AD8495 Amplifiers Introduction

Figure 1 AD8495ARMZ	Figure 2 Pin Configuration
Figure 3 Functional Block Diagram

Table of Contents

WHAT IS AD8495ARMZ ?

The AD8495ARMZ is an instrumentation amplifier with thermocouple cold junction compensator on an integrated circuit. The effects of temperature change on dissimilar metals (Thermocouple) produces a measurable voltage. But to make that measurement you need an amplifier circuit (A8495ARMZ) designed for the thermocouple being used. This device incorporates precision instrumentation amplifiers provide an amplified output directly from a type J or K thermocouples. The AD8495ARMZ can be powered from a single-ended supply and can measures temperature below 0°C. They can be used as a thermometers or as switched output setpoint controllers.

PINOUT DISCRIPTION

Table 1 PIN Configuration

PIN NO.	LABLE	DESCRIPTION
1	-IN	Connect this pin with -Ve terminal of thermocouple
2	REF	Reference
3	V_S	-Ve Supply
4	NC	No Connect (Floating)
5	SENSE	Sense Pin
		Measurement Mode	Connect to Output
		Setpoint Mode	Connect to Setpoint Voltage
6	OUT	Output
7	+V_S	Positive Supply
8	+IN	Connect this pin with +Ve terminal of thermocouple

ABSOLUTE MAXIMUM RATINGS^*

PARAMETER	VALUE
Supply Voltage	±18 V
Maximum Voltage at −IN or +IN	−V_S + 25 V
Minimum Voltage at −IN or +IN	+V_S − 25 V
REF Voltage	±V_S
Operating Temperature Range	−40°C to +125°C
Maximum IC Junction Temperature	140°C

*Operation beyond the maximum operating conditions for extended periods may affect product reliability.

FEATURES

Low cost
Easy to operate
suitable for J or K type thermocouples
Internal cold junction compensation (for monitoring changes in cold junction)
High impedance differential input
Can be used as Thermometer
offset adjustment
Thermocouple break detection
Laser wafer trimmed to 1°C initial accuracy
ambient temperature rejection
Low power consumption
Wide power supply range
Single supply: 2.7 V to 36 V
Dual supply: ±2.7 V to ±18 V

ALTERNATIVES FOR AD8495ARMZ

Table 2 equivalent for AD8495

IC NUMBER	THERMOCOUPLE TYPE	TEMPRATURE RANGE
IC NUMBER	THERMOCOUPLE TYPE	REFERENCE JUNCTION	MEASUREMENT JUNCTION
AD8495	K	0°C to 50°C	Full K type range
AD8494	J	0°C to 50°C	Full J type range
AD8496	J	25°C to 100°C	Full J type range
AD8497	K	25°C to 100°C	Full K type range

APPLICATION | FUNCTION

J or K type thermocouple temperature measurement
Setpoint controller
Celsius thermometer
Universal cold junction compensator
White goods (oven, stove top) temperature measurements
Exhaust gas temperature sensing
Catalytic converter temperature sensing

HOW TO USE AD8495ARMZ ? | Working of AD8495ARMZ

Fig.4 Shows connection of AD8495 with K type thermocouple. A filter at the input is recommended to remove high frequency noise. The 1 MΩ resistor to ground enables open thermocouple detection and proper grounding of the thermocouple. The sense pin should be connected to the output pin of the AD8495. Decoupling capacitors should be used to ensure clean power supply voltages on +VS and, if using dual supplies, on −VS, also. A 0.1 μF capacitor should be placed as close as possible to each AD8495 supply pin. A 10 μF tantalum capacitor can be used farther away from the part and can be shared.

Figure 4 Connection for AD8495

Figure 5 Connection for AD8495

2D-VIEW AND FOOTPRINT

Figure 6 2-D View and PCB Footprint of AD8495ARMZ

AD8495 RELATED PRODUCTS PRICE

Parts	Mfr.	Description	Stock	Prices
AD8495ARMZ	Analog	IC THERMOCOUPLE A W/COMP 8MSOP	26894	$2.390 Lowest
AD8495ARMZ	Analog	IC THERMOCOUPLE	21896	$2.390 Lowest
AD8497ARMZ	Analog	Thermocouple Amplifiers	6	$4.696 Lowest