Datasheet LT1083, LT1084, LT1085 (Analog Devices) - 9
| Manufacturer | Analog Devices |
| Description | 3A, 5A, 7.5A Low Dropout Positive Fixed Regulators |
| Pages / Page | 18 / 9 — block DiagraM. applicaTions inForMaTion. Stability |
| File Format / Size | PDF / 252 Kb |
| Document Language | English |
block DiagraM. applicaTions inForMaTion. Stability
Model Line for this Datasheet
- LT1085CM-3.3#PBF LT1085CM-3.3#PBF LT1085CM-3.3#TRPBF LT1085CM-3.3#TRPBF LT1085CM-3.6#PBF LT1085CM-3.6#PBF LT1085CM-3.6#TRPBF LT1085CM-3.6#TRPBF LT1085CT-12#PBF LT1085CT-12#PBF LT1085CT-3.3#PBF LT1085CT-3.3#PBF LT1085CT-3.6#PBF LT1085CT-3.6#PBF LT1085CT-5#PBF LT1085CT-5#PBF LT1085IM-3.6#PBF LT1085IM-3.6#PBF LT1085IM-3.6#TRPBF LT1085IM-3.6#TRPBF LT1085IT-12#PBF LT1085IT-12#PBF LT1085IT-5#PBF LT1085IT-5#PBF
Text Version of Document
LT1083/LT1084/LT1085 Fixed
block DiagraM
VIN + – THERMAL LIMIT VOUT GND LT1083/4/5 BD
applicaTions inForMaTion
The LT1083 family of three-terminal regulators are easy much smaller than this can be used with the LT1083. to use and have all the protection features that are ex- Many different types of capacitors with widely varying pected in high performance voltage regulators. They are characteristics are available. These capacitors differ in short circuit protected, have safe area protection as well capacitor tolerance (sometimes ranging up to ±100%), as thermal shutdown to turn off the regulator should the equivalent series resistance, and capacitance temperature temperature exceed about 165°C. coefficient. The 150µF or 22µF values given will ensure These regulators offer lower dropout voltage and more stability. precise reference tolerance. Further, the reference stability Normally, capacitor values on the order of 100µF are used with temperature is improved over older types of regula- in the output of many regulators to ensure good transient tors. The only circuit difference between using the LT1083 response with heavy load current changes. Output capaci- family and older regulators is that they require an output tance can be increased without limit and larger values of capacitor for stability. output capacitance further improve stability and transient response of the LT1083 regulators.
Stability
Another possible stability problem that can occur in mono- The circuit design used in the LT1083 family requires the lithic IC regulators is current limit oscillations. These can use of an output capacitor as part of the device frequency occur because in current limit the safe area protection compensation. For all operating conditions, the addition exhibits a negative impedance. The safe area protection of 150µF aluminum electrolytic or a 22µF solid tantalum decreases the current limit as the input-to-output volt- on the output will ensure stability. Normally capacitors age increases.That is the equivalent of having a negative 1083ffe For more information www.linear.com/LT1083 9 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Electrical Characteristics Typical Performance Characteristics Block Diagram Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
block DiagraM
VIN + – THERMAL LIMIT VOUT GND LT1083/4/5 BD
applicaTions inForMaTion
The LT1083 family of three-terminal regulators are easy much smaller than this can be used with the LT1083. to use and have all the protection features that are ex- Many different types of capacitors with widely varying pected in high performance voltage regulators. They are characteristics are available. These capacitors differ in short circuit protected, have safe area protection as well capacitor tolerance (sometimes ranging up to ±100%), as thermal shutdown to turn off the regulator should the equivalent series resistance, and capacitance temperature temperature exceed about 165°C. coefficient. The 150µF or 22µF values given will ensure These regulators offer lower dropout voltage and more stability. precise reference tolerance. Further, the reference stability Normally, capacitor values on the order of 100µF are used with temperature is improved over older types of regula- in the output of many regulators to ensure good transient tors. The only circuit difference between using the LT1083 response with heavy load current changes. Output capaci- family and older regulators is that they require an output tance can be increased without limit and larger values of capacitor for stability. output capacitance further improve stability and transient response of the LT1083 regulators.
Stability
Another possible stability problem that can occur in mono- The circuit design used in the LT1083 family requires the lithic IC regulators is current limit oscillations. These can use of an output capacitor as part of the device frequency occur because in current limit the safe area protection compensation. For all operating conditions, the addition exhibits a negative impedance. The safe area protection of 150µF aluminum electrolytic or a 22µF solid tantalum decreases the current limit as the input-to-output volt- on the output will ensure stability. Normally capacitors age increases.That is the equivalent of having a negative 1083ffe For more information www.linear.com/LT1083 9 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Electrical Characteristics Typical Performance Characteristics Block Diagram Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
