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LTC3630 Recommended for New Designs
The LTC3630 is a high efficiency step-down DC/DC converter with internal high side and synchronous power switches that draws only 12Î¼A typical DC supply...
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LTC3630 never reaches 15V

HoC

on May 17, 2023

Category: Hardware

Product Number: LTC3630

Hi,

I have an issue with the LTC3630. I am supplying the regulator with 30VDC and the output should be +15VDC. VPRG1 is connected to SS and VPRG2 to GND, therefore VFB is set to 5V. With the external divider R1 = 200k and R2 = 100k the output should be 15V. But unfortunately the output is always about 10.2VDC. Current draw is around 30mA.

Here the schematic:

Any clues, why the 15V are never achieved.

Thanks in advance!

Christian

0 FormerMember

on May 22, 2023 7:45 PM

Hello,

See snipped pin description below.

If you want to set the output voltage externally by divider resistor, BOTH VPRG ARE SUPPOSED TO BE GROUNDED.

What you did was set it to an output voltage of 5V. IT SETS OUTPUT VOLTAGE, NOT VFB VOLTAGE.

Regards,

Jhun

0 HoC

on May 23, 2023 10:51 AM in reply to FormerMember

Hi Jhun,

Thank you for your reply.

I am aware of the output selection. If you go to the next chapter you see this configuration, which I am using in my application

I also ran some simulations in LTSpice, which works perfectly there. But unfortunately in real life it is not working!!!!

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LTC3630 never reaches 15V