Power supplies
TIA400 is supplied from the terminal block (green):
+VCC: Positive supply input. Connect this pin to a +12 V supply.
-VCC: Negative supply input. Connect this pin to a -12 V power supply or a -5 V power supply depending on the red switch position. -12 V supply is needed for bipolar operation. -5 V supply can be used to reduce power consumption in applications requiring only a positive output voltage.
Output buffer gain
The output buffer gains are adjusted with the switches (blue). The gain can be 1 (2 kV/A) or 5 (10 kV/A).
Connecting photodiodes
On the diagrams below Cd and Ccoax are the parasitic capacitance of the photodiode and the coaxial cable, respectively.
Single-ended photodetector
Balanced photodetector
Coaxial cable length and input capacitance
The input capacitance is Cin = Cd + Ccoax for a single-ended photodetector and Cin = 2 Cd + Ccoax for a balanced photodetector. The TIA400 is stable with input capacitances up to 200 pF.
For a typical 50 Ω coaxial cable, the capacitance per unit of length is 1 pF/cm. Note that no specific characteristic impedance is required for the input coaxial cable.
