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LMK3H0102: REF_CTRL as CLK_READY output.

Tim Peng
Prodigy 150 points
Part Number: LMK3H0102
Other Parts Discussed in Thread: USB2ANY

Tool/software:

Hi 

Regarding REF_CTRL as CLK_READY output for LMK3H0102. 

As datasheet mentioned it is an active high signal. But what is the voltage level and output type ( open drain or push-pull)? Can I use this CLK_READY to drive a LED with proper current-limit resistor? 

  • 0
    TI__Mastermind 22430 points

    Tim,

    This pin is push-pull and the voltage level is VDD.

    How much current is needed to drive this LED? It may be feasible.

    Thanks,

    Kadeem

  • 0 in reply to Kadeem Samuel
    Prodigy 150 points

    Less than 5 mA is sufficient. 

    Where to find such pin current sinking characteristic in the LMK3H0102 datasheet? 

  • 0
    Prodigy 150 points

    Hi Kadeem, 

    by the way, could you please also help to reply: 

    (1) we prefer to use USB2ANY to control LMK3H0102,  is the I2C signal level 3.3V and already pull-up at USB2ANY?

    (2) In above case, if I don't  want to add extra level shift, the only VDD option  of LMK3H0102 is 3.3V? Is my understanding correct? 

    (3) regarding connection interface to USB2ANY (like J4 in SNAU287 EVM guide), please help to confirm that

    (3.1) I only need  I2C_SDA, I2C_SCL, GND. 

    (3.2) +3.3_EXT, GPIO2, GPIO3, GPIO4, GPIO5, GPIO6, GPIO7 are not required in any case like attached table.  

  • 0
    Prodigy 150 points

    Hi Kadeem, 

    could you please also help to reply: 

    (1) we prefer to use USB2ANY to control LMK3H0102, is the I2C signal level 3.3V and already pull-up at USB2ANY?

    (2) In the above case, if I don't want to add extra level shift, the only VDD option of LMK3H0102 is 3.3V? Is my understanding correct? 

    (3) regarding connection interface to USB2ANY (like J4 in SNAU287 EVM guide), please help to confirm that

           (3.1) I only need  I2C_SDA, I2C_SCL, GND. 

           (3.2) +3.3_EXT, GPIO2, GPIO3, GPIO4, GPIO5, GPIO6, GPIO7 are not required in any case like attached table. 

    (4) Is CLK_READY feasible to drive a LED less than 5 mA ?

    (5) Regarding IDDREF in datasheet, does it belong to VDD or VDDO? 

  • 0 in reply to Tim Peng
    TI__Expert 6065 points

    Tim,

    Tim Peng said:
    (1) we prefer to use USB2ANY to control LMK3H0102,  is the I2C signal level 3.3V and already pull-up at USB2ANY?

    Yes the USB2ANY operates at 3.3V and has internal pullups for the SDA/SCL lines. Though it is best practice to include depopulated pullup resistors for debug purposes.

    Tim Peng said:
    In above case, if I don't  want to add extra level shift, the only VDD option  of LMK3H0102 is 3.3V? Is my understanding correct? 

    Correct, the SDA/SCL lines require 3.3V

    Tim Peng said:
    I only need  I2C_SDA, I2C_SCL, GND.

    Correct

    Tim Peng said:
    +3.3_EXT, GPIO2, GPIO3, GPIO4, GPIO5, GPIO6, GPIO7 are not required in any case like attached table.

    Correct. The USB2ANY uses the USB/Computer connection to supply the 3.3V. The rest of the GPIO pins can but used but are not required for I2C communication

    Best,

    Cris

  • 0 in reply to Cris Kobierowski
    Prodigy 150 points

    Thanks, please also reply these two questions: 

    (4) Is CLK_READY feasible to drive a LED less than 5 mA ?

    (5) Regarding IDDREF in datasheet, does it belong to which domain VDD or VDDO? 

  • +1 in reply to Tim Peng
    TI__Mastermind 22430 points

    Tim,

    CLK_READY is feasible for driving a <5mA load. The driver during CLK_READY operation is the same as the one during LVCMOS clock operation for this pin.

    IDDREF is sourced from the VDD domain.

    Thanks,
    Kadeem