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LM3489-Q1: Request to check the circuit

Tomoyuki Taguchi
Prodigy 100 points
Part Number: LM3489-Q1
Other Parts Discussed in Thread: PSPICE-FOR-TI

I would like you to check the circuit.

Input voltage: 5 V, 9 V, 15 V, 20 V

Output voltage: 5V, 9V, 15V, 20V

Output current: 3A (MAX) It is designed according to the circuit diagram of TPS65988EVM.

However, use a ceramic capacitor for the output capacitor. I checked "8.2.2.2 Output Capacitor Selection (COUT)", It says that you have to insert a series resistor, Where and how many Ω resistance values should I put in?

  • 0
    TI__Mastermind 47060 points

    Hi,

    You can put a single resistor in series with the output capacitor C1003. Then you can control the the resistor value in series with that bulk output capacitor to the desired value.

    Make sure to properly verify and validate the circuit.

    Regards,

    Jimmy 

  • 0 in reply to Jimmy Hua
    Prodigy 100 points

    Dear Jimmy

    Thank you for your answer.
    "PSPICE-FOR-TI — PSpice® for TI design and simulation tool"
    I am running a simulation with the downloaded schematic using.
    The "ISENS" connection is connected to the FET sauce.
    In the data sheet and evaluation board, it is connected to the drain of the FET, so if you reconnect it as it is, it will not operate normally.
    Is this a simulation glitch?
    Which connection is correct?

  • 0 in reply to Tomoyuki Taguchi
    TI__Mastermind 47060 points

    Hi,

    From initially inspection, it looks like the PSPICE schematic is incorrect.

    The ISENSE resistor should be connected to the drain of the PFET terminal as shown in the evaluation board. 

    Regards,

    Jimmy