The LOG200 has a maximum supply voltage of 12.6 V (±6.3 V) and a minimum supply voltage of 4.5 V (±2.25 V). The device has two VCM pins (not internally connected to each other). Drive both VCM pins to the same potential by one of the two onboard voltage references, or by an external source. Likewise, drive the reference input of the difference amplifier by a reference or other low-impedance source. For proper operation, do not float the VCM, VCM2, and REFA pins.

Typically, apply the test current to be measured through the I1 input. Apply a fixed reference current, whether external or provided by the onboard IREF, through the I2 input. Two external currents can be measured through I1 and I2, but only the logarithmic ratio of the two currents can be measured, rather than the absolute values of either. The IBIAS feature is used to provide a reverse voltage bias for an input photodiode. If not used, float the IBIAS pin or connect the pin to the positive supply voltage V_S+.

The LOG200 also features an auxiliary amplifier that is used to create a differential output voltage or for any other purpose in the system (provided the amplifier input common-mode limitations and other conditions are met). If the auxiliary amplifier is not needed, apply a midsupply voltage or one of the onboard reference voltages to the noninverting input to keep the auxiliary amplifier fixed within the input common-mode range. Short the output and inverting input together, which causes the amplifier to act as a buffer in a known state, rather than float the pins, which can lead to erratic behavior in noisy environments.