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LMZ30606 Transient Response calculation

Amith Bhat
Intellectual 275 points
Other Parts Discussed in Thread: LMZ30606, TMS320C6455, LMZ30604

Hi,

I am using LMZ30606 regulator to generate 1.25V using 5V input.
In the device datasheet, there is information regarding Voltage Deviation for Transient response for certain output voltages and 2A or 3A load step.
I need to find the transient response for a load step of 1.5A for 1.25V output.
I did not find any details to calculate the transient at different voltages and loads in device datasheet.


What is the procedure to calculate the voltage deviation for different transient loads and output voltages?

Regards,
Amith

  • 0
    TI__Mastermind 28020 points
    Can you tell me the speed of the transient load step (A/us) and the amount and type of output capacitors?
  • 0 in reply to J Arrigo
    Intellectual 275 points

    Hi Arrigo,

    Thanks for your response.

    Actually we are using LMZ30606 regulator to generate core voltage 1.25V of DSP TMS320C6455.

    As per the power calculation sheet provided for DSP, total core current is found to be 4A and Dynamic current is found to be 1.5A.

    I did not find any Transient requirement details in a measure of A/us.

    So we considered the transient current requirement is 1.5A.

    Please let me know the procedure to find the transient current in a measure of A/us for DSP

    Following are the capacitor details.

    Cin: 47uF (C3225X5R1A476M250AC) in parallel with 220uF (T530D227M010ATE006)

    Cout: 47uF(C3225X5R1A476M250AC) in parallel with 470uF (T530D477M2R5ATE006) 

    Regards,

    Amit

  • 0 in reply to Amith Bhat
    TI__Mastermind 28020 points

    Hi Amit,

    Under your conditions and the capacitors you have listed, with a 1.5A (1A/us) current step, the voltage deviation should be 25mV.

  • 0 in reply to J Arrigo
    Intellectual 275 points

    Hi Arrigo,

    Thanks for your reply.

    Can you please explain the calculation steps to arrive at the voltage deviation of 25mV with above conditions?

    Thanks in advance.

    Ragards,

    Amit K Bhat

  • 0 in reply to Amith Bhat
    Intellectual 275 points

    Dear Arrigo,

    I am using LMZ30604 regulator to generate 1.25V  using 5V input in another card.

    I need to find the transient response for a load step of 1.2A for 1.25V output.
    Like LMZ30606, I did not find any details to calculate the transient at different voltages and loads in device datasheet.

    Following are the capacitor Details.

    Cin: 47uF (C3225X5R1A476M250AC) in parallel with 220uF (T530D227M010ATE006)

    Cout: 47uF(C3225X5R1A476M250AC) in parallel with 330uF (T530D337M006ATE006) 

    Can you please explain the calculation steps to arrive at the voltage deviation  with above conditions?

    This information will be very helpful for me in future, to calculate the Transient Characteristics of regulators.

    Regards,

    Amith K Bhat