RDK-193 Power Integrations, RDK-193 Datasheet - Page 9

• Manufacturer Part Number: RDK-193
• Description: KIT REF DESIGN FOR LNK403EG
• Manufacturer: Power Integrations
• Type: Power Factor Correctionr

Specifications of RDK-193

• Current - Output / Channel: 330mA
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 21V
• Features: Dimmable with Standard TRIAC Dimmer, Power Factor Correction
• Voltage - Input: 90 ~ 265VAC
• Utilized Ic / Part: LNK403EG
• Input Voltage: 90 V to 265 V
• Output Voltage: 21 V
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: LNK403EG
• Other names: 596-1307

09-Jun-10
RDR-193 7 W PAR20 LED Driver Using LNK403EG
4 Circuit Description
The LinkSwitch-PH device is a controller and integrated 725 V MOSFET intended for use
in LED driver applications. The LinkSwitch-PH is configured for use in a single-stage
continuous conduction mode Flyback topology and provides a primary side regulated
constant current output while maintaining high power factor from the AC input.
4.1 Input Filtering
Fuse F1 fuses the input and BR1 rectifies the AC line voltage. Inductor L1-L3, C2, R2,
and R3 form EMI filter with C7 Y capacitor. Small bulk capacitor C3 is required for a low
impedance path for the primary switching current. A low value of capacitance is
necessary to maintain a power factor of greater than 0.9.
4.2 LinkSwitch-PH Primary
Diode D6 and C8 detect the peak AC line voltage. This voltage is converted to a current
into the V pin via R4 and R7. This current is also used by the device to set the input
over/undervoltage protection thresholds. The V pin current and the FB pin current are
used internally to control the average output LED current. TRIAC phase-angle dimming
applications require 49.9 k resistors on the R pin and 4 M on the V pin to provide a
linear relationship between input voltage and the output current. Resistor R4 also sets the
internal references to select the brown-in and brown-out and input overvoltage protection
thresholds.
Diode D1 and VR1 clamp the drain voltage to a safe level from the leakage inductance
voltage spike. Diode D5 is necessary to prevent reverse current from flowing through the
LinkSwitch-PH device.
4.3 Bias and Output Rectification
Diode D3, C6, R5, R9 and R18 create the primary bias supply. This voltage created from
the transformer bias winding supplies bias current into the BYPASS pin through D4 and
R10. Capacitor C12 is the main supply for the LinkSwitch-PH, which is charged to ~6 V at
start-up from an internal high-voltage current source tied to the device DRAIN pin. A
current proportional to the output voltage from the primary bias winding is fed into the
FEEDBACK pin through R15. Diode D2 rectifies the secondary winding while capacitors
C4 and C5 filter the output. Diode D8, R24, C14, VR3, C15, R23, and Q2 provide an
open load overvoltage protection function. This protects output capacitors, C4 and C5
from excessive voltage should the load be disconnected.
4.4 TRIAC Phase Dimming Control
Components R12, R13, R20, R17, D7, Q1, C13, VR2, and Q3 in conjunction with R16
reduce the inrush current when the TRIAC dimmer turns on. This circuit allows the inrush
current to flow through R16 for the first 2.4 ms at 115 VAC (1.2 ms at 230 VAC) of the
TRIAC conduction. After approximately 2.4 ms, Q3 turns on and shorts R16. This keeps
the power dissipation on R16 low. Resistor R12, R13, R20 and C13 provide a 2.4 ms
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