Diodes Incorporated introduced four automotive-compliant asynchronous buck converters for 48 V low-voltage rail point-of-load (PoL) applications. The AP68255Q/AP68355Q and AP6A255Q/AP6A355Q use 500 mΩ power MOSFETs perform high-efficiency step-down DC-DC conversion with up to 3.5 A of continuous output current. These converters cover the full automotive battery range from 5.5 V to 80 V/100 V, which includes load dump applications. Engineers can use these converters in applications that include 48 V motor control, advanced driver assistance systems (ADAS), telematics, infotainment, body control, instrument clusters, and lighting systems.
These buck converters employ constant on-time (COT) control to maintain a nearly constant 300 kHz switching frequency. The technique produces fast load/line transient response, easy loop stabilization, and low output voltage ripple, which lets engineers reduce component count. The proprietary gate-driver arrangement reduces switch-node ringing effects without sacrificing the turn-on and turn-off times of the N-channel MOSFET switch. This method reduces the high-frequency radiated electromagnetic interference (EMI) noise normally associated with MOSFET switching.
The built-in over-current protection (OCP) with frequency foldback mode ensures high load-current support while reducing junction temperature under fault conditions. The over-temperature protection (OTP) circuit immediately shuts down the controller’s output voltage at 160°C. When the temperature drops below the 140°C safety threshold, the converter automatically restarts. These protection features prevent controller damage or malfunction, maximizing system reliability.
The AP68255Q/355Q and AP6A255Q/355Q asynchronous buck converters are available in the thermally enhanced SO-8EP package with an operating temperature range of -40°C to +125°C. The devices are available at $0.80 [AP68255Q], $0.86 [AP68355Q], $0.90 [AP6A255Q], and $0.96 [AP6A355Q] in 1,000-piece quantities. Standard-compliance versions are also available for industrial and commercial applications.
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