PROGRAMMABLE PRECISION SHUNT REGULATOR TL431/A /C

PROGRAMMABLE PRECISION SHUNT REGULATOR TL431/A /C 

PROGRAMMABLE PRECISION REFERENCES 

TO-92 (TOP VIEW) 

The TL431 is three-terminal adjustable shunt regulator 

with specified termal stability. 

The output voltage may be set to any value between 

V REF (Approx. 2.5V) and 36V with two external resistors. 

This device has a typical output inpedance of 0.2Ω. 

Active output circuitry provides a very sharp turn-on 

characteristic, making this device excellent 

replacement for zener diodes in many application. 

SOT-23 

1. 

SOT-89 

1 3. 

1. 

FEATURES 

1. REF 2. ANODE 3. CATHODE 

● Equivalent Full Range Temperature Coefficient 50PPM/℃ 

● Temperature Compensated For Operation Over 

Full Rate Operating Temperature Range 

● Adjustable Output Voltage 

● Fast Turn-on Response 

● Sink Current Capability 1mA to 100mA 

● Low (0.2Ω Typ.) Dynamic Output Impedance 

● Low Output Noise 

FUNCTION BLOCK DIAGRAM 

ORDERING INFORMATION 

Device Marking 

TL431 

TL431-A 


TL431-A 

TL431-C 

TL431SF 

TL431-ASF 

TL431-CSF 

TL431F 

TL431-AF 

TL431-CF 

TL431-C 

431 

* Packing label is 

different as Vref 

431 

* Packing label is 

different as Vref 

Package 

TO-92 

SOT-23 

SOT-89 

BLOCK DIAGRAM 

REFERENCE 

CATHODE 

CATHODE(K) 

2.5V REF 

REFERENCE(R) 

ANODE(A) 

ANODE 

Oct. 2003 - Rev 03 

1 

HTC


EQUIVALENT SCHEMATIC 

Reference 

Q10 

Cathode 

Q3 

Q2 

C1 

R21 

R20 

Q8 

Q9 

Q7 

C2 

Q13 

D2 

R2 

Q12 

Q1 

R19 

Q11 

R6 

D3 

R18 

R17 

R10 

Q4 


D1 

R1 

R11-R16 

Q6 

Q5 

Anode 

- All component values are nominal 

RECOMMENDED OPERATING CONDITIONS 

CHARACTERISTIC 

Cathode Voltage 

Cathode Current 

SYMBOL 

V KA 

I K 

MIN. 

V REF 

1 

MAX. 

36 

100 

UNIT 

V 

mA 

DISSIPATION RATING TABLE1-FREE-AIR TEMPERATURE 

Package 

TO-92 

SOT-89 

T A =25℃ 

Power Rating 

770mW 

500mW 

Derating Factor 

Above T A =25℃ 

6.2mW/℃ 

4.0mW/℃ 

T A =70℃ 

Power Rating 

491mW 

320mW 

SOT-23 230mW 1.8mW/℃ 149mW 

T A =85℃ T A =125℃ 

Power Rating Power Rating 

398mW 

- 

260mW 

- 

122mW - 

Oct. 2003 - Rev 03 

2 

HTC


ABSOLUTE MAXIMUM RATINGS 

(Full Operating Ambient Temperature Range Applies Unless Otherwise Noted) 


Cathode Voltage 

Continuous Cathode Current Range 

Reference Input Current Range 

Junction Temperature 

Operating Temperature 

Storage Temperature 

Total Power Dissipation 

SYMBOL 

V KA 

I KA 

I REF 

RATING 

37 

UNIT 

V 

-100~+150 

mA 

0.05~10 mA 

T J 150 ℃ 

T OPR 

T STG -65 ~ 150 

P D 

-20 ~ 85 

℃ 

700 

℃ 

mW 

TL431 ELECTRICAL CHARACTERISTICS (T A =25℃, unless otherwise specified) 


SYMBOL 

CIR-CUIT 

TEST CONDITION 

MIN. 

TYP. 

MAX. 

UNIT 

V REF 

Reference Input Voltage 1 V KA =V REF , I K =10mA 

Deviation of Reference V KA =V REF , I K =10mA 

2.440 

2.495 2.550 V 

Input Voltage Over ΔV REF /ΔT 1 T A =Full Range 

Full Temperature Range 

Ratio of Change in 

ΔV KA =10V-V REF 

Reference Input Voltage 

ΔV REF /ΔV KA 2 I K =10mA 

to the Change in Cathod 

ΔV KA =36V-10V 

Voltage 

Reference Input Current I REF 2 I KA =10mA, R1=10kΩ, R2=∞ 

Deviation of Reference I K =10mA, R1=10kΩ, R2=∞ 

Input Current Over Full ΔI REF /ΔT 2 T A =Full Range 

Temperature Range 

3 17 

-1.4 -2.7 

-1 -2 

1.8 4 

0.4 1.2 

mV 

mV/V 

μA 

μA 

Minimum Cathode ΔV KA =V REF 

I KA MIN 1 

Current for Regulation 

Off-State Cathode V KA =36V, V REF =0 

I KA OFF 3 

Current 

Dynamic Impedance V KA =V REF, I K =1mA~100mA, 

Z KA 1 

f≤1kHz 

0.5 1 mA 

0.2 1 μA 

0.2 0.5 Ω 

Oct. 2003 - Rev 03 

3 

HTC


TL431A ELECTRICAL CHARACTERISTICS (T A =25℃, unless otherwise specified) 

CHARACTERISTIC SYMBOL CIR-CUIT TEST CONDITION MIN. TYP. MAX. UNIT 

Reference Input Voltage V REF 1 V KA =V REF , I K =10mA 

2.470 2.495 2.520 V 



3 17 mV 




-1.4 -2.7 





-1 -2 

Voltage 

mV/V 


1.8 4 μA 



0.4 1.2 μA 


Minimum Cathode ΔV KA =V 

I REF 

KA MIN 1 


0.5 1 


I KA OFF 3 

Current 

0.2 1 


Z KA 1 

f≤1kHz 

0.2 0.5 

mA 

μA 

Ω 

TL431C ELECTRICAL CHARACTERISTICS (T A =25℃, unless otherwise specified) 

CHARACTERISTIC SYMBOL CIR-CUIT TEST CONDITION MIN. TYP. MAX. UNIT 

Reference Input Voltage V REF 1 V KA =V REF , I K =10mA 

2.482 2.495 2.508 V 



3 17 mV 




-1.4 -2.7 





-1 -2 

Voltage 

mV/V 


1.8 4 μA 



0.4 1.2 μA 


Minimum Cathode ΔV KA =V REF 

I KA MIN 1 



I KA OFF 3 

Current 


Z KA 1 

f≤1kHz 

0.5 

0.2 

0.2 

1 

1 

0.5 

mA 

μA 

Ω 

Oct. 2003 - Rev 03 

4 

HTC


Fig. 1 Test Circuit for V KA =V REF 

Fig. 2 Test Circuit for V KA ≥V REF 

INPUT 

V KA 

INPUT 

INPUT V KA 

V KA 

I KA 

I KA 

R1 

I 

DUT 

REF 

DUT 

V REF 

R2 V REF 

Fig. 3 Test Circuit for I KA (off) 

I KA 

V KA =V REF (1+R1/R2)+I REF R1 

DUT 

Oct. 2003 - Rev 03 

5 

HTC


The deviation parameters V REF(DEV) and I REF(DEF) are defined as the differences between the maximum and minimum 

values obtained over the recommended temperature range. The average full-range temperature coefficient of the 

reference voltage, αV REF , is defined as : 

Maximum V REF 

|αV REF | 

( ΔV 

V I(dev) 

( x10 6 

ppm V REF at 25℃ ) 

℃ ) = 

ΔT A 

Minimum V REF 

V I(dev) 

ΔT A 

Where : 

ΔT A is the recommended operating free-air temperature range of the device. 

αV REF can be positive or negative, depending on whether minimum V REF or maximum V REF , respectively, occurs at the 

lower temperature. 

Example : Maximum V REF =2496mV at 30℃, maximum V REF =2492mV at 0℃, V REF =2495mV at 25℃, ΔT A =70℃ 

for TL431C 

|αV REF |= 

4mV 

( ) 

2495mV x106 ~ 

23PPM/℃ 

70℃ 

Because minimum V REF occurs at the lower temperature, the coefficient is positive. 

Calculating Dynamic Impedance 

|Z 

The dynamic impedance is defined as : KA |= 

ΔV KA 

ΔI KA 

When the device is operating with two external resistors (see Figure 3), the total dynamic impedance of the circuit 

is given by : 

|Z'|= 

ΔI 

~ 

~|Z KA | 

R1 

(1+ 

R2 

) 

Figure 1. Calculating deviation parameters and dynamic impedance 

Oct. 2003 - Rev 03 

6 

HTC


TYPICAL PERFORMANCE CHARACTERISTICS 

REFERENCE VOLTAGE vs 

FREE-AIR TEMPERATURE† 

REFERENCE CURRENT vs 

FREE-AIR TEMPERATURE † 

2600 

2580 

2560 

V REF =2500mV‡ 

5 

4 

R1=10kΩ 

R2=∞ 

I KA =10mA 

VREF-REFERENCE VOLTAGE- 

2540 

2520 

2500 

2480 

2460 

2440 



VREF-REFERENCE VOLTAGE- 

3 

2 

1 

2420 

2400 

0 

-75 -50 -25 0 25 50 75 100 125 

T A -FREE-AIR TEMPERATURE-℃ 

-75 -50 -25 0 25 50 75 100 125 


† Data is applicable only within the recommended operating free-air † Data is applicable only within the recommended operating free-air 

temperature ranges of the various devices. temperature ranges of the various devices. 

‡ Data is for devices having the indicated value of REF V at I KA =10mV, 

T A =25℃ 

Figure 4. Figure 5. 

CATHODE CURRENT vs 

CATHODE VOLTAGE 

CATHODE CURRENT vs 

CATHODE VOLTAGE 

150 

800 

125 

V KA =V REF 

T A =25℃ 

V KA =V ERF 

T A =25℃ 

100 

600 

IKA-CATHODE CURRENT- 

75 

50 

25 

0 

IKA-CATHODE CURRENT- 

400 

200 

I MIN 

-25 

-50 

0 

-75 

-100 

-200 

-2 -1 0 1 2 3 

V KA -CATHODE VOLTAGE-V 

-1 0 1 2 3 

V KA -CATHODE VOLTAGE-V 


Oct. 2003 - Rev 03 

7 

HTC



2.5 

V KA =36 

V 

OFF-STATE CATHODE CURRENT 

vs FREE-AIR TEMPERATURE† 

-0.85 

V KA =3V TO 36V 

RATIO DELTA REFERENCE VOLTAGE TO 

DELTA CATHODE VOLTAGE vs 

FREE-AIR TEMPERATURE † 

2 

-0.95 

IOFF-OFFSTATE CATHODE CURRENT 

1.5 

1 

0.5 

ΔVREF/ΔVKA-mV/V 

-1.05 

-1.15 

-1.25 

-1.35 

0 

-1.45 

-75 -50 -25 0 25 50 75 100 125 


-75 -50 -25 0 25 50 75 100 125 


† Data is applicable only within the recommended operating free-air † Data is applicable only within the recommended operating free-air 

temperature ranges of the various devices. temperature ranges of the various devices. 


EQUIVALENT INPUT NOISE VOLTAGE 

VS FREQUENCY 

260 

240 

I O =10mA 

T A =25℃ 

VIN-EQUIVALENT NOISE VOLTAGE-nV 

220 

200 

180 

160 

140 

120 

100 

10 100 1K 10K 100K 

f-FREQUENCY-Hz 

Figure 10. 

Oct. 2003 - Rev 03 

8 

HTC



19.1V 

1kΩ 

500μF 

910Ω 


(DUT) 

820Ω 

16Ω 

0.1μF 

2000μF 

160kΩ 

+ 

- 

910Ω 

V CC 

TL2027 

A V =10V/mV 

16kΩ 16kΩ 

1μF 

V CC 

TO OSCILLOSCOPE 

1μF 

TL2027 22μF 

+ 

- 

33kΩ 

33kΩ A V =2V/V 

V EE 

Figure 11. Test Circuit for Equivalent Input Noise Voltage 

SMALL-SIGNAL VOLTAGE AMPLIFICATION 

VS FREQUENCY 

60 

AV-SMALL-SIGNAL VOLTAGE AMPLIFICATIO 

50 

40 

30 

20 

I KA =10mA 

T A =25℃ 

~ 

9μF 

15kΩ 

8.25kΩ 

I KA 

+ 

- 

OUTPUT 

232Ω 

GND 

10 

Test Circuit for Voltage Amplification 

0 

1K 10K 100K 1M 10M 


Figure 12. 

Oct. 2003 - Rev 03 

9 

HTC



REFERENCE IMPEDANCE 

VS FREQUENCY 

|ZKA|-REFERENCE IMPEDANCE 

100 

10 

1 

I KA =10mA 

T A =25℃ 

~ 

1kΩ 

50Ω 

- 

+ 

I KA 

OUTPUT 

GND 

Test Circuit for Reference Impedance 

0.1 

1K 10K 100K 1M 10M 


Figure 13. 

REFERENCE IMPEDANCE 

VS FREQUENCY 

6 

T A =25℃ 

INPUT 

5 

220Ω 

OUTPUT 

|ZKA|-REFERENCE IMPEDANCE 

4 

3 

2 

1 

OUTPUT 

PULSE 

GENERATOR 

f=100kHz 

50Ω 

GND 

Test Circuit for Pulse Response 

0 

-1 0 1 2 3 4 5 6 7 

t-TIME-μs 

Figure 14. 

Oct. 2003 - Rev 03 

10 

HTC


APPLICATION INFORMATION 

V I (BATT) 

R 

(SEE NOTE A) 

V O 

V REF 

R1 

0.1% 

R2 

0.1% 


R1 

V O =(1+ ) 

R2 

V REF 

RETURN 

NOTE A : R Should provide cathode current≥1mA to the TL431 at minimum V I (BATT) 

Figure 15. Shunt Regulator 

V I (BATT) 

INPUT 

V IT 

~ 2.5V 


V O 

V ON ~ 2.5V 

V OFF ~ V I (BATT) 

GND 

Figure 16. Single-Supply Comparator With Temperature-Compensated Threshold 

V I (BATT) 


R 

(SEE NOTE A) 

30Ω 

R2 

0.1% 

0.01μF 

R1 

0.1% 

2N222 

4.7kΩ 

2N222 

R1 

V O =(1+ ) 

R2 

V O 

V REF 

NOTE A : R Should provide cathode current≥1mA to the TL431 at minimum V I (BATT) 

Figure 17. Precision High-Current Series Regulator 

Oct. 2003 - Rev 03 

11 

HTC



V I (BATT) 

IN 

LM7805 

OUT 

V O 

COMMON 


R1 

R1 

V O =(1+ 

R2 

) 

V REF 

MINIMUM V O =V REF +5V 

R2 

Figure 18. Output Control of a 3-Terminal Fixed Regulator 

V I (BATT) 

V O 

R1 

R1 

V O = (1+ 

R2 ) 

V REF 

RETURN 

R2 


Figure 19. High-Current Shunt Regulator 

V I (BATT) 

V O 

R1 


R2 

C 

(SEE NOTE A) 

NOTE A : Refer to the stability boundary conditions in Figure 16 to determine allowable values for C. 

Figure 20. Crowbar Circuit 

Oct. 2003 - Rev 03 

12 

HTC



V I (BATT) 

IN 

8.2kΩ 

LM317 

Adjust 

OUT 

243Ω 

0.1% 

V O 

~ 5V, 1.5A 


243Ω 

0.1% 

Figure 21. Precision 5-V 1.5A Regulator 

V I (BATT) 

R B 

(SEE NOTE A) 

27.4MΩ 

0.1% 

V O 

~ 5V 


27.4MΩ 

0.1% 

NOTE A : R B Should provide cathode current≥1mA to the TL431. 

Figure 22. Efficient 5-V Precision Regulator 

12V 

6.8MΩ 

5V 

10MΩ 

- 


10MΩ 

0.1% 

10MΩ 

0.1% 

X 

NOT 

USED 

+ 

TL598 

FEED BACK 

Figure 23. PWM Converter With Reference 

Oct. 2003 - Rev 03 

13 

HTC



V I (BATT) 

R1A 


R3 

(SEE NOTE A) 

R1B 

OUT 

R4 

(SEE NOTE A) 

LOW LIMIT= 

R1B 

(1+ ) 

R2B 

V REF 

HIGH LIMIT= (1+ 

R1A 

) 

R2A 

V REF 

R2A 

R2B 

LED ON WHEN LOW LIMIT



V I (BATT) 

I O 

I O = 

V REF 

R S 


R S 

0.1% 

Figure 27. Precision Constant-Current Sink 

Oct. 2003 - Rev 03 

15 

HTC

PROGRAMMABLE PRECISION SHUNT REGULATOR TL431/A /C

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?