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One problem such open-collector and similar devices with a pull-up resistor is the resistor consumes power constantly while the output is low. Higher operating speeds require lower resistor values for faster pull-up, which consume even more power.
A pull-up resistor (or pull-down resistor) can be used as a medium-impedance source to try to pull the wire to a high (or low) voltage level. If the node is not in a high-impedance state, extra current from the resistor will not significantly affect its voltage level.
In electronic logic circuits, a pull-up resistor (PU) or pull-down resistor (PD) is a resistor used to ensure a known state for a signal. [1] It is typically used in combination with components such as switches and transistors , which physically interrupt the connection of subsequent components to ground or to V CC .
Fig. 2: The two operating states of a buck–boost converter: When the switch is turned on, the input voltage source supplies current to the inductor, and the capacitor supplies current to the resistor (output load). When the switch is opened, the inductor supplies current to the load via the diode D.
A voltage-controlled resistor (VCR) is a three-terminal active device with one input port and two output ports. The input-port voltage controls the value of the resistor between the output ports. VCRs are most often built with field-effect transistors (FETs). Two types of FETs are often used: the JFET and the MOSFET.
If all the input voltages are low (logical "0"), the transistor is cut-off. The pull-down resistor R 1 biases the transistor to the appropriate on-off threshold. The output is inverted since the collector-emitter voltage of transistor Q 1 is taken as output, and is high when the inputs are low. Thus, the analog resistive network and the analog ...
The input is left side, the output with load is right side. The switch is typically a MOSFET, IGBT, or BJT transistor. A buck converter or step-down converter is a DC-to-DC converter which decreases voltage, while increasing current, from its input to its output . It is a class of switched-mode power supply.
A DC-blocking capacitor may be inserted in series with the input resistor when a frequency response down to DC is not needed and any DC voltage on the input is unwanted. That is, the capacitive component of the input impedance inserts a DC zero and a low-frequency pole that gives the circuit a bandpass or high-pass characteristic.