April 6 2016
Today's task: Copy the USB hub from the LaunchPad. The USB hub provides just the PHY network layer and relays the data to one of four USB peripheral devices. In this case, port 1 is the control 5529, port 2 is the ezFET 5528, and devices 3 and 4 are not connected.
15:00> First I create the USB hub component (TI TUSB2046BIRHBIRHB).
"TUSB2046B" is the basic part number. "I" indicates the long-life
version rated for "Level-2-260C-1 Year", without the "I" is slightly
cheaper and rated "Level-3-260C-168 HR". "RHB" is the compact VQFN
package and "VF" is the LQFN package with legs. The legs make it
easier to verify the placement of the part, so I will go
would have gone with TUSB2046BIVFR -- except that part is marked as
"not recommended, end of life". So I will use exactly the same part as
the LaunchPad: TUSB20246BIRHBIRHB.
15:30> After spending half an hour deciphering the product codes, I am ready to create the component.
15:37> USB hub component is done, drop it onto the USB sheet.
15:39> Create the TPS62237DRY power regulator, TPD2E001 ESD array, and microUSB jack components. The USB connector requires a bit of artwork.
16:48> Start wiring the components together.
Replaced R401 33ohm resistor between the USB shield and the GND pin with 27ohm to reduce the part count.
CAP403 Digikey 493-4142-1-ND is no longer available, replaced with 718-1146-1-ND CAP TANT 4.7UF 10V 10% 1206
Replaced all the 22ohm data line resistors with 27ohm to reduce the part count.
Could I replace C405,C406 from 22pF to 33pF? Or replace C123 from 33pF to 22pF?
Replaced all 15K data line pull-down resistors with 20K to reduce part count.
21:30> My first draft of the USB hub circuit.
It seems as though the whole RC filter on the hub port 1 is duplicated unnecessarily in both the 5529 and Hub sheets. This is present in the original LaunchPad schematic. I suspect I could remove the RC pairs from the 5529 sheet, saving 4 components. I will leave them in place for the first version.
April 24 2016
The USB hub after condensing the hub and microUSB jack.
