7

LT1025

1025fb

3. Calibrate output by adding in a true offset term which

does not affect gain (by summing, etc.). Calibration may

be done at any temperature either by immersing the

thermocouple in a calibrated bath or by substituting a

precision input voltage. The method which tends to

is to calibrate at 1/6 or 5/6 of span. This may be modified

if best accuracy is desired at one particular point.

Breakpoint correction for nonlinearity is more compli-

cated than a simple offset, but a single breakpoint com-

bined with offset will reduce errors typically by 4:1 over a

simple offset technique.

APPLICATIO S I FOR ATIO

TYPICAL APPLICATIO S

–

–

+

+

4

6

7

2

3

–15V

15V

–15V

–10mV/

°C

15V

3k

300k

GND

K

TYPE K

C1

0.1

µF

C2

1

µF

LT1025

Eliminating Amplifier Feedback Resistors

(Output Goes Negative with Increasing Temperature)

Type K Thermometer with Grounded Thermocouple

–15V

10mV/

°C

V

+

V

–

V

–

V

–

GND

LT1025

–

+

V

+

R5

10k

R1

1k

1%

R6

9.1k

R4*

470k

R3

255k

1%

R2

100

Ω

TYPE K

0.1

µF

C2

1

µF

*R4

≤

30

µA

MUST BE DECREASED APPROPRIATELY. R4 IS NOT

REQUIRED (OPEN) FOR LT1025 TEMPERATURES

≥ 0°C

WHEN SOURCING CURRENT ONLY

IF OUTPUT MUST SINK CURRENT, R4

LTKA0x

††