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Original question:

TCA9509: A-side for Slave, B-side Master application

TCA9509: TCA9509

Jack Silson
Prodigy 20 points
Part Number: TCA9509

Hi,

I am looking to use the TCA9509 for HDMI DDC level translating from 5V to 3V3. With the B-Side connected to the HDMI connector and the A-Side connected to an FPGA.

What de-coupling capacitors (if any) are recommended for VCCB and VCCA. If VCCB is connected to the HDMI_5V rail, then surely any de-coupling capacitance here will affect the DDC limit of 50pF.

Please help me to understand how the TCA9509 can be used to pass HDMI compliance testing.

  • 0
    Guru 316920 points

    The 50 pF limit applies to the bus lines. But the decoupling capacitors are on the power rails. Just use standard 100 nF capacitors.

  • 0 in reply to Clemens Ladisch
    TI__Guru 53555 points

    Thanks Clemens!

    Hi Jack,

    I'm not familiar with HDMI compliance testing, but the DDC2 physical link is based on I2C so this buffer should serve the needs here well. Including this buffer will help with driving the relatively high line capacitance added by the HDMI cable by re-driving the data and buffering the capacitance added by the rest of the signal trances and devices on the local PCB. If there is any particular specification or test you are concerned about, please share details here and we can address it directly.

    Regards,
    Eric Schott