LM1086

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SNVS039J – JUNE 2000 – REVISED APRIL 2015

7 Detailed Description

7.1 Overview

A basic functional diagram for the LM1086-ADJ (excluding protection circuitry) is shown in Figure 13. The

topology is basically that of the LM317 except for the pass transistor. Instead of a Darlingtion NPN with its two

diode voltage drop, the LM1086 uses a single NPN. This results in a lower dropout voltage. The structure of the

pass transistor is also known as a quasi LDO. The advantage of a quasi LDO over a PNP LDO is its inherently

lower quiescent current. The LM1086 is specified to provide a minimum dropout voltage of 1.5V over

temperature, at full load.

Figure 13. Basic Functional Block Diagram

7.2 Functional Block Diagram

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