Lucas Tolbert

External Oscillator Stops when Vtest Voltage Applied on IRQ with MC908AP32ACBE

Discussion created by Lucas Tolbert on Mar 22, 2007
Latest reply on Mar 27, 2007 by Lucas Tolbert
I have a MC908AP32ACBE chip that I am trying to get running. Whenever I apply the Vtest voltage to the IRQ pin in order to enter monitor mode the external oscillator stops working. I have removed all the IRQ circuitry and applied the voltage directly to the pin and it is still happening. If I lower the Vtest voltage to 6.0V the oscillator continues to run but then I'm not entering monitor mode. I'm using the schematic shown in the monitor section of the user manaul except the circuity connected to the CGMXFC pin matchs what is shown in the CGM section. In general the oscillator will restart after the Vtest voltage is removed.

I have probed all of the pins as I apply and remove the Vtest voltage and nothing looked wrong.

I plan on changing the CGMXFC to circuitry to see if this fixes anything but I won't be able to do that until this afternoon.

Does anybody else have any ideas?