5 Amp Adjustable Regulator - LM338

LM338 (ACTIVE)

5 Amp Adjustable Regulator

Description

The LM138 series of adjustable 3-terminal positive voltage regulators is capable of supplying in excess of 5A over a 1.2V to 32V output range. They are exceptionally easy to use and require only 2 resistors to set the output voltage. Careful circuit design has resulted in outstanding load and line regulation—comparable to many commercial power supplies. The LM138 family is supplied in a standard 3-lead transistor package.

A unique feature of the LM138 family is time-dependent current limiting. The current limit circuitry allows peak currents of up to 12A to be drawn from the regulator for short periods of time. This allows the LM138 to be used with heavy transient loads and speeds start-up under full-load conditions. Under sustained loading conditions, the current limit decreases to a safe value protecting the regulator. Also included on the chip are thermal overload protection and safe area protection for the power transistor. Overload protection remains functional even if the adjustment pin is accidentally disconnected.

Normally, no capacitors are needed unless the device is situated more than 6 inches from the input filter capacitors in which case an input bypass is needed. An output capacitor can be added to improve transient response, while bypassing the adjustment pin will increase the regulator's ripple rejection.

Besides replacing fixed regulators or discrete designs, the LM138 is useful in a wide variety of other applications. Since the regulator is “floating” and sees only the input-to-output differential voltage, supplies of several hundred volts can be regulated as long as the maximum input to output differential is not exceeded, i.e., do not short-circuit output to ground. The part numbers in the LM138 series which have a K suffix are packaged in a standard Steel TO-3 package, while those with a T suffix are packaged in a TO-220 plastic package. The LM138 is rated for −55°C ≤ TJ ≤ +150°C, and the LM338 is rated for 0°C ≤ TJ ≤ +125°C.

Features

  • Specified 7A Peak Output Current
  • Specified 5A Output Current
  • Adjustable Output Down to 1.2V
  • Specified Thermal Regulation
  • Current Limit Constant with Temperature
  • P+ Product Enhancement Tested
  • Output is Short-Circuit Protected

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Parametrics Compare all products in Single Channel LDO

 
Iout (Max) (A)
Output Options
Vin (Min) (V)
Vin (Max) (V)
Vdo (Typ) (mV)
Output Capacitor Type
Additional Features
Rating
Operating Temperature Range (C)
Pin/Package
LM338
5    
Adjustable Output    
4.2    
40    
2700    
Non-Ceramic    
Overcurrent Protection
Thermal Shutdown    
Military    
0 to 125    
2TO-3
3TO-220    

Related end equipment

  • Adjustable Power Supplies
  • Constant Current Regulators
  • Battery Chargers

Companion parts

Part # Name Product Family Comments
LM2677   SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator with Sync   CONVERTER (INTEGRATED SWITCH) - STEP-DOWN (BUCK) CONVERTER    No Heatsink Required , On/off Pin  
LM2678   SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator   CONVERTER (INTEGRATED SWITCH) - STEP-DOWN (BUCK) CONVERTER    No Heatsink Required  
LM2679   SIMPLE SWITCHER 5A Step-Down Voltage Regulator with Adjustable Current Limit   CONVERTER (INTEGRATED SWITCH) - STEP-DOWN (BUCK) CONVERTER    No Heatsink Required , Adjustable Current Limit  
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