LM1084

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SNVS037G – SEPTEMBER 1999 – REVISED JANUARY 2015

8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

The LM1084 is versatile in its applications, including uses in programmable output regulation and local on-card

regulation. Or, by connecting a fixed resistor between the ADJUST and OUTPUT terminals, the LM1084 can

function as a precision current regulator. An optional output capacitor can be added to improve transient

response. The ADJUST terminal can be bypassed to achieve very high ripple-rejection ratios, which are difficult

to achieve with standard three-terminal regulators. Please note, in the following applications, if ADJ is mentioned,

it makes use of the adjustable version of the part, however, if GND is mentioned, it is the fixed voltage version of

the part.

8.2 Typical Applications

8.2.1 1.2-V to 15-V Adjustable Regulator

This part can be used as a simple low drop out regulator to enable a variety of output voltages needed for

demanding applications. By using an adjustable R2 resistor a variety of output voltages can be made possible as

shown in Figure 16 based on the LM1084-ADJ.

Figure 16. 1.2-V to 15-V Adjustable Regulator

8.2.1.1 Design Requirements

The device component count is very minimal, employing two resistors as part of a voltage divider circuit and an

output capacitor for load regulation.

8.2.1.2 Detailed Design Procedure

The voltage divider for this part is set based on the equation shown in Figure 16, where R1 is the upper feedback

resistor and R2 is the lower feedback resistor.

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