8

LTC2401/LTC2402

APPLICATIO S I FOR ATIO

12.5%

EXTENDED

RANGE

24012 F04

12.5%

EXTENDED

RANGE

Figure 4. Transfer Curve with Zero-Scale and Full-Scale Set

have negligible errors due to the 1nA (typ) leakage current

range (– 300mV to 5.3V) and low noise (0.6ppm RMS)

enable the LTC2401 or the LTC2402 to directly digitize the

output of the bridge sensor.

The LTC2402 is ideal for applications requiring continu-

ous monitoring of two input sensors. As shown in

Figure 5, the LTC2402 can monitor both a thermocouple

temperature probe and a cold junction temperature sen-

sor. Absolute temperature measurements can be

performed with a variety of thermocouples using digital

cold junction compensation.

The selection between CH0 and CH1 is automatic. Initially,

after power-up, a conversion is performed on CH0. For

each subsequent conversion, the input channel selection

Figure 5. Isolated Temperature Measurement

SCK

CH1

SDO

GND

CS

THERMOCOUPLE

COLD JUNCTION

ISOLATION

BARRIER

PROCESSOR

CH0

–

+

110

12k

THERMISTOR

100

Ω

9

8

7

6

2

3

4

5

2.7V TO 5.5V

LTC2402

24012 F05

LTC2401

GND

SCK

SDO

CS

3-WIRE

SPI INTERFACE

1

9

8

7

10

24012 F03

2

3

5

6

Figure 3. Half-Bridge Digitizer with

Zero-Scale and Full-Scale Sense