LM4040C20ILPR datasheet(25/58 Pages) TI

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7 Detailed Description

7.1 Overview

The LM4040 is a precision micro-power curvature-corrected bandgap shunt voltage reference. The LM4040 has

been designed for stable operation without the need of an external capacitor connected between the “+” pin and

the “−” pin. If, however, a bypass capacitor is used, the LM4040 remains stable.

LM4040 offers several fixed reverse breakdown voltages: 2.048V, 2.500V, 3.000V, 4.096V, 5.000V, 6.000,

8.192V, and 10.000V. The minimum operating current increases from 60 µA for the LM4040-N-2.048 and

LM4040-N-2.5 to 100μA for the 10.0-V LM4040. All versions have a maximum operating current of 15mA.

Each reverse voltage options can be purchased with initial tolerances (at 25°C) of 0.1%, 0.2%, 0.5% and 1.0%.

These reference options are denoted by A (0.1%), B (0.2%), C (0.5%) and D for (1.0%).

The LM4040xxxI devices are characterized for operation from –40°C to 85°C, and the LM4040xxxQ devices are

characterized for operation from –40°C to 125°C.

7.2 Functional Block Diagram

CATHODE

ANODE

7.3 Feature Description

A temperature compensated band gap voltage reference controls high gain amplifier and shunt pass element to

maintain a nearly constant voltage between cathode and anode. Regulation occurs after a minimum current is

provided to power the voltage divider and amplifier. Internal frequency compensation provides a stable loop for

all capacitor loads. Floating shunt design is useful for both positive and negative regulation applications.

7.4 Device Functional Modes

7.4.1 Shunt Reference

LM4040 does not operate in one mode, which is as a fixed voltage reference that cannot be adjusted. LM4040

does offer various Reverse Voltage options that have unique electrical characteristics detailed in Section 6.

For a proper Reverse Voltage to be developed, current must be sourced into the cathode of LM4040. The

minimum current needed for proper regulation is denoted in Section 6 as IZ,min.

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LM4040A, LM4040B, LM4040C, LM4040D

SLOS456O – JANUARY 2005 – REVISED JUNE 2024

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Product Folder Links: LM4040A LM4040B LM4040C LM4040D

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