DS90UB947-Q1: schematic review

Howdy!

I reviewed the schematic and here are the notes that I have:

- Pins 16 and 33 should be connected to a 1.8V supply instead of a 3.3V supply. The recommended range for this supply can be found under section 6.3 on the most recent datasheet on TI.com. The ferrite bead connected between the filter caps and the supply for these pins should be removed as our recommendation on the datasheet does not have a ferrite bead after the supply. In addition to this, our cap recommendation for these pins are a 1uF cap and a 0.1uF cap in series on each pin rather than two 10nF cap and one 1uF cap.

- Pins 24 and 62 are recommended on the datasheet to have one 10uF cap, one 1uF cap, one 0.1uF cap, and two caps within the range of 10nF and 0.1uF all in parallel. The schematic provided seems to have a few different cap values and an extra cap grounded between the supply and ferrite bead. In addition to this, the ferrite bead is recommended to have an impedance of 1k Ohms rather than the impedance of the current bead (33 Ohms).

- Pins 42 and 9 are recommended to have the same capacitor setup as pins 24 and 62, although the ferrite bead impedance should be 120 Ohms rather than 1k Ohms. The schematic provided seems to have a few different cap values and an extra cap grounded between the supply and ferrite bead.

- Pins 12, 17, 25, 28, and 21 should be connected to a parallel capacitor configuration with the following caps: one 10uF cap, one 1uF cap, one 0.1uF cap, and four caps within the range of 0.01uF to 0.1uF. The ferrite bead connected between the supply and caps on this node should have an impedance of 120 Ohms. Similar to the previous notes, the grounded cap between the supply and ferrite bead should be removed according to the recommended configuration on the datasheet.

- Pins 64, 50, and 61 should be connected to the same configuration as pins 12, 17, etc. Similarly, our recommendation is that there is no grounded cap between the supply and the ferrite bead.

- The schematic's PDB configuration seems to be okay, although the supply seems to be high. Our datasheet recommends a minimum Vhigh of 0.65 * VDDIO, and our example application uses a 1.8V supply.

- The supply connected to pin 49 should be 1.8V rather than 3.3V

All of these recommendations can be found in Figure 35 on page 67 of this device's datasheet. Please let me know if you have any other questions!

Best,

Cameron Carlson

hi Cameron

got it, thanks for your support.