https://community.nxp.com/t5/i-MX-Processors/imx8ulp-rtc-ldo-bypass/m-p/2133953#M239285 <P>refer to the data sheet,&nbsp;VDD_VBAT42 must be powered and stable before all other supplies begin to ramp up. for more detailed information, pls refer to the data sheet</P> <P><span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="joanxie_0-1752565363537.png" style="width: 400px;"><img src="https://community.nxp.com/t5/image/serverpage/image-id/347563i0E38176DA3C40D84/image-size/medium?v=v2&amp;px=400" role="button" title="joanxie_0-1752565363537.png" alt="joanxie_0-1752565363537.png" /><span class="lia-inline-image-caption" onclick="event.preventDefault();">joanxie_0-1752565363537.png</span></span></P> <P>&nbsp;</P> Tue, 15 Jul 2025 08:13:49 GMT joanxie 2025-07-15T08:13:49Z https://community.nxp.com/t5/i-MX-Processors/imx8ulp-rtc-ldo-bypass/m-p/2133814#M239280 <P>Hello everyone,<BR /><BR />I am currently designing a board based on a imx8ulp, and my PMIC (PCA9450B) provides a 1.8V always-on power rail.<BR /><BR />According to the schematics in the reference manual page751,&nbsp; the internal RTC LDO must be powered via the VDD_BVAT42 pin.<BR /><BR />Is it possible to bypass this regulator, by&nbsp; directly connect my external +1.8V always-on rail to the LDO output (VDD_VBAT18_CAP),&nbsp; leaving the input disconnected ?<BR /><BR />Thank you for your help !<BR /><BR />Cécile</P> Tue, 15 Jul 2025 06:42:16 GMT https://community.nxp.com/t5/i-MX-Processors/imx8ulp-rtc-ldo-bypass/m-p/2133814#M239280 Cécile 2025-07-15T06:42:16Z https://community.nxp.com/t5/i-MX-Processors/imx8ulp-rtc-ldo-bypass/m-p/2133953#M239285 <P>refer to the data sheet,&nbsp;VDD_VBAT42 must be powered and stable before all other supplies begin to ramp up. for more detailed information, pls refer to the data sheet</P> <P><span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="joanxie_0-1752565363537.png" style="width: 400px;"><img src="https://community.nxp.com/t5/image/serverpage/image-id/347563i0E38176DA3C40D84/image-size/medium?v=v2&amp;px=400" role="button" title="joanxie_0-1752565363537.png" alt="joanxie_0-1752565363537.png" /><span class="lia-inline-image-caption" onclick="event.preventDefault();">joanxie_0-1752565363537.png</span></span></P> <P>&nbsp;</P> Tue, 15 Jul 2025 08:13:49 GMT https://community.nxp.com/t5/i-MX-Processors/imx8ulp-rtc-ldo-bypass/m-p/2133953#M239285 joanxie 2025-07-15T08:13:49Z