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SN74VMEH22501A: Power sequencing subsystem for Artix -7 FPGA with SN74VMEH22501A

GAURAV UPADHYAY
Prodigy 70 points
Part Number: SN74VMEH22501A
Other Parts Discussed in Thread: TPS38700

Tool/software:

Hi Everyone,

I am looking for DC-DC converter or a solution to match power-up sequence between Artix-7 FPGA and SN74VMEH22501A with live insertion capability.

Below are the sequence for FPGA and SN74VMEH22501A

Power-Up Sequence for XC7A100T FPGA

  1. Power Supply Initialization:

    • VCCINT (Core Voltage): Typically 0.95V. This is the internal core voltage that powers the FPGA's logic and internal circuitry.
    • VCCO (I/O Bank Voltage): Depends on the I/O bank. Common voltages are 1.8V, 2.5V, or 3.3V. This powers the I/O banks and should match the required voltage level for the specific I/O configuration.
    • VCCAUX (Auxiliary Voltage): Typically 2.5V or 3.3V. This supplies power to auxiliary functions, including the configuration logic.
    • VCCBRAM (BRAM Power): Typically the same as VCCINT, around 0.95V, as it powers the Block RAMs.

    Recommended Sequence and Ramp Rates:

    • Apply VCCINT and VCCBRAM first, as these are critical for the core functionality.
    • Next, apply VCCAUX to power the auxiliary circuits.
    • Finally, apply VCCO to power the I/O banks. Ensure that the I/O voltage is stable before connecting to external peripherals.

    Ramp Rates:

    • Voltage ramp rates and settling times should be in accordance with the FPGA's datasheet. Typically, ramp rates of 50-100 mV/ms are used to avoid overshoot and ensure stable power.
  2. Power-up sequence for SN74VMEH22501A

Please help me to create Power sequencing subsystem using TI product line.

Thanks,

Gaurav

  • 0
    TI__Expert 6471 points

    Hi Guarav,

    I'm sending this thread over to our power sequencers team. I think they may be able to help you more.

    Regards,

    Owen

  • 0 in reply to Owen Westfall
    TI__Expert 6050 points

    Hello Gaurav, 

    Looks like our TPS38700 device could be a good fit here. I just one to clarify one point, is the anticipated VDD to the device 0.95V? our device requires a minimum 2.2V for proper operation. 

  • 0 in reply to Oscar Ambriz
    Prodigy 70 points

    Hi Oscar,

    Oscar Ambriz said:
    Looks like our TPS38700 device could be a good fit here.

    Is this solution similar to below image? (Integrated Power Supply Reference Design (ti.com))

    Thanks,

    Gaurav

  • 0 in reply to GAURAV UPADHYAY
    TI__Expert 6050 points

    Hello Gaurav, 

    Does every sequencing output require a distinct voltage level? I see 1.0,1.2 and 1.8 are specified. The TPS38700 device can sequence up to 12 rails, and can be programmed over I2C during operation. Note NVM is not available. Is the sequencer needed to enable the DC-DC converters? 

    Regards, 

    Oscar Ambriz

  • 0 in reply to Oscar Ambriz
    Prodigy 70 points

    Hi Oscar,

    Thanks for your response.

    Oscar Ambriz said:
    Does every sequencing output require a distinct voltage level?

    Below are the voltage level and sequence for XC7A100T-1FGG484I:

    Power-on is 1.0V->1.8V->(1.5 V, 3.3V, VCCIO) and 1.0V-> MGTAVCC -> MGTAVTT

    Oscar Ambriz said:
    Note NVM is not available. Is the sequencer needed to enable the DC-DC converters? 

    Can you please explain above statement? How it is different from below highlighted image?

    Thanks,

    Gaurav

     

  • 0 in reply to Oscar Ambriz
    Prodigy 70 points

    Hi Oscar,

    Below are the details from datasheet:

    I want to use TI product line for this power sequence. Please help me to get latest solution for this.

    Thanks,

    Gaurav

  • 0 in reply to Oscar Ambriz
    Prodigy 70 points

    Hi Oscar,

    Oscar Ambriz said:
    Is the sequencer needed to enable the DC-DC converters? 

    I want to enable below green highlighted DC-DC converters:

    Could you please tell me which signals are needed to enable a sequence using the factory default settings without any programming?

    Thanks,

    Gaurav

  • 0 in reply to GAURAV UPADHYAY
    TI__Expert 6050 points

    Hello Gaurav, 

    TPS38700 can operate in Open Drain or Push Pull enable configuration. In push pull configuration the sequencing output will have a high state equivalent to VDD of the device. In the Open Drain configuration the user can choose what voltage each enable output should be pulled up to through a pull up resistor and corresponding source. 

    The TPS38700 can be programmed at factory, this will make it such that whenever the device is power cycled it will revert back to its burned in OTP. During the operation the configuration of the device can be edited through I2C but the device will revert back to its default value when the device is power cycled. 

    Regards, 

    Oscar Ambriz 

  • 0 in reply to Oscar Ambriz
    TI__Expert 6050 points

    Hello Gaurav, 

    Regarding the sequencing of the device. The user only needs to enable the ACT pin to cause a power up sequence. As i mentioned the device has a burned in sequence so when the ACT pin enters a high state it will start the power up sequence according to the burned in configuration. For the scenario described above i believe the customer will require a custom configuration to be burned in, this will eliminate the need for SW intervention. We currently only have one variant of the device released which follows the following configuration: 

    Regards, 

    Oscar Ambriz 

  • 0 in reply to Oscar Ambriz
    Prodigy 70 points

    Hi Oscar,

    Oscar Ambriz said:
    TPS38700 can operate in Open Drain or Push Pull enable configuration.

    I want to enable and disable the dc-dc converter as per power sequence. What configuration i need to choose for it? do you have any reference design for this ?

    Thanks,

    Gaurav

  • 0 in reply to GAURAV UPADHYAY
    TI__Expert 6050 points

    Hello Gaurav, 

    As i mentioned the TPS38700 can be programmed at factory to a sequence defined by the user, this will make it such that whenever the device is power cycled it will revert back to its burned in OTP. During the operation the configuration of the device can be edited through I2C but the device will revert back to its default value when the device is power cycled. 

    If you would like a custom part, please reach out to a TI sales representative. 

    Regards, 

    Oscar Ambriz 

  • 0 in reply to Oscar Ambriz
    Prodigy 70 points

    Hi Oscar,

    Thanks for your support and suggestions.

    Oscar Ambriz said:
    If you would like a custom part, please reach out to a TI sales representative. 

    I will try to go with factory setting.

    Oscar Ambriz said:
    The user only needs to enable the ACT pin to cause a power up sequence.

    Do i need to tie VDD and ACT with same power rail?

    Oscar Ambriz said:
    it will start the power up sequence according to the burned in configuration.

    Can I connect below highlighted pins directly to the enable pin of DC-DC converter? 

    Can i make below highlighted signals  as NC or make it pull down?

    Thanks,

    Gaurav

  • 0 in reply to GAURAV UPADHYAY
    TI__Expert 6050 points

    Hello Gaurav, 

    Just to clarify by "factory setting" are you referring to a customer part or already released variant? 

    1. ACT does not need to be tied to VDD, so long as the voltage applied to ACT surpasses the ACT_H threshold it will be registered as active. 

    2. Yes the pins can be connected directly to the EN pin of DC DC

    3. It is recommended to pull NIRQ and NRST high, there is an internal check in the device which will flag a fault if the state differs from the expected state. This check can be disabled for custom parts, allowing for pins to be floating. 

    Sleep can be left open of sleep sequence is not required.

    SCL and SDA can be left open if I2C is not required, note I2C is needed to change the sequence of the device during operation. Custom sequence can be set for custom parts. 

    CLK32, XOut and Xin must be connected, there is a internal check in the device which will flag if the frequency of the CLK pin is not as expected. This check can be disabled for custom parts, allowing for pins to be floating. 

    Regards, 

    Oscar Ambriz