TPS536C7EVM-051: Internal Delay in TPSC536C7 controller

Sundaramoorthy Sridhar

Part Number: TPS536C7EVM-051
Other Parts Discussed in Thread: TPS536C7, CSD

Tool/software:

Hi,

I have some questions regarding TPS536C7 controller.

(1) Does the TPS536C7 controller have some internal delay in the control loop? I measured the control loop gain by injecting a small perturbation using VNA and I could see some sharp phase drop close to per-phase switching frequency (fsw).

(2) Could you please share with me more information related to compensation network in control loop for regulation? Datasheet mentions that it is a pure integrator, but I believe the additional pole for switching ripple attenuation here may also cause this phase drop.

Thanks!

Sincerely,

Sundar

over 1 year ago

0 Ryan Blake over 1 year ago

TI__Intellectual 1100 points

Hi Sundar,

I've linked below an overview of DCAP+ which covers the core of the control loop. Different elements of the loop operate on different time scales. The base of the compensation loop is PI where 1/ACLL represents proportional and the integration gain divided by time constant is the integral.

For ripple attenuation, the ramp setting has a large impact. Higher ramp reduces pwm jitter and Vout ripple at a cost to transient performance.

DCAP+
https://www.ti.com/cn/lit/an/slva867/slva867.pdf

Thanks,
Ryan

0 Sundaramoorthy Sridhar over 1 year ago in reply to Ryan Blake

Prodigy 25 points

Hi Ryan,

Thanks for the information about compensator. I have a follow-up question: Does the controller have any time delay (in the order of ns) between generation of a set_Ton pulse and turn-on instant of top-switch in CSD power-stages in the eval-board. I couldn't find this information in "slva867.pdf" and in the TPS536C7 datasheet "(https://www.ti.com/lit/ds/symlink/tps536c7.pdf?ts=1718722343284)"

Sincerely,

Sundar

0 Ryan Blake over 1 year ago in reply to Sundaramoorthy Sridhar

TI__Intellectual 1100 points

Hi Sundar,

Delays will vary based on the layout and power stage. There is delay from controller, PCB/layout, and from powerstage receiving pwm to actually switching. Rough estimate would be 50-200nS depending on the specifics.

Thanks,

Ryan

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TPS536C7EVM-051: Internal Delay in TPSC536C7 controller