Stackable DC/DC buck converter maximises power density

10th March 2020
Alex Lynn

Texas Instruments (TI) has introduced a new 40A SWIFT DC/DC buck converter, offering first-of-its-kind stackability of up to four integrated circuits (ICs). The TPS546D24A PMBus buck converter can deliver up to 160A of output current at an 85°C ambient temperature, four times more current than competing power ICs.

The TPS546D24A has the highest efficiency of any 40A DC/DC converter, allowing engineers to reduce power loss by 1.5W in high-performance data centre and enterprise computing, medical, wireless infrastructure, and wired networking applications. 

Solution size and thermal performance are two key considerations for engineers designing power supplies for modern field-programmable gate arrays (FPGAs). With its unique stackability, the TPS546D24A buck converter addresses both.

It comes with a PMBus interface that offers a selectable internal compensation network, enabling engineers to eliminate as many as six external compensation components from the board and shrink the overall power-supply solution size by more than ten percent (or 130 mm2) for higher-current FPGA/application-specific ICs (ASICs) when compared to discrete multiphase controllers.

Using DC/DC converters with high switching frequencies allows engineers to shrink the footprint of the power supply and facilitates the design of high-bandwidth systems. The TPS546D24A offers a switching frequency of 1.5 MHz, enabling engineers to deliver 40A of current per IC while reducing inductance and capacitance by one-third compared to similar converters.

To mitigate the negative impact on efficiency, which is typically associated with high switching frequencies, the TPS546D24A features a 0.9-mΩ low-side MOSFET, achieving 3.5% higher efficiency than competing DC/DC buck converters.

FPGAs are used in a variety of applications, but engineers designing power supplies for FPGAs are often surprised by the voltage accuracy required to support FPGA DC rails. The TPS546D24A makes it easier for engineers to meet these rigorous voltage tolerance requirements by offering an output voltage error of less than one percent. Furthermore, its extensive PMBus command set and pin-strapping configurability allow engineers to monitor current more accurately for fault reporting and to avoid overdesign.

The TPS546D24A is now available from TI and authorised distributors in a 5x7mm, 40-pin quad flat no-lead (QFN) package. Pricing starts at $4.27 in 1,000-unit quantities. The TPS546D24AEVM evaluation module is available on TI.com for $199. Pin-to-pin- and footprint- compatible, preproduction TPS546B24A (20-A) and TPS546A24A (10-A) DC/DC converters are available now, only from TI. Pricing starts at $3.25 and $2.49 in 1,000-unit quantities, respectively.

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