TL431MFKB datasheet(25/74 Pages) TI1

25 / 74 page

Time (s)

-5E-6

-3E-6

-1E-6

1E-6

3E-6

5E-6

-6

-3

D001

Vsup

Vka=Vref

R1=10k: & R2=10k:

R1=38k: & R2=10k:

TL431, TL431A, TL431B

TL432, TL432A, TL432B

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SLVS543O – AUGUST 2004 – REVISED JANUARY 2015

10.2.2.2.2

Total Accuracy

When programming the output above unity gain (VKA=VREF), TL43xx is susceptible to other errors that may effect

the overall accuracy beyond VREF. These errors include:

•

R1 and R2 accuracies

•

VI(dev) - Change in reference voltage over temperature

•

ΔVREF / ΔVKA - Change in reference voltage to the change in cathode voltage

•

|zKA| - Dynamic impedance, causing a change in cathode voltage with cathode current

Worst case cathode voltage can be determined taking all of the variables in to account. Application note

SLVA445 assists designers in setting the shunt voltage to achieve optimum accuracy for this device.

10.2.2.2.3

Stability

Though TL43xx is stable with no capacitive load, the device that receives the shunt regulator's output voltage

could present a capacitive load that is within the TL43xx region of stability, shown inFigure 16 and Figure 18.

Also, designers may use capacitive loads to improve the transient response or for power supply decoupling.

When using additional capacitance between Cathode and Anode, refer to Figure 16 and Figure 18. Also,

application note SLVA482 will provide a deeper understanding of this devices stability characteristics and aid the

user in making the right choices when choosing a load capacitor.

10.2.2.2.4

Start-up Time

As shown in Figure 28, TL43xx has a fast response up to ~2 V and then slowly charges to it's programmed

value. This is due to the compensation capacitance (shown in Figure 24) the TL43xx has to meet it's stability

criteria. Despite the secondary delay, TL43xx still has a fast response suitable for many clamp applications.

10.2.2.3 Application Curves

Figure 28. TL43xx Start-up Response

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TL431MFKB Datasheet(PDF) 25 Page - Texas Instruments

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