Single IC Power Solution Supports USB-C, PD 3.0, and QC 4.0 Applications

Active-Semi released the ACT4751, a 4.5V to 40V input high-efficiency, synchronous step-down dc-dc converter that supplies two additional output channels to support USB PD controllers such as the Cypress CCG3PA and active USB-C cable VCONN power requirements. The ACT4751 is fully integrated and controls the two integrated 50Ω MOSFETs. According to Active-Semi, the step-down dc-dc converter achieves the highest efficiency and enabling extremely compact designs.

The ACT4751 is a programmable step-down dc-dc converter that features bias supply rails for microcontrollers or USB PD controllers. The converter is a suitable solution for USB Power Delivery (PD) 3.0 and Programmable Power Supply (PPS) applications.

It uses a synchronous step-down (buck) voltage regulator architecture and integrates both the high-side and low-side MOSFETs. These 50mΩ RDS(on) transistors enable high efficiency to reduce power losses.

The ACT4751 integrates a 5V / 350mA mini-buck converter and a 20 mA AUX LDO to simplify application system designs. These rails can power up a controller and the 1.5W VCONN line in active USB-C cables.

The converter employs a multiple patent-pending proprietary control algorithm and is programmable via the I2C interface. The output voltage can be set in steps of 12.5mV from 3V to 24V, and the 4A output current can be adjusted with a 256-step resolution.

In addition, self-protection with thermal shutdown, under- and over-voltage protection and over-current protection with hiccup/latch off mode are integrated.

"Four of our ACT4751s have been demonstrated at the USB workshop in a four-port USB charging hub reference design. This total 175W power charger is USB-PD 3.0 certified by the USB-IF. The reference design supports two 80W USB-C PD channels and two 7.5W USB-A channels on a single board," stated David Briggs VP and General Manager of Power Solutions at Active-Semi. "This reference design and many others are available on our Web page."

The main buck converter can be dynamically programmed to an output voltage between 3V and 24V in 12.5 mV steps via the I2C or analog feedback. Also, it can dynamically program output current between 0A to 4A in 256 steps via the I2C in a constant-current (CC) operation mode.

The main-buck operates in a proprietary current mode control that supports external clock syncing for switching frequencies between 450kHz and 2.25MHz.

Features

• USB Certified Charger Design Available
• 50 mΩ Integrated High- / Low- Side FETs
• 4.5 to 40 V Operational Input Voltage
• 5 V Bias, 350 mA Buck Converter
• Programmable Output Voltage by I²C from 3 to 24V in 12.5 mV steps
• Programmable Output Current Limit from 0 to 4A in 256 Step Resolution
• Fixed-Frequency Current-Mode Control from 450k to 2.25 MHz with External Clock Sync, and a 100% Duty Operation
• Out of AM Radio / Spread-Spectrum Operation
• 20 mA AUX LDO Programmable Output Voltage from 0.9 to 4.0V
• I²C Interface, Fast-mode Plus (Fm+, 1 MHz) with Configurable Address
• Protections:
  • UVLO, OVP, UVP (Hiccup/Latch-off), OCP, TSD
• Thermally Enhanced 5×5 mm QFN Package

The ACT4751 is available in a small 32 pin 5x5mm QFN package.