SkyWave IDP-680, Hardware Manual

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IDP 600 Terminal Series - Hardware Guide
T200, Version 02 14 © SkyWave Proprietary
3.3.2 Digital Output
Figure 13 shows a schematic of the I/O when configured as a digital output. It must be
noted that I/O 04 is the only I/O with built-in short circuit protection for open drain
outputs.
Figure 13 Digital Output
Push-pull S1 = Open
Open drain S1 = Closed (Low Impedance)
S1 = Open (High Impedance)
The following tables describe the output specifications.
Push-pull
In the push-pull configuration the output is driven directly from the microprocessor.
Parameter Minimum Typical Maximum Units
Output high voltage - open circuit 2.85 3.0 3.15 V
Output high voltage (sourcing 25 µA) 2.80 - - V
Output low voltage (sinking 25 µA) - - 0.05 V
Open Drain (I/O 01 to I/O 03)
Parameter Minimum Typical Maximum Units
Sink current (do not exceed) - - 250 mA
Voltage (active drawing at 250 mA) - - 2.56 V
Protected Open Drain (I/O 04 only)
Parameter Minimum Typical Maximum Units
Sink current (current limited) - - 300 mA
Voltage at 250 mA - - 3.09 V
I/O4
2R
S1
I/O1
1M
1k
3V
1nF
3V 3V
ARM PROCESSOR
OUTPUT
DIGITAL
I/O2
I/O3
1k
3V
LIMITER