LT6003 datasheet(20/32 Pages) AD

20 / 32 page

LTC2063/LTC2064/LTC2065

Rev. C

For more information www.analog.com

OUT

2063 F10

–

RFB

1.58M

RTD

100k

10k

100k

LT5400-3

GND

LT6656-2.048

11k

110k

0.1%

±2ppm/°C

10µF

VOUT SCALE 10mV/°C

1V AT 25°C ROOM TEMP

ISUPPLY = 35µA

VISHAY PTS SERIES

1k PtRTD, CLASS F0.3

PTS12061B1K00P100

www.vishay.com

0.1µF

2.6V ≤ VSUPPLY ≤ 18V +

–

OUT

LTC2063

131:1 VOLTAGE DIVIDER

Figure 10. RTD Sensor

APPLICATIONS INFORMATION

RTD Sensor

This low power platinum resistance temperature detector

(RTD) sensor circuit draws only 35μA total supply current

on a minimum 2.6V rail, and is accurate to within ±1°C

at room temperature, including all error intrinsic to the

Vishay PTS Class F0.3 Variant RTD. It covers the tempera-

ture range from –40°C to 85°C in 10mV/°C increments

and produces an output of 1V at nominal room tempera-

ture of 25°C.

The LTC2063’s extremely low typical offset of 1μV and

typical input bias current of 3pA allows for the use of a

very low excitation current in the RTD. Thus, self-heating

is negligible, improving accuracy.

The LT5400-3, B-grade, is used to provide a ±0.025%

matched resistor network that is effectively a precision

131:1 voltage divider. This precision divider forms one

half of a bridge circuit, with the 0.1% 110kΩ and RTD in

the other branch. Note that the 110kΩ’s precision require-

ment is to ensure matching with the RTD. The 11kΩ R2

serves to provide a DC offset for the entire bridge so

that the output is 1V at room temperature. Since bridge

imbalances can lead to error, it is recommended to mini-

mize the length of the leads connecting the RTD to reduce

additional lead resistance.

The LT6656-2.048 reference helps create a known exci-

tation current in the RTD at each temperature of operation,

and also acts as a supply for the LTC2063, all while using

less than 1μA itself. The LT6656 can accept input voltages

anywhere between 2.6V and 18V, allowing for flexibility

in selection of supply voltage while maintaining a fixed

output range. The LT6656 reference can easily source

the 35μA required to run the entire circuit, thanks to the

LTC2063’s 2μA maximum supply current and ability to

handle microvolt signals produced by the RTD under low

excitation current.

Care should be taken to minimize thermocouple effects by

preventing significant thermal gradients between the two

op amp inputs. It is also important to choose feedback

and series resistors that are low-tempco to minimize error

due to drift over the entire temperature range.

LT6003 Datasheet(PDF) 20 Page - Analog Devices

LT6003 Datasheet(HTML) 20 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

Datasheet Download

Link URL