By Jean-Jacques DeLisle, contributing writer
A buck converter, or a step-down converter, is a type of DC/DC power converter that produces a lower voltage level at the output compared to the source input. Typically, buck converters are designed using switched-mode power supplies, comprised of several transistors/diodes, and passive components such as capacitors, inductors, and resistors. Buck converters are often used in place of linear regulators, as they are typically far more power-efficient, and step-up output current, though buck converters are generally more complex and potentially more expensive than some linear regulators.
These devices are used in a wide array of electronics applications, spanning virtually every electronics industry that requires multiple levels of DC voltage for an application. These applications include computers, automobiles, aircraft, handheld electronics, smartphones, sensors, and IoT devices. Here is a sampling of the latest buck converters available in the market.
Buck converters in 3-A or 6-A modules
GE’s new 60.8-mm2 Femto DLynx II buck converters, the FKX003 and FKX006, offer the company’s smallest point-of-load (PoL) footprint to date and are available in either 3-A or 6-A modules. These voltage regulators use minimal board space compared to designs that place power components directly on the main board, and the IPC9592 qualification ensures high reliability in all applications, said the company. The high-efficiency, fully integrated PoL power modules convert 5-V or 12-V bus voltages to lower voltages of 0.6 V to 5.5 V, as required by the load.
The FKX006 and FKX003 converters also have wide input and output voltage ranges — 4.5 V to 14.4 V and 0.6 V to 5.5 V, respectively — and high efficiencies of up to 93.5%. Both devices support patented Tunable Loop, which provides superior transient performance while minimizing required output capacitors. The 6.76 x 9-mm DLynx II PoL modules provide the same benefits as GE’s previous analog, low-current DLynx 3-A and 6-A DC/DC, non-isolated converters but in a 58% smaller package (61 mm2 instead of 144 mm2 ) without compromising the reliability and performance of the Lynx/TLynx/DLynx series, said the company.
The small footprint will be particularly appealing to applications that are limited in board space or where low-risk design is required, said GE. Applications range from portable industrial devices, industrial automation, and test and measurement to telecom and wireless infrastructure equipment to servers/storage and routers and switchers.
The FKX003 and FKX006 Femto DLynx II converters are available with prices starting at $3 and $6, respectively, in OEM quantities.
Synchronous buck converters for automotive applications
Maxim Integrated touts that the pin-compatible MAX20073 and MAX20074 PoL buck converters can significantly lower electromagnetic interference (EMI) in automotive applications thanks to its unique spread-spectrum and SYNC In features that mitigate system EMI radiation. The MAX20073/MAX20074 claim the lowest EMI in the industry for low-voltage PoL applications, reducing interference that can impact the function of sub-systems.
Other key features include high efficiency across the entire operating range and ultra-low quiescent current. The devices are housed in a small 3 x 3-mm, 10-pin TDFN-EP package, which translates into a lower overall system footprint.
The MAX20073/MAX20074 delivers up to 3-A load current from 0.5 V to 3.8 V. The devices operate from an input voltage range of 2.7 V to 5.5 V, making them suitable for on-board point-of-load and post-regulation applications. Total output error is less than ±1.5% over load, line, and temperature. The devices feature fixed-frequency PWM mode of operation with a 2.2-MHz switching frequency and an all-ceramic capacitor design. The low-resistance on-chip switches ensure high efficiency at heavy loads while minimizing critical inductances, said Maxim.
The output voltage accuracy makes these devices suited for applications that have these tight processor and memory voltage requirements, particularly automotive infotainment and ADAS applications, said Maxim.
The ICs also adhere to tight safety standards, operate with low-input voltages across a wide range of temperatures, and minimize radio frequency interference while exhibiting high accuracy, high efficiency, and high reliability.
The MAX20073 is priced at $1.20 and the MAX20074 is available for $1.30. The MAX20073EVKIT# and MAX20074EVKIT# evaluation kits are priced at $45. Designers are recommended to contact Maxim for pin-compatible ASIL variants.
Synchronous converters in tiny packages
Texas Instruments launched two wide-VIN synchronous SIMPLE SWITCHER DC/DC buck regulators in ultra-small HotRod quad flat no-lead (QFN) packaging. The highly integrated 3-A LMR33630 and 2-A LMR33620 step-down voltage converters feature full load efficiency at 92% with switching frequencies up to 2.1 MHz. When used in conjunction with TI’s WEBENCH Power Designer, the converters can simplify power conversion and speed the design process.
The 3.8-V to 36-V LMR33630 and LMR33620 buck regulators are offered in 3 x 2-mm thermally enhanced packaging. The small HotRod QFN package includes unique wettable flanks enabling post-solder optical inspection to simplify manufacturing and gives the LMR33630 the industry’s highest 0.5-A/mm2 power density at 3 A of current, said TI. In addition, the “optimized package construction and symmetrical pin placement minimizes parasitic inductance and facilitates optimal placement of input bypass capacitors to mitigate conducted and radiated noise emissions,” said the company.
Key specs:
● Operating input voltage ranges as high as 36 V for nominal 12-V or 24-V systems such as factory and home automation, motor drives, inverters and servo control units
● Full load efficiency of 92% at 24 VIN, 5 VOUT, and a 400-kHz switching frequency with a low 24-µA typical standby quiescent current to increase light load efficiency
● Devices are also available in eight-pin, 5 x 6-mm SOIC packages
The 36-V LMR33630 and LMR33620 are priced in small reels at $1.86 and $1.75, respectively, in quantities of 1,000. The 60-V LMR36015 and LMR36006 are priced in small reels at $1.84 and $1.61, respectively, in quantities of 1,000. All four devices are available in the 12-pin HotRod package. Available in the eight-pin SOIC package, the 36-V LMR33630 and LMR33620 are priced in small reels at $1.62 and $1.52, respectively, in quantities of 1,000. The EVMs can be ordered as follows:
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