Skip to main content
Skip table of contents

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

General Info

Table A2-1. IO Information

ParameterConditionsMinTypicalMaxUnits
Low Level Input Voltage--0.3-0.5Volts
High Level Input Voltage-2.64-5.8Volts
Hysteresis Voltage [1]-----
---Low to High Transition---1.15Volts
---High to Low Transition-0.90--Volts
Maximum Input Voltage [2]-----
---FIO (T4/T7) [5]--10-10Volts
---FIO (T8) [5]--6-6Volts
---EIO/CIO/MIO (T4/T7/T8) [5]--6-6Volts
Output Low Voltage [3][4]No Load-0.01-Volts
---FIO (T4/T7) [5]Sinking 1 mA-0.55-Volts
---FIO (T8) [5]Sinking 1 mA-0.15-Volts
---EIO/CIO/MIO (T4/T7/T8) [5]Sinking 1 mA-0.15-Volts
---EIO/CIO/MIO (T4/T7/T8) [5]Sinking 5 mA-0.75-Volts
Output High Voltage [3][4]No Load-3.3-Volts
---FIO (T4/T7) [5]Sourcing 1 mA-2.75-Volts
---FIO (T8) [5]Sourcing 1 mA-3.15-Volts
---EIO/CIO/MIO (T4/T7/T8) [5]Sourcing 1 mA-3.15-Volts
---EIO/CIO/MIO (T4/T7/T8) [5]Sourcing 5 mA-2.6-Volts
Short Circuit Current [3][4]-----
---FIO (T4/T7) [5]--6.3-mA
---FIO (T8) [5]--22.9-mA
---EIO/CIO/MIO (T4/T7/T8) [5]--22.9-mA
Output Impedance [3][4]-----
---FIO (T4/T7) [5]--550-Ω
---FIO (T8) [5]--180-Ω
---EIO/CIO/MIO (T4/T7/T8) [5]--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.

[5] The T4 and T7 have additional protection on their FIO lines. The T8 has the same protection on all digital IO lines.

Extended Features

Table A2-2. DIO extended features information

Extended FeaturesConditionsMinTypicalMaxUnits
Frequency Output [1]-0.02-5 MHz
Counter Input Frequency [2]---5MHz
Minimum High & Low Time [2]---50ns
"Interrupt" Total Edge Rate [3][4] T7/T4, No Stream--70kedges/s
T7 Streaming @ 50 kHz--20kedges/s
T4 Streaming @ 20 kHz--20kedges/s
T8, No Stream100kedges/s
T8, Streaming @ 20 kHz40kedges/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 CommunicationDeviceConditionsMinMaxUnits
SPI Characteristics----
Clock FrequenciesT7/T40.08718870kHz
T8FW 1.001412100kHz
I2C Characteristics----
Clock FrequenciesT7/T49.3472kHz
T8FW 1.001410524kHz

JavaScript errors detected

Please note, these errors can depend on your browser setup.

If this problem persists, please contact our support.