VDD_GPIO floating while VDD is supplied

[Luciano_]

Is my understanding correct that with VDD supplied and ENABLE = high, having VDD_GPIO floating (i.e. disconnected from a regulated 3.3 V supply) is a valid state? We intend to connect VDD directly to the battery voltage and in order to reduce power consumption in sleep mode we would like to switch off and disconnect the 3.3 V supply connected to VDD_GPIO. The Product Specification states "If VDD is supplied and VDD_GPIO is grounded, an extra current consumption can be generated on VDD", which is why we would like to keep VDD_GPIO floating during Sleep mode. Thanks for your help.

Kind Regards,
Luciano

[Håkon Alseth]

Hi,

 

Is my understanding correct that with VDD supplied and ENABLE = high, having VDD_GPIO floating (i.e. disconnected from a regulated 3.3 V supply) is a valid state? We intend to connect VDD directly to the battery voltage and in order to reduce power consumption in sleep mode we would like to switch off and disconnect the 3.3 V supply connected to VDD_GPIO. The Product Specification states "If VDD is supplied and VDD_GPIO is grounded, an extra current consumption can be generated on VDD", which is why we would like to keep VDD_GPIO floating during Sleep mode. Thanks for your help.

In order to disable the whole device (VDD, VDD_GPIO = GND, ENABLE pin = low), please see this section:

https://infocenter.nordicsemi.com/topic/ps_nrf9160/pmu.html?cp=2_0_0_4_0_0_0#system_disabled_mode

Especially this note:

Note: VDD_GPIO input must be driven low when device is disabled, failing to do so could result in increased leakage. For more information, see VDD_GPIO considerations in Operating conditions.

there will be a leakage through the system as per this specification:

https://infocenter.nordicsemi.com/topic/ps_nrf9160/_tmp/alta.nRF9160/autodita/CURRENT/parameters.id_system_disabled.html?cp=2_0_0_4_1_0_0

 

To enter CPU sleep mode, you should keep VDD_GPIO within the above operation conditions, and place the cpu in MCU on Idle or mcu off mode with these sleep currents: (https://infocenter.nordicsemi.com/topic/ps_nrf9160/_tmp/alta.nRF9160/autodita/CURRENT/parameters.id_current_sleep.html?cp=2_0_0_4_1_0_1

 

Kind regards,

Håkon