About the npm1300 Vout1 output voltage

[daxueseng]

I have an NPM1300 demo board. After testing, the default voltage of VOUT1 is 1.74 V. If I use this voltage to power the VDD of nRF54L15, will it affect the power-on reset (POR)?

I noticed that the minimum required voltage for nRF54L15’s VDDPOR is 1.75 V.

How can I get an accurate 1.8 V on VOUT1?

Can I fine-tune the resistor for VSET1? For example, change the 47 kΩ resistor to 47.5 kΩ.

[Kazi Afroza Sultana]

Hello,

you can get 1.8V as output on nPM1304 (Buck startup configuration).

The levels are discrete, you cannot fine tune it with resistor. Maybe with TWI register write you could increase it. But the output voltage accuracy specification is +/-5% so the output voltage can be 1.71V in some cases/devices. 

[daxueseng]

What do VDD_POR mean? Why is the minimum required voltage for VDD_POR higher than the minimum VDD voltage? Is there a risk of failure to start if I power the nRF54L15 with VDD = 1.71 V?

[Kazi Afroza Sultana]

VDD_POR is the voltage required to start the chip from reset. 

''Why is the minimum required voltage for VDD_POR higher than the minimum VDD voltage? ''

Circuit needs extra voltage margin to start on reliably.

''Is there a risk of failure to start if I power the nRF54L15 with VDD = 1.71 V?''

yes there is a risk. As a design rule, choose a nominal VDD (for example 1.8 V, 2.5 V, 3.0 V, or 3.3 V) such that even with worst‑case tolerances you remain above both 1.7 V and the specified VDDPOR.