LM34936: schematic check

Hello Gareth,

Please share your input voltage range, desired output voltage and maximum output current for the schematic review.

In general I recommend to use the quickstart calculator of LM5176 for a first check as these 2 devices are using the same regulation scheme. You only need to make sure to stay within the LM34936 voltage range:

Hi Brigitte

The voltage range of LM34936RHF is as follows:
VIN = 19V or 20V
VOUT = 5V / 9V / 12V / 15V / 20V (controlled by PD controller)
When VOUT = 5V / 9V / 12V / 15V, IOUT MAX = 3A
When VOUT = 20V, IOUT MAX = 5A
Can 3.3uH inductors be used for the above voltage/current settings?

Hello Gareth,

In general the device can work with different inductor values, so I do expect that it will work properly with this inductor as long as the current rating is high enough and you do not need a very fast transient response.

Please increase the input and output capacitors on your design. I would recommend to have some tantalum capacitors there. Or at least some places where you can add such caps.

You should place the current sense resistor on the output in the middle of the output capacitors to minimize noise from the converter as well as from the load on this resistor.

In the layout make sure that the sense signals on both sides of DP_R2 are layed out differentially. Even if the CSGND is a ground signal, you want to have exactly the GND value on the resistor and not somewhere else on the board.

How do you change the output voltage? FB seems to be connected with fixed resistors.

You do not need a capacitor on BIAS if you do not connect it to the output voltage.

Please again use the quickstart calculator and check if anything gets red after you decided about the external components with the different output voltages.