LYT4212 [POWERINT]

LYTSwitch High Power LED Driver IC Family;
LYT4212
型号: LYT4212
厂家: Power Integrations    Power Integrations
描述:

LYTSwitch High Power LED Driver IC Family

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LYT4211-4218/4311-4318  
LYTSwitch High Power LED Driver IC Family  
Single-Stage Accurate Primary-Side Constant Current (CC) Controller with  
PFC for Low-Line Applications, TRIAC Dimming and Non-Dimming Options  
Product Highlights  
•ꢀ Better than ±±5 CC regulation  
•ꢀ TRIAC dimmable to less than ±5 output  
•ꢀ Fast start-up  
•ꢀ <2±0 ms at full brightness  
•ꢀ <1s at 105 brightness  
•ꢀ High power factor >0.9  
•ꢀ Easily meets EN61000-3-2  
•ꢀ Less than 105 THD in optimized designs  
CONTROL  
•ꢀ Up to 925 efficient  
•ꢀ 132 kHz switching frequency for small magnetics  
High Performance, Combined Driver, Controller, Switch  
The LYTSwitch family enables off-line LED drivers with high  
power factor which easily meet international requirements for THD  
Figure 1. Typical Schematic.  
and harmonics. Output current is tightly regulated with better  
than ±±5 CC tolerance1. Efficiency of up to 925 is easily  
achieved in typical applications.  
Optimized for Different Applications and Power Levels  
Part Number  
LYT4211-LYT4218  
LYT4311-LYT4318  
Input Voltage Range  
-132 VAC  
TRIAC Dimmable  
Supports a Wide Selection of TRIAC Dimmers  
The LYTSwitch family provides excellent turn-on characteristics  
for leading-edge and trailing-edge TRIAC dimming applications.  
This results in drivers with a wide dimming range and fast  
start-up, even when turning-on from a low conduction angle.  
Large dimming ratio and low “pop-on” current.  
No  
-132 VAC  
Yes  
Output Power Table1,2  
Product6  
Minimum Output Power3 Maximum Output Power4  
Low Solution Cost and Long Lifetime  
LYTSwitch ICs are highly integrated and employ a primary-side  
control technique that eliminates the optoisolator and reduces  
component count. This allows the use of low-cost single-sided  
printed circuit boards. Combining PFC and CC functions into a  
single-stage also helps reduce cost and increase efficiency. The  
132 kHz switching frequency permits the use of small, low-cost  
magnetics.  
LYT4x11E/L5  
2.± W  
2.± W  
3.8 W  
4.± W  
±.± W  
6.8 W  
8.0 W  
18 W  
12 W  
1± W  
18 W  
22 W  
2± W  
3± W  
±0 W  
78 W  
LYT4x12E/L  
LYT4x13E/L  
LYT4x14E/L  
LYT4x15E/L  
LYT4x16E/L  
LYT4x17E/L  
LYT4x18E/L  
LED drivers using the LYTSwitch family do not use primary-side  
aluminum electrolytic bulk capacitors. This means greatly  
extended driver lifetime, especially in bulb and other high  
temperature applications.  
Table 1. Output Power Table.  
Notes:  
1. Performance for typical design. See Applications section.  
2. Continuous power in an open-frame design with adequate heat sinking; device  
local ambient of 70 °C. Power level calculated assuming a typical LED string  
voltage and efficiency >805.  
3. Minimum output power requires CBP = 47 µF.  
4. Maximum output power requires CBP = 4.7 µF.  
±. LYT4311 CBP = 47 µF, LYT4211 CBP = 4.7 µF.  
6. Package: eSIP-7C, eSIP-7F (see Figure 2).  
eSIP-7C (E Package)  
Figure 2. Package Options.  
eSIP-7F (L Package)  
www.powerint.com  
February 2013  
LYT4211-4218/4311-4318  
Topology  
Isolated Flyback  
Buck  
Tapped Buck  
Buck-Boost  
Isolation  
Efficiency  
885  
Cost  
High  
Low  
Middle  
Low  
THD  
Best  
Good  
Best  
Best  
Output Voltage  
Any  
Yes  
No  
No  
No  
925  
895  
905  
Limited  
Any  
High-Voltage  
Table 2.  
Performance of Different Topologies in a Typical Non-Dimmable 10 W Low-Line Design.  
Typical Circuit Schematic  
Key Features  
Flyback  
Benefits  
•ꢀ Provides isolated output  
•ꢀ Supports widest range of output voltages  
•ꢀ Very good THD performance  
Limitations  
•ꢀ Flyback transformer  
•ꢀ Overall efficiency reduced by parasitic capacitance  
and inductance in the transformer  
CONTROL  
•ꢀ Larger PCB area to meet isolation requirements  
•ꢀ Requires additional components (primary clamp and bias)  
•ꢀ Higher RMS switch and winding currents increases losses  
and lowers efficiency  
Figure 3a. Typical Isolated Flyback Schematic.  
Buck  
Benefits  
•ꢀ Highest efficiency  
•ꢀ Lowest component count – small size  
•ꢀ Simple low-cost power inductor  
•ꢀ Low drain source voltage stress  
•ꢀ Best EMI/lowest component count for filter  
Limitations  
•ꢀ Single input line voltage range  
•ꢀ Output voltage <0.6 × VIN(AC) × 1.41  
•ꢀ Output voltage for low THD designs  
•ꢀ Non-isolated  
AC  
IN  
LYTSwitch  
BP  
D
S
V
CONTROL  
R
FB  
PI-6841-081512  
Figure 3b. Typical Buck Schematic.  
Tapped Buck  
Benefits  
•ꢀ Ideal for low output voltage designs (<20 V)  
•ꢀ High efficiency  
•ꢀ Low component count  
•ꢀ Simple low-cost tapped inductor  
Limitations  
•ꢀ Designs best suited for single input line voltage  
•ꢀ Requires additional components (primary clamp)  
•ꢀ Non-isolated  
LYTSwitch  
AC  
IN  
D
V
CONTROL  
BP  
S
R
FB  
PI-6842-081512  
Figure 3c. Typical Tapped Buck Schematic.  
Buck-Boost  
Benefits  
•ꢀ Ideal for non-isolated high output voltage designs  
•ꢀ High efficiency  
•ꢀ Low component count  
•ꢀ Simple common low-cost power inductor can be used  
•ꢀ Lowest THD  
Limitations  
•ꢀ Maximum VOUT is limited by MOSFET breakdown voltage  
•ꢀ Single input line voltage range  
•ꢀ Non-isolated  
AC  
IN  
LYTSwitch  
BP  
D
V
CONTROL  
S
R
FB  
PI-6859-081512  
Figure 3d. Typical Buck-Boost Schematic.  
2
Rev. B 02/13  
www.powerint.com  
LYT4211-4218/4311-4318  
DRAIN (D)  
5.9 V  
REGULATOR  
BYPASS (BP)  
BYPASS  
CAPACITOR  
SELECT  
SOFT-START  
TIMER  
HYSTERETIC  
THERMAL  
SHUTDOWN  
+
-
FAULT  
PRESENT  
ILIM  
MI  
5.9 V  
5.0 V  
AUTO-RESTART  
COUNTER  
BYPASS PIN  
UNDERVOLTAGE  
Gate  
Driver  
1 V  
VOLTAGE  
MONITOR (V)  
SenseFet  
LEB  
STOP  
LOGIC  
JITTER  
CLOCK  
Comparator  
OSCILLATOR  
-
+
FBOFF  
3-VT  
DCMAX  
OCP  
OV  
LINE  
SENSE  
+
-
CURRENT LIMIT  
COMPARATOR  
ILIM  
IV  
FEEDBACK (FB)  
PFC/CC  
CONTROL  
VSENSE  
VBG  
MI  
IFB  
FBOFF  
FEEDBACK  
SENSE  
DCMAX  
IS  
REFERENCE  
BLOCK  
REFERENCE (R)  
VBG  
6.4 V  
PI-6843-071112  
SOURCE (S)  
Figure 4. Functional Block Diagram.  
Pin Functional Description  
DRAIN (D) Pin:  
VOLTAGE MONITOR (V) Pin:  
This pin is the power FET drain connection. It also provides  
internal operating current for both start-up and steady-state  
operation.  
This pin interfaces with an external input line peak detector,  
consisting of a rectifier, filter capacitor and resistors. The  
applied current is used to control stop logic for overvoltage (OV),  
provide feed-forward to control the output current and the  
remote ON/OFF function.  
SOURCE (S) Pin:  
This pin is the power FET source connection. It is also the  
ground reference for the BYPASS, FEEDBACK, REFERENCE  
and VOLTAGE MONITOR pins.  
Exposed Pad  
(Backside) Internally  
Connected to  
BYPASS (BP) Pin:  
SOURCE Pin  
E Package (eSIP-7C)  
This is the connection point for an external bypass capacitor for  
the internally generated ±.9 V supply. This pin also provides  
output power selection through choice of the BYPASS pin  
capacitor value.  
L Package (eSIP-7F)  
(Top View)  
7 D  
5 S  
4 BP  
3 FB  
2 V  
FEEDBACK (FB) Pin:  
1 R  
The FEEDBACK pin is used for output voltage feedback. The  
current into the FEEDBACK pin is directly proportional to the  
output voltage. The FEEDBACK pin also includes circuitry to  
protect against open load and overload output conditions.  
3
FB  
5
S
1
R
Exposed Pad  
(backside) Internally  
Connected to  
SOURCE Pin (see  
eSIP-7C Package  
Drawing)  
2
4
7
D
Lead Bend Outward  
from Drawing  
(Refer to eSIP-7F Package  
Outline Drawing)  
V BP  
PI-5432-082411  
REFERENCE (R) Pin:  
This pin is connected to an external precision resistor and is  
used to configure for dimming (LYT4311-4318) and non-TRIAC  
dimming (LYT4211-4218) modes of operation.  
Figure 5. Pin Configuration.  
3
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Rev. B 02/13  
LYT4211-4218/4311-4318  
Functional Description  
A LYTSwitch device monolithically combines a controller and  
high-voltage power FET into one package. The controller  
provides both high power factor and constant current output in  
a single-stage. The LYTSwitch controller consists of an  
oscillator, feedback (sense and logic) circuit, ±.9 V regulator,  
hysteretic over-temperature protection, frequency jittering,  
cycle-by-cycle current limit, auto-restart, inductance correction,  
power factor and constant current control.  
non-dimming or PWM dimming applications with LYT4211-4218,  
the external resistor should be a 24.9 kW ±15. For phase angle  
AC dimming with LYT4311-4318, the external resistor should be  
a 49.9 kW ±15. One percent resistors are recommended as  
the resistor tolerance directly affects the output tolerance.  
Other resistor values should not be used.  
BYPASS Pin Capacitor Power Gain Selection  
LYTSwitch devices have the capability to tailor the internal gain  
to either full or a reduced output power setting. This allows  
selection of a larger device to minimize dissipation for both  
thermal and efficiency reasons. The power gain is selected with  
the value of the BYPASS pin capacitor. The full power setting is  
selected with a 4.7 µF capacitor and the reduced power setting  
(for higher efficiency) is selected with a 47 µF capacitor. The  
BYPASS pin capacitor sets both the internal power gain as well  
as the over-current protection (OCP) threshold. Unlike the  
larger devices, the LYT4x11 power gain is not programmable.  
Use a 47 µF capacitor for the LYT4x11.  
FEEDBACK Pin Current Control Characteristics  
The figure shown below illustrates the operating boundaries of  
the FEEDBACK pin current. Above IFB(SKIP) switching is disabled  
and below IFB(AR) the device enters into auto-restart.  
IFB(SKIP)  
Skip-Cycle  
Switching Frequency  
CC Control  
Region  
IFB  
The switching frequency is 132 kHz during normal operation.  
To further reduce the EMI level, the switching frequency is  
jittered (frequency modulated) by approximately 2.6 kHz.  
During start-up the frequency is 66 kHz to reduce start-up time  
when the AC input is phase angle dimmed. Jitter is disabled in  
deep dimming.  
IFB(DCMAXR)  
Soft-Start  
Soft-Start and  
CC Fold-Back  
Region  
The controller includes a soft-start timing feature which inhibits  
the auto-restart protection feature for the soft-start period (tSOFT  
to distinguish start-up into a fault (short-circuit) from a large  
output capacitor. At start-up the LYTSwitch clamps the  
maximum duty cycle to reduce the output power. The total  
)
soft-start period is tSOFT  
.
Remote ON/OFF and EcoSmart™  
IFB(AR)  
Auto-Restart  
The VOLTAGE MONITOR pin has a 1 V threshold comparator  
connected at its input. This voltage threshold is used for  
remote ON/OFF control. When a signal is received at the  
VOLTAGE MONITOR pin to disable the output (VOLTAGE  
MONITOR pin tied to ground through an optocoupler photo-  
transistor) the LYTSwitch will complete its current switching  
cycle before the internal power FET is forced off.  
DC10  
Maximum Duty Cycle  
DCMAX  
PI-5433-060410  
Figure 6. FEEDBACK Pin Current Characteristic.  
The FEEDBACK pin current is also used to clamp the maximum  
duty cycle to limit the available output power for overload and  
open-loop conditions. This duty cycle reduction characteristic  
also promotes a monotonic output current start-up characteristic  
and helps preventing over-shoot.  
The remote ON/OFF feature can also be used as an eco-mode  
or power switch to turn off the LYTSwitch and keep it in a very  
low power consumption state for indefinite long periods. When  
the LYTSwitch is remotely turned on after entering this mode, it  
will initiate a normal start-up sequence with soft-start the next  
time the BYPASS pin reaches ±.9 V. In the worst case, the  
delay from remote on to start-up can be equal to the full  
discharge/charge cycle time of the BYPASS pin. This reduced  
consumption remote off mode can eliminate expensive and  
unreliable in-line mechanical switches.  
REFERENCE Pin  
The REFERENCE pin is tied to ground (SOURCE) via an external  
resistor. The value selected sets the internal references,  
determining the operating mode for dimming (LYT4311-4318)  
and non-dimming (LYT4211-4218) operation and the line  
overvoltage thresholds of the VOLTAGE MONITOR pin. For  
4
Rev. B 02/13  
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LYT4211-4218/4311-4318  
completed. Special consideration must be made to appropriately  
size the output capacitor to ensure that after the soft-start  
period (tSOFT) the FEEDBACK pin current is above the IFB(AR)  
threshold to ensure successful power-supply start-up.  
After the soft-start time period, auto-restart is activated only  
D
S
V
CONTROL  
when the FEEDBACK pin current falls below IFB(AR)  
.
BP  
Over-Current Protection  
R
FB  
The current limit circuit senses the current in the power FET.  
When this current exceeds the internal threshold (ILIMIT), the power  
FET is turned off for the remainder of that cycle. A leading edge  
blanking circuit inhibits the current limit comparator for a short  
time (tLEB) after the power FET is turned on. This leading edge  
blanking time has been set so that current spikes caused by  
capacitance and rectifier reverse recovery will not cause  
premature termination of the power FET conduction.  
PI-5435-052510  
Figure 7. Remote ON/OFF VOLTAGE MONITOR Pin Control.  
Line Overvoltage Protection  
5.9 V Regulator/Shunt Voltage Clamp  
This device includes overvoltage detection to limit the maximum  
operating voltage detected through the VOLTAGE MONITOR pin.  
An external peak detector consisting of a diode and capacitor is  
required to provide input line peak voltage to the VOLTAGE  
MONITOR pin through a resistor.  
The internal ±.9 V regulator charges the bypass capacitor  
connected to the BYPASS pin to ±.9 V by drawing a current  
from the voltage on the DRAIN pin whenever the power FET is  
off. The BYPASS pin is the internal supply voltage node. When  
the power FET is on, the device operates from the energy stored  
in the bypass capacitor. Extremely low power consumption of the  
internal circuitry allows LYTSwitch to operate continuously from  
current it takes from the DRAIN pin. A bypass capacitor value  
of 47 or 4.7 µF is sufficient for both high frequency decoupling  
and energy storage. In addition, there is a 6.4 V shunt regulator  
clamping the BYPASS pin at 6.4 V when current is provided to  
the BYPASS pin through an external resistor. This facilitates  
powering of LYTSwitch externally through a bias winding to  
increase operating efficiency. It is recommended that the  
BYPASS pin is supplied current from the bias winding for  
normal operation.  
The resistor sets line overvoltage (OV) shutdown threshold which,  
once exceeded, forces the LYTSwitch to stop switching. Once  
the line voltage returns to normal, the device resumes normal  
operation. A small amount of hysteresis is provided on the OV  
threshold to prevent noise-generated toggling. When the power  
FET is off, the rectified DC high voltage surge capability is  
increased to the voltage rating of the power FET (670 V), due to the  
absence of the reflected voltage and leakage spikes on the drain.  
Hysteretic Thermal Shutdown  
The thermal shutdown circuitry senses the controller die  
temperature. The threshold is set at 142 °C typical with a 7± °C  
hysteresis. When the die temperature rises above this threshold  
(142 °C) the power FET is disabled and remains disabled until  
the die temperature falls by 7± °C, at which point the power FET  
is re-enabled.  
Auto-Restart  
In the event of an open-loop fault (open FEEDBACK pin resistor  
or broken path to feedback winding), output short-circuits or an  
overload condition the controller enters into the auto-restart  
mode. The controller annunciates both short-circuit and  
open-loop conditions once the FEEDBACK pin current falls  
below the IFB(AR) threshold after the soft-start period. To minimize  
the power dissipation under this fault condition the shutdown/  
auto-restart circuit turns the power supply on (same as the  
soft-start period) and off at an auto-restart duty cycle of  
typically DCAR for as long as the fault condition persists. If the  
fault is removed during the auto-restart off-time, the power  
supply will remain in auto-restart until the full off-time count is  
Safe Operating Area (SOA) Protection  
The device also features a safe operating area (SOA) protection  
mode which disables FET switching for 40 cycles in the event  
the peak switch current reaches the ILIMIT threshold and the switch  
on-time is less than tON(SOA). This protection mode protects the  
device under short-circuited LED conditions and at start-up during  
the soft-start period when auto-restart protection is inhibited.  
The SOA protection mode remains active in normal operation.  
5
www.powerint.com  
Rev. B 02/13  
LYT4211-4218/4311-4318  
Application Example  
25 W TRIAC Dimmable High Power Factor LED Driver  
Design Example (DER-350)  
peak drain voltage of U1 below the 72± V rating of the internal  
power FET. Bridge rectifier BR1 rectifies the AC line voltage.  
EMI filtering is provided by L1-L3, C1, C4, R2, R24 and R2±  
together with the safety rated Y class capacitor (CY1) that bridges  
the safety isolation barrier between primary and secondary.  
Resistor R2, R24 and R2± act to damp any resonances formed  
between L1, L2, L3, C1 and the AC line impedance. A small  
bulk capacitor (C4) is required to provide a low impedance  
source for the primary switching current. The maximum value  
of C2 and C4 is limited in order to maintain a power factor of  
greater than 0.9.  
The circuit schematic in Figure 8 shows a TRIAC dimmable high  
power factor LED driver based on LYT4317E from the LYTSwitch  
family of devices. The design is configurable for non-dimmable  
only applications by simple component value changes. It was  
optimized to drive an LED string at a voltage of 36 V with a  
constant current of 0.7 A ideal for Lumens PAR lamp retro-fit  
applications. The design operates over an input voltage range  
of 90 VAC to 132 VAC.  
LYTSwitch Primary  
The key goals of this design were compatibility with standard  
leading edge TRIAC AC dimmers, very wide dimming range  
(1000:1, 700 mA:0.7 mA), high efficiency (>8±5) and high power  
factor (>0.9). The design is fully protected from faults such as  
no-load (open load), overvoltage and output short-circuit or  
overload conditions and over temperature.  
To provide peak line voltage information to U1 the incoming  
rectified AC peak charges C6 via D2. This is then fed into the  
VOLTAGE MONITOR pin of U1 as a current via R10. This  
sensed current is also used by the device to set the line input  
overvoltage protection threshold. Resistor R9 provides a  
discharge path for C6 with a time constant much longer than  
that of the rectified AC to prevent generation of line frequency  
ripple.  
Circuit Description  
The LYTSwitch device (U1- LYT4317E) integrates the power FET,  
controller and start-up functions into a single package reducing  
the component count versus typical implementations. Configured  
as part of an isolated continuous conduction mode flyback  
converter, U1 provides high power factor via its internal control  
algorithm together with the small input capacitance of the  
design. Continuous conduction mode operation results in  
reduced primary peak and RMS current. This both reduces  
EMI noise, allowing simpler, smaller EMI filtering components  
and improves efficiency. Output current regulation is maintained  
without the need for secondary-side sensing which eliminates  
current sense resistors and improves efficiency.  
The VOLTAGE MONITOR pin current and the FEEDBACK pin  
current are used internally to control the average output LED  
current. For TRIAC phase-dimming applications a 49.9 kW  
resistor (R14) is used on the REFERENCE pin and 2 MW (R10)  
on the VOLTAGE MONITOR pin to provide a linear relationship  
between input voltage and the output current and maximizing  
the dimming range.  
Diode D3, R1± and C7 clamp the drain voltage to a safe level  
due to the effects of leakage inductance. Diode D4 is  
necessary to prevent reverse current from flowing through U1  
for the period of the rectified AC input voltage that the voltage  
across C4 falls to below the reflected output voltage (VOR).  
Input Stage  
Fuse F1 provides protection from component failures while RV1  
provides a clamp during differential line surges, keeping the  
C13  
100 pF  
200 V  
R26  
30  
C11  
C12  
63 V  
D9  
D2  
DFLU1400  
36 V,  
R23  
20 kΩ  
330 µF 330 µF  
DFLU1400-7  
700 mA  
63 V  
12  
1
FL1  
R24  
D7  
47 kΩ  
R9  
510 kΩ  
1/8 W  
C7  
2.2 nF  
630 V  
BYW29-200  
R15  
200 kΩ  
1/8 W  
BR1  
MB6S  
600 V  
FL2  
10  
D6  
RTN  
BAV21  
R20  
39 Ω  
1/8 W  
C9  
C5  
100 nF  
50 V  
D3  
US1J  
56 µF  
50 V  
11  
R10  
C1  
220 nF  
250 V  
R1  
510  
1/2 W  
T1  
RM8  
2 MΩ  
R19  
20 kΩ  
1%  
1/8 W  
D4  
C2  
C4  
C6  
R6  
US1D  
100 nF  
250 V  
100 nF 2.2 µF  
360 kΩ  
250 V 250 V  
L3  
5 mH  
D5  
R2  
R25  
47 kΩ  
1/8 W  
L1  
1 mH  
L2  
1 mH  
BAV16  
47 kΩ  
D8  
1/8 W  
R17  
3 kΩ  
1/10 W  
R18  
165 kΩ  
1%  
BAV21  
D
S
V
1/16 W  
CONTROL  
LYTSwitch  
U1  
LYT4317E  
BP  
RV1  
140 VAC  
F1  
5 A  
Q1  
Q2  
MMBT3904  
R
FB  
R14  
C15  
100 nF  
50 V  
X0202MA2BL2  
90 - 132  
VAC  
C3  
470 nF  
50 V  
L
N
49.9 kΩ  
1%  
1/16 W  
R27  
R22  
1 kΩ  
1/10 W  
C14  
10 nF  
50 V  
R8  
100 Ω  
1 W  
10 Ω  
C8  
47 µF  
16 V  
1/10 W  
CY1  
470 pF  
250 VAC  
PI-6875-101812  
Figure 8. DER-350 Schematic of an Isolated, TRIAC Dimmable, High Power Factor, 90-132 VAC, 25 W / 36 V / 700 mA LED Driver.  
6
Rev. B 02/13  
www.powerint.com  
LYT4211-4218/4311-4318  
Diode D6, C±, C9, R19 and R20 create the primary bias supply  
from an auxiliary winding on the transformer. Capacitor C8  
provides local decoupling for the BYPASS pin of U1 which is the  
supply pin for the internal controller. During start-up C8 is  
charged to ~6 V from an internal high-voltage current source  
tied to the device DRAIN pin. This allows the part to start  
switching at which point the operating supply current is provided  
from the bias supply via R17. Capacitor C8 also selects the  
output power mode (47 µF for reduced power was selected to  
reduce dissipation in U1 and increase efficiency for this design).  
TRIAC Phase Dimming Control Compatibility  
The requirement to provide 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 can cause  
undesirable behaviors such as limited dimming range and/or  
flickering as the TRIAC fires inconsistently. 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.  
Feedback  
The bias winding voltage is proportional to the output voltage  
(set by the turns ratio between the bias and secondary  
windings). This allows the output voltage to be monitored  
without secondary-side feedback components. Resistor R18  
converts the bias voltage into a current which is fed into the  
FEEDBACK pin of U1. The internal engine within U1 combines  
the FEEDBACK pin current, the VOLTAGE MONITOR pin current  
and drain current information to provide a constant output  
current over a 1.±:1 output voltage variation (LED string voltage  
variation of ±2±5) at a fixed line input voltage.  
To overcome these issues simple two circuits, the SCR active  
damper and R-C passive bleeder, are incorporated. The  
drawback of these circuits is increased dissipation and  
therefore reduced efficiency of the supply. For non-dimming  
applications these components can simply be omitted.  
The SCR active damper consists of components R6, C3, and  
Q1 in conjunction with R8. This circuit limits the inrush current  
that flows to charge C4 when the TRIAC turns on by placing R8  
in series for the first ~1 ms of the TRIAC conduction. After  
approximately 1 ms, Q1 turns on and bypasses R8. This keeps  
the power dissipation on R8 low and allows a larger value  
during current limiting. Resistor R6 and C3 provide the delay  
on Q1 turn on after the TRIAC conducts. Diode D9 blocks the  
charge in capacitor C4 from flowing back after the TRIAC turns  
on which helps in dimming compatibility especially with high  
power dimmers.  
To limit the output voltage at no-load an output overvoltage  
protection circuit is set by D8, C1±, R22, VR4, R27, C14 and Q2.  
Should the output load be disconnected then the bias voltage  
will increase until VR4 conducts, turning on Q2 and reducing  
the current into the FEEDBACK pin. When this current drops  
below 10 µA the part enters auto-restart and switching is  
disabled for 300 ms allowing time for the output and bias  
voltages to fall.  
Output Rectification  
The transformer secondary winding is rectified by D7 and  
filtered by C11 and C12. An ultrafast TO-220 diode was  
selected for efficiency and the combined value of C11 and C12  
were selected to give peak-to-peak LED ripple current equal to  
305 of the mean value. For designs where lower ripple is  
desirable the output capacitance value can be increased.  
The passive bleeder circuit is comprised of R1 and C1. This  
helps keep the input current above the TRIAC holding current  
while the input current corresponding to the effective driver  
resistance increases during each AC half-cycle.  
A small pre-load is provided by R23 which discharges residual  
charge in output capacitors when turned off.  
7
www.powerint.com  
Rev. B 02/13  
LYT4211-4218/4311-4318  
Modified DER-350 25 W High Power Factor LED Driver  
for Non-Dimmable and Enhanced Line Regulation  
•ꢀ For maximum output power column  
•ꢀ Reflected output voltage (VOR) of 6± V  
•ꢀ FEEDBACK pin current of 16± µA  
•ꢀ BYPASS pin capacitor value of 4.7 µF (LYT4x11 = 4.7 µF)  
The circuit schematic in Figure 9 shows a high power factor  
LED driver based on a LYT4317 from the LYTSwitch family of  
devices. It was optimized to drive an LED string at a voltage of  
36 V with a constant current of 0.7 A, ideal for high lumen PAR  
lamp retro-fit applications. The design operates over the  
low-line input voltage range of 90 VAC to 132 VAC and is  
non-dimming application. A non-dimming application has  
tighter output current variation with changes in the line voltage  
than a dimming application. It’s key to note that, although not  
specified for dimming, no circuit damage will result if the end  
user does operate the design with a phase controlled dimmer.  
Note that input line voltages above 8± VAC do not change the  
power delivery capability of LYTSwitch devices.  
Device Selection  
Select the device size by comparing the required output power  
to the values in Table 1. For thermally challenging designs, e.g.,  
incandescent lamp replacement, where either the ambient  
temperature local to the LYTSwitch device is high and/or there  
is minimal space for heat sinking use the minimum output  
power column. This is selected by using a 47 µF BYPASS pin  
capacitor and results in a lower device current limit and therefore  
lower conduction losses. For open frame design or designs  
where space is available for heat sinking then refer to the  
maximum output power column. This is selected by using a  
4.7 µF BYPASS pin capacitor for all but the LYT4x11 which has  
only one power setting. In all cases in order to obtain the best  
output current tolerance maintain the device temperature below  
100 °C  
Modification for Non-Dimmable Configuration  
The design is configurable for non-dimmable application by  
simply removing the component for SCR active damper (R6,  
R8, C3, and Q1), blocking diode D9 and R-C bleeder (R1, C1)  
changes and replacing the reference resistor R14 with 24.9 kW.  
(See Figure 9)  
Key Application Considerations  
Power Table  
Maximum Input Capacitance  
The data sheet power table (Table 1) represents the minimum  
and maximum practical continuous output power based on the  
following conditions:  
To achieve high power factor, the capacitance used in both the  
EMI filter and for decoupling the rectified AC (bulk capacitor)  
must be limited in value. The maximum value is a function of  
the output power of the design and reduces as the output  
power reduces. For the majority of designs limit the total  
capacitance to less than 200 nF with a bulk capacitor value of  
100 nF. Film capacitors are recommended compared to  
ceramic types as they minimize audible noise with operating  
with leading edge phase dimmers. Start with a value of 10 nF  
for the capacitance in the EMI filter and increase in value until  
there is sufficient EMI margin.  
•ꢀ Efficiency of 805  
•ꢀ Device local ambient of 70 °C  
•ꢀ Sufficient heat sinking to keep the device temperature below  
100 °C  
•ꢀ For minimum output power column  
•ꢀ Reflected output voltage (VOR) of 120 V  
•ꢀ FEEDBACK pin current of 13± µA  
•ꢀ BYPASS pin capacitor value of 47 µF  
C13  
100 pF  
200 V  
R26  
30  
R24  
C11  
C12  
63 V  
47 kΩ  
D2  
DFLU1400  
36 V,  
R23  
20 kΩ  
330 µF 330 µF  
1/8 W  
700 mA  
63 V  
12  
1
FL1  
D7  
R9  
510 kΩ  
1/8 W  
BYW29-200  
C7  
2.2 nF  
630 V  
R15  
200 kΩ  
BR1  
MB6S  
600 V  
FL2  
10  
D6  
RTN  
BAV21  
R20  
39 Ω  
1/8 W  
C9  
C5  
100 nF  
50 V  
D3  
US1J  
56 µF  
50 V  
11  
R10  
T1  
RM8  
2 MΩ  
R19  
20 kΩ  
1%  
1/8 W  
D4  
C2  
100 nF  
250 V  
C4  
C6  
US1D  
R2  
47 kΩ  
1/8 W  
R25  
47 kΩ  
1/8 W  
100 nF 2.2 µF  
L1  
1 mH  
L2  
1 mH  
250 V 250 V  
L3  
5 mH  
D5  
BAV16  
D8  
R17  
3 kΩ  
1/10 W  
R18  
165 kΩ  
1%  
BAV21  
D
S
V
1/16 W  
CONTROL  
LYTSwitch  
U1  
LYT4317E  
RV1  
BP  
140 VAC  
F1  
5 A  
Q2  
MMBT3904  
R
FB  
R14  
C15  
100 nF  
50 V  
90 - 132  
VAC  
L
N
24.9 kΩ  
1%  
1/16 W  
R27  
R22  
1 kΩ  
1/10 W  
C14  
10 nF  
50 V  
10 Ω  
C8  
47 µF  
16 V  
1/10 W  
CY1  
470 pF  
250 VAC  
PI-6875a-101512  
Figure 9. Modified Schematic of RD-350 for Non-Dimmable, Isolated, High Power Factor, 90-132 VAC, 25 W / 36 V LED Driver.  
8
Rev. B 02/13  
www.powerint.com  
LYT4211-4218/4311-4318  
REFERENCE Pin Resistance Value Selection  
Operation with Phase Controlled Dimmers  
The LYTSwitch family contains phase dimming devices,  
LYT4311-4318, and non-dimming devices, LYT4211-4218. The  
non-dimmable devices use a 24.9 kW ±15 REFERENCE pin  
resistor for best output current tolerance (over AC input voltage  
changes). The dimmable devices (i.e. LYT4311-4318) use 49.9  
kW ±15 to achieve the widest dimming range.  
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.  
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.  
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.  
Primary Clamp and Output Reflected Voltage VOR  
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.  
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.  
For the highest efficiency, the clamping voltage should be  
selected to be at least 1.± times the output reflected voltage,  
VOR, as this keeps the leakage spike conduction time short.  
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 VOR limits are based on the BVDSS rating of the internal  
FET, a VOR of 60 V to 100 V is typical for most designs, giving  
the best PFC and regulation performance.  
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.  
Series Drain Diode  
PI-5983-060810  
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, VOR. The current rating should exceed two times the  
average primary current and have a peak rating equal to the  
maximum drain current of the selected LYTSwitch device.  
350  
250  
150  
50  
0.35  
0.25  
0.15  
0.05  
-0.05  
-0.15  
-0.25  
Voltage  
Current  
0.5  
50  
100  
150  
200  
250  
300  
350  
400  
-50  
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.  
-150  
-250  
-350  
-0.35  
Conduction Angle (°)  
Figure 10a. Ideal Input Voltage and Current Waveform for a Leading Edge  
TRIAC Dimmer at 90°.  
9
www.powerint.com  
Rev. B 02/13  
LYT4211-4218/4311-4318  
PI-5984-060810  
PI-5986-060810  
350  
0.35  
0.3  
350  
250  
150  
50  
0.35  
0.25  
0.15  
0.05  
-0.05  
-0.15  
-0.25  
Voltage  
Voltage  
Current  
300  
Current  
250  
200  
150  
100  
50  
0.25  
0.2  
0
50  
100  
150  
200  
250  
300  
350  
0.15  
0.1  
-50  
-150  
-250  
0.05  
0
0
-350  
-0.35  
50  
100  
0
150  
200  
250  
300  
350  
400  
Conduction Angle (°)  
Conduction Angle (°)  
Figure 10b. Resultant Waveforms Following Rectification of TRIAC Dimmer Output.  
Figure 12. Ideal Dimmer Output Voltage and Current Waveforms for a Trailing  
Edge Dimmer at 90° Conduction Angle.  
Figure 11 shows undesired rectified bus voltage and current  
with the TRIAC turning off prematurely and restarting.  
Start by adding a bleeder circuit. Add a 0.44 µF capacitor and  
±10 W 1 W resistor (components in series) across the rectified  
bus (C1 and R1 in Figure 8). If the results in satisfactory operation  
reduce the capacitor value to the smallest that result in acceptable  
performance to reduce losses and increase efficiency.  
If the TRIAC is turning off before the end of the half-cycle  
erratically or alternate half AC cycles have different conduction  
angles then flicker will be observed in the LED light due to  
variations in the output current. This can be solved by including  
a bleeder and damper circuit.  
If the bleeder circuit does not maintain conduction in the TRIAC,  
then add an active damper as shown in Figure 12. This consists  
of components R6, C3, and Q1 in conjunction with R8. This  
circuit limits the inrush current that flows to charge C4 when the  
TRIAC turns on by placing R8 in series for the first 1 ms of the  
TRIAC conduction. After approximately 1 ms, Q1 turns on and  
shorts R8. This keeps the power dissipation on R8 low and  
allows a larger value to be used during current limiting.  
Increasing the delay before Q1 turns on by increasing the value  
of resistor R6 will improve dimmer compatibility but cause more  
power to be dissipated across R8. Monitor the AC line current  
and voltage at the input of the power supply as you make the  
adjustments. Increase the delay until the TRIAC operates  
properly but keep the delay as short as possible for efficiency.  
Dimmers will behave differently based on manufacturer and  
power rating, for example a 300 W dimmer requires less  
dampening and requires less power loss in the bleeder than a  
600 W or 1000 W dimmer due to different drive circuits and  
TRIAC holding current specifications. Multiple lamps in parallel  
driven from the same dimmer can introduce more ringing due to  
the increased capacitance of parallel units. Therefore, when  
testing dimmer operation verify on a number of models,  
different line voltages and with both a single driver and multiple  
drivers in parallel.  
PI-5985-060810  
350  
300  
250  
200  
150  
100  
50  
0.35  
0.3  
Voltage  
Current  
As a general rule the greater the power dissipated in the bleeder  
and damper circuits, the more types of dimmers will work with  
the driver.  
0.25  
0.2  
Trailing Edge Phase Controlled Dimmers  
0.15  
0.1  
Figure 11 shows the line voltage and current at the input of the  
power supply with a trailing edge dimmer. In this example, the  
dimmer conducts at 90 degrees. Many of these dimmers use  
back-to-back connected power FETs rather than a TRIAC to  
control the load. This eliminates the holding current issue of  
TRIACs and since the conduction begins at the zero crossing,  
high current surges and line ringing are minimized. Typically these  
types of dimmers do not require damping and bleeder circuits.  
0.05  
0
0
50  
100  
0
150  
200  
250  
300  
350  
400  
Conduction Angle (°)  
Figure 11. Example of Phase Angle Dimmer Showing Erratic Firing.  
10  
Rev. B 02/13  
www.powerint.com  
LYT4211-4218/4311-4318  
Audible Noise Considerations for Use with  
Leading Edge Dimmers  
lifetime. For every 10 °C rise in temperature, component life is  
reduced by a factor of 2. Therefore it is important to properly  
heat sink and to verify the operating temperatures of all devices.  
Noise created when dimming is typically created by the input  
capacitors, EMI filter inductors and the transformer. The input  
capacitors and inductors experience high di/dt and dv/dt every  
AC half-cycle as the TRIAC fires and an inrush current flows to  
charge the input capacitance. Noise can be minimized by  
selecting film vs. ceramic capacitors, minimizing the capacitor  
value and selecting inductors that are physically short and wide.  
Layout Considerations  
Primary-Side Connections  
Use a single point (Kelvin) connection at the negative terminal of  
the input filter capacitor for the SOURCE pin and bias returns.  
This improves surge capabilities by returning surge currents  
from the bias winding directly to the input filter capacitor. The  
BYPASS pin capacitor should be located as close to the  
BYPASS pin and connected as close to the SOURCE pin as  
possible. The SOURCE pin trace should not be shared with the  
main power FET switching currents. All FEEDBACK pin  
components that connect to the SOURCE pin should follow the  
same rules as the BYPASS pin capacitor. It is critical that the  
main power FET switching currents return to the bulk capacitor  
with the shortest path as possible. Long high current paths  
create excessive conducted and radiated noise.  
The transformer may also create noise which can be minimized  
by avoiding cores with long narrow legs (high mechanical  
resonant frequency). For example, RM cores produce less  
audible noise than EE cores for the same flux density. Reducing  
the core flux density will also reduce the noise. Reducing the  
maximum flux density (BM) to 1±00 Gauss usually eliminates  
any audible noise but must be balanced with the increased core  
size needed for a given output power.  
Thermal and Lifetime Considerations  
Lighting applications present thermal challenges to the driver.  
In many cases the LED load dissipation determines the working  
ambient temperature experienced by the drive so thermal  
evaluation should be performed with the driver inside the final  
enclosure. Temperature has a direct impact on driver and LED  
Secondary-Side Connections  
The output rectifier and output filter capacitor should be as  
close as possible. The transformer’s output return pin should  
have a short trace to the return side of the output filter capacitor.  
BYPASS Pin  
Capacitor  
LYT4317EG  
Output  
Diode  
Clamp Transformer  
Input EMI Filter  
Bullk  
Capacitor  
Output  
Capacitor  
REFERENCE Pin  
Resistor  
FEEDBACK Pin  
Resistor  
Output  
Capacitors  
VOLTAGE MONITOR Pin  
Resistor  
PI-6904-101612  
Figure 13. DER-350 25 W Layout Example, Top Silk / Bottom Layer.  
11  
www.powerint.com  
Rev. B 02/13  
LYT4211-4218/4311-4318  
Quick Design Checklist  
Maximum Drain Voltage  
Verify that the peak VDS does not exceed 670 V under all  
operating conditions including start-up and fault conditions.  
Maximum Drain Current  
Measure the peak drain current under all operation conditions  
including start-up and fault conditions. Look for signs of  
transformer saturation (usually occurs at highest operating  
ambient temperatures). Verify that the peak current is less than  
the stated Absolute Maximum Rating in the data sheet.  
Thermal Check  
At maximum output power, both minimum and maximum line  
voltage and ambient temperature; verify that temperature  
specifications are not exceeded for the LYTSwitch, transformer,  
output diodes, output capacitors and drain clamp components.  
12  
Rev. B 02/13  
www.powerint.com  
LYT4211-4218/4311-4318  
Absolute Maximum Ratings(1,4)  
Lead Temperature(3) ........................................................260 °C  
Storage Temperature …………………................... -6± to 1±0 °C  
Operating Junction Temperature(2)........................ -40 to 1±0 °C  
DRAIN Pin Peak Current(±): LYT4x11 .................................1.37 A  
LYT4x12 ................................ 2.08 A  
LYT4x13 .................................2.72 A  
LYT4x14 ................................ 4.08 A  
LYT4x1± ................................ ±.44 A  
Notes:  
1. All voltages referenced to SOURCE, TA = 6± °C.  
2. Normally limited by internal circuitry.  
3. 1/16 in. from case for ± seconds.  
LYT4x16 ................................ 6.88 A  
LYT4x17 ................................. 7.73 A  
LYT4x18 ................................ 9.00 A  
4. Absolute Maximum Ratings specified may be applied, one  
at a time without causing permanent damage to the  
product. Exposure to Absolute Maximum Ratings for  
extended periods of time may affect product reliability.  
±. Peak DRAIN current is allowed while the DRAIN voltage is  
simultaneously less than 400 V. See also Figure 13.  
DRAIN Pin Voltage ……………………................ -0.3 to 670 V  
BYPASS Pin Voltage ................................................. -0.3 to 9 V  
BYPASS Pin Current ……………………..................... 100 mA  
VOLTAGE MONITOR Pin Voltage............................... -0.3 to 9 V  
FEEDBACK Pin Voltage …….................................... -0.3 to 9 V  
REFERENCE Pin Voltage .......................................... -0.3 to 9 V  
Thermal Resistance  
Thermal Resistance: E or L Package  
Notes:  
(qJA) ....................................................10± °C/W(1) 1. Free standing with no heat sink.  
(qJC).................................................... 2 °C/W(2) 2. Measured at back surface tab.  
Conditions  
SOURCE = 0 V; TJ = -20 °C to 12± °C  
(Unless Otherwise Specified)  
Parameter  
Symbol  
Min  
Typ  
Max  
Units  
Control Functions  
Average  
TJ = 6± °C  
124  
132  
±.4  
140  
Switching Frequency  
fOSC  
kHz  
kHz  
Peak-Peak Jitter  
Frequency Jitter  
Modulation Rate  
TJ = 6± °C  
See Note B  
fM  
2.6  
LYT4x11  
-4.1  
-7.3  
-3.4  
-6.1  
-2.7  
-4.9  
-7.0  
-8.3  
-0.43  
-1.7  
-3.1  
-4.2±  
LYT4x12  
VBP = 0 V,  
ICH1  
TJ = 6± °C  
LYT4x13-4x17  
-12  
-9.±  
LYT4x18  
LYT4x11  
-13.3  
-0.81  
-3.1  
-10.8  
-0.62  
-2.4  
BYPASS Pin  
Charge Current  
mA  
LYT4x12  
VBP = ± V,  
ICH2  
TJ = 6± °C  
LYT4x13-4x17  
-±.6  
-4.3±  
-±.±  
LYT4x18  
See Note A, B  
-6.7±  
Charging Current  
Temperature Drift  
0.7  
5/°C  
BYPASS Pin Voltage  
VBP  
0 °C < TJ < 100 °C  
0 °C < TJ < 100 °C  
±.7±  
±.9±  
0.8±  
6.1±  
6.6  
V
V
BYPASS Pin  
Voltage Hysteresis  
VBP(H)  
BYPASS Pin  
Shunt Voltage  
IBP = 4 mA  
0 °C < TJ < 100 °C  
VBP(SHUNT)  
tSOFT  
6.1  
±±  
6.4  
76  
V
TJ = 6± °C  
VBP = ±.9 V  
Soft-Start Time  
ms  
13  
www.powerint.com  
Rev. B 02/13  
LYT4211-4218/4311-4318  
Conditions  
SOURCE = 0 V; TJ = -20 °C to 12± °C  
Parameter  
Symbol  
Min  
Typ  
Max  
Units  
(Unless Otherwise Specified)  
Control Functions (cont.)  
0 °C < TJ < 100 °C  
FET Not Switching  
ICD2  
ICD1  
0.±  
1
0.8  
2.±  
1.2  
4
Drain Supply Current  
mA  
0 °C < TJ < 100 °C  
FET Switching at fOSC  
VOLTAGE MONITOR Pin  
TJ = 6± °C  
R = 24.9 kW  
RRR = 49.9 kW  
Threshold  
Hysteresis  
11±  
123  
6
131  
Line Overvoltage  
Threshold  
IOV  
µA  
VOLTAGE MONITOR  
Pin Voltage  
0 °C < TJ < 100 °C  
VV  
2.7±  
16±  
0.±  
3.0  
3.2±  
20±  
V
µA  
V
IV < IOV  
VOLTAGE MONITOR Pin  
Short-Circuit Current  
VV = ± V  
TJ = 6± °C  
IV(SC)  
18±  
Remote ON/OFF  
Threshold  
VV(REM)  
TJ = 6± °C  
FEEDBACK Pin  
FEEDBACK Pin Current  
at Onset of Maximum  
Duty Cycle  
IFB(DCMAXR)  
0 °C < TJ < 100 °C  
0 °C < TJ < 100 °C  
90  
µA  
FEEDBACK Pin Current  
Skip Cycle Threshold  
IFB(SKIP)  
DCMAX  
VFB  
220  
90  
µA  
5
V
IFB(DCMAXR) < IFB < IFB(SKIP)  
0 °C < TJ < 100 °C  
Maximum Duty Cycle  
FEEDBACK Pin Voltage  
99.9  
2.±6  
480  
IFB = 1±0 µA  
0 °C < TJ < 100 °C  
2.1  
2.3  
FEEDBACK Pin  
Short-Circuit Current  
VFB = ± V  
TJ = 6± °C  
IFB(SC)  
320  
17  
400  
µA  
DC10  
DC40  
DC60  
IFB = IFB(AR), TJ = 6± °C, See Note B  
IFB = 40 µA, TJ = 6± °C  
Duty Cycle Reduction  
34  
±±  
5
IFB = 60 µA, TJ = 6± °C  
Auto-Restart  
TJ = 6± °C  
VBP = ±.9 V  
Auto-Restart ON-Time  
tAR  
±±  
76  
2±  
ms  
5
TJ = 6± °C  
See Note B  
Auto-Restart  
Duty Cycle  
DCAR  
tON(SOA)  
IFB(AR)  
SOA Minimum Switch  
ON-Time  
TJ = 6± °C  
See Note B  
1.7±  
10  
µs  
µA  
FEEDBACK Pin Current  
During Auto-Restart  
0 °C < TJ < 100 °C  
6.±  
14  
Rev. B 02/13  
www.powerint.com  
LYT4211-4218/4311-4318  
Conditions  
SOURCE = 0 V; TJ = -20 °C to 12± °C  
Parameter  
Symbol  
Min  
Typ  
Max  
Units  
(Unless Otherwise Specified)  
REFERENCE Pin  
REFERENCE Pin  
Voltage  
VR  
IR  
1.223  
48.69  
1.24±  
49.94  
1.273  
±1.19  
V
RR = 24.9 kW  
0 °C < TJ < 100 °C  
REFERENCE Pin  
Current  
µA  
Current Limit/Circuit Protection  
di/dt = 174 mA/µs  
di/dt = 174 mA/µs  
di/dt = 22± mA/µs  
di/dt = 320 mA/µs  
di/dt = 3±0 mA/µs  
di/dt = 426 mA/µs  
di/dt = 133 mA/µs  
di/dt = 19± mA/µs  
di/dt = 192 mA/µs  
di/dt = 240 mA/µs  
di/dt = 33± mA/µs  
di/dt = 380 mA/µs  
di/dt = 483 mA/µs  
di/dt = 930 mA/µs  
LYT4x12  
LYT4x13  
LYT4x14  
LYT4x1±  
LYT4x16  
LYT4x17  
LYT4x11  
LYT4x12  
LYT4x13  
LYT4x14  
LYT4x1±  
LYT4x16  
LYT4x17  
LYT4x18  
1.00  
1.24  
1.46  
1.76  
2.43  
3.26  
0.74  
0.81  
1.00  
1.19  
1.17  
1.44  
1.70  
2.04  
2.83  
3.79  
0.86  
0.9±  
1.16  
1.38  
1.66  
2.0±  
2.73  
±.70  
Full Power  
Current Limit  
(CBP = 4.7 µF)  
ILIMIT(F)  
A
T = 6± °C  
J
Reduced Power  
Current Limit  
(CBP = 47 µF)  
ILIMIT(R)  
A
T = 6± °C  
1.43  
1.76  
2.3±  
4.90  
J
Minimum ON-Time  
Pulse  
tLEB + tIL(D)  
tLEB  
TJ = 6± °C  
300  
1±0  
±00  
700  
±00  
ns  
ns  
ns  
°C  
°C  
Leading Edge  
Blanking Time  
TJ = 6± °C  
See Note B  
TJ = 6± °C  
See Note B  
Current Limit Delay  
tIL(D)  
1±0  
142  
7±  
Thermal Shutdown  
Temperature  
See Note B  
See Note B  
13±  
1±0  
Thermal Shutdown  
Hysteresis  
BYPASS Pin Power-Up  
Reset Threshold  
Voltage  
VBP(RESET)  
0 °C < TJ < 100 °C  
2.2±  
3.30  
4.2±  
V
15  
www.powerint.com  
Rev. B 02/13  
LYT4211-4218/4311-4318  
Conditions  
SOURCE = 0 V; TJ = -20 °C to 12± °C  
Parameter  
Symbol  
Min  
Typ  
Max  
Units  
(Unless Otherwise Specified)  
Output  
TJ = 6± °C  
LYT4x11  
11.±  
13.±  
6.9  
8.4  
±.3  
6.3  
3.4  
3.9  
2.±  
3.0  
1.9  
2.3  
1.7  
2.0  
1.3  
1.6  
13.2  
1±.±  
8.0  
9.7  
6.0  
7.3  
3.9  
4.±  
2.9  
3.4  
2.2  
2.7  
2.0  
2.4  
1.±  
1.8  
ID = 100 mA  
TJ = 100 °C  
TJ = 6± °C  
LYT4x12  
ID = 100 mA  
TJ = 100 °C  
TJ = 6± °C  
LYT4x13  
ID = 1±0 mA  
TJ = 100 °C  
TJ = 6± °C  
LYT4x14  
ID = 1±0 mA  
TJ = 100 °C  
ON-State Resistance  
RDS(ON)  
W
TJ = 6± °C  
LYT4x1±  
ID = 200 mA  
TJ = 100 °C  
TJ = 6± °C  
LYT4x16  
ID = 2±0 mA  
TJ = 100 °C  
TJ = 6± °C  
LYT4x17  
ID = 3±0 mA  
TJ = 100 °C  
TJ = 6± °C  
LYT4x18  
ID = 600 mA  
TJ = 100 °C  
VBP = 6.4 V  
VDS = ±60 V  
TJ = 100 °C  
OFF-State Drain  
Leakage Current  
IDSS  
±0  
µA  
VBP = 6.4 V  
TJ = 6± °C  
Breakdown Voltage  
BVDSS  
670  
36  
V
V
Minimum Drain  
Supply Voltage  
TJ < 100 °C  
Rise Time  
Fall Time  
tR  
tF  
100  
±0  
ns  
ns  
Measured in a Typical Flyback  
See Note B  
NOTES:  
A. For specifications with negative values, a negative temperature coefficient corresponds to an increase in magnitude with increasing  
temperature and a positive temperature coefficient corresponds to a decrease in magnitude with increasing temperature.  
B. Guaranteed by characterization. Not tested in production.  
16  
Rev. B 02/13  
www.powerint.com  
LYT4211-4218/4311-4318  
Typical Performance Characteristics  
10000  
300  
200  
100  
Scaling Factors:  
Scaling Factors:  
LYT4x11 0.18  
LYT4x12 0.28  
LYT4x13 0.38  
LYT4x14 0.56  
LYT4x15 0.75  
LYT4x16 1.00  
LYT4x17 1.16  
LYT4x18 1.55  
LYT4x11 0.18  
LYT4x12 0.28  
LYT4x13 0.38  
LYT4x14 0.56  
LYT4x15 0.75  
LYT4x16 1.00  
LYT4x17 1.16  
LYT4x18 1.55  
1000  
100  
0
0
0
100 200 300 400 500 600  
0
100 200 300 400 500 600 700  
DRAIN Pin Voltage (V)  
DRAIN Voltage (V)  
Figure 14. Drain Capacitance vs. Drain Pin Voltage.  
Figure 15. Power vs. Drain Voltage.  
5
4
3
1.2  
1
0.8  
0.6  
0.4  
0.2  
Scaling Factors:  
LYT4x11 0.18  
LYT4x12 0.28  
LYT4x13 0.38  
LYT4x14 0.56  
LYT4x15 0.75  
LYT4x16 1.00  
LYT4x17 1.16  
LYT4x18 1.55  
2
1
LYT4x28 TCASE = 25 °C  
LYT4x28 TCASE = 100 °C  
0
0
0
2
4
6
8
10 12 14 16 18 20  
0
100 200 300 400 500 600 700 800  
DRAIN Voltage (V)  
DRAIN Voltage (V)  
Figure 16. Drain Current vs. Drain Voltage.  
Figure 17. Maximum Allowable Drain Current vs. Drain Voltage.  
17  
www.powerint.com  
Rev. B 02/13  
LYT4211-4218/4311-4318  
eSIP-7C (E Package)  
C
2
0.403 (10.24)  
0.397 (10.08)  
0.264 (6.70)  
Ref.  
0.081 (2.06)  
0.077 (1.96)  
A
B
Detail A  
2
0.290 (7.37)  
Ref.  
0.325 (8.25)  
0.320 (8.13)  
0.198 (5.04) Ref.  
0.519 (13.18)  
Ref.  
0.207 (5.26)  
0.187 (4.75)  
Pin #1  
I.D.  
0.016 (0.41)  
Ref.  
0.140 (3.56)  
0.120 (3.05)  
3
4
0.047 (1.19)  
0.118 (3.00)  
SIDE VIEW  
0.070 (1.78) Ref.  
0.033 (0.84)  
0.028 (0.71)  
0.010 M 0.25 M C A B  
6×  
0.100 (2.54)  
0.050 (1.27)  
0.016 (0.41)  
0.011 (0.28)  
3
6×  
0.020 M 0.51 M C  
FRONT VIEW  
BACK VIEW  
0.100 (2.54)  
10° Ref.  
All Around  
0.050 (1.27)  
0.050 (1.27)  
0.020 (0.50)  
0.060 (1.52)  
Ref.  
0.021 (0.53)  
0.019 (0.48)  
PIN 1  
0.048 (1.22)  
0.046 (1.17)  
0.019 (0.48) Ref.  
0.155 (3.93)  
0.059 (1.50)  
0.378 (9.60)  
Ref.  
0.023 (0.58)  
0.027 (0.70)  
PIN 7  
END VIEW  
0.059 (1.50)  
Notes:  
DETAIL A  
1. Dimensioning and tolerancing per ASME Y14.5M-1994.  
0.100 (2.54)  
0.100 (2.54)  
2. Dimensions noted are determined at the outermost  
extremes of the plastic body exclusive of mold flash,  
tie bar burrs, gate burrs, and interlead flash, but including  
any mismatch between the top and bottom of the plastic  
body. Maximum mold protrusion is 0.007 [0.18] per side.  
MOUNTING HOLE PATTERN  
(not to scale)  
3. Dimensions noted are inclusive of plating thickness.  
4. Does not include inter-lead flash or protrusions.  
5. Controlling dimensions in inches (mm).  
PI-4917-061510  
18  
Rev. B 02/13  
www.powerint.com  
LYT4211-4218/4311-4318  
eSIP-7F (L Package)  
C
2
0.403 (10.24)  
0.397 (10.08)  
0.081 (2.06)  
0.077 (1.96)  
A
0.264 (6.70) Ref.  
0.198 (5.04) Ref.  
B
Detail A  
0.325 (8.25)  
0.320 (8.13)  
0.290 (7.37)  
2
Ref.  
3
0.490 (12.45) Ref.  
0.016 (0.41)  
0.011 (0.28)  
6×  
0.020 M 0.51 M C  
0.173 (4.40)  
0.163 (4.15)  
1
7
7
1
0.084 (2.14)  
0.047 (1.19) Ref.  
Pin 1 I.D.  
0.089 (2.26)  
0.079 (2.01)  
0.070 (1.78) Ref.  
3
4
0.100 (2.54)  
0.050 (1.27)  
0.033 (0.84)  
0.028 (0.71)  
0.129 (3.28)  
0.122 (3.08)  
6×  
0.010 M 0.25 M C A B  
BOTTOM VIEW  
Exposed pad hidden  
SIDE VIEW  
TOP VIEW  
Exposed pad up  
Notes:  
1. Dimensioning and tolerancing per ASME  
Y14.5M-1994.  
1
7
0.021 (0.53)  
0.019 (0.48)  
0.020 (0.50)  
0.023 (0.58)  
0.060 (1.52) Ref.  
2. Dimensions noted are determined at the  
outermost extremes of the plastic body  
exclusive of mold flash, tie bar burrs, gate  
burrs, and interlead flash, but including  
any mismatch between the top and bottom  
of the plastic body. Maximum mold  
protrusion is 0.007 [0.18] per side.  
3. Dimensions noted are inclusive of plating  
thickness.  
0.019 (0.48) Ref.  
0.378 (9.60)  
Ref.  
0.048 (1.22)  
0.046 (1.17)  
0.027 (0.70)  
END VIEW  
DETAIL A (Not drawn to scale)  
4. Does not include inter-lead flash or  
protrusions.  
5. Controlling dimensions in inches (mm).  
PI-5204-061510  
Part Ordering Information  
LYTSwitch Product Family  
• 4 Series Number  
• PFC/Dimming  
2
3
PFC No Dimming  
PFC Dimming  
• Voltage Range  
1
Low-Line  
• Device Size  
• Package Identifier  
E
L
eSIP-7C  
eSIP-7F  
LYT  
4 2 1 3 E  
19  
www.powerint.com  
Rev. B 02/13  
Revision  
Notes  
Date  
11/12  
A
B
B
Initial Release.  
Corrected Min and Typ parameter table values on pages 13 and 14.  
Updated parameters ICH1, ICH2, ICD1, DCAR, ILIMIT(F), ILIMIT(R), on pages 13, 14 and 1±.  
02/13  
02/20/13  
For the latest updates, visit our website: www.powerint.com  
Power Integrations reserves the right to make changes to its products at any time to improve reliability or manufacturability. Power  
Integrations does not assume any liability arising from the use of any device or circuit described herein. POWER INTEGRATIONS MAKES  
NO WARRANTY HEREIN AND SPECIFICALLY DISCLAIMS ALL WARRANTIES INCLUDING, WITHOUT LIMITATION, THE IMPLIED  
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT OF THIRD PARTY RIGHTS.  
Patent Information  
The products and applications illustrated herein (including transformer construction and circuits external to the products) may be covered  
by one or more U.S. and foreign patents, or potentially by pending U.S. and foreign patent applications assigned to Power Integrations. A  
complete list of Power Integrations patents may be found at www.powerint.com. Power Integrations grants its customers a license under  
certain patent rights as set forth at http://www.powerint.com/ip.htm.  
Life Support Policy  
POWER INTEGRATIONS PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR  
SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF POWER INTEGRATIONS. As used herein:  
1. A Life support device or system is one which, (i) is intended for surgical implant into the body, or (ii) supports or sustains life, and (iii)  
whose failure to perform, when properly used in accordance with instructions for use, can be reasonably expected to result in significant  
injury or death to the user.  
2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause  
the failure of the life support device or system, or to affect its safety or effectiveness.  
The PI logo, TOPSwitch, TinySwitch, LinkSwitch, LYTSwitch, DPA-Switch, PeakSwitch, CAPZero, SENZero, LinkZero, HiperPFS, HiperTFS,  
HiperLCS, Qspeed, EcoSmart, Clampless, E-Shield, Filterfuse, StakFET, PI Expert and PI FACTS are trademarks of Power Integrations, Inc.  
Other trademarks are property of their respective companies. ©2013, Power Integrations, Inc.  
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Germany  
Japan  
Taiwan  
±24± Hellyer Avenue  
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Germany  
Phone: +49-89±-±27-39110  
Fax: +49-89±-±27-39200  
e-mail: eurosales@powerint.com Phone: +81-4±-471-1021  
Fax: +81-4±-471-3717  
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Yokohama-shi Kanagwan  
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Nei Hu Dist.  
Taipei 11493, Taiwan R.O.C.  
Phone: +886-2-26±9-4±70  
Fax: +886-2-26±9-4±±0  
e-mail: taiwansales@powerint.com  
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Phone: +1-408-414-966±  
Fax: +1-408-414-976±  
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