Measurement Computing BTH-1208LS - Manual (Page 23)

BTH-1208LS User's Guide Specifications
23
Digital input/output
Table 11. Digital I/O specifications
Parameter Specification
Digital type 3.3 V open drain
Output value mapping 0 written: output drives to DGND
1 written: output is pulled up to 3.3 V via internal resistor
Number of I/O (Note 5) 8
Configuration Individually configurable
Input voltage range (Note 6) 0 V to 5.5 V
Pull up/pull-down configuration 47.5 k
Ω pull-up resistors (to 3.3 V), 2.2 kΩ series resistors
Input high voltage threshold 2.0 V min
Input high voltage limit 5.5 V absolute max
Input low voltage threshold 0.8 V max
Input low voltage limit –0.5 V absolute min
0 V recommended min
Output voltage range 0 V to 3.3 V (no external pull up resistor)
0 V to 5.5 V max (Note 6 )
Output off state leakage current . (Note 7 ) 1.0 µA typ
Sink current capability 50 mA max (continuous) per pin
Transistor on resistance 0.7
Ω max
Power on and reset state USB operation: All input
Bluetooth operation: The digital I/O can either be all input at power on /
reset or may be configured to have user-configurable patterns written to the
DIO when the Bluetooth host is connected or disconnected.
Note 5: Each transistor source pin is internally connected to DGND.
Note 6: The external pull-up is connected to the digital output bit through an external pull-up resistor. Adding
an external pull-up resistor connects it in parallel with the internal 47.5
kΩ pull-up resistor of that
particular digital input/output bit. Careful consideration should be made when considering the external
pull-up resistor value and the resultant pull-up voltage produced at the load.
Note 7: Does not include the additional leakage current contribution through the internal or any external pull-
up resistor.
External trigger
Table 12. Digital trigger specifications
Parameter Specification
Trigger source External digital; TRIG terminal
Trigger mode Software configurable for edge or level sensitive, rising or falling edge, high or low
level.
Trigger latency 10 µs max
Trigger pulse width 1 µs min
Input type
Schmitt trigger, 47 kΩ pull-down to ground
Schmitt trigger hysteresis 0.76 V typ
0.4 V min
1.2 V max
Input high voltage threshold 1.74 V typ
1.3 V min
2.2 V max
Input high voltage limit 5.5 V absolute max