What are the advantages of a open drain ckt ?

ADv of Open Drain ckt

What are the advantages of a open drain ckt as compared to others?

Re: ADv of Open Drain ckt

1st hit when you google "open drain" :
https://www.mcc-us.com/Open-collectorFAQ.htm

If you just check out the first page of hits, you'll get a good idea
of what the advantages are.

Re: ADv of Open Drain ckt

Hi Puneet31,

There is more, you also could use an open drain (or open collector) to interface
with other logic families, say from a circuit that operates from a 5V supply to
another circuit that operates at a different voltage, and that can be anything
between 0V and the maximum drain to source voltage of the FET.
You can even drive relays, light bulbs, LED's ... directly, from the same supply
voltage or another.
You could also connect two open drain circuits together and combine them to
form a new logic function.
It's a really versatile building block.

Regards,

on1aag.

Re: ADv of Open Drain ckt

Open drain is one of the many different electrical input/output standards in digital designs today.
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Definition of Open-Drain

Open-drain refers to the drain terminal of a MOSFET transistor. (The analog for BJT devices is the open collector.) An open drain terminal is connected to ground in the low voltage (logic 0) state, but has high impedance in the logic 1 state. This prohibits current flow, but as a result, such a device requires an external pull-up resistor which is also connected to the positive voltage rail.

When a device is in the high-impedance state, the pull-up resistor keeps the line at logic 1. The line stays there until the device goes into the logic 0 state, and begins to sink current. This current flow creates a voltage drop across the pull-up resistor, and the line drops to the logic 0 voltage.
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Applications of Open-Drain Devices

One useful property is that the resistor need not be connected to the same voltage as the chip supply voltage Vcc: a lower or higher voltage can be used instead. Open drain circuits are therefore sometimes used to interface two series of devices that have different operating logic levels (voltages.)

Another advantage is that more than one open-drain output can be attached to a single wire. If all outputs attached to the wire are in the high-impedance/logic 1 state, the pull-up resistor will hold the wire in a high voltage state. If at least one of the device outputs is in the ground/logic 0 state, it will sink current and bring the line voltage low. This is analogous to a logical-AND function.

One common use of Open Drain pin is that it enables the device to provide system-level control signals (that is, interrupt and write-enable signals) that can be asserted by several outside devices.