How can I add additional components and connections to make this USB hub functional?
The datasheet of this particular chip lacks several design details that you can find in the FE2.1 datasheet, which is from the same family of products but offers 7 downstream USB ports.

Now then, as it was said before, the chip includes both 3.3V and 1.8V LDO internal regulators. That means there's no need for a volage divider to feed that part of the circuit, but we do still need a voltage divider for another purpose.


"VBUSM" pin monitors the V+ line of the upstream USB port. For safety reasons the use of this pin is mandatory if the devices is bus powered. The problem is that we can't connect it directly to 5V as the chip operates on a 3.3 voltage level, to do that, we need a voltage divider. The values suggested by the manufacturer for this divider are 47K for R1 and 100K for R2, which creates an output of around 3.4 volts with an output impedance of 31.9K ohms.
"REXT" pin creates an internal voltage reference for the chip internals. Use a 2.7K 1% tolerance resistor to connect it to ground.
"XRSTJ" will reset the chip when pulled low. Connect this pin to 5V with a 100K resistor to avoid a reset loop.
"TEST" pin is only present in the LQFP package, and it should be pulled low for regular operation.
"BUSJ" acts as a bus power indicator to the chip. When pulled up to 5V with a 100K resistor, it tells the chip the hub is "Self Powered", and when pulled down to ground with a 10K resistor, it tells the chip the hub is "Bus Powered". The manufacturer indicates there's a third way to combine both states, but it's considered unsafe.
"VDD5" is a 5V input for the 3.3V LDO. Then, the 3.3V LDO output is connected to the input of a 1.8V LDO. The outputs of these LDOs are connected to "VD33_O" and "VD18_0". They should be wired to "VD33" and "VD18" respectively. Each power line needs a 10uF decoupling capacitor.
"PWRJ" is an output pin intended for Ganged Power Switching (Downstream ports overcurrent protection). If you choose to implement this protection in your circuit, it works as follows: When "OVCJ" input pin is pulled low, PWRJ will be pulled up. This signaling scheme is compatible with most electronical switches. If you don't want to include this protection in your circuit, leave PWRJ floating and connect OVCJ to 3V3.
The EEPROM is optional if you want to provide custom device information. If you choose to not include an EEPROM and operate the chip with the default descriptors, leave "TESTJ" pin floating.
LED1 and LED2 high voltage can be anywhere from 2V to 5V. Connect them through a 330 ohm resistor to avoid over current.


This chip has a lot to offer, but it has some flaws, one being the lack of information on the chip and the cheap LDOs with usually terrible tolerances that are used inside of the chip.

Here's the Self Powered recommended application.



USB6 is used as a power input.

If you want to create a Bus Powered hub, leave USB6, C9 and R5 out, connect USB5 VCC to the 5V line, swap C4, C5, C6, C7, and C8 with 2.2uF capacitors and pull BUSJ low with a 10K resistor.

Theres a third way to configure the chip to use both Bus Powered and Self Powered modes, but it caused instability when I tested it. Nonetheless, it was used in the official demo board. To do this third configuration, connect USB5 VCC to the circuit through a 2A 220 Ohm Ferrite Bead. Fine tune C8 and then connect VDD5 to 5V through a low forward voltage Schotkky Barrier Diode with the cathode facing the 5V net. Remember to pull BUSJ up with a 100k resistor.