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USB-2020 User's Guide Specifications

Digital input/output

Table 5. Digital I/O specifications

Parameter Specification

Digital type

CMOS

Number of I/O

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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