AC to DC power supply with PFC for lamp

• US 20070040516A1
• Filed: 08/15/2005
• Published: 02/22/2007
• Est. Priority Date: 08/15/2005
• Status: Abandoned Application

• Current Assignee: Liang Chen
• Original Assignee: Liang Chen
• Inventors: Chen, Liang
• Application Number:
  US11/204,307
• Publication Number:
  US 20070040516A1
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H05B 39/045 with high-frequency bridge converters H05B39/048 takes precedence
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

An AC-to-DC converter with PFC or without PFC generates an output constant voltage at any predetermined value (no matter less or more than input line peak voltage, or even equal to input line peak voltage) with an input line AC voltage with wide range (Typical sinusoidal 110 VAC, 60 Hz or 220 VAC, 50 Hz). It is mainly used as power supply for lamp. Previous power supply for lamp has low frequency component or high frequency component. (1) Low frequency light cause eyes pupil and crystalline lens will adjust 60 times, 120 or many times per second to cause eyes tired. Pupil open wide and crystalline lens adjust to collect more light to focus on retina for seeing clearly at weak light while pupil open narrow and crystalline lens adjust to collect less light to focus on retina at strong light to prevent retina from strong light harm and hurt. In the long run, muscles to control pupil and crystalline lens become very tired and become flabby. Then the muscle can'"'"'t adjust pupil and crystalline according to distance and brightness so that myopia is caused. (2) High frequency voltage causes lamp brightness changes too fast. Eyes can not adjust fast enough to follow the brightness change of lamp for high frequency voltage. But high frequency large current on the secondary cause high EMI that has risk to harm people'"'"'s health. High frequency light causes EMI issue. Peoples'"'"' eyes can'"'"'t keep up with high frequency light. Peak strong light shine on the retina for pupil can'"'"'t shrink at high frequency light. In the long run, retina will be harmed and affect eyesight is affected, cornea dryness or crystalline lens opacity is caused. My invention of power supply lamp has only DC constant voltage on lamp. Lamp'"'"'s brightness is constant and has no low frequency or high frequency component Thus peoples'"'"' eyes and health are protected to maximum extent. The output voltage is regulated at predetermined DC constant value by feedback. You can adjust feedback potentiometer value to set output voltage. Potentiometer and resistor voltage divider with auxiliary winding, (opto-coupler, digital isolator or direct feedback) compose the dimming feedback circuit. It is convenient to adjust the brightness of lamp for eyes'"'"' comfort by adjusting the potentiometer resistance value. My invention can be used directly on second category lamp that doesn'"'"'t need high voltage with ballast to start the lamp. Most of them use heat generated by filament or diode etc to create light. Such as Halogen, Incandescent, LED, PAR lamp, miniature sealed beam lamp, Projection lamp, automotive lamp, some stage and studio lamp, DC fluorescent lamp etc. The converter realized pulse-by-pulse or other current limit protection by sense the current sense resistor or signal transformer.

One stage DC sinusoidal to DC constant converter 206 can be implemented by all kinds of topologies other than the following topologies as long as they can convert DC sinusoidal voltage to DC constant voltage. Buck, Boost, Buck-boost, Noninverting buck-boost ,H-Bridge, Watkins-Johnson, Current-fed bridge, Inverse of Watkins-Johnson, Cuk, SEPIC, Inverse of SEPIC, Buck square, full bridge, half bridge, Forward, Two-transistor Forward, Push-pull, Flyback, Push-pull converter basedon Watkins-Johnson, Isolated SEPIC, Isolated Inverse SEPIC, Isolated Cuk, Two-transistor Flyback etc

One stage AC to DC converter 206 can be realized by discrete components without controller 209, active startup circuit, feedback circuit or sample circuit. Main switch and active startup circuit can be integrated in IC controller. The AC to DC converter is not used only for lamp. It is can also be used for any device requires DC power supply in all the industrial areas. (Telecommunication, Storage, Personal computer, cell phone power supply and charger, video game etc) For example, Bus AC to DC converter, PFC converter, PFC converter for lighting Computer power supply, Monitor power supply, notebook adapter, LCD TV, AC/DC adapter, adjusted voltage charger, Power tool charger, Electronic ballast, Video game power supply etc.

Claims

1. A power supply operable to convert AC sinusoidal voltage in wide range voltage (input voltage) into a constant DC voltage having a predetermined value with Feedback with PFC function or without PFC function.

The DC voltage value can be lower than input AC peak voltage or higher than input AC peak voltage or equal to input AC peak voltage.

Normal operating without dimming, Vout=rating voltage of lamp;

Dimming operating, Vout=dimming voltage set by potentiometer.

Feedback signal is fed from voltage divider of secondary output voltage to feedback pin of controller 209 as in FIG. 7 or the feedback signal can be coupled to primary from secondary or secondary output voltage divider by opto-coupler, signal transformer, auxiliary winding or digital isolator IC etc and then send to feedback pin of controller 209 as in FIG. 7.

Potentiometer (rheostat) voltage divider functions as dimming function and set dimming level.

The power supply of claim 1 has one stage converter operable to transfer DC sinusoidal voltage into a DC constant voltage at predetermined value.

Before, two stages of converters were applied to realize same function as power supply of claim 1, especially when converting a high input AC sinusoidal line voltage to a low DC constant voltage less than peak input voltage of AC line.

The first stage is a boost AC to DC converter that can only convert an Ac input line voltage to a DC constant voltage higher than or equal to input peak voltage of AC line. Boost converter can have PFC or have no PFC function.

The second stage is a DC-to-DC converter that can convert a high DC voltage to a low DC voltage.

Traditional two stage circuits have higher cost and lower efficiency. So the power supply of claim 1 saves the cost and increases the efficiency to maximum extent.

2. Power supply of claim 1 can be applied directly on second category lamp. Lamps have two categories:

First category uses ballast to strike the lamp to start. Most of them use gas to create light such as Fluorescent, HID, Compact, metal halide lamp etc. Bulbs need ballast because they use gas to create light. When the gas is excited by electricity, it emits invisible ultraviolet light that hits the white coating inside the bulb. The coating changes the ultraviolet light into light you can see. It needs a very high voltage strike to startup the operation of the lamp. But my invention is not applied directly to this category. The invention must be combined with second stage ballast to drive the lamp.

Second category doesn'"'"'t need ballast to start the lamp. Most of them use heat generated by filament or diode etc to create light. Such as Halogen, Incandescent, LED, PAR lamp, miniature sealed beam lamp, Projection lamp, automotive lamp, some stage and studio lamp, DC fluorescent lamp etc. They can use as Lamp 211.

My patent (power supply of claim

     1) can be used directly on second category lamp.

3. Power supply of claim 1 has protection to eyesight and people'"'"'s health to maximum extent for lamp has constant DC level output voltage that does not contain low frequency or high frequency voltage component.

Brightness of lamp is proportional to applied voltage magnitude.

For example, higher voltage causes higher brightness in second category lamp of claim 2 (such as halogen lamp).

Hz or 50 Hz sinusoidal voltage applied on lamp will cause lamp brightness to change 60 or 50 times per second because 60 Hz or 50 Hz sinusoidal voltage will change magnitude 60 or 50 times per second.

Low frequency light cause eyes pupil and crystalline lens will adjust 60 times, 120 or many times per second to cause eyes tired. Pupil open wide and crystalline lens adjust to collect more light to focus on retina for seeing clearly at weak light while pupil open narrow and crystalline lens adjust to collect less light to focus on retina at strong light to prevent retina from strong light harm and hurt.

In the long run, muscles to control pupil and crystalline lens become very tired and become flabby. Then the muscle can'"'"'t adjust pupil and crystalline according to distance and brightness so that myopia is caused.

To relieve eye'"'"'s tiredness, current technology for fluorescent lamp uses high frequency voltage in a DC envelope. High frequency voltage causes lamp brightness changes too fast. Eyes can not adjust fast enough to follow the brightness change of lamp for high frequency voltage. But high frequency large current on the secondary cause high EMI that has risk to harm people'"'"'s health.

High frequency light causes EMI issue.

Peoples'"'"' eyes can'"'"'t keep up with high frequency light. Peak strong light shine on the retina for pupil can'"'"'t shrink at high frequency light. In the long run, retina will be harmed and affect eyesight, cornea dryness or crystalline lens opacity is caused.

On the market, most of filament lamp use power supply that contains 60 Hz or 50 Hz low frequency component;

Lamps such as fluorescent that needs high voltage strike use power supply containing high frequency component.

My invention of power supply lamp has only DC constant voltage on lamp. Lamp'"'"'s brightness is constant and has no low frequency or high frequency component. Thus peoples'"'"' eyes and health are protected to maximum extent.

4. The power supply of claim 1 is comprising:

(refer to FIG. 7)

In one implementation, power supply 200 includes an RF1 201, an input filter 202, a rectifier 203, a one stage substantially DC sinusoidal to DC constant voltage converter 206, a controller 209, feedback and dimmer circuit 205, sample circuit 207, active startup circuit 208 and lamp 211. Some circuit may have more or less block. In some application, 208 or main switch of 206 can be integrated into IC controller 209. Or other block can be integrated into one IC.

Each block can use all kinds of different circuits with similar function as the following.

An input voltage (210) has AC sinusoidal waveform. It could come from 50 Hz 220VAC or 60 Hz 110VAC etc sinusoidal power system line voltage or other voltage sources (AC or DC);

Input RF1 201 provides input current protection for converter 200. In particular, in one implementation, input fuse is designed to provide current protection for converter 206 by cutting off current flow to converter 206 in an event that current being drawn through input fuse 201 exceeds a predetermined design rating.

In another implementation, RF1 201 is a flameproof, fusible, wire wound type and functions as a fuse, inrush current limiter.

In another implementation, RF1 201 can be a NTC or PTC thermistor. (Negative temperature coefficient thermal resistor or Positive temperature coefficient thermal resistor)

Input filter 202 minimizes an effect of electromagnetic interference (EMI) on power supply 200, converter 206 and exterior power system.

Input filter 202 can be LC filter, π

filter, differential mode filter, common mode filter or any type of filter that provides a low impedance path for high-frequency noise to protect power supply 200 and exterior power system from EMI.

Input filter 202 can be placed in front of rectifier 203 or behind rectifier 203.

Rectifier 203 is any type of rectifier that converts the input sinusoidal AC source voltage (like FIG. 8 in one implementation) from voltage source 210 into a substantially DC sinusoidal voltage (like FIG. 9 in one implementation).

In one implementation, rectifier 203 is a full-wave rectifier that includes four rectifiers in a bridge configuration.

In another implementation, rectifier 203 contains 2 diodes as shown in FIG. 29. In another implementation, rectifier 203 can use bridgeless PFC.

One stage DC sinusoidal to constant DC converter 206 converts the substantially DC sinusoidal voltage (like FIG. 9) received from rectifier 203 into a DC constant voltage at predetermined value suitable to support an output device (e.g., halogen lamp 211).

In one implementation, converter 206 converts the substantially DC sinusoidal voltage received from rectifier 203 into DC constant voltage. For example 12 volts (FIG. 10). Usually the input voltage source 210 comes from 60 Hz 110v AC or 50 Hz 220v AC sinusoidal line voltage (FIG. 8) in power system.

Controller 209 is operable to control an output voltage level of converter 206.

In one implementation, controller 209 is operable to adjust the duty cycle, on time of main switch or switching frequency of converter 206 so that converter 206 outputs a DC constant output voltage having a predetermined voltage value.

The controller 209 can use all kinds of method, mode and control to regulate a DC constant voltage at predetermined level. Such as digital control, analogy control, DSP, bang-bang control, skipping switching cycles as in LNK302/304-306, Pulse Train control as in IW2210 etc.

The controller 209 operable to realize PFC function (When using IW2202 controller, it is realized with pins VinAC and VinDC) or without PFC finction;

The controller 209 operable to realize current limit protection and short circuit protection (When using IW2202 controller, it is realized with pin Isense;

) Of course, controller 209 also can realize such functions as OVP-over voltage protection, OTP-over temperature protection, SCL-Secondary-side current limit) etc.

Controller 209 can also be a linear control type controller, PWM controller or PFC controller etc. Controller 209 can control an output voltage level of converter 206 responsive to a predetermined value set by potentiometer voltage divider. Feedback control voltage comes from feedback and dimmer circuit 205 as discussed in greater detail below.

Sample 207 sense the signal proportional to output DC constant voltage. Such as auxiliary winding, opto-coupler, voltage divider, digital isolator or voltage divider on output etc

Feedback and dimmer circuit 205 is operable to provide a feedback dimming control voltage to controller 209 for dimming (or decreasing) output voltage (e.g., lamp 211) by changing potentiometer value to set predetermined output value (Vset).

When Vout is greater than Vset, Feedback signal on FB pin of controller is compared to interior reference. Then duty cycle, frequency or switch mode etc are changed to decrease output voltage until Vout equals to Vset;

When Vout is lower than Vset, Feedback signal on FB pin of controller is compared to interior reference. Then duty cycle, frequency or switch mode etc are changed to increase output voltage until Vout equals to Vset;

Thus, the output voltage is regulated at set value by Feedback.

Normal operation, the predetermined value Vset is set to lamp rating voltage.

Dimming, the predetermined value Vset is set to lower than lamp rating voltage.

In one implementation, 205 can be realized by a resistor voltage divider composed of potentiometer and resistor (or zenor diode and resistor voltage divider composed of potentiometer and resistor) and voltage across one resistor or secondary is coupled to Feedback pin of controller 209 by opto-coupler, signal transformer, auxiliary winding, digital isolator or voltage divider on output etc). as in FIG. 12,13,14,15,16,17,24,25, 27,28,29,31,32,33 etc

An Active startup circuit 208 is operable to startup the circuit before power supply operates normally. 208 can use different circuits as shown in FIG. 20,21,22 etc or other circuits. Sometimes, it is integrated with controller 209 in one IC.

A lamp 211 can be any lamp without requirement for high voltage strike start as second category lamp in claim 2.

The power supply of claim 1 can contain more blocks or less blocks than blocks shown in FIG. 7. Some blocks can be integrated into one block or some blocks can be integrated into one IC. Block sequence can be changed. The power supply of claim 1 can be realized by discrete components. The power supply of claim 1 can have no external compensation components or have external compensation components.

5. The controller 209 of power supply of claim 1 can have PFC function as in IW2202 etc and no PFC function as in IW2210, iW1688, LNK362-364 and LNK302/304-306 etc.

PFC function guarantees power factor is always almost unity at normal operating or dimming. That is input sinusoidal current is always in phase with input sinusoidal voltage. That will increase power quality for the power system. The power supply of claim 1 realizes green mode efficiency with PFC function.

PFC can be realized by multiplier in controller or by μ

PFC (Integrator with Reset) such as in IR1150 OR DSP, digital control as in IW2202 or any method.

6. The power supply of claim 1 has dimming and feedback function that keep output voltage at a DC constant value Vo set by potentiometer or signal;

Dimming signal can come from wireless controller or power line communication. Feedback can be voltage feedback, current feedback or power feedback etc

(6.1) The power supply of claim 1 with IW2202 as controller 209 is shown in FIG. 12,13,14;

In real application, component can be more or less than FIG. 12,13,14. Components code or value maybe different from FIG. 12,13,14. Components connect way can be different from FIG. 12,13,14.

In FIG. 12, the voltage Va coupled on auxiliary winding in sample circuit is proportional to Vo (Va=Vo*Na/Ns Na is turns of auxiliary winding;

Ns is turns of secondary winding, Vo is output voltage). Vo is less than or equal to lamp rating voltage. Then a voltage divider get a sample voltage Vsense=Va*Voltage divider ratio (R12/(R12+R15+R6)) and compare Vsense with interior reference voltage Vinterior ref.

If Vo is larger than predetermined value, then Vsense is greater than Vinterior ref, the controller 209 will adjust duty cycle, switching frequency or switch mode of main switch in converter 206 until Vo decreases to predetermined value.

If Vo is less than predetermined value, then Vsense is less than Vinterior ref, the controller 209 will adjust duty cycle, switching frequency or switch mode of main switch in converter 206 until Vo increases to predetermined value. Thus feedback function keeps output Voltage at a predetermined DC constant level.

For steady operation, Vsense=Vinterior ref.

Vsense=Va*(R12/(R12+R15+R6))=Vo*(Na/Ns)*(R12/(R12+R15+R6))
So Vo=Vinterior ref*Ns*(R12+R15+R6)/R12/Na
Vo=Vinterior ref*(Ns/Na)*(1+(R15+R6)/R12).

Knowing Vinterior ref, we can regulate Vo by select value of Ns,Na,R15,R6,R12 etc;

The feedback circuit of claim 1 also finctions as dimming circuit. Any one of R15, R6 or R12 can be a potentiometer (Analog potentiometer or digital potentiometer). We can change the potentiometer value to decrease Vo to realize dimming. For example, R12 is a potentiometer. We can increase R12 to decrease Vo to realize dimming. If R15 or R6 is a potentiometer, we can decrease R15 or R6 resistance to decrease output voltage for dimming at predetermined level.

(6.2) The power supply of claim 1 with IW2210 as controller 209 is shown in FIG. 15,16,17.

In real application, component can be more or less than FIG. 15,16,17 and component value maybe different from components in FIG. 15,16,17. Components connect way can be different from FIG. 15,16,17.

In FIG. 15, the voltage cross primary winding is Vo*n. (Vo is output DC voltage and n is transformer turns ratio n=np/ns, np is primary turns;

ns is secondary turns).

The voltage coupled cross auxiliary winding is Vo*Na/Ns. Voltage on

Vsense=(Vo*Na/Ns)*R11/(R9+R10+R11).

Power pulse, sense pulse and Power skip mode keep output voltage constant. The feedback guarantees the output voltage is constant at predetermined value.

Vsense=(Vo*Na/Ns)*R11/(R9+R10+R11)=Vinterior ref.

(Vinterior ref is interior reference voltage).

Vo=Vinterior ref*(Ns/Na)*[(R9+R10)/R 11+1].

In one implementation, R11 is a potentiometer. So increase R11 value to decrease Vo to realize dimming with feedback. If R9 or R10 is a potentiometer, then decrease R9 or R10 value to decrease Vo to realize dimming.

The power supply of claim 1 can realize dimming with LNK302/304˜

306 and LNK362-364 etc.

(6.3) Power supply of claim 1 realized dimming with LNK302/304˜

306 shown in FIG. 27,28,29,31,32,33 in one implementation.

In real application, component can be more or less than FIG. 27,28,29,31,32,33 and component value maybe different from components in FIG. 27,28,29,31,32,33. Components connect way can be different from FIG. 27,28,29,31,32,33.

Dimming Feedback type1 use voltage divider with potentiometer.

Dimming Feedback type2 use voltage divider with potentiometer and zener diode or voltage reference.

For isolated converter, optocoupler, signal transformer, digital isolator can be used with type1 and type2 circuit.

The current goes into FB pin is proportional to output voltage. Regulation is maintained by skipping switching cycles. As the output voltage rises, the current into the FB pin will rise. If this exceeds Ifb (means output voltage is larger than predetermined voltage value) then subsequent cycles will be skipped until the current reduces below Ifb. Vice versa.

Thus, as the output load is reduced, more cycles will be skipped and if the load increases, fewer cycles are skipped.

So we adjust voltage divider value to adjust current into FB pin to regulate output voltage at predetermined value.

(6.4) The power supply of claim realizes dimming with LNK362-364 shown in FIG. 25 in one implementation.

In real application, component can be more or less than FIG. 25 and component value maybe different than components in FIG. 25. Components connect way can be different from FIG. 25.

Dimming Feedback type1 use voltage divider with potentiometer.

Dimming Feedback type2 use voltage divider with potentiometer and zener diode or voltage reference.

For isolated converter, opto-coupler, signal transformer, digital isolator can be used with type1 and type2 circuit.

When the output voltage is larger than predetermined value, current fed into the FEEDBACK pin of U1 (controller) increases until the turnoff threshold current is reached, disabling further switching cycles of U1, the output voltage is decreased until output voltage decreases to predetermined value. Vice versa.

So we adjust voltage divider value to adjust current into FB pin to regulate output voltage at predetermined value to realize dimming.

7. In the power supply of claim 1, in one implementation. Active startup circuit is used to start up the circuit when using IW2202 as controller. Active startup circuit can be integrated into IC controller.

In real application, component can be more or less than FIG. 20,21,22 and component value maybe different than components in FIG. 20,21,22. Active startup circuit is integrated in controller in other implementation. FIG. 20,21,22 has similar function. So we discuss with FIG. 20. FIG. 20 shows an active startup circuit. ASU pin is designed to drive the Mosfet of the active startup circuit. An external zener Z1 diode is to clamp the ASU pin. Before startup, ASU is floating. Once a voltage is supplied to Vg(t) (DC sinusoidal voltage after bridge rectifier like FIG. 9). The gate capacitor C31 starts to charge via the startup resistor R31. When Vcc reaches the threshold voltage of Q2, transistor Q2 conducts. (Q2 can be NPN transistor or N channel Mosfet). The startup capacitor C32 starts to be charged via the charge resistor R32 and R33 (R32 can be removed). When Vcc reaches the startup threshold voltage, controller (IW2202) starts operating. Converter main switch Q1 switches and auxiliary winding has voltage coupled from secondary output. ASU goes low, thus turns off Q2. Vcc is supplied from C32 that is charged by auxiliary winding and D4. Thus, supply voltage for PWM (IW2202) no longer uses linear regulator Q2 and the efficiency is improved. FIG. 23 Startup Timing Diagram on pins of IC controller shows that. By select auxiliary winding and secondary winding turns ratio carefully, we guarantee the voltage on the auxiliary winding during minimum dimming is larger than Vcc threshold+Voltage drop on D4;

We guarantee the voltage on the auxiliary winding during normal operating is not high enough to damage R33 and Z2. Thus, we can guarantee PWM(IW2202) works well no matter in normal operation or dimming. Q2 can be a bipolar transistor;

We can also connect a resistor between ASU pin and base of bipolar transistor. Some circuit may not need active startup circuit. Some circuits integrate active startup circuit in the controller.

Active startup circuit can also use topology as FIG. 20,21 or 22. Or even some circuit has more or less component as FIG. 20,21 or 22. Or component code or values may be different from FIG. 20,21,22. Or some components are integrated in IC. Active startup circuit may use components in different connection way from FIG. 20,21,22.

Active startup circuit can use other circuit different from FIG. 20,21 or 22;

such as valley filled circuit, linear regulator or battery etc.

8. In the power supply of claim 1 has current limit protection.

In one implementation using IW2202 as controller 209, the primary peak current is limited by the Isense threshold voltage on a cycle-by-cycle basis. Isense pin is connected to the current sense resistor between ground and source of main switch Q1. At the moment the voltage level at Isense reaches the threshold, the main switch Q1 turns off, the minimum on-time is 180 ns. We can also use current sense transformer to replace current sense resistor. Secondary is rectified by a diode and connect to a resistor, then the voltage on the resistor is sent to Isense pin.

IW2210 also limits peak current cycle-by-cycle, it terminates the ON-time of the MOSFET if the current sense signal reaches its threshold.

LNK 302/304-306 and LNK362-364 have current limit circuit senses the current in the power MOSFET. When this current exceeds the internal threshold (Ilimit), the POWER MOSFET is turned off for the remainder of that cycle. The leading edge blanking circuit inhibits the current limit comparator for a short time (tleb) after the power MOSFET is turned on. This leading edge blanking time has been set so that current spikes caused by capacitance and rectifier reverse recovery time will not cause premature termination of the switching cycle.

9. The power supply of claim 1 has short circuit protection function in controller in one implementation (as LNK302/304-306 and LNK362-364 etc);

The power supply of claim 1 has short circuit protection with Isense pin in one implementation as IW2202 and IW2210 etc, When short circuit happens, large current goes through main switch, Isense or controller interior circuit detect the large current and shuts down the main switch. In LNK302/304-306 or LNK362-364, when the current in Mosfet is larger than internal threshold, the power Mosfet is turned off for the remainder of that cycle.

For example, in IW2202, A short circuit condition on the DC supply output will cause a significant change of the output voltage. This change is detected typically within 10˜

20 us by the Vsense signal. There are two conditions for output short-circuit detection as in IW2202.

(1) Vsense detects the rise of the DC supply output. If Vsense is less than 0.5V (typical) within 60 ms of the first OUTPUT pulse, the controller detects this as a short circuit condition and shuts down in a non-latched mode.

(2) After start-up, if the pulse width of Vsense is larger than 23 us for 2 consecutive cycles, the controller detects a short circuit condition and shuts down in a non-latched mode.

10. The power supply of claim 1 can have over voltage protection.

The signal of auxiliary winding passes diode D4 and a voltage divider then send to pin SD in IW2202 or OVP/OTP pin in IW2210.

If the voltage on SD or OVP/OTP pin exceeds the threshold voltage, the train of output pulses stops and the controller is latched off in one implementation or automatic restart in one implementation.

In one implementation with IW2210 as FIG. 15, OVP is realized by voltage divider R6,R7,R8 with auxiliary winding Na. When the output voltage is higher than threshold, the voltage coupled on the auxiliary winding is also higher than some value. Then the voltage sensed on OVP/OTP pin is higher than interior threshold. So the controller performs a latched shutdown operation which turns off the power supply. The operation resumes after cycling of the input line voltage.

LNK302/304-306 and LNK362-364 realize OVP with FB pin. Over voltage cause large current larger than threshold into FB pin. Then controller shuts down switch MOSFET. Thus output voltage will go down.

11. The power supply of claim 1 can have over temperature protection (OTP) function with SD pin in IW2202 or OVP/OTP pin in IW2210. OTP circuit is integrated in controller in LNK302/304-306 and LNK362-364 etc which senses the die temperature. A voltage divider composed of a thermistor and a resistor is connected to SD pin in IW2202 or OVP/OTP pin in IW2210. When the temperature goes high, thermistor value has catastrophe change, the voltage on the SD pin exceeds the threshold, the controller goes into a latched shutdown mode. Of course, a transistor or a Mosfet can be used with thermistor and resistor to realize same function.

12. The power supply of claim 1 can be parallel with the same power supply as claim 1 to minimize ripple. Output inductor is coupled or not coupled. Two controllers can be synchronized or not. Or even three or more power supplies of claim 1 are paralleled to minimize the ripple. (Input is connected together;

Output is connected together.) Three or more controllers can be synchronized, not synchronized or multiphase control.

13. The secondary diode in power supply of claim 1 can be replaced by a Mosfet Q3 (Synchronized rectifier). When main switch Q1 is on, Q3 is off;

When main switch Q1 is off, Q3 is on. The gate signal of Q3 can come from signal transformer, digital isolator IC, auxiliary winding or secondary winding or secondary IC controller etc

14. A filter in power supply of claim 1 can be connected between secondary diode and output lamp. The filter can be π

filter, LC filter, differential mode filter, common mode filter or any kind of filter. The output filter can be a two winding transformer with opposite polarity winding. Top winding left is connected to secondary diode cathode;

Top winding right is connected to output. Bottom winding left is connected to anther diode D5 cathode, bottom winding right is connected to output. The anode of D5 can connect to ground or another converter'"'"'s secondary winding to minimize ripple.

15. In one implementation of power supply of claim 1, the main switch can be integrated in the controller as LNK302/304-306 or LNK362-364 in the power supply of claim 1. Other circuit or block can be integrated into IC controller such as active startup circuit 208.

16. In power supply of claim 1, the switching power supply can be installed in the metal lampstand. The insulation is applied between metal lampstand and switching power supply converter. Thus EMI will be shielded and be prevented from going outside.

17. The one stage AC to DC converter in power supply of claim 1 can be realized by flyback topology with IW2202 controller and IW2210;

The one stage AC to DC converter in power supply of claim 1 can be realized with LNK302/304-306 or LNK 362-364. Component code, value or connection way may be different from FIG. 12,13,14,15,16,17,24,25,27,28,29,31,32,33 etc.

The one stage converter 206 in power supply of claim 1 can use

Buck, Boost, Buck-boost, Noninverting buck-boost , H-Bridge, Watkins-Johnson, Current-fed bridge, Inverse of Watkins-Johnson, Cuk, SEPIC, Inverse of SEPIC, Buck square, full bridge, half bridge, Forward, Two-transistor Forward, Push-pull, Flyback, Push-pull converter based on Watkins-Johnson, Isolated SEPIC, Isolated Inverse SEPIC, Isolated Cuk, Two-transistor Flyback etc or any topology converter that convert DC sinusoidal voltage (FIG. 9) to DC constant voltage (FIG. 10).

Of course controller 209 may be different from IW2202, IW2210, iW1688, LNK302/304-306 or LNK362-364 for other topologies.

In real circuit, the component can be less or more than FIG. 11 to 53 etc. Components value and code can be different from FIG. 11 to 53 etc. Components connect way can be different from FIG. 11 to 53 etc.

19. The power supply of claim 1 can also be realized by two stage circuits, for example, PFC converter-first stage;

DC/DC converter-second stage.

20. The power supply of claim 1 can also be used as charger with voltage adjustable.

18. The AC to DC converter is not used only for lamp. It is can also be used for any device requires DC power supply in all the industrial areas. (Telecommunication, Storage, Personal computer, cell phone power supply and charger, video game etc) For example, Bus AC to DC converter, PFC converter, PFC converter for lighting, Computer power supply, Monitor power supply, notebook adapter, LCD TV, AC/DC adapter, Battery charger, Power tool charger, Electronic ballast, Video game power supply, rotter power supply etc