A-2 Digital I/O [T-Series Datasheet] | LabJack
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A-2 Digital I/O [T-Series Datasheet]

General Info

T-series Digital Input/Output lines information:

Table A2-1. IO Information

Parameter Conditions Min Typical Max Units
Low Level Input Voltage   -0.3   0.5 Volts
High Level Input Voltage   2.64   5.8 Volts
Hysteresis Voltage [1]          
---Low to High Transition       1.15 Volts
---High to Low Transition   0.90     Volts
Maximum Input Voltage [2] FIO -10   10 Volts
  EIO/CIO/MIO -6   6 Volts
Output Low Voltage [3][4] No Load   0.01   Volts
---FIO Sinking 1 mA   0.55   Volts
---EIO/CIO/MIO Sinking 1 mA   0.15   Volts
---EIO/CIO/MIO Sinking 5 mA   0.75   Volts
Output High Voltage [3][4] No Load   3.3   Volts
---FIO Sourcing 1 mA   2.75   Volts
---EIO/CIO/MIO Sourcing 1 mA   3.15   Volts
---EIO/CIO/MIO Sourcing 5 mA   2.6   Volts
Short Circuit Current [3][4] FIO   6.3   mA
  EIO/CIO/MIO   22.9   mA
Output Impedance [3][4] FIO   550   Ω
  EIO/CIO/MIO   180   Ω
[1] The "Low Level" and "High Level" input voltage specify input voltage ranges guaranteed to produce the correct logic state at any digital input. The "Hysteresis Voltage" represents the voltage where a logic transition will actually occur. Input hysteresis will result in different transition voltages, depending on transition from HIGH to LOW or LOW to HIGH logic states. The overall hysteresis band is ~0.25 volts.     
[2] Maximum voltage to avoid damage to the device. Protection works whether the device is powered or not, but continuous voltages over 5.8 volts or less than -0.3 volts are not recommend when the device is unpowered, as the voltage will attempt to supply operating power to the device possibly causing poor start-up behavior.     
[3] These specifications provide the answer to the question. "How much current can the digital I/O sink or source?". For instance, if EIO0 is configured as output-high and shorted to ground, the current sourced by EIO0 is configured as output-high and shorted to ground, the current sourced by EIO0 into ground will be about 16 mA (3.3/180). If connected to a load that draws 5 mA, EIO0 can provide that current but the voltage will droop to about 2.4 volts instead of the nominal 3.3 volts. If connected to a 180 ohm load to ground, the resulting voltage and current will be about 1.65 volts @ 9 mA.     
[4] It is recommended to use the EIO/CIO digital I/O lines for UART, SPI, I²C, 1-Wire, and other digital communication protocols.     


Extended Features

T-series DIO-EF information:

Table A2-2. DIO extended features information

Extended Features Conditions Min Typical Max Units
Frequency Output [1]   0.02   5 M Hz
Counter Input Frequency [2]       5 MHz
Minimum High & Low Time [2]       50 ns
"Interrupt" Total Edge Rate [3][4] No Stream     70k edges/s

T7 Streaming @ 50 kHz

    20k edges/s
  T4 Streaming @ 20 kHz     20k edges/s
[1] Frequencies up to 40MHz are possible, but they are heavily filtered.     
[2] Hardware counters. 0 to 3.3 volt square wave.     
[3] This is for the "Interrupt" modes. To avoid missing edges, keep the total number of applicable edges on all applicable timers below this limit.     
[4] Excessive processor loading could reduce these limits further.     


Serial Communication

T-series serial communication abilities information is below. T-series devices use 3.3V logic levels and provide 5V output along the VS screw terminal. Some ICs require the same logic level as provided to the chip's VCC line so extra steps may be required to integrate specific sensors.

Table A2-3. Serial communication information

Serial Communication Conditions Min Max Units
SPI Characteristics        
Clock Frequencies   0.08718 870 kHz
I2C Characteristics        
Clock Frequencies   9.3 472 kHz