Hello, We are having a problem getting the TI TUSB2046B to output the VID and PID from the EEPROM. We have used the same circuit as laid out in Figure 8 of the TI TUSB2046B data sheet. We are using the VQFN32 TUSB2046B and an SOIC8 ST Micro M93C46 (called out in the data sheet) and M93C76 (same family, larger memory size, better availability). When we boot up our board we almost always see a VID of 0x0000 and a PID of 0x0000. If we turn the power off and on VERY quickly, many times the correct (custom) VID/PID (read from the EEPROM) will display in our USB viewer program. Another oddity is that I have to shift the VID and PID over by one nybble (4 bits) when I program the EEPROM vs what Table 1 shows for an EEPROM Memory Map to get it to display correctly.
So, if I want to program a hypothetical:
Address Contents
00000 0000 (USB power ports not GANGED, they are individual)
00001 ABCD
0002 WXYZ
I need to burn the EEPROM with:
000A
BCDW
XYZ0
We've tried many different EEPROMs and contents, as well as changing the 1K resistor between pins 3 and 4 on the EEPROM (in TI TUSB2046B data sheet, Figure 8; I've read that 1K may be too strong so we tried a 4.7K so far), to no avail. Originally we had the DU pin (7) of the M93C76 EEPROM attached to GND, but have since lifted it so it is floating now, which the EEPROM seems to prefer.
Help would be greatly appreciated.
