I have designed a DC-DC converter using MP4575 with below requirement:
Input voltage range: 9V to 36VDC
Output voltage: 7.5VDC/3A
Input source is from a battery.
I have doubt on input and output capacitor selections as theoretically based on calculation we get less ripple voltage but practically it is more.
Also we would be designing it on 2 layer PCB.
Request you to go through the circuit sketch I have attached here and let me know improvements.
Hi Manjesh, welcome to the forum!
Since you are concerned about the output ripple, you can increase Cout to 2x 47uF instead of 22uF.
For your comp network, with a 15k Rcomp, set C3 from Rcomp to GND somewhere > 2nF. The value of C4 in parallel with Rcomp and C3 depends on the ESR of your output caps.
EN should be pulled high or low, so you should probably depopulate the 22k Rdown. You can connect EN to some additional circuitry to pull the pin down to disable it if necessary.
I think the rest of the application looks fine. If the duty cycle is consistently high and you’re operating on the lower end of your Vin range, you might consider a BST diode as well.
Thanks for your quick reply !
I have concerns, regarding BST diode as there might be a case, where we will be operating at lower VIN range as input source is a battery which will drop to lower side of input voltage range i.e 9VDC.
Since input voltage range to BST pin is 3V-5V rail and this entire dc-dc module is a standalone circuit in our design we do not have external voltage source of 3-5VDC to apply at BST via diode as output is set to 7.5VDC.
What will be the case at VOUT here in absence of BST diode during higher duty cycle ??
It’s possible it will affect your converter efficiency at higher duty cycles, since there’s less time available to charge the BST cap.
Hello, I am using the MP4575 for 5V,5A output with 46V input. I need help with reviewing the schematic to make sure there is no error. Please advise
David
Hi David,
Please send the schematic to mpsnow@monolithicpower.com along with your project details. Our FAEs can help with the schematic review.
Hello, I sent it to you for review and comments. Do you have any update? thanks, David
Hi David, we had sent you a response in the same email thread. Let us continue the conversation there.
Please resend it since I never received any response about the circuit.
Hi.
I’m Braian Bannert, the R&D Manager of an Argentinian company.
I’m responsible for designing new devices in the company and now I’m designing a device that has embedded the MP4575GF-Z IC. I designed the power supply to have an output of 12V/5A with an input voltage that could be 12V or 24V and when I power the input power supply I get an output voltage of 0.3V. Please see attached the configuration made for this power supply mentioned before.
I need to mention that I noticed the diode D1 was not properly connected. I made the changes needed to connect it to BST pin and the track of the output of the power supply (12V in this case).
Please let me know if there is something I made a bad calculation or connection to be improved.
Thanks in advance,
Braian Bannert
Hi @bbannert,
For this request, please fill out the MPS NOW Technical Support form. A member from the MPS NOW team will contact you within 24–36 hours about this request.
Link to MPS NOW Technical Support form: MPS NOW Technical Support - Contact
Thank you
Saurabh
