ACS108-6SA Просмотр технического описания (PDF) - STMicroelectronics
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ACS108-6SA Datasheet PDF : 13 Pages
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ACS108-6SA
Alternating current mains switch - basic application
2
Alternating current mains switch - basic application
The ACS108 switch is triggered by a negative gate current flowing from the gate pin G. The switch can be driven
directly by the digital controller through a resistor as shown in Figure 13. Typical application schematic
Thanks to its overvoltage protection and turn-off commutation performance, the ACS108 switch can drive a small
power high inductive load with neither varistor nor additional turn-off snubber.
Figure 13. Typical application schematic
Lamp
Motor
M
Solenoid
Vss
MCU
Vdd
Rg = 220 Ohm
OUT
ACS108
GATE
COM
AC Mains
2.1
2.1.1
Protection against overvoltage: the best choice is ACS
In comparison with standard Triacs the ACS108 is over-voltage self-protected, as specified by the parameter VCL.
This feature is useful in two operating conditions: in case of turn-off of very inductive load, and in case of surge
voltage that can occur on the electrical network.
High inductive load switch-off: turn-off overvoltage clamping
With high inductive and low rms current loads the rate of decrease of the current is very low. An overvoltage can
occur when the gate current is removed and the OUT current is lower than IH.
As shown in Figure 14. Switching off of a high inductive load - typical clamping capability of ACS108 (Tamb = 25
°C), at the end of the last conduction half-cycle, the load current decreases ① . The load current reaches the
holding current level IH ② , and the ACS turns off ③ . The water valve, as an inductive load (up to 15 H), reacts
as a current generator and an overvoltage is created, which is clamped by the ACS ④ . The current flows through
the ACS avalanche and decreases linearly to zero. During this time, the voltage across the switch is limited to the
DS1641 - Rev 6
page 7/13
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