LTC2057/LTC2057HV
applicaTions inForMaTion
§
#
R
F
HEAT SOURCE/
POWER DISSIPATOR
RELAY
**
V
V
THERMAL
THERMAL
GRADIENT
R
R
+
G
–
§
LTC2057
R
L
–IN
+IN
†
THERMAL
G
**
V
+
–
IN
‡
MATCHING RELAY
NC
*
R
F
2057 F06
* CUT SLOTS IN PCB FOR THERMAL ISOLATION.
**INTRODUCE DUMMY JUNCTIONS AND COMPONENTS TO OFFSET UNAVOIDABLE JUNCTIONS OR CANCEL THERMAL EMFs.
†
‡
§
#
ALIGN INPUTS SYMMETRICALLY WITH RESPECT TO THERMAL GRADIENTS.
INTRODUCE DUMMY TRACES AND COMPONENTS FOR SYMMETRICAL THERMAL HEAT SINKING.
LOADS AND FEEDBACK CAN DISSIPATE POWER AND GENERATE THERMAL GRADIENTS. BE AWARE OF THEIR THERMAL EFFECTS.
COVER CIRCUIT TO PREVENT AIR CURRENTS FROM CREATING THERMAL GRADIENTS.
Figure 6. Techniques for Minimizing Thermocouple-Induced Errors
LEAKAGE
CURRENT
GRD
–IN
SD
LTC2057
MS10
R **
G
SDCOM
+
+
V
+IN
V
V
V
BIAS
*
GRD
NC
HIGH-Z
SENSOR
–
V
OUT
GUARD
RING
OUT
NO SOLDER MASK
OVER GUARD RING
–
V
R
F
*
**
NO LEAKAGE CURRENT. V = V
+IN
GRD
SENSOR
V
= I
• R ; R << Z
ERROR LEAK
G
G
R
F
+
V
R
G
–
V
BIAS
†
LTC2057
V
OUT
R
IN
+
IN
–
V
+
R´
ALTERNATIVE GUARD RING
–
F
V
GUARD RING
DRIVE CIRCUIT IF R MUST
G
ALTERNATIVE
GUARD RING
DRIVE
HIGH-Z SENSOR
BE HIGH IMPEDANCE.
RF R'
=
F ; R'G <<RG
†
R´
G
LEAKAGE CURRENT
RG R'G
2057 F07a
Figure 7a. Example Layout of Non-Inverting Amplifier with Leakage Guard Ring
2057f
20
For more information www.linear.com/LTC2057
LINEAR_DIMENSIONS [ Linear Dimensions ]
