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LM63635-Q1: Questions of LM63625-Q1 and LM63635-Q1

Part Number: LM63635-Q1
Other Parts Discussed in Thread: LM63625-Q1

Hello 

I  work at design house and work with Tier-1 customer for automotive apps.
Our customer is very interested in your products, LM63625-Q1 and LM63635-Q1.
I have some questions about it. 
 
(1)
Can LM63625/35-Q1 use an external sync function at FPWM mode?
Because these products cobine sync_pin and mode_pin. 
(2)
Can LM63625/35-Q1 change from FPWM mode to Auto mode(from Auto mode to FPWM) dynamically? 
(3)
The input voltage range of LM63625-Q1 is from 3.5V to 36V.
The input voltage range of LM63635-Q1 is from 3.5V to 32V.
Why are the input voltage ranges different between LM63625-Q1 and LM63635-Q1?
(4)
TI already released HotRod package products.
I knew these produts are good noise performance.
Are these products HotRod products? 
 
  • Hi Rie,

    To answer your question

    (1) Can LM63625/35-Q1 use an external sync function at FPWM mode?  

    By default when you SYNC it will go to FPWM mode. Therefore you don't need to connect this pin to VCC. You can just inject your SYNC signal and the part will operate in FPWM

    (2) Can LM63625/35-Q1 change from FPWM mode to Auto mode(from Auto mode to FPWM) dynamically? 
    Yes, they should be able to change the mode dynamically from these two mode. As long the SYNC pin is 0 when you want to change into PFM mode
    (3)
    The input voltage range of LM63625-Q1 is from 3.5V to 36V.
    The input voltage range of LM63635-Q1 is from 3.5V to 32V.
    Why are the input voltage ranges different between LM63625-Q1 and LM63635-Q1?
    The input voltage range is difference is due to a higher current on the LM63635-Q1. We put a limit on this due to a higher current that can cause more switching noise on the part. 
    (4)
    TI already released HotRod package products.
    I knew these produts are good noise performance.
    Are these products HotRod products? 
    Unfortunately no, these are not Hot Rod products. We have a TSSOP package and WSON package for the part
    Thanks
    -Arief
  • Hello Arief, 
    Thank you for your support.

    I'm sorry...I have an additional question about Spread Spectrum function.
    I want to use LM63625 or LM63635 at 400kHz of Fsw.
    Can I use the spread spectrum function at 400kHz?

    Best Regards,
    Rie

  • Hi Rie,

    Yes, the spread spectrum should work ok at 400kHz. 


    Thanks

    -Arief

  • Hello Arief,
    Thank you for your prompt reply.
    According to the datasheet of LM63635-Q1 on page 36, I confirmed the EMI data at 400kHz.
    Is it the EMI data using Spread Spectrum function at 400kHz?
    If your answer is Yes, the peak values are very high, I think.
    I would like to know the reason about it.

    And I plan to use it under 300k, 330k and 360kHz using an external clock.
    Can LM63635-Q1 use Spread Spectrum function w/ an external clock function?

    Best Regards,
    Rie

     

  • Hello Rie,

    Device meets CISPR-25 Class 5 EMI standard as shown by emi plot limit lines. This standard (if you are not familar with it) is much more stringent than most commercial emi standards.

    Filter used is very smaller. Spread spectrum has very small dither.

    With bigger filter components, further attenuation can be achieved. We try and balance good emi performance and low cost with the device and filter design.

  • spread spectrum is turned off when sync'ed.