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How much current does a pull-up resistor draw?
For switch and resistive sensor applications, the typical pull-up resistor value is 1-10 kΩ. If in doubt, a good starting point when using a switch is 4.7 kΩ. Some digital circuits, such as CMOS families, have a small input leakage current, allowing much higher resistance values, from around 10 kΩ up to 1 MΩ.
What Colour is a 10K resistor?
Technical Specifications
| Resistance | 10K ohm | |
|---|---|---|
| Color Code | Brown / Black / Orange / Gold | |
| Type | Carbon Film | |
| Voltage | Maximum Operating | 350V |
| Polarization | None |
What do you need to know about pull up resistors?
The short and easy answer is that you want a resistor value on the order of 10kΩ for the pull-up. A low resistor value is called a strong pull-up (more current flows), a high resistor value is called a weak pull-up (less current flows). The value of the pull-up resistor needs to be chosen to satisfy two conditions:
How does the pull up resistor work on a VCC?
When the button is pressed, the input pin is pulled low. The value of resistor R1 controls how much current you want to flow from VCC, through the button, and then to ground. When the button is not pressed, the input pin is pulled high. The value of the pull-up resistor controls the voltage on the input pin.
What is the input impedance of a MCU?
The input impedance will vary between MCU’s, but it’s usually on the order of several Mega-Ohms to approaching 100M Ohms. Current does flow through all available paths and it’s inversely proportional to resistance. The current that flows through the input pin is referred to as leakage current, and is usually on the order of micro-Amps.
Why does no current flow through the input pin?
If you hear that no current flows through the input pin, that’s because in most cases micro-Amp leakage currents can be effectively ignored in circuit design. The voltage after the pull up resistor will be a reduced voltage, however not by much. A voltage divider is still formed between the MCU input resistance and the pull up resistor.