LYT4211E Power Integrations, LYT4211E Datasheet - Page 9

• Manufacturer Part Number: LYT4211E
• Description: LED Lighting Drivers HighPower LED Driver 12 W (85-132 VAC)
• Manufacturer: Power Integrations

Specifications of LYT4211E

• Rohs: yes
• Input Voltage: 85 V to 132 V
• Operating Frequency: 124 kHz to 140 kHz
• Maximum Supply Current: 1.2 mA
• Output Current: 0.86 A
• Maximum Operating Temperature: + 150 C
• Mounting Style: Through Hole
• Package / Case: eSIP-7C
• Minimum Operating Temperature: - 40 C

REFERENCE Pin Resistance Value Selection
The LYTSwitch family contains phase dimming devices,
LYT4311-4318, and non-dimming devices, LYT4211-4218. The
non-dimmable devices use a 24.9 kW ±1% REFERENCE pin
resistor for best output current tolerance (over AC input voltage
changes). The dimmable devices (i.e. LYT4311-4318) use 49.9
kW ±1% to achieve the widest dimming range.
VOLTAGE MONITOR Pin Resistance Network Selection
For widest AC phase angle dimming range with LYT4311-4318,
use a 2 MW (1.7 MW for 100 VAC (Japan)) resistor connected to
the line voltage peak detector circuit. Make sure that the
resistor’s voltage rating is sufficient for the peak line voltage. If
necessary use multiple series connected resistors.
Primary Clamp and Output Reflected Voltage V
A primary clamp is necessary to limit the peak drain to source
voltage. A Zener clamp requires the fewest components and
board space and gives the highest efficiency. RCD clamps are
also acceptable however the peak drain voltage should be
carefully verified during start-up and output short-circuits as the
clamping voltage varies with significantly with the peak drain
current.
For the highest efficiency, the clamping voltage should be
selected to be at least 1.5 times the output reflected voltage,
V
This will ensure efficient operation of the clamp circuit and will
also keep the maximum drain voltage below the rated
breakdown voltage of the FET. An RCD (or RCDZ) clamp
provides tighter clamp voltage tolerance than a Zener clamp.
The RCD clamp is more cost effective than the Zener clamp but
requires more careful design to ensure that the maximum drain
voltage does not exceed the power FET breakdown voltage.
These V
FET, a V
the best PFC and regulation performance.
Series Drain Diode
An ultrafast or Schottky diode in series with the drain is
necessary to prevent reverse current flowing through the
device. The voltage rating must exceed the output reflected
voltage, V
average primary current and have a peak rating equal to the
maximum drain current of the selected LYTSwitch device.
Line Voltage Peak Detector Circuit
LYTSwitch devices use the peak line voltage to regulate the
power delivery to the output. A capacitor value of 1 µF to 4.7 µF
is recommended to minimize line ripple and give the highest
power factor (>0.9), smaller values are acceptable but result in
lower PF and higher line current distortion.
www.powerint.com
OR
, as this keeps the leakage spike conduction time short.
OR
OR
OR
limits are based on the BV
of 60 V to 100 V is typical for most designs, giving
. The current rating should exceed two times the
DSS
rating of the internal
OR
Operation with Phase Controlled Dimmers
Dimmer switches control incandescent lamp brightness by not
conducting (blanking) for a portion of the AC voltage sine wave.
This reduces the RMS voltage applied to the lamp thus reducing
the brightness. This is called natural dimming and the LYTSwitch
LYT4311-4318 devices when configured for dimming utilize
natural dimming by reducing the LED current as the RMS line
voltage decreases. By this nature, line regulation performance is
purposely decreased to increase the dimming range and more
closely mimic the operation of an incandescent lamp. Using a
49.9 kW REFERENCE pin resistance selects natural dimming
mode operation.
Leading Edge Phase Controlled Dimmers
The requirement to provide flicker-free output dimming with low-
cost, TRIAC-based, leading edge phase dimmers introduces a
number of trade-offs in the design.
Due to the much lower power consumed by LED based lighting
the current drawn by the overall lamp is below the holding
current of the TRIAC within the dimmer. This causes
undesirable behaviors such as limited dimming range and/or
flickering. The relatively large impedance the LED lamp presents
to the line allows significant ringing to occur due to the inrush
current charging the input capacitance when the TRIAC turns
on. This too can cause similar undesirable behavior as the
ringing may cause the TRIAC current to fall to zero and turn off.
To overcome these issues two circuits, the active damper and
passive bleeder, are incorporated. The drawback of these
circuits is increased dissipation and therefore reduced efficiency
of the supply so for non-dimming applications these components
can simply be omitted.
Figure 10a shows the line voltage and current at the input of a
leading edge TRIAC dimmer with Figure 10b showing the
resultant rectified bus voltage. In this example, the TRIAC
conducts at 90 degrees.
Figure 10a. Ideal Input Voltage and Current Waveform for a Leading Edge
-150
-250
-350
350
250
150
-50
50
0.5
TRIAC Dimmer at 90°.
50
100
Conduction Angle (°)
150
LYT4211-4218/4311-4318
200
250
300
PI-5983-060810
Voltage
Current
350
400
Rev. B 02/13
0.35
0.25
0.15
0.05
-0.05
-0.15
-0.25
-0.35
9