PCA9538: standby mode and question on additional current in standby mode

1. "Standby" simply means that the I²C bus is idle. This device does not have an internal oscillator; the state machine is triggered entirely by the SCL clock edges. Standby is not really a separate operating mode that needs to be entered or left.

2. The additional current happens only when an input has a voltage that is not near V_CC or GND. The standby mode is just a test condition that makes measuring this current easier; the shoot-through current happens also when the I²C bus is not idle. (This specification is not very useful because the shoot-through current increases when the offset is larger than 0.6 V. Just avoid such input voltages.)

Hi Kai,

Clemens' basically summed up the answer to your question. Standby is not a mode for the device, but is the state of the I2C bus when idle (no communication, SCL and SDA pulled up to VCC through pull up resistors). 

To your second point, this has to do with shoot-through current and occurs when the I2C bus is active. This only applies if you have a known input that is not going to be near the HIGH or LOW levels of VCC or GND. Worst case additional ICC current occurs when your input is somewhere in the middle of VCC and GND. To avoid this, follow Clemens' suggestion of pulling up the voltage fully to VCC and driving to GND fully by adjusting the pull-up resistance value.

Regards,

Tyler