22.214.171.124 Direction Command (DIR)
This pin is a triple function pin.
- When the DIR pin is actively pulled above 2 V (logic state of 1), the LM5170 operates in buck mode, and current flows from the HV-Port to the LV-Port.
- When the DIR pin is actively pulled below 1 V (logic state of 0), the LM5170 operates in boost mode, and current flows from the LV-Port to the HV-Port.
- When the DIR pin is in the third state that is different from the above two, it is considered an invalid command and the LM5170 remains in standby mode regardless of the EN1 and EN2 states. This tri-state function prevents faulty operation when losing the DIR signal connection to the MCU.
- When DIR changes state between 1 and 0 dynamically during operation, the transition causes the SS pin to discharge first to below 0.23 V, then the SS pin pulldown is released and the LM5170 goes through a new soft-start process to produce the current in the new direction. This eliminates surge current during the direction change.
- The built-in 10-µs glitch filter prevents errant operation by noise on the DIR signal.