I am connecting a 10k potentiometer to an ADC chip (LTC1273BCN) that has a 12-bit parallel output, like in the diagram at the end of the post. The 12-bits will be connected to an FPGA input bus after I can get it to work correctly. The ADC chip circuit is powered off a stable 5V from a lab benchtop power supply.
I have tied the CS and RD inputs low as I thought this will continuously run the conversion but maybe this is my problem, I am unsure.
When I measure the voltage of the 12 output pins, only pin 14 (D2) seems to be high, the rest are 0V. The Ain voltage is perfect between 0 and 4.99V from the potentiometer, and I have tied the HBEN input to 5V as I want to use all 12-bits in one conversion.
Any advice as to how to use this chip correctly? Will I have to pulse the CS and RD inputs low to get the chip to behave as I would like? I don't really want to use signals from the FPGA to control the analog to digital conversion.
Below is my reasoning behind the pin connections:
Pin 1 : 0V to 5V from potentiometer, to be converted to 0 to 4095 by ADC chip.
Pin 2 : I haven't used this pin but have attached capacitors to pin 3 according to datasheet.
Pin 3 : Tied to analog ground which is the same ground as chip supply.
Pins 4 to 11 : D11 to D4 output bits are left unconnected.
Pin 12 : Tied to ground of power supply.
Pins 13 to 16 : D3 to D0 output bits are left unconnected.
Pins 17 and 18 : Left unconnected as in datasheet.
Pin 19 : Tied to 5V to use the full 12 bits in one conversion instead of splitting into 2 conversions in one byte.
Pin 20 : Tied to ground for continuous conversion ( if this is possible).
Pin 21 : Tied to ground to allow for continuous conversion ( if this is possible).
Pin 22 : Left unconnected as I am not using it.
Pin 23 : NC
Pin 24 : +5V from power supply to power up ADC chip.