LM138| Datasheet

LM138, LM138K, LM238, LM238K, LM338, LM338K

Datasheet preview, take a look at Datasheets before downloading (Data Sheet is available on manufacturer site)

LM138/LM238 LM338
THREE-TERMINAL 5 A ADJUSTABLE VOLTAGE REGULATORS
s

s s s s s s

GUARANTEED 7A PEAK OUTPUT CURRENT GUARANTEED 5A OUTPUT CURRENT ADJUSTABLE OUTPUT DOWN TO 1.2V LINE REGULATION TYPICALLY 0.005%/V LOAD REGULATION TYPICALLY 0.1% GUARANTEED THERMAL REGULATION CURRENT LIMIT CONSTANT WITH TEMPERATURE STANDARD 3-LEAD TRANSISTOR PACKAGE

TO-3

DESCRIPTION The LM138/LM238/LM338 are adjustable 3-terminal positive voltage regulators 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-de-pendent current limiting. The current limit circuitry allows peak currents of up to 12A to be drawn from the regulator for short periods of time. SCHEMATIC DIAGRAM

bs O

let o

Pr e

du o

(s) ct

so Ob -

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 far from the input filter capacitors in which case an input bypass is needed. An optional output capacitor can be added to improve transient response. The adjustment terminal can be bypassed to achieve.very high ripple rejection ratios which are

te le

ro P

uc d

s) t(

April 2003

1/14