The LT1083 series of positive adjustable regulators are designed to provide 7.5A with higher efﬁciency than currently available devices. All internal circuitry is designed to operate down to 1V input-to-output differential and the dropout voltage is fully speciﬁ ed as a function of load current. Dropout is guaranteed at a maximum of 1.5V at maximum output current, decreasing at lower load currents. On-chip trimming adjusts the reference voltage to 1%. Current limit is also trimmed, minimizing the stress on both the regulator and power source circuitry under overload conditions. The LT1083 device are pin compatible with older 3-terminal regulators. A 10μF output capacitor is required on these new devices. However, this is included in most regulator designs. Unlike PNP regulators, where up to 10% of the output cur-rent is wasted as quiescent current, the LT1083 quiescent current ﬂows into the load, increasing efﬁciency.
- Terminal Adjustable
- Output Current of 3A, 5A or 7.5A
- Operates Down to 1V Dropout
- Guaranteed Dropout Voltage at Multiple Current Levels
- Line Regulation: 0.015%
- Load Regulation: 0.1%
- 100% Thermal Limit Functional Test
- Fixed Versions Available
- Available in 3-Lead Plastic TO-220, TO-3P and DD Packages
- High Efﬁ ciency Linear Regulators
- Post Regulators for Switching Supplies
- Constant Current Regulators
- Battery Chargers
The LT1083 family of 3-terminal adjustable regulators is easy to use and has all the protection features that are expected in high performance voltage regulators. They are short-circuit protected, and have safe area protection as well as thermal shutdown to turn off the regulator should the junction temperature exceed about 165°C.
These regulators are pin compatible with older 3-terminal adjustable devices, offer lower dropout voltage and more precise reference tolerance. Further, the reference stability with temperature is improved over older types of regulators. The only circuit difference between using the LT1083 family and older regulators is that this new family requires an output capacitor for stability.
The circuit design used in the LT1083 family requires the use of an output capacitor as part of the device frequency compensation. For all operating conditions, the addition of a 150μF aluminium electrolytic or a 22μF solid tantalum pin instantaneously shorted to ground, can damage occur.
A crowbar circuit at the input of the LT1083 can generate those kinds of currents, and a diode from output to input is then recommended. Normal power supply cycling or even plugging and unplugging in the system will not generate current large enough to do any damage.
The adjustment pin can be driven on a transient basis ± 25V, with respect to the output without any device degradation. Of course, as with any IC regulator, exceeding the maximum input to output voltage differential causes the internal transistors to break down and none of the protection circuitry is functional.
Although the devices maximum operating voltage is limited, (20V for a 3V, 5V device, and 25V for a 12V device) the devices are guaranteed to withstand transient input voltages up to 30V. For input voltages greater than the maximum operating input voltage some degradation of specifications will occur. For input/output voltage differentials greater than 15V, a minimum external load of 5mA is required to maintain regulation.
Schematic of regulated power supply with adjustable CI LT 1083 by Linear Technologies
Suggested PCB mounting adjustable power supply LT1083
List of material to mount the adjustable regulated power supply using integrated circuit LT1083
|R2||100 Ohms 1W|
|D1, D2, D3, D4||10A10|
|LED1||Red Led 3mm|
|X1||Connector Terminal block 2 pins – Connecting the transformer|
|X2||Connector Terminal block 2 pins – Output|
|P||4.7K – Single potentiometer|
|Transformer||21V 8A – Or according to your need for voltage and current|
|Printed circuit board, solder, wires, heatsink for IC, Box, etc|
Download PDF Files: Suggested printed circuit board (Copper side, side components, Silk Screen) Schematic and Datasheet.