Question for LTC1605-1CG#TRPBF

Hi SK,

If you look at the block diagram, you will see that a voltage divider is formed by the 2.5V reference and 33.2k, 4k, 20k and 10k resistors. If you calculate the voltage at pin1 caused by this voltage divider it works out to approximately 0.8V. The input impedance of the LTC1605-1 is listed as 10k ohms. It is necessary to drive the analog input of this ADC with a low source impedance.

Hi ghoover,

Thank you for your response. OK. with your comment, approximately 0.8V is right at pin1. My customer's input range is 0.1V ~ 4V. There is a phenomenon that reads as 0.8V when 0.1V is applied. How should the circuit be configured to apply 0.1V?

If the customer's signal has a low source impedance like an op amp, it will overdrive the 10k impedance of the ADC. If the signal has a high source impedance, then it should be buffered with an op amp before it is applied to the ADC input.