LTM4650A & LTC2971 application issue

Hi Klex

I will let the LTM4650 support person answer the first question.

Re: the LTC2971 managing the 4650, you won't need the high voltage capability to manage a 1.5V rail. This might better managed by the LTC2972.  Have you considered using the LTC3888?  It has PMBus functionality built-in.  This could replace the 4650+2972.  There are a few multi-phase examples in the datasheet.

https://www.analog.com/en/products/ltc3888.html

Mike

Hi Mike,
Thanks very much for your reply.
Customer has LTM4650/LTC2971 in stock. they are worried about the delivery time issue, so they don't consider the LTC3888 for now, unless the LTM4650/LTC2971 is unattainable.

Hi Klex,

I am an app engineer supporting LTM4650A. Thanks for your inquiry.

As for the application circuit of 12-phase 300A, totally 6x LTM4650A parts need to be used. Let's just call them U01, U02, ..., U06. For U01, it is in the similar role as U1 on Page 33 in LTM4650A datasheet, and for U02, U03, ..., U06, they are in the similar role as U2 on Page 33 in LTM4650A datasheet. You may use the identical design for most pin connections by referring to that page, except for the following ones:

To achieve the best possible interleaving and ripple cancellation effect, I recommend U01, U02, U04, U05's PHASMD pin be connected to GND, and U03's PHASMD pin be floated. At the same time, tie U01's CLKOUT to U02's MODE_PLLIN, tie U02's CLKOUT to U03's MODE_PLLIN, ..., tie U05's CLKOUT to U06's MODE_PLLIN. In this way, all 12 phases are 30 degree apart from each other.

Below is a picture to illustrate the above-mentioned point. This configuration is based on Page 15 in LTM4650A datasheet.

Feel free to let me know if you have any questions.

Best regards,

Zhengrong