5.4 Thermistor
The thermistor is very important to adjust the strobe time (Tstrobe) ~ (SLT) in function of the head temperature and to moni-
tor the temperature to prevent the head damage if the substrate temperature is over the limit of 70 °C .
•
Resistance R25:
30 kΩ ± 5% at 25 °C
•
β value:
3950 K ± 2%
• Operating temperature:
– 40 ~ + 125 °C
• Time constant:
0 .5 s (in the air)
Then the resistance value, R, versus temperature, T (in °C) is given by the formula:
R(T
X
) = R25 × EXP [ β × (1/TX – 1/T25) ]
Fig. 5.4.1 Thermistor curve
0
200000
400000
600000
800000
1000000
1200000
1400000
-4
0,
00
-3
5,
00
-3
0,
00
-2
5,
00
-2
0,
00
-1
5,
00
-1
0,
00
-5
,0
0
0,
00
5,
00
10
,0
0
15
,0
0
20
,0
0
25
,0
0
30
,0
0
35
,0
0
40
,0
0
45
,0
0
50
,0
0
55
,0
0
60
,0
0
65
,0
0
70
,0
0
75
,0
0
80
,0
0
85
,0
0
90
,0
0
95
,0
0
10
0,
00
10
5,
00
11
0,
00
11
5,
00
12
0,
00
12
5,
00
R
es
is
ta
nc
e
(K
O
hm
)
Temperature (°C)
22
