Contents
What is open collector used for?
Open-collector devices are commonly used to connect multiple devices to one interrupt request signal or a shared bus such as I²C. This enables one device to drive the bus without interference from the other inactive devices.
Why is a pull up resistor needed for an open-collector gate?
A pull-up resistor connects unused input pins (AND and NAND gates) to the dc supply voltage, (Vcc) to keep the given input HIGH. Some open-collector gates, such as the 74LS06 are capable of driving larger loads because their outputs can be connected to supplies of up to 30 volts via an external pull-up resistor.
What can an open collector output be used for?
An open-collector output is used to connect one side of the device being controlled to ground. The other side of the device will be connected to power. If you look at the CRICKIT “drive” outputs you will see that this is exactly what they are.
How does an open collector turn on a transistor?
Basics: Open Collector Outputs. This “turns on” the transistor, which means that if there is any voltage (above about 1.5 V) connected to the collector– that is, connected to the output of the SN7407N channel –current will flow from the collector, through the transistor to ground.
How does the open collector work on a relay?
To do this, connect an open collector digital output to the control terminal of the relay board, with a 10kΩ resistor pulling the line up to +5V. This way, the relay will be constantly powered until the open collector digital output is switched on, which will then cause the control line to become grounded.
Are there any problems with an open collector?
One problem with open-collector devices is power consumption, since the pullup resistor dissipates power whenever the output is pulled low, and the higher the desired operating speed, the lower the resistor value (i.e. the stronger the pullup) needs to be, resulting in increased consumption.