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Synchronous buck converters with low EMI for automotive POL applications

Diodes has announced the AP64350Q/AP64351Q/AP64352Q series of automotive-compliant, 3.5A, synchronous buck converters for point of load (POL) applications.

The AP6435xQ combines a low quiescent current with a wide input voltage range of 3.8V to 40V. The devices have been developed for use in automotive applications including infotainment systems, instrument clusters, telematics, advanced driver assistance systems (ADAS), and forward lighting.

With a fully integrated 75mΩ high-side power MOSFET and 45mΩ low-side power MOSFET, the AP6435xQ provides high-efficiency step-down DC-DC conversion. The design of the AP6435xQ’s gate drive/bootstrap enables the devices to operate in low drop out (LDO) mode, allowing near 100% duty cycle.

To increase efficiency as the load current approaches zero, the devices enter pulse frequency modulation (PFM), resulting in a quiescent current of just 22μA. They also feature frequency spread spectrum (FSS) with a switching frequency jitter of ±6% and a proprietary gate driver scheme, which reduces high frequency radiated EMI noise caused by MOSFET switching.

The AP64350Q, AP64351Q, and AP64352Q have distinct additional feature sets that optimise performance in slightly different ways.

The AP64350Q and AP64352Q have an adjustable switching frequency (100kHz - 2.2MHz) and can also be synchronised to an external clock. This provides the design flexibility to deliver a choice of low frequency with extremely high efficiency, or high frequency for small form factor solutions whose switching frequency is outside the AM band. The AP64351Q and AP64352Q have programmable soft-start, which reduces in-rush currents, while the AP64350Q and AP64351Q have external compensation to optimise loop response.

The AP64350Q, AP64351Q, and AP64352Q are qualified to AEC-Q100 Grade 1, support PPAP documentation, and are manufactured in IATF 16949 certified facilities.

Author
Neil Tyler

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