Digital Input/Output - Measurement Computing USB-2020 User Manual

USB-2020 User's Guide

Digital input/output

Parameter
Digital type
Number of I/O
Configuration
Input voltage range
Input characteristics
Abs. Maximum input voltage
Pull-up/pull-down configuration
Digital I/O transfer rate (software paced)
Input high voltage
Input low voltage
Output characteristics
Output voltage range
Drain to source breakdown voltage
Off state leakage current
Sink current capability
DMOS transistor on-resistance (drain to
source)
Adding external pull-up resistors connects the output bit in parallel with the internal 47 kΩ pull-up
Note 1:
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.
Does not include the additional leakage current contribution that can occur when using an external
Note 2:
pull-up resistor.
Table 5. Digital I/O specifications
Specification
CMOS
8
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.
0 V to 15 V
47 kΩ pull-up/pull-down resistor, 28 kΩ series resistor
+20 V max
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.
33 S/s to 4,000 S/s typ; system-dependent
2.0 V min
0.8 V max
47 kΩ pull-up, open drain (DMOS transistor, source connected to ground)
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)
42.5 V min (Note 2)
1.0 µA
150 mA max (continuous) per output pin

150 mA max (continuous), total for all eight channels

4 Ω
20
Specifications