ACT3780QY410-T Ver la hoja de datos (PDF) - Active-Semi, Inc
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ACT3780QY410-T Datasheet PDF : 18 Pages
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kHOT(@TC) = VTHH/(RNOM × (ITH + (VCHG_IN - VTHH)/R))
kHOT(@TC) = 0.5V/(6.8kΩ × (100µA + (5V - 0.5V)/82kΩ))
= 0.4748
Reviewing the characteristic curves, the upper
threshold is found to move to 45°C, a change of
about 14°C. Adding the parallel resistance has
allowed us to achieve our desired lower threshold of
0°C with an operating temperature range of 0°C to
45°C, vs. our design target of 0°C to 40°C.
Thermal Regulation and Protection
The ACT3780 features an internal thermal
regulation loop that reduces the charging current as
necessary to ensure that the die temperature does
not rise beyond the thermal regulation threshold of
110°C. This feature protects the ACT3780 against
excessive junction temperature and makes the
device more accommodating to aggressive thermal
designs. Note, however, that attention to good
thermal designs is required to achieve the fastest
possible charge time by maximizing charge current.
In order to account for the extended total charge
time resulting from operation in thermal regulation
mode, the charge timeout periods are extended
proportionally to the reduction in charge current.
The conditions that cause the ACT3780 to reduce
charge current in accordance to the internal thermal
regulation loop can be approximated by calculating
the power dissipated in the part.
The ACT3780 also features thermal shutdown for
further protection. When the device temperature
exceeds 160°C, the device will automatically turn
off to prevent the IC from damage. After the die
temperature decreases below 135°C, the IC will
ACT3780
Rev 8, 09-Jul-13
automatically restart.
Charging Safety Timers
The ACT3780 features a programmable safety
charging timer by setting an external resistor from
BTR pin to G (RBTR). The time out period is
calculated as shown in Figure 2. The maximum RBTR
should not be larger than 68kΩ.
If the timeout period expires without change
termination, the ACT3780 will jump to EOC state.
If the ACT3780 detects that the charger remains in
precondition for longer than the precondition time
out period (which determined as TNORMAL/3), the
ACT3780 turns off the charger and generates a
FAULT to ensure prevent charging a bad cell.
Figure 2:
TNORMAL vs. RBTR
190
160
130
100
70
30 35 40 45 50 55 60 65 70
RBTR (kΩ)
Figure 3:
Fix VTHL Configuration
Figure 4:
Fix VTHH Configuration
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