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ADS1675REF: Current Limit

Part Number: ADS1675REF
Other Parts Discussed in Thread: THS4503


Good Day.

Customer is using an ADS1675REF board. He is wondering what the current limit to expect/set on the analog input +5V driver is?

Section 3.2 of the manual: "The ADS1675REF board requires an independent analog +5V supply to power the analog portion of the device under test, the external reference, and the external reference buffer, as well as provide the amplifier common-mode voltage. This voltage is applied to J5 pin 3 and is denoted as +5VA. This supply can be monitored at TP7"

This is the driver for the +-2.5V differential analog input. So a power supply not a signal input?

Please advise. Thank you very much.

Best Regards,

Ray Vincent

  • Hi Ray,

    The ADS1675REF is pre-configured to use a single 5V supply connected to J5, +5VA.  There is a resistor on the board that connects the analog and digital 5V supplies together.  This same 5V is also provided to the XEM3010 data capture card through jumper JP4 and the XEM3010 regulates this supply to 3V and provides it back to the EVM through JP2.  

    So, by default, all supplies except the THS4503 input amplifier are powered from this single 5V supply.  In this case, you should set the current limit to 400mA to power the XEM3010 board, and all circuitry on the ADS1675REF board except the THS4503.

    The details are in section 3 of the user's guide:

    If you want to use the THS4503 amplifier, then you also need to supply +9V and -4V to J4 as well.

    If the customer is asking how much current is needed to drive the ADS1675REF analog inputs on SMA connectors J1 and J3, then the maximum can be about 14mA.  This is due to the THS4503 resistor network, and would occur with a +/-3V single ended input signal on J1 with J3 connected to ground.

    Keith Nicholas
    Precision ADC Applications