Diodes Incorporated has introduced four new automotive-compliant asynchronous buck converters for 48 V low-voltage rail point-of-load (PoL) applications. The AP68255Q/AP68355Q and AP6A255Q/AP6A355Q incorporate 500 milli-ohms power MOSFETs to deliver 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, including load dump scenarios. They can be used in various applications, including 48 V motor control, advanced driver assistance systems (ADAS), telematics, infotainment, body control, instrument clusters, and lighting systems.
The new buck converters employ constant on-time (COT) control to maintain a nearly constant switching frequency (300kHz). This technique results in fast load/line transient response, easy loop stabilization, and low output voltage ripple, making the devices easier to incorporate by requiring fewer external components. The proprietary gate-driver arrangement in these devices reduces switch node ringing effects without sacrificing the turn-on and turn-off times of the N-channel MOSFET switch. This method helps reduce the high-frequency radiated electromagnetic interference (EMI) noise normally associated with MOSFET switching.
The built-in overcurrent protection (OCP) with frequency foldback mode ensures high load-current support while reducing junction temperature under fault conditions. The overtemperature 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 1000-piece quantities. Standard-compliance versions are also available for industrial and commercial applications.
Click here to learn more about the Power Converter hub in everything PE.
