What is the function of an error amplifier in the linear regulator circuit?
An error amplifier is a kind of operational amplifier that amplifies the voltage difference between two input terminals (positive and negative) and outputs the amplified voltage. Inside a linear regulator, the positive terminal receives the feedback voltage, and the negative terminal receives the reference voltage.
How does error amplifier work?
The error amplifier amplifies the difference between the reference voltage and a fraction of the output voltage and controls the series pass transistor such that a stable output voltage is achieved. The circuit depends for its operation on negative feedback.
What is voltage regulator power supply?
A voltage regulator is a component of the power supply unit that ensures a steady constant voltage supply through all operational conditions. It regulates voltage during power fluctuations and variations in loads. A voltage regulator usually takes in higher input voltage and emits a lower, more stable output voltage.
Is the LDO able to regulate the output voltage?
The LDO cannot regulate the output voltage, so other parameters such as line-and-load regulation, accuracy, PSRR, and noise are meaningless. Figure 1.
What is the definition of line regulation in LDO?
Line regulation is a measure of the LDO’s ability to maintain the specified output voltage with varying input voltage. Line regulation is defined as Figure 7 shows the output voltage of the ADM7172 vs. input voltage at different load currents.
What are the sources of output noise in a LDO?
Output Noise Voltage. The major sources of output noise in LDOs are the internal reference voltage and the error amplifier. Modern LDOs operate with internal bias currents of just a few tens of nanoamps in order to achieve quiescent currents of 15 μA or less. These low bias currents require the use of bias resistors of up to a GΩ.
What’s the range of a low drop out regulator?
For example, a typical Li-ion battery has a range of 4.2 V at fully charged to 2.7 V at fully discharged. Even when the battery voltage is below 3 V, an LDO can still maintain the desired 2.5 V at the output. You might have seen / used several Linear Voltage Regulator ICs in your circuit design.