MX4428 MXP Engineering / Technical Manual
Document: LT0273
MXP Loop Filter Board
Page 9-10
24 March 2006
Issue 1.5
9.7
MIM800 / CIM800 / MIM801 PROCESSING
The MIM800 and CIM800 return a value which depends on the external resistance across
the contact terminals and which can be modelled by the equation –
VALUE = 226 * (150 + 3) / (150 + Rext + 3)
The MIM801 returns a value which depends on the external resistance across the contact
terminals and which can be modelled by the equation –
VALUE = 226 * (Rext + 3) / (150 + Rext + 3)
(unless Rext is open circuit, then value = 255)
(Note 150 represents an internal 150
Ω
resistor, 3 represents a 3
Ω
FET on resistance, and
226 represents (3.3V - DIODEV) / 3.3V * 255
Graphs of these values are show in Figure 9.7. Also shown are the default thresholds, and
the interpretations of the input ranges between the thresholds.
0
20
40
60
80
100
120
140
160
180
200
220
240
0
50
100
150
200
250
300
350
400
450
500
550
600
R
Read
ing
MIM801
MIM800
N/O : Optional S/C Fault
N/O : Alarm
N/C:
O/C Fault
N/C : S/C Fault
N/O :
Alarm
N/O :
Optional S/C Fault
Normal
Normal
N/O :
O/C Fault
N/C :
Alarm
N/O :
O/C
Fault
N/C :
Alarm
176
122
110
40
50
170
Figure 9.7 MIM800 / MIM801 Reading versus resistance
The usual parameters are as follows –
MIM800 / CIM800
MIM801
P0 P1 P2 P3 P4 P5
No alarm resistor
(Default)
122 50 0 110 170 0
With alarm
resistor
176
40