Post Go back to editing

LTC1605

Hello! I am using two LTC1605ACG ADCs, they work in parallel with each other. They are controlled by a common R /C signal, the CS signal turns on the conversion and read mode sequentially for each ADC. After a while, the value at the ADC outputs becomes 801F and is held for about 2 s. Tell me this is due to the peculiarity of the ADC?

Parents
  • Hi,

    I am not aware of such a peculiarity in the LTC1605. What is the input voltage when this occurs? Does your PCB have a solid ground plane? You say after a while this occurs. Is it always the same amount of time? After 2 s do the ADCs go back to reading properly?

    Can you provide a schematic of your circuit and oscilloscope waveforms showing R/C, both CS and one of the BUSY? Also, if you have a logic analyzer provide a waveform showing R/C, CS, BUSY and D15-D0.

  • Good day! Input voltage = 0, Vin is connected to AGND. There is a grounding plate. The files contain oscillograms RC&CS, CS & BUSY, CS & BYTE. The ADC connection diagram corresponds to the description on the microcircuit. Data reading from the ADC is 8-bit when BYTE = 0 and when BYTE = 1 and CS = 0. The graph shows spikes when the ADC outputs 801F, at different intervals, then goes back to normal operation.  CS&RC (CS Blue)CS&BUSY (CS Blue)CS&BYTE(CS blue)
  • Hi,

    Your schematic doesn't show any bypass capacitors on the supplies, CAP or REF pins. Do you have capacitors there and if so what are the values?

    Do you have the voltage divider from VIN to CAP shown in the data sheet?

    What is generating the 5V supplies?

    Are you driving REF externally and if so, with what?

    Can you provide a more detailed photo of RC and CS? I need to be able to see the time between the two falling edges to make sure the setup time is adequate.

    Can you provide a photo of your setup? 

    What is driving R/C, CS and BYTE?

Reply
  • Hi,

    Your schematic doesn't show any bypass capacitors on the supplies, CAP or REF pins. Do you have capacitors there and if so what are the values?

    Do you have the voltage divider from VIN to CAP shown in the data sheet?

    What is generating the 5V supplies?

    Are you driving REF externally and if so, with what?

    Can you provide a more detailed photo of RC and CS? I need to be able to see the time between the two falling edges to make sure the setup time is adequate.

    Can you provide a photo of your setup? 

    What is driving R/C, CS and BYTE?

Children
No Data