AIC1781A Datasheet, PDF (14/18 Pages) Analog Intergrations Corporation – Battery Charge Controller

AIC1781A
Procedure
(a) First, determine the temperature protection
limits TH and TL. Then, substitute TH & TL into
the following equation:
∆VTS ₌ 0.72VCC − 0.29VCC ₌ 0.43VCC
∆TBASE
TH − TL
TH − TL
(b) Determine the safety timer to obtain the value of
∆t_BASE .
∆tBASE(sec.) = ^56(sec.) × Safety Timer(min.)
80(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 ₌ y
∆t x
(d) Calculate the value of V_ADJ
VADJ = 30 × ^∆VTS × ^∆T × ∆tBASE
∆TBASE ∆t
Example
(a) Let TH=50°C, TL=0°C, V_CC =5V. We have
∆VTS ₌ 0.43 × 5 _{= 0.043V/° C}
∆TBASE 50 − 0
which means that V_TS decreases 43mV as
temperature rises 1°C.
(b) If safety timer is equal to 80 minutes, ∆t_BASE is
then 56 seconds.
(c) If fast charge should be terminated when
temperature rises 1°C in 60 seconds, then
∆T/∆t = ¹ = 0.0166
60
(d) V_ADJ =30 x 0.043x 0.0166 x 56 = 1.2(V)
If the temperature range is from 0°C to 50°C,
the voltage of V_ADJ under different setting
conditions should be set as tabulated below.
TABLE 6 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)
0.45
0.60
0.75
80 min. (1C)
0.90
1.20
1.50
120 min. (0.67C) ^1.35
1.80
2.25
160 min. (0.5C) ^1.80
2.40
3.01
200 min. (0.4C) ^2.25
3.01
3.76
240 min. (0.33C) ^2.70
3.61
4.51
A similar table for temperature range from 0°C to
60°C is as below.
TABLE 7 ADJ Pin Voltage (TL=0°C, TH=60°C)
∆T / ∆t 0.75
1.0
1.25
S.T.
40 min. (2C)
(°C/min.) (°C/min.) (°C/min.)
0.37
0.50
0.62
80 min. (1C)
0.75
1.00
1.25
120 min. (0.67C) ^1.12
1.50
1.88
160 min. (0.5C) ^1.50
2.00
2.50
200 min. (0.4C) ^1.88
2.50
3.13
240 min. (0.33C) ^2.25
3.01
3.76
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 > V_CC - 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
temperature is either too low or too high,
same as abnormal battery voltage. Latch for
charge-suspending function is provided for
high temperature protection, but not for low
temperature protection.
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