Synchronous buck converters have low EMI for automotive design

Three automotive-compliant, 3.5A, synchronous buck converters from Diodes are designed for point of load (PoL) applications.

The AP64350Q, AP64351Q and AP64352Q converters combine a low quiescent current with a wide input voltage range of 3.8 to 40V.

They have a fully integrated 75mOhm high side power MOSFET and 45mOhm low side power MOSFET for high-efficiency, step down DC/DC conversion. The design of the AP6435xQ converter’s gate drive or bootstrap enables the devices to operate in low drop out (LDO) mode, allowing near 100 per cent duty cycle, says Diodes.

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

The AP64350Q and AP64352Q have an adjustable switching frequency (100kHz to 2.2MHz) and can also be synchronised to an external clock for a choice of low frequency with extremely high efficiency, or high frequency where a small form factor is required and 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.

All three devices are available in the SO-8EP package.

Target applications are automotive applications including infotainment systems, instrument clusters, telematics, advanced driver assistance systems (ADAS), and forward lighting.

Diodes provides semiconductor products to customers in the consumer electronics, computing, communications, industrial, and automotive markets. Its product portfolio includes discrete, analogue and mixed-signal products. It offers application-specific solutions, worldwide operations of 28 sites, including engineering, testing, manufacturing, and customer services.

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