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Part Number: LMK03000CEVAL
Other Parts Discussed in Thread: LMK03000, LMK04832, USB2ANY


I see in the schematic of the LMK03000 evaluation board that the CLK,DATA and LE of the SPI bus are connected to big resistors (15K in series to 27K to GND).

Are these resistors required?

I am asking this because I looked at another evaluation board LMK04832 and I saw that in this evaluation board the signals are connected to 10 ohm serial resistor

Why is the difference ? If I use USB2ANY in both cases, shouldn't them have the same schematic?


  • Hello Yuval,

    The 15k and 27k resistors for the LMK03000 are not required if your microcontroller provides a voltage of 3.3 V to the SPI. If your microcontroller provides 5 V, then the 15k and 27k resistors are used as a voltage divider to divide the voltage down to 3.3 V.

    The 10 ohm resistor in the LMK04832 is a SPI line series resistor. This series resistor is used during high frequency communication, such as in SPI communication, and protects against high voltage spikes during communication. The series resistor is also used for impedance matching between the source and the load to maximize power transfer.

    If a USB2ANY provides 3.3 V to the SPI, then the schematics should be the same.


    Kia Rahbar

  • HI,

    I have a USB2ANY module. Does it provides 3.3V or 5V?

    If it can be both then how do I know if it is 3.3V or 5V?

    The part number of the USB is HPA665-001


  • Hello Yuval,

    The USB2ANY can provide both 3.3 V and 5 V. 

    To determine which voltage the USB2ANY is outputting, you must look at the device's pinouts. The pinouts for the USB2ANY are provided in the USB2ANY user guide. If you use the 10 pin configuration, the 3.3 V is supplied from cable pin 5 (shown below).

    For the 30-pin configuration, cable pin 15 provides 3.3 V and cable pin 3 provides 5 V (shown below).


    Kia Rahbar