Overview: DATASHEET ISL78220
6-Phase Interleaved Boost PWM Controller with Light Load Efficiency Enhancement FN7688 Rev 4.00 September 2, 2014 The ISL78220 6-phase controller is targeted for applications where high efficiency (>95%) and high power are required. The multiphase boost converter architecture uses interleaved timing to multiply channel ripple frequency and reduce input and output ripple. Lower ripple results in fewer input/output capacitors and therefore lower ponent cost and smaller implementation area.
The ISL78220 has a dedicated pin to initiate the phase dropping scheme for higher efficiency at light load by dropping phases based on the load current, so the switching and core losses in the converter are reduced significantly. As the load increases, the dropped phase(s) are added back to acmodate heavy load transients and improve efficiency.
Input current is sensed continuously by measuring the voltage across a dedicated current sense resistor or by inductor DCR. This current sensing provides precision channel-current balancing, and per-phase overcurrent protection. A separate totalizing current limit function provides overcurrent protection for all the phases bined. This two-stage current protection provides maximum performance and circuit reliability.
The ISL78220 can also provide for input voltage tracking via the VREF2 pin. The parison reference voltage will be the lower of the VREF2 pin or the internal 2V reference. By using a resistor network between VIN and VREF2 pin, the output voltage can track input voltage to limit the output power during automotive cranking conditions.
The ISL78220 can output a clock signal for expanding operation to 12 phases, which offers high system flexibility. The threshold-sensitive enable input is available to accurately coordinate the start-up of the ISL78220 with any other voltage rail.
