topic crystal drive level in MPC5xxx https://community.nxp.com/t5/MPC5xxx/crystal-drive-level/m-p/638965#M6243 <HTML><HEAD></HEAD><BODY><P>Dear all</P><P>I´m working on a new design with MPC5744 (LQFP) microcontroller. As far as I know, the crystal unit drive level could be obtained from the following equation:</P><P>P=2*Rl*(pi*freq*Vdd*(Cl+Co))2</P><P>Taking in to account MPC5744 evaluation board, we have following values:</P><P>Rlà crystal series resistance 50R</P><P>Freqà40 MHz</P><P>VDDà1,7V (from datasheet)</P><P>Clà8 pF (stray capacitance 4 pF)</P><P>Coà6 pF (shunt capacitance)</P><P>Applying those values in the equation I obtain that the crystal unit requires 894uW Drive level. I don’t understand how the &nbsp;eval board crystal unit could work, as it has a 500uW drive capability.</P><P>I think that I´m doing something wrong but I don´t know what.</P><P>Thanks in advance.</P></BODY></HTML> Wed, 21 Sep 2016 12:28:13 GMT Txurfer 2016-09-21T12:28:13Z crystal drive level https://community.nxp.com/t5/MPC5xxx/crystal-drive-level/m-p/638965#M6243 <HTML><HEAD></HEAD><BODY><P>Dear all</P><P>I´m working on a new design with MPC5744 (LQFP) microcontroller. As far as I know, the crystal unit drive level could be obtained from the following equation:</P><P>P=2*Rl*(pi*freq*Vdd*(Cl+Co))2</P><P>Taking in to account MPC5744 evaluation board, we have following values:</P><P>Rlà crystal series resistance 50R</P><P>Freqà40 MHz</P><P>VDDà1,7V (from datasheet)</P><P>Clà8 pF (stray capacitance 4 pF)</P><P>Coà6 pF (shunt capacitance)</P><P>Applying those values in the equation I obtain that the crystal unit requires 894uW Drive level. I don’t understand how the &nbsp;eval board crystal unit could work, as it has a 500uW drive capability.</P><P>I think that I´m doing something wrong but I don´t know what.</P><P>Thanks in advance.</P></BODY></HTML> Wed, 21 Sep 2016 12:28:13 GMT https://community.nxp.com/t5/MPC5xxx/crystal-drive-level/m-p/638965#M6243 Txurfer 2016-09-21T12:28:13Z