Flexible buck converter extends battery life of USB Type-C PD devices

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By Nick Flaherty

USB Type-C products must generate an always-on 3.3V rail to detect USB insertions. Products using the Power Delivery (PD) voltage range (5V to 20V) can generate an always-on (1.8V/3.3V/5.0V) digital supply rail for the port controller using the MAX77756 step-down converter. In addition, the MAX77756 has a 20µA quiescent current that extends battery life by reducing idle power consumption.

To simplify the system design, the MAX77756 has a dual input ideal diode ORing circuit that allows the chip to power from the external USB source if the battery is empty. The integrated power mux provides up to 92% efficiency.

Multi-cell battery-operated devices—such as ultrabooks, laptops, tablets, drones, and home automation appliances—can move to Type-C with PD using the flexible MAX77756 power supply through the combination of wide input voltage range, low quiescent current, higher current load, dual input, and I²C for flexibility and programmability. There is also a default power mode if customers do not want to use the I²C bus. The MAX77756 is a robust IC with short-circuit and thermal protection, 8ms internal soft-start to minimize inrush current, proven current-mode control architecture, and up to 26V input voltage standoff.

“The MAX77756 saves board space and reduces series voltage drop by integrating FETs, eliminating the need to use external Schottky diodes,” said Jia Hu, Executive Business Manager for Mobile Power at Maxim Integrated. “The MAX77756 also helps engineers minimize power consumption and extend battery life for the end application by offering highest efficiency and lowest Iq compared to other products.”

The MAX77756 is packaged in a 2.33mm x 1.42mm 15-bump WLP and no external Schottky array is needed. It is available from stock and priced at $0.65 (10,000-up). The MAX77756EVKIT# is available from stock and priced at $70.

More information is available at


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