discharge before hitting 2.4V.

    Need help on what is the setting go wrong. New bie in TINA Simulation.

     

    2082 schottky_actual_app.TSC