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LMK04832-SP: RESET/GPO Question

Jack Zhang
Intellectual 540 points
Part Number: LMK04832-SP
Other Parts Discussed in Thread: LMK04832,

Hi,

I have verifying a design that includes the LMK04832 device. I am trying to assert the RESET to the LMK04832, but it doesnot generate the reset event. The schematic snippets of the RESET signal path are shown below - it is voltage translated from 1.5V to 3.3V and the signal also has a 10 Kohm pulldown in addition to AC termination. The voltage measured from the output of the voltage translator at R214 was ~1.945V when asserted, and 0V when deasserted, but the digital input VIH requirement is 1.2V min, so I am confused on why the reset is functioning properly. Could some tips be provided? Also, are there pull-up resistors (or any sort of terminations) that are internal to the LMK04832-SP device on the RESET/GPO pin?

Thanks!

  • +1
    TI__Mastermind 33430 points

    The RESET/GPO pin is programmable by register 0x14A. The default state for this register initializes the RESET pin as an input pin with an internal pulldown (range 50kΩ to 100kΩ, varies over PVT). Presumably you have not sent register programming to the device since you are resetting it via pin, but in case you have programmed anything to the device registers via SPI before toggling the RESET line, confirm that the RESET/GPO pin is still configured as an input.