This reference design is a four-switch, buck-boost DC/DC converter used for battery backup unit (BBU) applications, targeting Open Compute Project® (OCP) Open Rack V3 Power BBU specifications. This design has a 1.4kW power capability. The converter works in either buck, buck-boost, or boost mode depending on the VIN and VOUT voltage. The converter transients smoothly between each mode. Peak current mode control is employed in this design, providing a fast load transient response. Relying on the LM51770 features, no extra driver is needed for field-effect transistors.
Features
- 1.4kW power capability per phase then N-number of phases can be connected in parallel for higher power battery discharge operation
- Bidirectional conversion under varying VIN–VOUT
- Multimode operation: seamless transition between buck to buck-boost and buck-boost to boost
- Integrated average input and output current monitor or limiter either in input or output
- Peak efficiency >98.5%; high load efficiency for VIN ≅ VOUT over the full range of the output current
- Meets OCP-V3, 50V BBU power conversion function