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OMAP-L138 internal pull resistors

Michi Yama
Guru 10030 points
Other Parts Discussed in Thread: OMAP-L138, OMAPL138

Hi,

I have a question regarding the USB module of OMAP-L138.

The above figure is from USB 2.0 Specification. I understand USB FS/LS host controller must be connected DP/DM to GND through 15kohm resistor.

Also, according to the data sheet of OMAP-L138,  USB0_DM and USB0_DP signal has  the IPD resistor.

My customer uses OMAP-L138 as host controller. And customer would like to connect the HID class keyboard. The speed are LS and FS.

In the above situation,

1) Does customer need to add any external resistors to USB line for connecting LS/FS Keyboard?

2) What is the value of IPD of OMAP-L138? Is it 15kohm?

3) Are there other requirements for HID class keyoboard connection?

Please advise me.

I appreciate your quick reply.

Best regards,

Michi

  • 0
    TI__Guru**** 177836 points

    Michi-san

    1) Does customer need to add any external resistors to USB line for connecting LS/FS Keyboard?

    It depends on the LS/FS keyboard, if the LS/FS keyboard has built-in 1.5k pull up resistor, then no external pull-up resistor is required.

    2) What is the value of IPD of OMAP-L138? Is it 15kohm?

    Minimum value is 15k, typical value is 18k

    3) Are there other requirements for HID class keyoboard connection?

    This would depend on the HID class keyboard requirement. From OMAPL138, it needs to provide VBUS using external charge pump, and possible USB2.0 certified ESD protection circuit (if needed) on DP/DM.

    Thanks

    David