TIP606 User Manual Issue 1.3
Page 13 of 15
5 Functional Description
U_in-
U_in+
R1
Differential Amp.
Schmitt-Trigger
+12V
V1
U_ref
V2
R2
R4
R5
R6
R3
R7
R9
R8
R10
Figure 5-1 : Input Circuit
The input stage for each of the 16 inputs consists of a Differential Amplifier V1 followed by a Schmitt-
Trigger V2. The Differential Amplifier provides a high impedance input for the input voltage. The input
impedance between U_in+ and U_in- is typically 112 kOhm. The Differential Amplifier amplifies only
the voltage difference across R2. The maximum frequency of the input signals should not exceed 10
kHz.
The thresholds of the TIP606 are determined by the resistor network around Opamp V2. At +25°C
ambient temperature the TIP606 will detect a high level typically at input voltages greater than 14.0V
and a low level at input voltages typically lower than 3.5V. These values can vary with the resistor
deviation (max +/-1%) and the operating temperature of the module (see product specification for
threshold bandwidth). The output voltage of each Schmitt-Trigger is fed to a separate optocoupler for
each input. The outputs of the optocouplers are connected to the inputs of a FPGA which are doing
the logic adaptation for the IP bus signaling.
To reduce power consumption of the TIP606 and avoid noise due to open inputs it is
recommended to connect unused U_in+ inputs to a signal level of 28V and U_in- inputs to the
respective ground signal.
The ground signal of the input signal source must be connected to the ground potential of the
input stage (pin 49 and 50 on IP connector P2) to guarantee the specified switching threshold
bandwidth.
