LM56

SNIS120G – APRIL 2000 – REVISED FEBRUARY 2013

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VT1 = 1.250V x (R1)/(R1 + R2 + R3)

VT2 = 1.250V x (R1 + R2)/(R1 + R2 + R3)

where:

(R1 + R2 + R3) = 27 k

Ω and

VT1 or T2 = [6.20 mV/°C x T] + 395 mV therefore:

R1 = VT1/(1.25V) x 27 kΩ

R2 = (VT2/(1.25V) x 27 k)Ω–R1

R3 = 27 k

Ω − R1 − R2

Application Hints

LM56 TRIP POINT ACCURACY SPECIFICATION

For simplicity the following is an analysis of the trip point accuracy using the single output configuration shown in

Figure 14 with a set point of 82°C.

Trip Point Error Voltage = VTPE,

Comparator Offset Error for VT1E

Temperature Sensor Error = VTSE

Reference Output Error = VRE

Figure 14. Single Output Configuration

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