AD22105
Leakage at the R
SET
Pin
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
Leakage currents at the R
SET
pin, such as those generated from a
moist environment or printed circuit board contamination, can
have an adverse effect on the programmed setpoint temperature
of the AD22105. Depending on its source, leakage current can
flow into or out of the R
SET
pin. Consequently, the actual
setpoint temperature could be higher or lower than the intended
setpoint temperature by about 1°C for each 75 nA of leakage.
With a 5 V power supply, an isolation resistance of 100 MΩ
would create 50 nA of leakage current giving a setpoint
temperature error of about 0.7°C (the R
SET
pin is near ground
potential). A guard ring can be placed around the R
SET
node to
protect against leakage from the power supply pin (as shown in
Figure 13).
V
S
8-Lead SOIC
(SO-8)
C2099–6–1/96
0.0196 (0.50)
x 45°
0.0099 (0.25)
8°
0°
0.0500 (1.27)
0.0160 (0.41)
0.1968 (5.00)
0.1890 (4.80)
8
1
5
4
0.1574 (4.00)
0.1497 (3.80)
0.2440 (6.20)
0.2284 (5.80)
PIN 1
0.0098 (0.25)
0.0040 (0.10)
0.0688 (1.75)
0.0532 (1.35)
C1
R
SET
SEATING
PLANE
0.0500 0.0192 (0.49)
(1.27) 0.0138 (0.35)
BSC
0.0098 (0.25)
0.0075 (0.19)
GND
PIN 1
OUT
Figure 13. Suggested PCB Layout
–8–
REV. 0
PRINTED IN U.S.A.
AD [ ANALOG DEVICES ]
