MC9S12ZVC Power consumption in stop-mode

[julianhauser]

In my current application I need to run the µC in stop-mode with the CANPHY in power-down mode to enable a CAN-wake up.
For this setup, the current consumption is required to be below 100uA. @(T_J = 85°C, VSUP=12V, without external PNP for VDDX)

On page 725 of the "MC9S12ZVC-Family Reference Manual and Datasheet" in table "E.1 VREG Electrical Specifications":
-the load current in reduced performance mode (stop mode) and without external PNP transistor is given with I_DDX=  min:0 / max:5 mA.
-the load current of VDDC in reduced performance mode (stop mode) is given with: I_DDC min:0 / max:2.5 mA.

-> Is there a possibility to match the 100uA requirement?

-> Is there a more precise information available about the µC internal load current in stop mode?

In my application a few external components (HEF4094B-shiftregisters) are supplied via the µC internal voltage regulator through the VDDX pins.
The supply of these components needs to be disabled in stop-mode, otherwise it will be impossible to match any quiescent current requirement.

-> Will the 5V output at the VDDX Pins be disabled in stop mode?
or
-> Is there a possibility (within the µC) to disable the 5V output at the VDDX Pins in stop-mode?

Thanks.

[RadekS · Accepted solution]

Hi Julian,

Typical power consumption of MCU in full stop mode is around 20uA (this value is temperature dependent, see Table A-14. Stop Current Characteristics in RM).

VDDX power supply and GPIO pin voltage levels are not affected by enter into stop mode. Unfortunately VDDX power supply cannot be disabled during stop mode.

In fact, also pin PP2 takes energy from VDDX voltage source. Difference in compare with other GPIO pins is just in higher capability and overcurrent protection on this pin.

For your purpose, we could use advantage of PP2 pin for powering shift registers. We could just set low level (log 0) at this pin prior we enter into stop mode and this way disable connected shift registers.

Direct connection of load to VDDX pin do not allow disable load during stop mode.

I would like to recommend connect load trough GPIO pins or trough any other switch, that we could disable this load during stop mode.

I hope it helps you.

Have a great day,
RadekS

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