Schematic of a Low Dropout Voltage Regulator
Low-dropout regulator
From Wikipedia, the free encyclopedia
Schematic of a low-dropout regulator
A low-dropout or LDO regulator is a DC linear voltage regulator which can operate with a very small input–output differentialvoltage.[1] The advantages of a low dropout voltage include a lower minimum operating voltage, higher efficiency operation and lower heat dissipation.[2]
The main components are a power FET and a differential amplifier (error amplifier). One input of the differential amplifier monitors the fraction of the output determined by the resistor ratio of R1 and R2. The second input to the differential amplifier is from a stable voltage reference (bandgap reference). If the output voltage rises too high relative to the reference voltage, the drive to the power FET changes to maintain a constant output voltage.
For the circuit given in the figure the output voltage is given as
Contents [hide]
1 Overview
1.1 Regulation
1.2 Efficiency and Heat Dissipation
1.3 Quiescent current
1.4 Filtering
1.4.1 Ripple Rejection
1.4.2 Output Noise
1.5 Specifications
2 See also
3 References
4 External links
Overview[edit source]
Die of the LM1117 low-dropout linear voltage regulator.
The adjustable low-dropout regulator debuted on April 12, 1977 in an Electronic Design article entitled "Break Loose from Fixed IC Regulators". The article was written by Robert Dobkin, an IC designer then working for National Semiconductor. Because of this, National Semiconductor claims the title of "LDO inventor".[3] Dobkin later left National in 1981 and founded Linear Technology where he is currently chief technology officer.[4]
Regulation[edit source]
Low-dropout (LDO) regulators work in the same way as all linear voltage regulators. The main difference between LDO and non-LDO regulators is their schematic topology. Instead of an emitter follower topology, low-dropout regulators utilize open collector or open drain topology. This enables
From Wikipedia, the free encyclopedia
Schematic of a low-dropout regulator
A low-dropout or LDO regulator is a DC linear voltage regulator which can operate with a very small input–output differentialvoltage.[1] The advantages of a low dropout voltage include a lower minimum operating voltage, higher efficiency operation and lower heat dissipation.[2]
The main components are a power FET and a differential amplifier (error amplifier). One input of the differential amplifier monitors the fraction of the output determined by the resistor ratio of R1 and R2. The second input to the differential amplifier is from a stable voltage reference (bandgap reference). If the output voltage rises too high relative to the reference voltage, the drive to the power FET changes to maintain a constant output voltage.
For the circuit given in the figure the output voltage is given as
Contents [hide]
1 Overview
1.1 Regulation
1.2 Efficiency and Heat Dissipation
1.3 Quiescent current
1.4 Filtering
1.4.1 Ripple Rejection
1.4.2 Output Noise
1.5 Specifications
2 See also
3 References
4 External links
Overview[edit source]
Die of the LM1117 low-dropout linear voltage regulator.
The adjustable low-dropout regulator debuted on April 12, 1977 in an Electronic Design article entitled "Break Loose from Fixed IC Regulators". The article was written by Robert Dobkin, an IC designer then working for National Semiconductor. Because of this, National Semiconductor claims the title of "LDO inventor".[3] Dobkin later left National in 1981 and founded Linear Technology where he is currently chief technology officer.[4]
Regulation[edit source]
Low-dropout (LDO) regulators work in the same way as all linear voltage regulators. The main difference between LDO and non-LDO regulators is their schematic topology. Instead of an emitter follower topology, low-dropout regulators utilize open collector or open drain topology. This enables