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UCC33420: Looking for differences of two TI isolation chips

Hans Zhang
Prodigy 70 points
Part Number: UCC33420
Other Parts Discussed in Thread: UCC12050

Tool/software:

Hi TI, 

I am investigating the usage of two TI's isolation chips: UCC12050 and UCC33420.

In the datasheet of UCC12050, there is only power from the primary side to the secondary side from the function block diagram. The control block is on the secondary side to determine the output voltage. In the datasheet of UCC33420, the information on the secondary side is transferred to the primary side using a pair of independent (I guess) coils. 

My question is what is the performance differences between these two device? The UCC33420 seems more comprehensible. In UCC12050, how to realize the output voltage stable using only a diode rectifer (I guess)? Is there an adjustable LDO or other methods? 

An additional question: Can you show the frequencies used in these two devices? 

Thanks,

Hans Zhang

  • 0
    TI__Mastermind 32775 points

    Both the UCC33420 and UCC12050 process power from primary to secondary through an integrated transformer and secondary side information if fed back to the primary through capacitive isolation. the details/differences related to the control methods, transformer isolation and capacitive isolation are TI proprietary technologies. Thanks for your interest in these exciting technologies.

    Switching frequencies for each device are shown in the parametric table of each data sheet as:

    Fsw_UCC33420=76MHz

    Fsw_UCC12050=8MHz

    Regards,

    Steve

  • 0 in reply to Steven Mappus1
    Prodigy 70 points

    Hello Mappus,

    Thanks for your timely reply. I have an additional question. As you said, capacitive isolation is utilized in both devices for information transfer. However, the block diagram in UCC33420 (Page 10) shows that there is a pair of transformer coils for RX and TX. And the block diagram in UCC15420 (Page 18) shows that the feedback is realized using capacitive isolation. There seems inconsistent. 

    Additionally, can these devices operate normally when a ferrire core is placed on top of them?

    Hans Zhang

  • 0 in reply to Hans Zhang
    TI__Mastermind 32775 points

    Yes, follow the high level description illustrated in the block diagrams for each. IAs far as placing a ferrite on top of the IC, this is not a conventional use of either of these devices but please let us know what you are learning and how it is working?

    Regards,

    Steve

  • 0 in reply to Steven Mappus1
    Prodigy 70 points

    Hi Mappus,

    Thanks for your reply.

    1. In your first reply, you said that the feedback of UCC33420 is capacitive isolation. But its datasheet shows that the feedback of UCC33420 is transformer (inductive) isolation. Which one is correct?

    2. In MPS's chip descriptions, it is stated that when a ferrite core is placed on top of the chip, the chip can operate normally. Then some customers will ask the same way. That is why I have this related question. I think the power is transferred through a pair of coils. The ferrite will definitely influence the operation. I have no idea what should be attentioned.

    Hans Zhang

  • 0 in reply to Hans Zhang
    TI__Mastermind 32775 points

    1. In your first reply, you said that the feedback of UCC33420 is capacitive isolation. But its datasheet shows that the feedback of UCC33420 is transformer (inductive) isolation. Which one is correct?

    • My error in first reply - UCC33420 is using magnetic feedback

    2. In MPS's chip descriptions, it is stated that when a ferrite core is placed on top of the chip, the chip can operate normally. Then some customers will ask the same way. That is why I have this related question. I think the power is transferred through a pair of coils. The ferrite will definitely influence the operation. I have no idea what should be attentioned.

    • I am not familiar with context of what you are reading from MPS? 

    Steve