Components

80V, 6A Synchronous Step-Down DC-DC in a 6mm X 6mm Package

The NCP4060 from ON Semiconductor is a 6A, 80V synchronous step-down converter capable of operating from 16V to 80V and can deliver 6A at 85 degrees C at common output voltage such as 5V, 12V, 24V. The device offers a 1%, 1.25V internal reference, which allows for accurate output voltages.

Two external resistors are used to set the output voltage. Other adjustable features include soft-start time, current limit, frequency, and UVLO. This IC is fully protected against overvoltage, undervoltage, overcurrent, and overtemperature conditions.

The NCP4060 is designed for use in cellular base stations and telecom / networking equipment in applications such as base station power systems, industrial power systems, 48-Vdc power architectures and so on.

There are a number of important factors and challenges to consider when adopting buck−boost topologies. The NCP4060 80V synchronous buck regulator includes integrated power FETs that can accommodate up to 6-Adc loads. It is an example of a device that provides the flexibility to down convert from high input voltages to negative output voltages just by exchanging Vout with Gnd on a buck.

Telecom vendors tend to adopt a two−stage design to generate a negative voltage rail for the GaN PA driver. The first stage steps down the input voltage (48- to 6- V typically) to 12V, followed by a second stage that generates −6.5V. Using a device such as the NCP4060, designers can consolidate this into one stage that takes the high input voltage and converts it down to a negative output voltage while sustaining good efficiency and offering a solution for space−constrained applications.

(click on schematic to enlarge)

The above inverting buck−boost topology is implemented with the NCP4060 with minor modifications to the buck circuit. The inductor is connected to GND and the NCP4060 is referenced to Vout. This reconfiguration in the design allows the output voltage to be inverted and always−below GND.

During the ‘ON’−Time the control switch is closed, the inductor sees the input voltage across it and current flows to charge it while the output capacitor supplies the load current. During the ‘OFF’−Time, the control switch goes open circuit and the inductor discharges to the load and the output capacitor via the Sync switch. Additional details are available in the NCP4060 Application Note.

Summary of NCP4060 features:

  • Wide input voltage range from 16V to 80V
  • Adjustable switching frequency from 100kHz to 500kHz
  • Lossless low-side FET current sensing for overcurrent protection
  • 25V 1% accurate internal reference voltage
  • External programmable soft-start
  • Output Over-voltage Protection and Under-voltage Protection
  • Internal thermal protection
  • Hiccup Mode Operation for all Faults
  • Pre-bias Start-up
  • Adjustable Output Voltage
  • Power Good Output
ON Semiconductor Corp.
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