Why does MC34VR500V3ES output wrong voltage value Hi, a MC34VR500V3ES is used to source LS1021A on my board. During the first power on, it output wrong voltage value like below list shown. The Vin of MC34VR500V3ES is 3.3V correctly, and check the EN pin is 3.3V too. I compare this part of schematic to LS1021A-IOT design, and they are the same almost besides LS1021A-IOT use MC34VR500V1ES. The default device start-up configuration for MC34VR500V3ES is indicated in the page.15 of datasheet. So, during the first power on, it will output all default voltage according to the sequence without programming through IIC, right? but it won't, could you please give me some suggestion to debug it? Thanks in advance! Best regards Jason Power solution Re: Why does MC34VR500V3ES output wrong voltage value Hi, sun: Okay, I'll go find the electronic load. There's another issue: two LDOs (LDO1 and LDO3) are not being used, so they're not connected to a load, and the voltage output from these two lines is abnormal. Thank you! Best regards! Jason Re: Why does MC34VR500V3ES output wrong voltage value Hi
First, please apply a load to test the actual output and see what the results are. Just add 100-200mA, testing one path at a time. Re: Why does MC34VR500V3ES output wrong voltage value Hi, sun: Since V3 is a factory pre-programmed version and its output voltage and timing follow the default configuration on page 15, section 6.1.1 of the manual, the design is actually very simple. It mainly involves supplying VIN and enabling the EN pin. Furthermore, all output feedback and loop circuits (including SW and LDO) are integrated on-chip. Currently, almost all eight power outputs are incorrect, especially the LDOs, which is very strange. I tested the impedance of each power output; except for the 1.2V output of SW1, which has an impedance of 92 ohms, the other eight are very high, which is normal. The schematic diagram is shown below, and this part of the design is almost identical to the schematic diagram of the official demo board LS1021A-IOT. Thank you! Best regards! Jason Re: Why does MC34VR500V3ES output wrong voltage value Hi Jason_in_job
Your system is version V3, which defaults to V3 output upon power-up. If the voltage is incorrect:
1. Try adding a 100mA load to each channel.
2: The probability of a major problem with the PCB layout is not high.
3: If the first suggestion doesn't work, you can take a look at the schematic diagram.
BR
Re: Why does MC34VR500V3ES output wrong voltage value Hi, sun: If I need to reset the output voltage values and power-on sequence of the SW and LDO, how do I operate the registers via I2C? I see that this part of the manual isn't very detailed. Could you provide an application manual explaining the software configuration? For example... 1. Are the addresses of the first two pages 5'b00000 and 5'b00001? 2. Both the Functional page and Extended page 1 (internal RAM) have similar registers. Which space should I access? 3. When switching from a functional page to extended page 1, do I need to write to the Page Register register at 0x7F first? Thank you! Best regards! Jason Re: Why does MC34VR500V3ES output wrong voltage value
Hi Jason
This is another topic where I invite you to submit a new ticket from the path below.
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Thanks!
BR
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