S12 / MagniV MicrocontrollersのトピックRe: Colpits blocking cap value for MC9S12DP256 https://community.nxp.com/t5/S12-MagniV-Microcontrollers/Colpits-blocking-cap-value-for-MC9S12DP256/m-p/221853#M9249 <HTML><HEAD></HEAD><BODY><P>Impedance of 10nF cap at 16MHz is less than 1 Ohm...</P></BODY></HTML> Sun, 21 Oct 2012 05:46:52 GMT kef 2012-10-21T05:46:52Z Colpits blocking cap value for MC9S12DP256 https://community.nxp.com/t5/S12-MagniV-Microcontrollers/Colpits-blocking-cap-value-for-MC9S12DP256/m-p/221852#M9248 <HTML><HEAD></HEAD><BODY><P>Freescale recommends use of a blocking cap with the MC9S12DP256 Colpits clock circuit.&nbsp; The cap blocks DC voltage between Extal and the crystal.&nbsp; It is referred to as C11 in the Developer User's Guide (V2.05).&nbsp; What is a recommended value for C11 if the device is using a 16 MHz crystal with 18 pF caps?&nbsp; Apparently this cap is recommended to limit DC voltage applied to the crystal (thereby reducing crystal life expectancy) and minimizing startup issues.</P></BODY></HTML> Sun, 21 Oct 2012 03:00:04 GMT https://community.nxp.com/t5/S12-MagniV-Microcontrollers/Colpits-blocking-cap-value-for-MC9S12DP256/m-p/221852#M9248 kevinhuffman 2012-10-21T03:00:04Z Re: Colpits blocking cap value for MC9S12DP256 https://community.nxp.com/t5/S12-MagniV-Microcontrollers/Colpits-blocking-cap-value-for-MC9S12DP256/m-p/221853#M9249 <HTML><HEAD></HEAD><BODY><P>Impedance of 10nF cap at 16MHz is less than 1 Ohm...</P></BODY></HTML> Sun, 21 Oct 2012 05:46:52 GMT https://community.nxp.com/t5/S12-MagniV-Microcontrollers/Colpits-blocking-cap-value-for-MC9S12DP256/m-p/221853#M9249 kef 2012-10-21T05:46:52Z Re: Colpits blocking cap value for MC9S12DP256 https://community.nxp.com/t5/S12-MagniV-Microcontrollers/Colpits-blocking-cap-value-for-MC9S12DP256/m-p/221854#M9250 <HTML><HEAD></HEAD><BODY><P>Perfect.&nbsp; Thanks for the reply.&nbsp; The Freescale documentation refers back to the crystal manufacturer for the correct value of a blocking cap.&nbsp; This cap value doesn't appear to be addressed on ay crystal datasheets that I looked at.&nbsp; I'll proceed with the 10 nF and see what happens.</P></BODY></HTML> Sun, 21 Oct 2012 14:27:51 GMT https://community.nxp.com/t5/S12-MagniV-Microcontrollers/Colpits-blocking-cap-value-for-MC9S12DP256/m-p/221854#M9250 kevinhuffman 2012-10-21T14:27:51Z