Need more information about LS1028A Processor SENSEVDD and SENSEGND pins

[Nithya]

Hi,

I am looking at the LS1028A RDB eval board which utilizes the LTC7151S supply.

I need confirmation on few points regarding SENSEVDD and SENSEGND pins,

1. Are these pins are output from Processor?

2. I was confused as to how the VDD sense lines were connected. I have attached the design of this. What is the purpose of the 49.9 ohm resistors (R19 and R26)?

3. In our design we are using LTM4631IY#PBF regulator to generate VDD_1V voltage where upper feedback resistor is internal to the IC, so

   i. Can I connect SENSEVDD and SENSEGND pins to the output voltage VDD_1V and GND signals            respectively?

  ii. Can I connect SENSEVDD pin to VOUTSENSE pins of LTM4631IY#PBF regulator?  

Thanks!

[r8070z · Accepted solution]

1. SENSEVDD/SENSEGND is just a signal connected VDD/GND net in the processor, (SENSEVDD-SENSEGND) voltage is used to measure actual voltage at the processor die instead of the Power IC output in order to exclude voltage drops on the power/ground lines.

2. I guess it is for the control loop testing and also for the regulator stability.

3. I think you can connect SENSEVDD pin to VOUTSENSE, but it is better to implement conections like on figure from
https://www.nxp.com/webapp/Download?colCode=FTF-NET-F0036

I.e. connect SENSEVDD/SENSEGND pins to the LTM4631IY#PBF  DIFFP/DIFFN pins and DIFFOUT to VOUTSENSE pin.

[Nithya]

thank you for your reply