Design Support


Today, the brains of telecom and datacom systems - i.e., microprocessors, DSPs, ASICs, and programmable logic - are evolving to ever-lower operating voltages. Typical ICs run at supply levels of 3.3 V, 2.5 V, and even lower. As this occurs, new devices and modules are being developed to address the functions of hot-swapping the standard ?48 Vdc bus, and subsequent conversion to local regulation levels. These devices provide a high level of integration for the point-of-use power supplies, saving the system designer both design time and critical board space. This application report presents one possible solution to the telecom plug-in power problem, based on a nominal ?48 Vdc system bus and a module needing two low-voltage supply outputs. The material includes a detailed design methodology for tailoring the circuit to the specific requirements of the reader?s system. The solution is based on two device families offered by Texas Instruments, the UCC3913 and UCC3921 hot swap power manager ICs, and the PT3320 series of integrated switching regulators (ISRs).