AIC1781A Datasheet, PDF (13/18 Pages) Analog Intergrations Corporation – Battery Charge Controller

AIC1781A
The calculation for Rx and Ry in the circuit is as
following.
Ry//RTH
0.29 V_CC = _{Rx + (Ry// RTH)} x V_CC
R_TH= The resistance of thermistor at upper limit of
temperature protection.
Ry//R TL
0.72 V_CC = _{Rx + (Ry// R TL )} x V_CC
R_TL= The resistance of thermistor at lower limit of
temperature protection.
Substitution and rearranging the equations yield
RTL × RTH
Rx= 2.061 ×
RTL − RTH
5. 3 × RTL × RTH
Ry =
RTL − 6. 3RTH
If temperature characteristic of the thermistor is like
that of SEMITEC 103AT-2, the resistance of Rx and
Ry is tabulated for different TL and TH as below.
(Note: TL is lower temperature limit and TH is upper
temperature limit.)
TABLE 4 Values of Rx and Ry at TL = 0°C
TH (°C)
Rx(KΩ)
Ry (KΩ)
50
10.1
551.1
51
9.7
300.7
52
9.4
204.8
53
9.0
153.9
54
8.7
122.8
55
8.4
101.8
56
8.1
86.5
57
7.8
75.0
58
7.5
66.0
59
7.2
58.7
60
7.0
52.8
61
6.8
47.8
62
6.5
43.6
63
6.3
39.9
64
6.1
36.8
65
5.9
34.0
66
5.7
31.6
67
5.5
29.5
68
5.3
27.5
69
5.2
25.8
70
5.0
24.3
TABLE 5 Values of Rx and Ry at TL = -10°C
TH (°C)
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
Rx (KΩ)
11.4
11.0
10.6
10.2
9.8
9.5
9.1
8.8
8.5
8.2
7.9
7.6
7.4
7.1
6.9
6.7
6.4
6.2
6.0
5.8
5.6
Ry (KΩ)
95.6
85.0
76.2
68.9
62.8
57.5
52.9
48.8
45.3
42.1
39.4
36.8
34.6
32.5
30.7
29.0
27.4
26.0
24.6
23.4
22.2
Setting the ADJ Pin Voltage
The slope of ∆T/∆t detection is determined by ADJ
pin voltage of the AIC1781A.
The calculation of ADJ pin voltage is shown in the
following procedure followed by an example.
13