Datasheet

CCRACGEVB
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6
Figure 8. Cap−Drop LED Driver with Triac Dimming (120 VAC example)
Chopper LED Driver Topology 85 VAC to 250 VAC,
Non−dimming:
The Chopper circuit is selected for high efficiency and a
wide input voltage range.
To set up the CCRACGEVB for the Chopper LED driver
non-dimming topology, place jumpers according to Table 6.
Figure 9 depicts the schematic with the evaluation board
reference designators.
Table 6. JUMPERS PLACED ONTO THE EVB
Jumpers in Place Reference Data
J1, J8, J10, J13, J19, J22, J25,
J26
Appendix G
The operation of the Chopper circuit can be broken into
two sub-circuits; a simple buck and a straight LED driver
with output capacitance. The AC is then rectified using an
AC bridge (D1 – D4).
A CCR (CCR3, 4, 5 or 6) controls the current through the
LED string.
The Buck circuit is comprised of a voltage divider R8 &
R16/R10 that are used to set the voltage through TL431, that
the MOSFET switch M2 turns off. When the output from the
bridge is below the set voltage, M2 is ON and capacitor
C7/C8 is charged. If the voltage is above the threshold
voltage Vf of the LED string, then the CCR will limit the
current through the LEDs. When the voltage is above the set
voltage, the MOSFET is turned OFF. The LEDs then draw
current from the charge on capacitor C7/C8 which is limited
by the CCR.
Chopper LED Driver Topology 85 VAC to 250 VAC, with
Triac Dimming:
This circuit is the same as Figure 9 with the addition of the
Triac Dimming Detect circuit as described in the Cap-Drop
description above (Figure 8).
To setup the CCRACGEVB for the Chopper LED driver
non-dimming topology, place jumpers according to Table 7.
Figure 10 depicts the schematic with the evaluation board
reference designators.
Table 7. JUMPERS PLACED ONTO THE EVB
Jumpers in Place Reference Data
J1, J8, J13, J10, J19, J21, J25,
J26
Appendix H