USB-2020 User's Guide
Specifications
Digital input/output
Table 5. Digital I/O specifications
Parameter
Specification
Digital type
CMOS
Number of I/O
8
Configuration
Each bit can be independently configured as input (power on default) or
output
Input bits can be read at any time whether the digital output is active or tri-
stated.
Input voltage range
0 V to 15 V
Input characteristics
47 kΩ pull-up/pull-down resistor, 28 kΩ series resistor
Abs. Maximum input voltage
+20 V max
Pull-up/pull-down configuration
The port has 47 kΩ resistors that can be configured as pull-up or pull-down
with an internal jumper. The factory configuration is pull-up (J10 shorting
block default position is pins 1 and 2)
Pull down capability is available by placing the J10 shorting block across
pins 2 and 3.
Digital I/O transfer rate (software paced)
33 S/s to 4,000 S/s typ; system-dependent
Input high voltage
2.0 V min
Input low voltage
0.8 V max
Output characteristics
47 kΩ pull-up, open drain (DMOS transistor, source connected to ground)
Output voltage range
0 V to 5 V (using 47 KΩ internal pull up resistors)
0 V to 15 V max through optional, user-supplied external pull-up resistors
(Note 1)
Drain to source breakdown voltage
42.5 V min (Note 2)
Off state leakage current
1.0 µA
Sink current capability
150 mA max (continuous) per output pin
150 mA max (continuous), total for all eight channels
DMOS transistor on-resistance (drain to
source)
4 Ω
Note 1:
Adding external pull-up resistors connects the output bit in parallel with the internal 47 kΩ pull-up
resistor. The resulting load voltage depends on the value of the external resistor value and the pull-up
voltage used. In general, external 10 KΩ pull-up resistors are sufficient for most applications.
Note 2:
Does not include the additional leakage current contribution that can occur when using an external
pull-up resistor.
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