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48V Input 3500V, 3mA Power Supply design

Shiv Mishra
Prodigy 10 points
Other Parts Discussed in Thread: TPS40210, UCC28C43, UCC28C55-Q1

Hello Team,

I want to design the power supply with below specification.

Input : 48V

Output : 3500Vdc, 3mA

Protection : Overvoltage, Overcurrent, short-circuit.

Isolation : Yes

Also I need programable output, lets say output voltage vary from 2000V to 3500V.

Could you please help me to select the topology selection, transformer design, switcher ic selection etc ?

I found PMP9198primary over internet using TPS40210DGQ as a reference document but this document has no information about transformer design.

Looking forward to your suggestion !

Thanks in Advance !  

  • 0
    TI__Guru 51285 points

    Hi,

    You can start with PMP9198. Your design basically is ok with a flyback like PMP9198 and use TPS40210. You need to adjust the transformer turns ratios to obtain a higher voltage.

    R224 can be adjusted for different output voltage. For 48V to 3500V transformer design, there would be the same for other transformer design with different turns ratios. If you want to design the transformer yourself, it is better to search on the internet where you can find many reference. You can also use a transformer vendor. Also, you can talk to transformer vendors to see if any off-the-shelf transformers can be for your design. 

  • 0 in reply to Hong Huang
    Prodigy 10 points

    Flyback_1000V.pdf

    I have designed this from TI workbench wherein i get the transformer design as well. Inspite of using one secondary winding to generate 4KV, my idea here is to use 4 transformer stacked winding to generate 4KV at output. By doing this i will be able to reduce the stress from secondary diode and other components.

    Your opinion here is needed to understand if this is okay if i use same turns ratio for other 3 transformer secondary winding and if yes do we need to change the primary inductance value etc.

    Could you please check if this chip has short circuit, over current, overvoltage protection ?

  • 0 in reply to Hong Huang
    Prodigy 10 points

    Could you please suggest any application notes to design the transformer ?

    This case should we operate transformer in CCM or DCM mode ?

    Can we limit the output short circuit to 5mA ?

  • 0 in reply to Hong Huang
    Prodigy 10 points

    How to calculate the duty cycle of flyback ?
    1. CCM

    2. DCM

    3. TM

  • 0 in reply to Shiv Mishra
    TI__Guru 51285 points

    Hi,

    I suggest you to use a single transformer. Four transformer stack up would create many unforeseen challenges which we are not able to predict at this stage.

    For operation in different mode, it is based on the transformer primary winding inductance value along with the input voltage and the load current.

    the inductance at TM is called critical inductance. You can review UCC28C43 datasheet from ti.com of its application section to have good understanding. You can also search the internet flyback critical inductance to help your understanding.

  • 0 in reply to Hong Huang
    Prodigy 10 points

    Hi,

    I was not talking about to use 4 transformer. I will be single transformer with 4 winding to get 4KV output. Refer PMP9198 to understand i am talking about. 

    Could you answer below question as well ?

    If i consider UCC2 8 C5 5 -Q1 D in my design.

    Will i meet overcurrent, short circuit, overvoltage requirement ?

    As per your knowledge, should i design CCM flyback ? or DCM would be okay ?

  • 0 in reply to Shiv Mishra
    TI__Guru 51285 points

    Hi,

    4 windings in one transformer is ok - it is just a single transformer structure. If you do similar to PMP9198, it would be ok.

    Yes you can use UCC28C55-Q1 in your design.

    No, it does not look to me CCM is good to your design - you have only 3mA and about 10W, DCM should be used. Your mentioned protection needs external circuit to achieve. 

  • 0 in reply to Hong Huang
    Prodigy 10 points

    Hi,

    Thanks for your reply !

    I still have some doubts. 

    1. Could you suggest the part number who has above mentioned protection ?

    2. Do you have any gate driver IC for this application who has digitally controlled that means gate signal of mosfet is being controlled by microcontroller ?

    3. Could you please suggest some circuit to achieve overcurrent, overvoltage, shortcut protection ?

  • 0 in reply to Shiv Mishra
    TI__Guru 51285 points

    Hi,

    1.

    We do not have a part that can do all these protections.

    2. 

    You can search to find one to your need from the below link

    Gate drivers product selection | TI.com

    3.

    Output OVP is usually based on a crowbar circuit when OV, the crowbar short across the output so to create a short circuit current then using the same short circuit protection to make over voltage protection. You can search the internet to find crowbar circuit in your favor.

    OCP - for cycle by cycle protection, UCC28C55Q1, when its CS reaches about 1V, it is in cycle by cycle current limit.

    OCP - hiccup, you would need to design a comparator circuit so when the current sensing reaches your defined threshold, using that comparator to pull down UCC28C55Q1 COMP.

    The output short circuit actually can use the same OCP hiccup.