Great part! I have a 5V to 5V isolation barrier working with the EN_IO pin floating (enabled). EN/FLT is pulled up to VIO with 100K. With Vdd power at 5V the current into VIO is 4mA. With Vdd removed the current into VIO remains close to 4mA. The SPI bus in not connected to anything yet so no consumption there.
What is the best way to reduce current consumption on VIO? Connect both EN/FLT and EN_IO and bring to ground?
Hi Chuck,
Thank you for reaching out.
EN/FLT is the key enable pin which controls most of the device. When EN/FLT is made LOW, most of the device stays disabled and current consumption goes down significantly. Please see below snapshot from datasheet that shows the current into VDD and VIO when EN/FLT = LOW. EN_IO connection to ground is optional when EN/FLT is made LOW.
Let me know if you have any other questions, thanks.
Regards,
Koteshwar Rao
I use level translators more these days for auto switching of IO in systems that get powered down rather than for converting voltage levels. They tristate if either side supply is removed. Possibly passing VIO through a single level translator would auto switch the VIO out if the 5V side power were removed.
Here is an example of a way to get uA consumption on a disable system.
The main Vdd is supplied at 5V from an LDO with uA current when disabled. The system VIO is passed through the single channel level translator so that the 7741 VIO is powered from the 74LVC1T45. If VCCA (5V) is removed the level translator isolates the B to A connection and the B1 VIO is powered off saving the 300uA consumption. A two transistor power switch could be used to control VIO but involves multiple part placements and consumes some power in transistor biasing even when using FETs. The $0.12 1T45 is by nature a very low power device (2uA).
