PTMP6331DECT datasheet(13/20 Pages) TI1

13 / 20 page

Temperature (qC)

100

125

150

D014

RBias

200 k

5 V

RTMP63

200 k

VOut

10 k

200 k

VTemp

RFB

300 k

VRef

TMP63

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SNIS211 – OCTOBER 2019

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Typical Application (continued)

Figure 8. Thermal Foldback Using TMP63 Voltage Divider and a Rail-to-Rail Op Amp

The op amp will remain high as long as the voltage output is below VRef. When the temperature goes above

110°C, then the output will swing low to the 0-V rail of the op amp. The rate at which the foldback occurs is

dependent on the feedback network, RFB and R1, which varies the gain of the op amp, G, given by Equation 6.

This in return controls the voltage/temperature sensitivity of the circuit. This voltage output is fed into a LED

driver IC that will adjust output current accordingly. The final output voltage used for thermal foldback is VOUT,

and is given in Equation 7. In this example where the knee point is set at 110°C, the output voltage curve is as

shown in Figure 9.

(5)

(6)

(7)

Figure 9. Thermal Foldback Voltage Output Curve

PTMP6331DECT 데이터시트(PDF) 13 Page - Texas Instruments