#Dc to converter plus#

The LTC7821вЂ™s powerful 1 в„¦ N-channel MOSFET gate driversВ maximize efficiency and can drive multiple MOSFETs in parallel for higher power applications. The same efficiency can only be achieved in a traditional synchronous step-down converter by switching at в…“ rd the operating frequency, forcing the use of much larger magnetics and output filter components. In a typical 48 V to 12 V/20 A application, an efficiency of 97% is attainable with the LTC7821 switching at 500 kHz. External MOSFETs switch at a fixed frequency, programmable from 200 kHz to 1.5 MHz. The LTC7821В operates over a 10 V to 72 V (80 V abs max) input voltage range andВ can produce output currents in multiple tens of amps,В depending on the choice of external components. Other benefits include low EMI emissions due to a soft-switched front end ideal for the next generation ofВ nonisolated intermediate bus applications in power distribution, datacom, and telecom, as well as emerging 48 V automotive systems. Alternatively, when operating at the same frequency, an LTC7821-based solution can provide up to a 3% higher efficiency. This improvement is enabled by a 3Г— higher switching frequency without compromising efficiency. The LTC7821В merges a switched capacitor circuit with a synchronous step-down converter, enabling up to a 50% reduction in dc-to-dc converter solution size compared to traditional buck converter alternatives.

#Dc to converter plus#

A switched capacitor plus a synchronous buck combine into an LTC7821 hybrid converter. Figure 2 shows how this combination has formed the hybrid step-down synchronous controller. Other benefits include lower switching losses and reduced MOSFET voltage stress due the inherent soft switching characteristic of the switched capacitor front-end converter resulting in lower EMI.

This technique of reducing the input voltage in half and then bucking down to the desired output voltage results in higher efficiency or a much smaller solution size by operating at a much higher switching frequency. The switched capacitor circuit reduces the input voltage by a factor of two and then feeds into the synchronous buck. The new innovative approach to controllers combines a switched capacitor converter with a synchronous buck. Operating the LTC3891 at higher frequencies results in lower efficiency due to the MOSFET switching losses that occur with the relatively high 48 V input voltage. The LTC3891 from Analog Devices can be used for this approach and provides an efficiency of about 97% when operating at a relatively low 150 kHz switching frequency. It would need to operate over an input voltage range from 36 V to 72 V and produce a 5 V to 12 V output voltage. Now that nonisolated conversion is allowed in some distributed power architectures, one could consider using the single stage buck converter for this application. A typical distributed power architecture is shown in Figure 1. As a result, nonisolated IBCs are being designed into many new applications, which significantly reduces the solution size and cost while also increasing the operating efficiency and providing design flexibility. In many applications, a hot swap front-end device is required to use a nonisolated IBC. However, in many new applications, such as a 48 V direct conversion application, isolation is not necessary in the IBC since the upstream 48 V or 54 V input is already isolated from the hazardous ac mains.

The intermediate bus voltage is used as the input to point-of-load regulators that will power FPGAs, microprocessors, ASICs, I/O, and other low voltage downstream devices. A typical IBC has a nominal input voltage of 48 V or 54 V and produces a lower intermediate voltage between 5 V to 12 V with an output power level from several hundred watts to several kilowatts. These IBCs are available from a wide variety of suppliers and are typically housed in industry-standard 1/ 16 th, в…› th, and Вј th brick footprints.

This type of converter is commonly used in datacom, telecom, and medical distributed power architectures. They also normally require an inductor for output filtering. Most intermediate bus converters (IBCs) provide isolation from input to output with the use of a bulky power transformer. 72 V Hybrid DC-to-DC Converter Reduces Intermediate Bus Converter Size by up to 50%