Hi!We wanna use the LTC2439-1 configured with 16-Channel Single-Ended Inputs, the Reference-Voltage is 5.0V and the Input-Channel Voltages are from 0-5.0VBut the datasheet does not clearly describe the function for us with this configuration.We are not sure if the LTC2439-1 converts a Input-Channel Voltage from 0-5V (CHx/COM) to a 16-Bit result (with the above decribed configuration) ?Or the channel voltage must be between -FS (-0.5 * Vref) and +FS (0,5 * Vref) ?Thank you !Martin
The absolute input voltage range for IN+ and IN- is GND-0.3V to VCC+0.3V so the input voltage range will be 0-2.5V with COM grounded. This is a bipolar part. With COM grounded you will have access to only half the input range.
Thank you for your reply ghoover !The absolute input voltage range is clear described in the datasheet, we understand this.We also suspect, that a input voltage of 0-5.0V (with Single-Ended-Inputs and Reference-Voltage of 5.0V) is converted into a 16-Bit value of 0-65535.But we are not sure, because we don`t find a clear statement for the conversion in Single-Ended mode in the datasheet.On some paragraphs in the datasheet the conversion is described for the bipolar differential input signal, but not for the single-ended.Only in the datasheet under "Input Data Format" (page 11, third paragraph) there is a indication to single-ended conversion.So can you confirm that a input voltage of 0-5.0V (with Single-Ended and Reference-Voltage of 5.0V), is converted into a 16-Bit value of 0-65535 ?Thank you !!
My earlier reply was incorrect and I have edited it so that it does not confuse anyone else. This is a bipolar part. The input range is -0.5VREF to +0.5VREF. To use the full range of this part with COM held constant, it is necessary to bias COM at REF/2. The CH0 to CH15 inputs can then swing from 0-Vref.
The output code is a 19-bit digital word. Bit 18 is an end of conversion signal. Bit 17 is a dummy that is always zero. Bit 16 is a sign bit that in conjunction with Bit 15 can be used as an over range and under range indication. Bit 15 through Bit 0 are the 16-bit data in two's complement format.