[DCDC] RT7258 core, 8A adjustable buck module

• Input voltage range: 4.5-24V

• Output voltage range: 2.8-15V (potentiometer adjustable)

• Output current capability: 8A

• The efficiency is up to 95%, with built-in high-voltage side MOS, the chip package is small in size and high in power.

• Working frequency is constant 600KHZ

• The chip work is controllable, and the external toggle switch controls whether it is running or not.

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• Let’s load my update log here first!

• Screenshot of the first test: (2020-6-11) The inductor welded here is 100UH. As a result, when the multimeter measured the output current at the 10A current range, it was less than 2A. The inductor is too large. In addition, the EN switch cannot be used directly, and the switch needs to be moved closer. The two legs of the switch are short-circuited, because the legs on both sides of the switch will not be connected no matter how you turn the handle. Just short-circuit any leg on both sides with the middle leg. I also repaired the schematic diagram and PCB in time. mistake.

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• Second test: 2020-6-12: I got a 10UH chip inductor, but no matter how I turn the potentiometer, I can only set the maximum voltage to 3.58V. I am now preparing to re-solder the FB voltage regulating resistor combination.

The third test: everything failed, and my mentality was a bit broken. I will not test this thing for now. I am currently testing 1-5 multi-function lithium chargers.

2020-6-20 update: The V4 version PCB has been designed and is ready to be printed and retested, so stay tuned

2020-7-3 Important update:

The printed V4-PCB has been soldered. Turn the potentiometer and the output voltage will change normally. Next, prepare for the load test!

• The output load is carbon heating wire resistance 2.1R

• Output 10V@4.1A

• Output 12V@4.7A

• The current measured maximum output power is about 55W

• EN pin test passed

• When EN is connected high (the LED will light up at this time), the module turns on the output voltage switch and disconnects, and the LED turns off.

• EN is low, the output voltage is 0V

• At present, the voltage regulating resistor group is adjustable from 6.2K to +11.8K and to +200K, and the control output voltage accuracy is 0.01V.

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The following are my development notes:

For more details and details, please see the attached chip data sheet. If you feel good about my project or it is helpful to you, please don't be stingy with your thumbs! Your likes and collections will be my powerful motivation for open source! Thanks