Diodes Incorporated Releases Buck Converter Family Designed to Combat EMI

October 31, 2019 by Gary Elinoff

Diode Incorporated’s 40V, 2.2MHz synchronous buck converters are designed for high efficiency across all loads.

Power has never been more important than it is today, especially with the demand for quick charging devices that won't overheat. Buck converters prove far more efficient as DC-to-DC converters than their linear regulator counterparts, which are simple devices that work with lower voltages but do so by dissipating power in the form of heat.

Diodes Incorporated has introduced five synchronous buck converters sporting integrated high-side and low-side MOSFETs. All members of his new family deliver continuous output currents of either 3.5A or 5A. The units deliver superior EMI performance and are designed for use in consumer, networking, industrial, and automotive applications. 


AP64350, AP64351, and AP64352 buck converters

Diode Incorporated’s family of synchronous buck converters. Image from Diodes Incorporated


The AP64350, AP64351, and AP64352 feature a quiescent current (Iq) of 22μA, and the Iq of the AP64500 and AP64501 is slightly higher at 25μA. The units all operate from supply voltages that range from 3.8V to 40V and operate in low-dropout mode. In addition, the AP64351 and AP64501 feature a programmable soft-start. This allows a more efficient implementation of power sequencing and can also limit the effects of inrush currents. 


Features of the Buck Converter Family

All members of the new buck converter family include:

  • 0.8V ± 1% reference voltage 

  • Efficiency at 5mA light load of up to 85%

  • Precision enable threshold to adjust undervoltage-lockout (UVLO)

The family also features a protection circuitry, which includes undervoltage-lockout (UVLO), output overvoltage protection (OVP), cycle-by-cycle peak current limit, and thermal shutdown.


Combatting EMI

In order to reduce EMI, members of the family employ a frequency spread spectrum topology. They employ gate driver methods designed to resist switching node ringing without sacrificing MOSFET turn-on and turn-off times. This reduces the high-frequency radiated EMI noise that can be caused by MOSFET switching.

Most importantly, all units feature Frequency Spread Spectrum (FSS) with a ±6% switching frequency jitter. This serves to further reduce EMI noise by not allowing any emitted noise energy to linger at any one frequency for a substantial amount of time.


Key Differences Between the Devices

These devices are all available in SO-8EP packages. The few key distinctions between each member are outlined below:  


Key differences between the Diodes Incorporated buck converter family


Members of this family are free of lead, halogen, and antimony. They are also fully RoHS compliant. 


Around the Industry

Because of their power efficiency, buck converters are the go-to choice for design engineers. As such, Diodes Incorporated is not without competitors in this important arena.

Semtech offers its FemtoBuck DC-DC regulators and controllers. There are many to choose from in this large family of devices. They operate at 4 MHz, and this high-switching frequency allows these devices to operate with very small inductors. They feature adjustable output voltage and internal soft-start.
Maxim’s MAX77324 operates over an input range of 2.5V to 4.8V with the output voltage adjustable over 0.6V to 2V. This device employs a switching frequency of 2 MHz.



What applications do you use buck converters for? Let us know in the comments below.