9S12HY64 ,VDDA dont connect is 4.2V ??

[easylife]

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!

[kef]

See absolute maximum ratings # 2, 6 and 7. All these deltas are +-0.3V. You can't pull down VDDA without pulling down other supply pins.

[easylife]

thank you,  i use a amplifer to solve the problem at last