The UCC2895x controllers offer many operational modes. These modes are described in detail in Section 6.3.

• Current mode¹. The UCC2895x controller operates in current mode control when the RSUM pin is connected to GND through a resistor (R_SUM) . The resistor sets the amount of slope compensation.
• Voltage mode¹. The controller operates in voltage mode control when the RSUM pin is connected to VREF through a resistor (R_SUM). The chosen resistor value gives the correct amount of slope compensation for operation in current limit mode (cycle-by-cycle current limit).
• DCM mode. The controller enters DCM mode when the signal at the CS pin falls below the level set by the resistor at the DCM pin. The SR drives (OUTE and OUTF) turn off and secondary rectification occurs through the body diodes of the SRs.
• Burst mode. The controllers enter burst mode when the pulse width demanded by the feedback signal falls below the width set by the resistor at the TMIN pin.
• Leader mode. This is the default operation mode of the controller and is used when there is only one UCC2895x controller in the system. Connect the timing resistor (R_T) from the RT pin to VREF. In a system with more than one UCC2895x controller, configure one as the leader and the others as followers¹.
• Follower mode. The follower controller operates with a 90° phase shift relative to the leader (providing their SYNC pins are tied together). Connect the timing resistor (R_T) from the RT pin to GND and connect an 825kΩ ±5% resistor from the SS/EN pin to GND¹.
• Synchronized mode. When a UCC2895x controller is configured as a follower, its SYNC pin is used as an input. The follower synchronizes its internal oscillator at 90° to the signal at its SYNC pin. The application note, Synchronizing Three or More UCC28950 Phase-Shifted, Full-Bridge Controllers, discusses how multiple follower controllers may be synchronized to a single leader oscillator.
• Hiccup mode. This mode provides overload protection to the power circuit. The UCC2895x controller stops switching after a certain time in current limit. It starts again (soft-start) after a delay time. The user can control the time spent in current limit before switching is stopped and the delay time before the soft start happens.
• Current-limit mode. The UCC2895xc ontroller provides cycle-by-cycle current limiting when the signal at the CS pin reaches 2V.
• Latch-off mode. Connect a resistor between the SS pin and VREF. The UCC2895x controller then latches off when the controller enterscurrent-limit mode. ⁽¹⁾