LM613 datasheet(16/22 Pages) NSC

Numer części	LM613

Szczegółowy opis	Dual Operational Amplifiers, Dual Comparators, and Adjustable Reference

PDF	22 Pages

Scroll/Zoom	100%

Producent	NSC [National Semiconductor (TI)]

Strona internetowa	http://www.national.com

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16 / 22 page

Application Information (Continued)

Understanding that V

r is fixed and that voltage sources, re-

sistors, and capacitors may be tied to the FEEDBACK pin, a

range of V

r temperature coefficients may be synthesized.

Connecting a resistor across Cathode-to-FEEDBACK cre-

ates a 0 TC current source, but a range of TCs may be

synthesized.

DS009226-33

R1 = Vr/I = 1.24/32µ = 39k

R2 = R1 {(Vro/Vr) − 1} = 39k {(5/1.24) − 1)} = 118k

FIGURE 5. Resistors R1 and R2 Program Reference

Output Voltage to be 5V

DS009226-34

FIGURE 6. Output Voltage has Negative Temperature

Coefficient (TC) if R2 has Negative TC

DS009226-35

FIGURE 7. Output Voltage has Positive TC

if R1 has Negative TC

DS009226-36

FIGURE 8. Diode in Series with R1 Causes Voltage

Across R1 and R2 to be Proportional to Absolute

Temperature (PTAT)

DS009226-37

I = Vr/R1 = 1.24/R1

FIGURE 9. Current Source is Programmed by R1

DS009226-38

FIGURE 10. Proportional-to-Absolute-Temperature

Current Source

DS009226-39

FIGURE 11. Negative-TC Current Source

LM613 Arkusz danych(PDF) 16 Page - National Semiconductor (TI)