These pins are tri-state function pins. DIR1
controls CH-1, and DIR2 controls CH-2.
- When the DIR1 pin is actively pulled above 2V
(logic state of 1), CH-1 operates in buck mode, and current flows from the
HV-Port to the LV-Port.
- When the DIR1 pin is actively pulled below 1V
(logic state of 0), CH-1 operates in boost mode, and current flows from the
LV-Port to the HV-Port.
- When the DIR1 pin is in the third state that is
different from the above two, it is considered an invalid command and CH-1
remains in standby mode regardless of the EN1 states. This tri-state function
prevents faulty operation when losing the DIR signal connection to the MCU.
- When DIR1 changes the logic state between 1 and 0
dynamically during operation, the transition causes the SS/DEM1 pin to discharge
first to below 0.3V, then the SS/DEM1 pin pulldown is released and CH-1 goes
through a new soft-start process to produce the current in the new direction.
This eliminates the surge current during the direction change.
- Similar behaviors for DIR2, CH-2, EN2, and SS/DEM2.
- The built-in 10µs glitch filter prevents errant
operation by noise on the DIR1 and DIR2 signals.