LM5176: LM5176 12V TO 5V Schematic review / check

Hi Hins,

thank you for using the E2E forum.

I have a few comments / questions regarding your schematic.

What is input supply voltage range ?

Your total capacity of the input caps look low - may you check if this would fit for your input ripple 
(you can also use the design calculator for checking that: LM5176 data sheet, product information and support | TI.com

The voltage divider on mode might be wrong - no sure about the intention but for setting the mode only a pull down resistor is required as there in an internal current source.
Please see also datasheet for more details

Why do you use two transistors in parallel - this might not be required based on the design information I have seen in the schematic

Best regards,

 Stefan

Hi Stefan,

Please review the clarification  information. There are two parts for the LM5176 application.

1. For LM5176 6-38V BUCK-BOOST 12V, the input supply voltage range is 6V to 38V, it is Automotive battery power, want to use LM5176 to Buck-Boost output 12V.  i.e. When the automotive battery is 6V, it needs to boost output 12V. When the automotive battery is 38V, it needs to buck output 12V.

2. For LM5176 VCC_SRC_FET 12V BUCK 5V, the input supply voltage range is 12V, want to use LM5176 to buck output 5V.

In the schematic, R542 and R582 don't need to install it. If confirm the mode only a pull down resistor is required, I will delete it later.

For two transistors in parallel, that is refer to LM5176EVM-HP Schematic. Thanks.

24-25-LM5176.pdf

Hi Hins,

thanks for the details, will review and come back in the next 2-3 days.

Best regards, 

 Stefan

Hi Hins,

just a few minor items:

for the first schematic:

C slope looks a little bit low (470pF would be better)

MODE only requires a resistor to GND

for the second schematic:

C slope looks a little bit low (470pF would be better)

MODE only requires a resistor to GND

Note: do you also know the Design Calculator tool - this can help a lot for getting this info as well:

LM5176 data sheet, product information and support | TI.com

Best regards,

Stefan