Oscillators for nRF9151

[BilalMalik]

Could you please clarify for the clock and oscillator setup, are the LFXO oscillator and  LFRC RC oscillator internal oscillators on the chip? Or is an external oscillator required?

[Turbo J]

LFRC is internal, LFXO requires an external crystal.

[BilalMalik]

Is it a requirement to use the LFXO? 

What pins should be used for the LFXO?