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1. Description
The LM317D2T-TR are monolithic integrated circuits in TO-220, TO-220FP and D²PAK packages intended for use as positive adjustable voltage regulators. They are designed to supply more than 1.5 A of load current with an output voltage adjustable over a 1.2 to 37 V range. The nominal output voltage is selected by means of a resistive divider, making the device exceptionally easy to use and eliminating the stocking of many fixed regulators.
2. Features
1. Output voltage range: 1.2 to 37 V
2. Output current in excess of 1.5 A
3. 0.1 % line and load regulation
4. Floating operation for high voltages
5. Complete series of protections: current limiting, thermal shutdown and SOA control
3. Pin connections (top view)
4. Application information
LM217, LM317 provide 1.25V internal reference voltage between output and output Adjust the terminals. This is used to set the constant current flowing through the external resistor Voltage divider , the output voltage VO given is:
Basic adjustable regulator
The device is designed to minimize IADJ (100 µA maximum) and keep it at a very high level. Constant with line and load changes. Generally, the error term IADJ×R2 can be ignored. to After obtaining the previous requirements, the quiescent current of all regulators is returned to the output Terminal, apply the minimum load current condition. If the load is insufficient, output The voltage will rise. Since the LM317D2T-TR is a floating regulator and only "sees" the differential voltage from input to output, it can provide extremely high voltage power relative to ground It can be adjusted as long as it does not exceed the maximum input and output difference. In addition, Programmable regulators are easy to obtain, and by connecting a fixed resistor between the two regulators After adjustment and output, the device can be used as a precision current regulator. in order to In order to optimize the load regulation, the current setting resistor R1 should be connected as As close as possible to the regulator, and the ground terminal of R2 should be close to the ground Load to provide remote ground sensing. May increase by increasing performance The capacitance is as follows:
1. 0.1 µF input bypass capacitor
2. Grounded 10 µF capacitor adjustment terminal to improve ripple suppression About 15 dB (CADJ).
3. There is a 1 µF tantalum (or 25 µF aluminum electrolytic) capacitor on the output to improve
Transient response. In addition to external capacitors, it is best to add The protection diode, as shown in Figure 7 D1, can protect the device from input short circuits Circuit, and D2 can prevent output short circuit to discharge the capacitor.
5. Schematic diagram
