TUSB8020B: Question of IBIS model and Internal/External pull-up/down resister value.

Motoyasu Hattori said:

1. IBIS Model : usb2_HS_R / usb2_HS_RC

We can find the two models of USB2.0 High speed mode, usb2_HS_R and usb2_HS_RC.  What is different?

In other words, What does "recommended C load of 1pF" mean?

|   USB 2.0 High Speed mode, for DP pin 240MHz (Internal Termination ON) with

|   recommended C load of 1pF.

This means model has a Cload, the other does not, similar to this load as shown in the USB 2.0 specification:

Motoyasu Hattori said:

2. IBIS model : C_comp on usb2_HS_R / usb2_HS_RC

My customer simulates his board with IBIS model.  However, he doubts too C_comp value (around 6pF).  He thinks C_comp is usually <1pF on other devices (such as I2C pin etc.).  Please let us know your comments.

This is the correct value for these pins.

Motoyasu Hattori said:

3. Iozp condition

On the TUSB8020B datasheet P.7, we can see the following.

My understanding is "MAX Iozp is max current value from pin to external while Input voltage moves from 0V to VDD33 (3.3V)."   Is it correct?  Please let us know.

This determines the min / max value of the internal pullup / pulldown resistors

Motoyasu Hattori said:

4. Internal PU/PD resister value

Could you please let us know the internal PU/PD resister value?

14.67K min, but 22K typical

Motoyasu Hattori said:

5. External Pull-up/Pull-down resister value.

On the datasheet P.26,27, 4.7kohm resisters are used on the following pins.

GANGED / SMBA2 / HS_UP : 4.7kohm external pull-down

FULLPWRMGMTZ / SMBA1 / SS_UP : 4.7kohm external pull-down

PWRCTL1 / BATEN1 : 4.7kohm external pull-up

PWRCTL2 / BATEN2 : 4.7kohm external pull-up

Yes, these are the suggested values, but pullups on the PWRCTL/BATEN lines will enable battery charging mode.

Regards,

JMMN