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ADC128S102EVM pin description

Nam Nguyen73
Prodigy 80 points
Other Parts Discussed in Thread: ADC128S102, ADC128S102EVM

Hello,

Please verify some information.

1. ADC128S102 has 8 channels, but I only see 7 input channels on J1?

2. I will connect my 8 input data source to ADC128S102EVM and use ProASCI3 Stater kit  A3PE-Starter-Kit-2 from Microsemi  to read my data source through the ADC board. I can not find the pin, jumper, power level descriptions of the Eval board. Please show me the link to get these information.

Thanks,

Nam Nguyen

  • 0
    TI__Mastermind 25900 points
    Nam
    you are correct and unfortunately the evm does not appear to be an ideal tool for your needs. in order to satisfy a larger application audience, one of the inputs to the ADC is connected to the on board temperature sensor. therefore, you are correct that J1 only provides access to 7 of the 8 channels.
    the input signal level that you can provide to the ADC input varies on this board. I see that the user's guide does not spell this out specifically and I am answering your question by reading the evm schematic on page 19 of the user's guide. the channels that are connected to amplifiers will be limited by the supply voltage of the amplifiers and that is 3.3V. there is a jumper called JVA which selects the voltage for VA. if pins 2 and 3 are shorted, the on board 3.3V regulator is selected for VA and thus the direct inputs to the ADC also need to be limited to 3.3V.
    From the EVM schematic, it appears that 3.3V was the assumed supply voltage for the system. I can imagine that you may want to power at 5V and drive the inputs with signal levels up to 5V. if that is the case, you would need to make some modifications to the EVM.
    Sorry, our evm does not seem ideally suited for your needs.
    Chuck
  • 0 in reply to Chuck Sins
    Prodigy 80 points
    Hi Chuck,

    Thank you for your answer. I was out of office last few days so I did not reply. So, let me verify. The evm board needs 3.3 V and I think it provides for both analog and digital sides. 3.3 V will be connected to VA-EXT connector. There are 7 inputs. Are they single or differential?

    My FPGA board communicate with ADC evm board via SPI bus, so I can connect SPi Bus Clk to JA7, SPI Bus Chip Enable to JA2, SPI Bus Write to JB6 and JB7 to SPI Bus Read. Please veify.

    Thanks,

    Nam Nguyen
  • 0 in reply to Nam Nguyen73
    TI__Mastermind 25900 points
    to be clear, the device itself has 8 single ended inputs, the EVM on J1 connects you to 4 single ended buffers, 2 direct connections (unbuffered), and one differential input (2 pins feed a difference amplifier), the 8th channel of the adc is connected to the onboard temp sensor
    chuck
  • 0 in reply to Chuck Sins
    Intellectual 510 points

    Hi chuck,

    sorry , I didn't understand the previous Point of ADC Voltage.

    if I connected VA External with 5v , Does this Enable me to connect analogue input with 5v to the Kit ?
    and which Analogue Input pins Can work with 5v ?

    as I have a Analogue Device worked with 5 volt and I need to connect it with tiva-c with this Adc kit.

    Thank you in advance.

  • 0 in reply to ibrahem mostafa
    TI__Genius 16890 points
    If you have VA set to 5V, you can use IN4 and IN5 with inputs up to 5V. IN0 - IN3 and IN6 are limited to 3.3V because of the op amp that is in the signal path, which is powered by a 3.3V supply. Putting 5V on IN0 - IN3 and IN6 will damage the op amp. If you want to use these inputs with a 5V input signal, you will need to modify the board.

    Mike