Datasheet

LTC2057/LTC2057HV
20
2057f
For more information www.linear.com/LTC2057
applicaTions inForMaTion
Figure 7a. Example Layout of Non-Inverting Amplifier with Leakage Guard Ring
LEAKAGE
CURRENT
HIGH-Z
SENSOR
GUARD
RING
NO SOLDER MASK
OVER GUARD RING
V
–
V
–
GRD
+IN
GRD
–IN
OUT
NC
V
+
V
+
V
OUT
SD
SDCOM
*
* NO LEAKAGE CURRENT. V
+IN
= V
GRD
** V
ERROR
= I
LEAK
• R
G
; R
G
<< Z
SENSOR
R
F
V
BIAS
R
G
**
2057 F07a
+
–
R
IN
HIGH-Z SENSOR
GUARD RING
†
LEAKAGE CURRENT
ALTERNATIVE
GUARD RING
DRIVE
ALTERNATIVE GUARD RING
DRIVE CIRCUIT IF R
G
MUST
BE HIGH IMPEDANCE.
†
V
IN
V
OUT
V
BIAS
R
G
R
F
LTC2057
R´
F
+
–
V
+
V
–
R´
G
R
F
R
G
=
R'
F
R'
G
; R'
G
<< R
G
LTC2057
MS10
Figure 6. Techniques for Minimizing Thermocouple-Induced Errors
LTC2057
THERMAL
GRADIENT
RELAY
MATCHING RELAY
NC
* 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.
HEAT SOURCE/
POWER DISSIPATOR
R
L
§
–IN
+IN
R
F
§
R
G
R
F
V
IN
*
R
G
2057 F06
**
†
‡
**
#
+
–
+
–
V
THERMAL
V
THERMAL