Hi Ashish Sachdeva ,

in the cases I'm aware of, floating inputs are used in order to reduce the number of necessary pins by employing three valued logic (or sometimes even four or more valued), i. e. low, floating, and high. This way, by two pins the user can choose one of 9 possibilities instead of 4.

I never implemented such an input myself but the first solution that comes to mind is to control two transistors by the input voltage, one with a threshold of about 1/3 of the supply voltage, the other with a threshold of 2/3 of the supply. Assuming two n-channel-FETs and an internal high resistance voltage divider providing 1/2 of the supply voltage, this would result in three possible states:

low => both transistors off; unconnected = floating => low threshold transistor on, the other off; high => both transistors on.

Hello,

Floating circuits usually defined as the circuits with no direct power supply (VDD) and ground (GND) in their structures.

Float techniques used in digital circuits more than the analog counterparts.

To implement float inputs in digital circuits you do not need VDD and GND, you can drive the circuit with only high ("1") and low ("0") signals at the inputs of the circuit. on the other hand, the circuit should be designed so that it dose not need VDD and GND.

for more information you can see the following paper:

https://www.researchgate.net/publication/235217918_A_new_8-Transistors_Floating_Full-Adder_Circuit

Regards.

Aparna Sathya Murthy thanks, but what is its physical implication on circuit? whether it leads more to ground or more towards Vdd??

@Ashish Sachdeva

After surface, it is floating, the reasoning of the secondary winding is sloshing, both may be rational 1/0 but you can always note that the amperage rates are not exclusive to Vdd or Vss.

Vinay Tomar Sir, Harekrishna Kumar need your support in this matter if possible.

All CMOS devices are subject to damage from the ESD. They must be handled with special care. Review the following precautions:

1. All CMOS devices are shipped in conductive foam to prevent electrostatic charge buildup. When they are removed from the foam, the pins should not he touched.

2. The devices should be placed with pins down on a grounded surface, such as a metal plate, when removed from protective material. Do not place CMOS devices in polystyrene foam or plastic trays. .

3. All tools, test equipment, and metal workbenches should be earth-grounded. A person working with CMOS devices should, in certain environments, have his or her wrist grounded with a length of cable and a large-value series resistor. The resistor prevents severe shock.

4. Do not insert CMOS devices (or any other ICs) into sockets or PC boards with the power on.

5. All unused inputs should be connected to the supply voltage or ground. If they left open, an input can acquire electrostatic charge and "float" to unpredictable levels.

6. After assembly on PC boards, protection should be provided by storing or shipping boards with their connectors in conductive foam. The CMOS input and output pins may also be protected with large-value resistors connected to ground.