AMG-LI080 Datasheet, PDF (5/24 Pages) alpha microelectronics gmbh – Timer/Dimmer with Gate Driver, Zero Detection & Protection

AMG-LI080
Timer/Dimmer with Gate Driver, Zero Detection & Protection
5. Block Descriptions
5.1. Zero Crossing
Detects the Zero Crossing of the AC sine wave. The INZ input is connected to the rectified
mains with a resistor divider. For noise suppression, the INZ input should also be connected to
GND with a capacitor. This capacitor will cause a time delay between the actual zero crossing
and the detection. Bigger capacitors will cause a longer time delay than smaller ones. This
time delay may or may not affect the function.
5.2. Time Reset
Determines the on time of the output, thus the duty cycle, or the time of the reverse phase cut.
The Time Reset is triggered by the zero crossing. The Time Reset is reset by an external R
and C, which determines the time to reset.
5.3. Gate Driver + Output Latch
Supplies the gate charge for the external MOSFETs. Continuous current capability is around
10mA. The output latch is set by the Zero Crossing and reset by the Time Reset.
5.4. Protection Logic
The IC has 3 sense inputs for over voltage, over current and over temperature protection.
OVP: Over Voltage Protection
OTP: Over Temperature Protection
OCP: Over Current Protection
These sense inputs have an internal pull up and are connected to a comparator. The
comparator thresholds are set according to their dedicated protection function, but
nevertheless, they can be used for something else. The sense inputs all need some additional
external circuitry to enable the protection. Please refer to the example application diagram or
the application note. If a specific protection function is not needed, the corresponding sense
input should be connected to GND. All 3 protection comparators individually set a latch when
the threshold is reached. When set, the latch will inhibit the Zero Crossing and thus the output
of the device and activate the LED driver. The protective latch is reset at power up. As such
the protection functions work like a recoverable fuse.
5.5. Soft Start
Soft Start is in essence adjustable current source. With an external C, the time to reach max.
current can be adjusted. In that way, a soft start function can be built. Please refer to the
example application diagram or the application note. In case, a 1-10V analog signal shall
control the dimmer, it can be connected to the CS pin.
AMG-LI080 Revision: B
8. Nov. 2012 © All rights reserved Page 5 of 24