Fixed Power Allocation Scheme for 2C and 2C1A Using Dual Buck Converters
8 12, 2025
Dual Buck + HUSB380B 2C Fixed Power Allocation Scheme
In this solution, two HUSB380B chips can be interconnected via the FC pin for device insertion detection. The design supports charging devices over a 3-meter cable, delivering 65W on each USB-C port when used individually. When both ports are in use simultaneously, the power output is fixed in a reduced configuration—for example, 45W (C1) + 20W (C2) or 30W (C1) + 30W (C2). The demo below illustrates the 45W (C1) + 20W (C2) scenario under dual-port operation.
For USB PD protocol handling, the HUSB380B requires only a single SMD capacitor externally. It integrates the VBUS MOSFET, current-sense resistor, and loop compensation RC network, enabling a near-zero external component design and greatly simplifying PCB layout.
Figure 1: 2C Cascaded Block Diagram Implemented with Dual Buck and HUSB380B
Figure 2: 2C Cascaded Demo Board Implemented with Dual Buck and HUSB380B
Program Measurement
This dual-Buck converter solution with HUSB380B implementation features a fixed power allocation scheme for 2 cascaded USB-C ports. The system delivers 65W fast charging when using either port individually, and automatically adjusts to 45W (C1) + 20W (C2) power distribution when both ports are simultaneously connected.
Figure 3: Single-port (C1) Output at 65W
Figure 4: Single-port (C2) Output at 65W
Figure 5: Dual-Port Mode (C1: 45W, C2: 20W)
Dual Buck + HUSB380B+HUSB382D 2C1A Fixed Power Allocation Scheme
Dual Buck_65W 2C1A_power down program, using Wisers HUSB380B+HUSB382D cascade, when used alone any C port can output 65W, and single-plugged use of each port can enter the fast charging. Dual-port use, the same plug C1 + C2 or C1 + A can also be fast-charging and fixed allocation of power (eg: 45W + 20W); three-port same plug fixed allocation of power 45W (C1) + 15W (C2 + A) and so on. The program can be interconnected between the two chips FC pins through a wire, the device is inserted into the automatic detection. Very few peripheral devices, debugging is extremely simple. USB PD protocol part, the same can do zero peripheral, greatly reducing the size of the PCB board.
Figure 6: Block diagram of 2C1A cascade realized with dual Bucks and HUSB380B+HUSB382D
Figure 7: 2C1A Cascade Demo Board with Dual Bucks and HUSB380B+HUSB382D Implementation
Program Measurement
Adopt double Buck and HUSB380B+HUSB382D to realize 2C1A cascade fixed distribution power scheme, single plug any C port can realize 65W fast charging; double port same plug C1 port output 45W, C2 port output 20W; double port same plug C1 port output 45W, A port output 20W; three ports same plug when the fixed distribution of power 45W (C1) +15W (C2 + A).
Figure 8: Single-port (C1) Output at 65W
Figure 9: Single-port (C2) Output at 65W
Figure 10: Single-port (A) Output at 65W
Fig. 11: Dual-port co-plugged C1 port output 45W, C2 port output 20W
Figure 12: Dual-port co-insertion 45W on port C1, 20W on port A
Figure 13:Three ports are plugged into the same C1 port output 45W, C2 and A port share 5V
