Synchronous buck converters deliver high efficiency with low EMI

Diodes Incorporated has launched the AP64350Q/AP64351Q/AP64352Q series of automotive-compliant, 3.5A, synchronous buck converters for POL applications. The converters combine a low quiescent current with a wide input voltage range between 3.8V to 40V. The devices have been produced for employment in automotive applications covering infotainment systems, instrument clusters, telematics, ADAS, and forward lighting.

With a fully integrated 75mOhm high-side power MOSFET and 45mOhm low-side power MOSFET, the device provides high-efficiency step-down DC-DC conversion. The design of the device's gate drive/bootstrap allows the devices to run in LDO mode, providing near 100% duty cycle.

To improve efficiency as the load current nears zero, the devices enter PFM, resulting in a quiescent current of only 22μA. They also provide frequency spread spectrum with a switching frequency jitter of ±6% and a proprietary gate driver scheme, which decreases high frequency radiated EMI noise created by MOSFET switching.

The devices have distinct further feature sets that optimise performance in slightly varying ways. The AP64350Q and AP64352Q have an adjustable switching frequency (100kHz-2.2MHz) and can be synchronised to an external clock. This gives the design flexibility to produce a choice of low frequency with remarkably high efficiency or high frequency for small form factor solutions whose switching frequency is outside the AM band. The AP64351Q and AP64352Q offer programmable soft-start, which decreases in-rush currents, while the AP64350Q and AP64351Q provide external compensation to optimise loop response.

The devices are qualified to AEC-Q100 Grade 1, support PPAP documentation, and are manufactured in IATF 16949 certified facilities.