Joey Chan

9S12HY64 ,VDDA dont connect is 4.2V ??

Discussion created by Joey Chan on Sep 1, 2011
Latest reply on Nov 2, 2011 by Joey Chan

Hi all!


sorry! my english is poor,may be difficult to read.


 I have a problem. my design has double power:VCC and +5V.VCC is always exist ,+5V can be controlled.


To make sure AD sample currect,i connect +5V to VDDA.and pullup res. VCC connect to VDDR,VDDX,VDDM. But,when in low power mode.stop mode. VDDA is a nearly 4.2V. influence +5V net. So current can not be reduced. i test the current can reach to 90 mA.  MCU still can working after a reset.


i read the sheet find there is a LVR function.

 " Monitors VDDA, active only in Full Performance Mode. Indicates I/O & ADC performance degradation due to low supply" "VDDA Low Voltage Interrupt Assert Level voltage. 4.04V 4.23V 4.40V”


it is truely can work.when i pulldown the VDDA to 0V.MCU reset.


is it the reason why 4.2 exist?OR the clamp diode cause? how can i shutdown the 4.2V?



Thanks a lot!