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

General Info

Table A2-1. IO Information

Parameter	Conditions	Min	Typical	Max	Units
Guaranteed Logic Low _[1]	-	-0.3	-	0.5	Volts
Guaranteed Logic High _[1]	-	2.64	-	5.8	Volts
Low to High Transition	-	-	2.1	2.64	Volts
High to Low Transition	-	0.5	0.9	-	Volts
Maximum Input Voltage _[2]	_-	_-	_-	_-	_-
---FIO (T4/T7) _[5]	_-	-10	-	10	Volts
---FIO (T8) _[5]	_-	-6	-	6	Volts
---EIO/CIO/MIO (T4/T7/T8) _[5]	_-	-6	-	6	Volts
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] Voltages above the max or below the min will produce undefined behavior.

[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 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]	T7/T4, No Stream	-	-	70k	edges/s
	T7 Streaming @ 50 kHz	-	-	20k	edges/s
	T4 Streaming @ 20 kHz	-	-	20k	edges/s
	T8, No Stream			100k	edges/s
	T8, Streaming @ 20 kHz			40k	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	Device	Conditions	Min	Max	Units
SPI Characteristics		-	-	-	-
Clock Frequencies	T7/T4		0.08718	870	kHz
	T8	FW 1.0014	1	2100	kHz

I2C Characteristics		-	-	-	-
Clock Frequencies	T7/T4		9.3	472	kHz
	T8	FW 1.0014	10	524	kHz