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SN65DP159: OE pin Low but I2C lines high

Malsekar Karthik Krishna
Prodigy 150 points

Part Number: SN65DP159

Hi Team,

I am using SN65DP159 for my HDMI application, where i assume, the OE pin in the IC acts as a RESET pin for the IC SN65DP159.
I have connected a RC time delay circuit to allow a 2ms delay or for the IC to be in RESET state until my other voltages are stable. In this case, whether the I2C lines of the IC be already pulled high before the 2ms? Since, the IC will be getting VCC input instantly although to come out of RESET, it will take around 2ms.

Attached is the image of the IC time delay circuit, requesting your valuable support here.

image.png

Regards,
M Karthik

  • 0
    TI__Guru**** 189841 points

    M Karthik

    The DP159 has internal pullup of 200k, so external pullup resistor (R36) is not needed and only pulldown capacitor is needed. When implementing the external pulldown capacitor, the size of the external capacitor depends on the power-up ramp of the VCC supply, where a slower ramp-up results in a larger value external capacitor. Refer to the latest reference schematic for SNx5DP159; consider approximately 200-nF capacitor as a reasonable first estimate for the size of the external capacitor. 

    When OE is low, SCL_CTL and SDA_CTL are disabled as shown below. SCL_CTL and SDA_CTL are also failsafe I/O pins so it is ok for them to be pulled up when OE is low, in reset. 

    Thanks
    David