Rainbow Electronics MAX6636 - Manual (Page 17)

MAX6636
7-Channel Precision Temperature Monitor
______________________________________________________________________________________ 17
Twisted-Pair and Shielded Cables
Use a twisted-pair cable to connect the remote sensor
for remote-sensor distances longer than 8in or in very
noisy environments. Twisted-pair cable lengths can be
between 6ft and 12ft before noise introduces excessive
errors. For longer distances, the best solution is a
shielded twisted pair like that used for audio micro-
phones. For example, Belden 8451 works well for dis-
tances up to 100ft in a noisy environment. At the
device, connect the twisted pair to DXP and DXN and
the shield to GND. Leave the shield unconnected at the
remote sensor. For very long cable runs, the cable’s
parasitic capacitance often provides noise filtering, so
the 2200pF capacitor can often be removed or reduced
in value. Cable resistance also affects remote-sensor
accuracy. For every 1Ω of series resistance the error is
approximately +1/2°C.
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
GND
SMBCLK
SMBDATA
DXN2
DXP2
DXN1
DXP1
TOP VIEW
V CC
N.C.
STBY DXN4
DXP4
DXN3
DXP3
12
11
9
10
DXP6
DXN6 DXN5
DXP5
MAX6636
TSSOP
+
ALERT
OVERT
Pin Configuration
Chip Information
PROCESS: BiCMOS