Other Parts Discussed in Thread: TS12A4517
The TS12A4517 normally closed "switch state" table on page 2 of the datasheet shows that when the INPUT pin is low the switch state is ON.
1. What is the switch position when in the ON state? Remain closed or is it open?
2. Can the Input pin be pulled high or low with a 10k to keep the switch in a know state at power on?
Jim,
1) The terminology is a little confusing when we are mixing mechanical switch terms (Normally Open NO and Normally Closed NC) with solid state switch vocabulary ("ON" and "OFF".) Solid state switches are semiconductor devices and do not have any moving parts like a mechanical switch. These solid state switches either conduct or insulate. When the switches are "ON" they conduct like a mechanical switch would when it is "closed" completing the circuit. When the switches are "OFF" they insulate like mechanical switch would if it was "open" not completing the circuit.
You can also check out the FAQ thread for more information on solid state switches.
2) Yes, absolutely. It is very common practice to keep the switch in a know state at power on by pulling the logic control high or low through a resistor. We also recommend this practice as with CMOS logic having the input in an undefined state can cause excess current leakage through the logic pin. You can see this app note Implications of Slow or Floating CMOS Inputs for more information on this topic.
Thank you,
Adam
