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3.3 V power supply on LX16EVK01

Marc Koltermann
Prodigy 40 points
Other Parts Discussed in Thread: DS92LX1621

I tested this evalkit with 1.8 V power supply. The Jumper JP2 was connected to VDDI and +1.8 V and the supply to J3 and J4. The supply current was 40 - 50 mA per board. The level of the inputsignals was 0- 1.8 V and everything worked without any problems.

Now I tried to operate this evalkit with 3.3 V power supply. I connected the 3.3 V power supply to JP1 connectors  and 1.8 V supply to J3 and J4. The Jumper JP2 is connected to +3.3V and VDDI. Now the supply current increased to 80 mA per board. Both Leds on the deserialiserboard was glowing brighter than with 1.8 V supply. The level of the inputsignals was 0- 3.3 V. It was not possible to transmit any signals.

Do I have to change any settings to operate this kit with 3.3 V?

  • 0
    TI__Expert 7395 points

    Hi Marc,

    Just to clarify, the VDDI/VDDIO on JP2 sets the I/O supply voltage for interfacing 3.3V or 1.8V logic I/O to upstream/downstream devices. The DS92LX1621/2 operates off a single 1.8V core power supply. In addition, the VDDIO voltage may different on either serializer/deserializer sides since the boards are separated.  For example, the serializer VDDIO=3.3V and Deserializer VDDIO=1.8V or vice-versa. So to configure serializer for 3.3V I/O, short JP2 to +3.3V and provide 3.3V supply on JP1 with 1.8V on J3. Make sure the single-end signals to DINn and PCLK are swinging levels from 0~3.3V. For the deserializer, either the 1.8V or 3.3V logic can be used depending driving peripheral. Note the 1.8V core supply current should not vary; since the VDDIO is sourced on a separate power supply. Based on your description, seems you are also running the deserializer at 3.3V I/O and therefore the LEDs are brighter (vs the 1.8V I/O).

    Dac Tran

    SVA / APPS