LM4041 datasheet(15/28 Pages) TI

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APPLICATION INFORMATION

Adjustable Version

LM4041

(Adjustable)

VZ = VREF 1 )

VREF

−

Cathode and Load Currents

* VZ

) IZ)

(1)

LM4041

IZ + IL

LM4041

PRECISION MICROPOWER SHUNT VOLTAGE REFERENCE

SLCS146E – FEBRUARY 2005 – REVISED FEBRUARY 2006

The adjustable version allows VZ to be set by a user-defined resistor divider. The output voltage, VZ, is set

according to the equation shown in Figure 14.

Figure 14. Adjustable Shunt Regulator

In a typical shunt regulator configuration (see Figure 15), an external resistor, RS, is connected between the

supply and the cathode of the LM4041. RS must be set properly, as it sets the total current available to supply

the load (IL) and bias the LM4041 (IZ). In all cases, IZ must stay within a specified range for proper operation of

the reference. Taking into consideration one extreme in the variation of the load and supply voltage (maximum IL

and minimum VS), RS must be small enough to supply the minimum IZ required for operation of the regulator, as

given by data sheet parameters. At the other extreme, maximum VS and minimum IL, RS must be large enough to

limit IZ to less than its maximum recommended rating of 12 mA.

RS is calculated as shown in Equation 1.

Figure 15. Shunt Regulator

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