Isolated Input (Version 4)

Applies to Closed3621 Coaxlink Mono CXP-12, 3621-LH Coaxlink Mono CXP-12 LH, 3622 Coaxlink Duo CXP-12 and 3622-LH Coaxlink Duo CXP-12 LH.

Isolated current-sense input with wide voltage input range up to 30V, compatible with totem-pole LVTTL, TTL, 5V CMOS drivers, RS-422 differential line drivers, potential free contacts, solid-state relays and opto-couplers

Simplified schematic

Input Current vs. Input Voltage Characteristics

DC characteristics

Parameter Conditions Min. Typ. Max. Units
Differential voltage   -30   +30 V
Input current threshold     1   mA
Differential voltage @1 mA 1.5 1.65 1.9 V
  Input current @(VIN+ - VIN-) < 1 V     10 µA
@(VIN+ - VIN-) = 1.65 V   1   mA
@(VIN+ - VIN-) = 2.5 V   2   mA
@(VIN+ - VIN-) = 5 V   2.3   mA
@(VIN+ - VIN-) = 12 V   3   mA
@(VIN+ - VIN-) = 30 V     5 mA

AC characteristics

Parameter Conditions Min. Typ. Max. Units
Positive pulse width   10     µs
Negative pulse width   10      
Pulse rate   0   50 kHz
Turn-ON delay1

30°C; 50 kHz; 2 V square wave signal
LineFilterStrength = Lowest

(LineFilterDelay = 500 ns)

   6.9   µs
Turn-OFF delay2   9.8   µs
1. The "Turn-ON" delay is defined as the time difference between a transition of state at the input that turns ON the opto-coupler and the subsequent transition in the FPGA.
2. The "Turn-OFF" delay is defined as the time difference between a transition of state at the input that turns OFF the opto-coupler and the subsequent transition in the FPGA.

These delays include the delay introduced by the digital line filter controlled by the LineFilterStrength GenApi feature!

Isolation characteristics

Parameter Value
Isolation grade Functional
Max. DC voltage 250 V
Max. AC voltage 170 VRMS

The functional isolation is only for the circuit technical protection. It does not provide an isolation that can protect a human being from electrical shock!

Logical map

The state of the port is reported as follows:

Input current Logical State
IIN > 1 mA HIGH
IIN < 1 mA LOW
Unconnected input port LOW

Compatible drivers

The following drivers are compatible with this version of the isolated current-sense inputs:

● Totem-pole LVTTL, TTL, 5 V CMOS drivers
● RS-422 Differential line drivers
● Potential free contact, solid-state relay, or opto-isolators
● 12 V and 24 V signaling voltages are also accepted
□ The +12 V power supply on the I/O connector(s) can be used for powering drivers requiring a power supply.
□ No external resistors are required. However, to obtain the best noise immunity with 12 V and 24 V signaling, it is recommended to insert a series resistor in the circuit. The recommended resistor values are: 4.7k Ohms for 12 V signaling and 10k Ohms for 24 V signaling.