LM615 datasheet(9/14 Pages) NSC

9 / 14 page

Application Information (Continued)

Understanding that Vr is fixed and that voltage sources re-

sistors and capacitors may be tied to the FEEDBACK pin a

range of Vr temperature coefficients may be synthesized

TLH11057 – 14

FIGURE 6 Output Voltage has Negative Temperature

Coefficient (TC) if R2 has Negative TC

TLH11057 – 15

FIGURE 7 Output Voltage has Positive TC

if R1 has Negative TC

TLH11057 – 16

FIGURE 8 Diode in Series with R1 Causes Voltage

Across R1 and R2 to be Proportional to Absolute

Temperature (PTAT)

Connecting a resistor across VRO-to-FEEDBACK creates a

0 TC current source but a range of TCs may be synthe-

sized

TLH11057 – 17

I e Vr R1 e 124R1

FIGURE 9 Current Source is Programmed by R1

TLH11057 – 18

FIGURE 10 Proportional-to-Absolute-Temperature

Current Source

TLH11057 – 19

FIGURE 11 Negative-TC Current Source

Reference Hysteresis

The reference voltage depends slightly on the thermal his-

tory of the die Competitive micro-power products varyal-

ways check the data sheet for any given device Do not

assume that no specification means no hysteresis

LM615 데이터시트(PDF) 9 Page - National Semiconductor (TI)