AIC1781 データシートの表示（PDF） - Analog Intergrations
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AIC1781 Datasheet PDF : 17 Pages
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AIC1781
Procedure
(a) First, determine the temperature protection limits
TH and TL. Then, substitute TH & TL into the
following equation:
∆V TS
∆TBASE
=
0.72 VCC − 0. 29 VCC
TH − TL
=
0. 43 VCC
TH − TL
(b) Determine the safety timer to obtain the value of
∆tBASE .
∆t ( BASE sec. )
=
56 (sec. )
80(min. )
×
Safety
Timer
(min. )
(c) Determine the expected slope of ∆T / ∆t at
which temperature rises y°C in x seconds and
fast charge is subsequently cut off.
∆T
∆t
=
y
x
(d) Calculate the value of VADJ
V ADJ
=
25
×
∆V TS
∆TBASE
×
∆T
∆t
×
∆t BASE
Example
(a) Let TH=50°C, TL=0°C, VCC =5V. We have
∆VTS
∆TBASE
=
0.43 × 5
50 − 0
=
0.043V/° C
which means that VTS decreases 43mV as
temperature rises 1°C.
(b) If safety timer is equal to 80 minutes, ∆tBASE is
then 56 seconds.
(c) If fast charge should be terminated when
temperature rises 1°C in 60 seconds, then
∆T/∆t
=
1
60
=
0.0166
(d) VADJ =25 x 0.043x 0.0166 x 56 = 1(V)
If the temperature range is from 0°C to 50°C,
the voltage of VADJ under different setting
conditions should be set as tabulated below.
TABLE. 3 ADJ pin Voltage (TL=0°C, TH=50°C)
∆T / ∆t
0.75
1.0
1.25
S.T.
(°C/min.) (°C/min.) (°C/min.)
40 min. (2C)
0.37
0.5
0.63
80 min. (1C)
0.75
1.0
1.25
120 min. (0.67C) 1.12
1.5
1.87
160 min. (0.5C) 1.5
2.0
2.5
200 min. (0.4C) 1.87
2.5
3.12
240 min. (0.33C) 2.25
3.0
3.75
A similar table for temperature range from 0°C to
60°C is as below.
TABLE. 4 ADJ Pin Voltage (TL=0°C, TH=60°C)
∆T / ∆t
S.T.
40 min. (2C)
80 min. (1C)
120 min. (0.67C)
160 min. (0.5C)
200 min. (0.4C)
240 min. (0.33C)
0.75
1.0
1.25
(°C/min.) (°C/min.) (°C/min.)
0.31
0.42
0.52
0.62
0.84
1.05
0.94
1.25
1.56
1.25
1.67
2.08
1.56
2.08
2.60
1.87
2.5
3.12
VBT Range and Temperature Protection
The acceptable voltage range of VBT pin and
mode of temperature protection function is
determined by the voltage of SEL3 pin, shown as
the following:
(a) SEL3 > VCC - 0.3V
Acceptable VBT Range:
Before initial timer: 0.16V~2.7V
After initial timer: 0.69V~2.7V
Temperature Protection Mode:
Entering charge-suspending mode when
13
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