Questions about MP2372

DC-DC Power Converters
1

Hello, I was looking for alternatives to the now NRND MP2307, and found the MP2372. I have some questions after reading the datasheet:

  • What is this “OPEN = AUTOMATIC STARTUP” that is marked on the EN pin on the sample application circuit?
  • In the PCB Layout Guide, there is a resistor R4 that is connected between the EN pin and the IN pin. What does it do?
  • Does the 4.7uH inductor still be usable if I were to follow Figure 5 and change the resistors so that I could get 12V output and/or higher? Or should I change it? I’ll be having a VIN of 24V, and am looking for output voltages of 3.3V, 5V, and 12V
2

Hi Joshua,
Thank you for utilizing MPS Techincal Forum,

Can you please let me know what your application and Vin/Vout/Iout , I can help identify a optimal device

Answers to your question:

  1. EN pin basically tells the device to start switching and provide an output. You can refer to block diagram on pg.6 , if you leave this pin floating, then EN will be supplied via internal regulator and device will turn on from Vin.
  2. R4, is a current limiting resistor. Current fed to EN pin should be in the order of couple uA. Typically a 100k is used.
  3. I suggest to utilize 6.8uH for 3.3/5V , for 12V, it is recommended to utilize higher inductance.

Regards.
Nouman

3

I want to build fixed output power supply circuits using this buck converter, with VIN = 24V and IOUT = 3A
My outputs would be:

  • Circuit 1: VOUT = 3.3V (maybe I could use the Figure 6 sample circuit from the datasheet for this)
  • Circuit 2: VOUT = 5V
  • Circuit 3: VOUT = 9V
  • Circuit 4: VOUT = 12V

I’m currently calculating for the L1 and R1 for these, maybe you could help with the recommended MPN? Especially for L1

4

Hi Joshua,
Apologies on delayed response,

For the requirements you have listed, I recommend utilizing MP2338.

Refer to pg18 for output selection configuration, the inductor and feedback network is listed.

Kind Regards,
Nouman

5

Hello Nouman,

I’m currently exploring your MPS DC-DC Designer Online tool, is it alright to follow what the tool has generated for a MP2372 buck converter circuit using my required input and output values?

6

Hi Joshua,
You may use those values, yes.

Regards,
Nouman

7

Dear Sir
We use Buck MP2372 to do 22V to 12V. Sometimes it cannot output 12V normally.
The normal and abnormal signals found in the measurement are as follows:

MP2372
MP23721267×716 95.2 KB

May I ask where the problem is that causes this phenomenon and how to solve it?

Thanks.
Ming

8

Dear Sir,
We have measured the EN PIN and it has a strange waveform as follows;

MP2372-EN pin
MP2372-EN pin1267×678 90.7 KB

Why is there a stepped waveform? how to solve it.
Thanks.
Ming

9

Dear Sir,
Regarding the stepped input of EN PIN, it is mainly caused by the soft start setting of the previous level Buck IC;
But we still don’t know the relationship between EN and protection. When testing DC-Level below 1.2V, the output is turned off; when DC-Level 2.6 or above, the output shows protection such as Abnormal waveform, but the external voltage dividing resistor does not; whether this process Missed something?
Thanks.
Ming