Recently introduced dc-dc bus converters present further evidence that interest in intermediate voltage bus architectures is growing. These latest entries convert a nominal 48-V input (with restricted voltage variation) to an unregulated but isolated 12-V output. They also deliver output power levels ranging from 200 to 300 W while operating with an efficiency of about 96%.
Though several vendors are adopting the quarter-brick package for bus converter designs, Datel is offering a different option (see the figure). Its 240-W bus converter comes in a single in-line package (SIP) that measures 1.25 by 2.5 by 0.465 in. By exploiting the SIP's vertical mounting, the SBC-12/20-L48 bus converter limits board space requirements to just 1.16 in.2 The company also plans to offer the converter in the quarter-brick package (model QBC-12/20-L48).
Datel's bus converter specifies an input-voltage range of 42 to 55 V and a nonregulated 12-V output that can vary from 9.7 to 13.3 V. When cooled with minimal airflow, the unit delivers full power in ambients up to 70°C. Pricing is $45 in quantities of 10,000.
Meanwhile, Cherokee and Astec Power have opted to introduce bus converters with 300-W ratings in the quarter brick. These units deliver 25 A at a nominal 12-V output. Like the Datel bus converter and other models, the input-voltage ranges on the Astec and Cherokee devices are restricted, though the voltage ranges vary slightly from vendor to vendor.
Cherokee International's C-BUS (CBQ2548G1) quarter-brick converter comes in open-frame and baseplate versions. The C-BUS also provides a choice of both positive or negative control logic. Now sampling, the converter costs $49 in lots of 1000.
The ALQ25B50 from Astec Power is offered as an open-frame quarter brick. It provides a choice of either positive or negative logic control for the remote on/off pin and a choice of either 3.7- or 5-mm pin lengths. It costs less than $48 in OEM quantities.