cb-obs411 electrical mechanical data sheet - SE Spezial-Electronic ...

connectBlueFigure 25: No restore switch used but a green LED in a 5V host system. The status of the signal can also be used as input to ahost controller.A serial resistor to the restore switch must be used to prevent a short circuit when the GREEN/Switch-1 pin is in output HIGH state andthe switch is pressed (see Figure 26).Sometimes, over time, switch contacts can get an oxide layer. This may cause the closed switch resistance to become too high to sinkthe signal to logic LOW because the signal is internally pulled-up (see Input/Output signals). A design that prevents this can be found inFigure 27. The GREEN/Switch-1 pin can be left unconnected if none of its functionality is required.Figure 26: A low resistance restore switch used. Notice the 1kOhm serial resistor.Figure 27: If the resistance in the switch is not guaranteed to be low enough, a safer design can be used. Notice the 1kOhmserial resistor.Copyright © 2010 connectBlue AB Page 39 of 42