The following disclosure relates to electrical circuits and signal processing.
Power supplies are used to power many types of electronic devices, for example, lamps. Conventional power supplies (e.g., for halogen lamps) typically include a converter. A converter is a power supply switching circuit.
Lamps have two categories:
Q1 and Q2 complementary on/off with 50% duty cycle. Output voltage waveform is 120 Hz low frequency envelope with high switching frequency square waveform in it. As shown in
Vo=60*(4/3.14159)*ns/np (np is primary turns and ns is secondary turns.)
Dimming is realized by applying phase cut dimmer in the converter in trailing edge mode. This means that at the beginning of the line voltage half cycle, the switch inside the dimmer is closed and mains voltage is supplied to the converter allowing the converter to operate normally. At some point during the half cycle, the switch inside the dimmer is opened and voltage is no longer applied. The DC bus inside the converter almost immediately drops to 0 V and the output is no longer present. In this way, bursts of high frequency output voltage are applied to the lamp. The RMS voltage across the lamp will naturally vary depending on the phase angle at which the dimmer switch switches off. In this way the lamp brightness may easily be varied from zero to maximum output as shown in
Advantage of this typical low-voltage halogen-lamp converter 100 is simple without IC controller.
Disadvantage:
In general, in one aspect, this specification describes new block diagram for Halogen lamp converter as
Implementations can include one or more of the following advantages.
Traditional PFC only use boost (
The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims.
Input RF1201 provides input current protection for converter 200. In particular, in one implementation, input fise 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, RF1201 is a flameproof, fusible, wire wound type and functions as a fuse, inrush current limiter. In another implementation, RF1210 can be a NTC or PTC thermistor.
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, common mode filter, differential mode filter or any type filter that provide 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 converts the input AC source voltage from voltage source 210 (like
In one implementation, rectifier 203 is a full-wave rectifier that includes four rectifiers in a bridge configuration as in
One stage DC sinusoidal voltage to constant DC voltage converter 206 converts the substantially DC sinusoidal voltage like
Controller 209 is operable to regulate output voltage at predetermined value.
Controller 209 can be any type and have any type of control with PFC or without PFC function. (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.)
In such an implementation, controller 209 is operable to adjust the duty cycle, switching frequency or on time of main switch of converter 206 so that converter 206 outputs a DC constant output voltage having a predetermined voltage value. Controller 209 can control an output voltage level of converter 206 responsive to a predetermined value set by voltage divider composed of potentiometer and resistor at dimming or normal operating.
Normal operating; predetermined value set to rating voltage of lamp; dimming operating, predetermined value set to lower voltage than rating voltage of lamp.
Feedback control voltage comes from feedback circuit 205, as discussed in greater detail below.
Sample circuit 207 sense the signal proportional to output DC constant voltage or directly sense the voltage cross the lamp.
Feedback and dimmer circuit 205 is operable to provide a feedback dimming control voltage to controller 209 for dimming (or reducing) output voltage (e.g., halogen lamp 211) by changing potentiometer value to change voltage divider ratio. Duty cycle, switching frequency or on time of main switch are changed to change output voltage.
In one implementation (non-isolated feedback), 205 can be realized by a voltage divider composed of potentiometer and resistor (or zener diode and resistor voltage divider) and voltage cross one resistor goes to Feedback pin of controller 209;
In one implementation (isolated feedback), 205 can be realized by a voltage divider composed of potentiometer and resistor (or zener diode and resistor voltage divider) and voltage across one resistor or voltage across secondary winding is coupled to Feedback pin of controller 209 by auxiliary winding, opto-coupler or digital isolator etc
In real application, block can be more or less than
Flyback converter is shown in
During Q1 on, 0<t<DTs, voltage across transformer primary winding is Vg. (Vg input voltage). During Q1 off, DTs<t<Ts, voltage across transformer primary winding is −Vo*n1/n2. (Vo is output voltage, n1 is primary turns; n2 is secondary turns.) In continues conduction mode, primary winding balance: D is duty cycle, D′=1−D
Vg*D*Ts−Vo*D′*Ts*n1/n2=0Vo=Vg*D*n2/(D′*n1)
The detail is discussed below.
During the period when Q1 is on (0<t<=DTs), the ‘•’ end is negative with respect to no ‘•’ end of primary and secondary transformer windings, thus diode D3 could not turn on. Energy is saved in the magnetic inductance Lm. The voltage cross primary winding is Vg. (Vg is voltage after AC voltage rectified, In one implementation, Vg is DC sinusoidal voltage like
During the period when Q1 is off (DTs<=t<Ts), the polarity of the transformer winding changes. ‘•’ end is positive with respect to no ‘•’ end for both primary and secondary winding of transformer. Thus D3 turns on; energy is delivered to the output. The voltage cross primary winding is Vo*np/ns. (Vo is output DC voltage and np is primary turns; ns is secondary turns).
For normal operating, transformer set and reset must be balanced. It can be shown by ∫vdt=0. That is Vg*DTs−(Vo*np/ns)*D′Ts=0
From (3.8), for a predetermined constant DC value Vo, we can adjust duty cycle D(t) according to value of input voltage to guarantee the output voltage constant. Thus the converter converters a 120 Hz or 100 Hz DC sinusoidal waveform to a DC constant voltage.
Dimming can be realized by adjust potentiometer. In
So Vs=Vr=N2*Vo*R12/(R12+R15+R6) for steady state. Vr is constant and N2 is constant.
So Vo=Vr*(R12+R15+R6)/(R12*N2). (3.9)
We can adjust potentiometer R15 to change value of (R12+R15+R6)/R12=1+(R15+R6)/R12 to change predetermined Vo. Increase R15, Vo increase; decreases R15, Vo decrease. Thus lamp can be dimmed by change R15 to set output voltage and it is stable with constant voltage. R6 can be potentiometer, then increase R6 to increase Vo, Vice versa. R12 can be potentiometer, we can decrease R12 resistance to increase output voltage or increase R12 resistance to decrease output voltage. Dimming voltage is also DC constant voltage. There is no low frequency component. So the eyes will not feel fatigue due to the low frequency flicker. There is no high frequency light. No EMI issue or no retina harm by peak brightness because eyes pupil can't keep pace with high frequency light. Thus eyes are protected to maximum extent to avoid myopia or retina harm.
Sometimes opto-coupler is used as isolated feedback. In
In
In one implementation, PFC (power factor correction) can be realized by modulating the average input current ipr(t)av in phase with the input line voltage Vin(t). Thus power factor is unity. PFC also can be done by multiplier, μPFC as in IR1150S or DSP.
Please see
We know the input current is in phase with the AC line if k is constant. The converter accomplishes by modulating the average input current iin(t) in phase with the input line voltage Vin(t). Thus the power factor is very near to unity no matter in normal operation or dimming.
Active startup circuit is used to start up the circuit. In other implementation, Active startup circuit can be realized by other way or removed. In other circuit, active startup circuit can have more or less component than
Before startup, ASU is floating. Once a voltage is supplied to Vg(t) (DC sinusoidal voltage after bridge rectifier like
Thus, supply voltage for PWM (IW2202) no longer uses linear regulator Q2 and the efficiency is improved.
In
In
L1, C1 and C2 become a II filter and EMI filter to prevent high frequency component enter line. (function as Filter 202 in
BR is a full bridge rectifier to rectify AC sinusoidal voltage (
Q1, T1, D20 compose a flyback power converter. (function as Converter 206 in
Halogen lamp is parallel with C20. (function as Lamp 211 in
R6, R12 and Potentiometer R15 compose a voltage divider and connect to pin2-Vsense. (function as Feedback and dimmer 205 in
Active startup circuit is shown in
Controller use IW2202 (function as 209 in
Pin3-SCL is secondary current-limit feedback input. It is pulled up to Vrega through a 10 kohm resistor when secondary current limit function is not used.
Pin4-ASU is gate drive for the external Mosfet in the active start-up circuit. Similar to
Scaled voltage from line by voltage divider R3, R4 and filter R5, C4 is sent to pin 5-Vindc.
(Sense signal input representing the average line voltage for line regulation, under voltage and over voltage protection.).
Scaled voltage from line by voltage divider R1, R2 is sent to pin 6-Vinac (sense signal input representing AC line voltage.) that is for input current shaping.
R13 and C5 are connected to pin7-Vref (2.0v reference voltage output).
Pin 8-AGND (Analog ground) is grounded.
Pin9-SD (shut down pin. The input signal on SD is sampled during every switching cycle. When the voltage is above the shutdown threshold, the converter goes in a latched shutdown mode). SD can be used as OVP and OTP.
The voltage on R9 is sent to Pin 10-Isense (Primary power switch current limit. This is used to provide cycle-by-cycle current limit). It is used as current limit or over current protection.
C7 is connected to Pin 11-Vrega (Analog regulator output. The internal 3.3v regulator is used for internal analog circuits.)
C6 is connected to Pin 12-Vregd (Digital regulator decoupling pin. Internal 3.3v regulator is used for internal digital circuits.)
Pin 13-PGND is power ground and is grounded.
Pin 14-Output is gate drive signal for the external Mosfet switch. CY1 is a Y cap between primary and secondary ground.
We can also use
so we get Vo=(Vref−Vsense)*(R21+R22)/(CTR*R12). All other values except R21 are fixed. R21 is a potentiometer that can be adjusted to adjust output voltage Vo. If we want to dim down lamp, we just need to decrease R21 value, vice versa. Of Course we can select R22 as potentiometer. We can add components or delete component on
In real application, components can be more or less than
Other controllers with PFC function can be used in power supply with PFC based on Flyback converter. Components, connection way or components value may be different from
In one implementation, AC to constant DC power supply without PFC for Lamp can be realized with IW2210 as in
Full bridge rectifier D1˜D4 rectify AC sinusoidal input line voltage (shown in
C1 is a filter to pass high frequency component caused by switching to avoid EMI on line voltage. C1 functions as Filter 202 in
R3 connect between line voltage and Vcc to startup the controller IW2210, after it operates, Auxiliary winding will charge C3 through D5. This functions as Active Startup Circuit 208 in
Transformer T1, D8, C4 and Q1 compose flyback topology. That works as One Stage DC Sinusoidal to DC Constant Converter 206 in
IW2210 works as controller 209 in
Output voltage can be coupled to primary through auxiliary winding and connect to Vsense pin by voltage divider composed of R9, R10 and R11. Vsense: Sense signal input from auxiliary winding. This provides the secondary voltage feedback used for output regulation.
Auxiliary winding works as Sample 207 in
Voltage divider R9, R10 and R11 works as Feedback and dimmer 205 in
R1 and R2 voltage divider connect to Vin pin that is used for line regulation, under voltage and over voltage protection;
Vref is reference voltage output and connected with decoupling capacitor C2 and R4 in parallel;
GND (Analog ground) is grounded;
Isense senses primary switch current to provide cycle-by-cycle current limit.
Output pin output square waveform to switching on/off Main Switch Mosfet Q1.
R6, R7 and R8 become a voltage divider and connect to pin OVP/OTP. When output voltage is higher than a threshold, the voltage coupled on OVP/OTP pin through auxiliary winding will reach a threshold of interior controller, it shuts down. So it functions as OVP. It can also function as OTP. For example, if R8 is a thermistor and changes to a very high value during high temperature, then the voltage on pin OVP/OTP can reach threshold and shuts down controller. Any of R6, R7 or R8 can be a thermistor, thermal resistor; NTC (negative temperature coefficient) or PTC (positive temperature coefficient) depends on the OTP function requirement;
During the period when Q1 is on (0<t<=DTs), the ‘•’ end voltage is negative with respect to no ‘•’ end of both primary and secondary transformer windings, thus diode D3 could not turn on. Energy is saved in the magnetic inductance Lm. The voltage cross primary winding is Vg. (Vg is DC sinusoidal voltage as
As shown in
As shown in
If the voltage is still too high, the controller sends more sense pulses. If the feedback voltage is still too high after 12 sense pulse, the converter transitions into SmartSkip mode operation, sending out very narrow skip pulses and gradually decreasing the operating frequency until the generated power is in balance with the load. The minimum operating period at no load is about 2 ms.
Thus 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)*(1+(R9+R10)/R11).
In one implementation, R10 is a potentiometer. So decrease R10 value to decrease Vo to realize dimming with feedback. R9 or R11 can be a potentiometer, then decrease R9 or increase R11 value to decrease Vo to realize dimming.
In one implementation, Controller 209 is IW2210 that uses Pulse Train control algorithm, which is a discrete time bang-bang type control that provides ultra-fast transient response, and guarantees loop stability without external loop compensation components. The controller provides three types of pulses to output driver, depending on the real-time value of the output voltage. (1) If output voltage Vo is too low, the controller sends out a power pulse that is high-energy pulses that transfer enough energy to the output to provide up to 130% of the rated output power for the converter; (2) If the output voltage Vo is too high, the controller sends out a sense pulse which represents significantly less energy than the power pulses. While in regulation, the controller adjusts the average mix of power and sense pulses to balance the energy provided by the converter and used by the load, thus regulating the output voltage within its specified limits. (3) If the load is very light, the controller operates in Smart Skip mode which generates ultra-narrow skip pulses and gradually reduces the frequency to keep the output in regulation down to zero load current.
We can also use
so we get Vo=(Vref−Vsense)*(R21+R20)/(CTR*R10). All other values except R21 are fixed. R21 is a potentiometer that can be adjusted to adjust output voltage Vo. If we want to dim down lamp, we just need to decrease R21 value, vice versa. Of Course we can select R20 as potentiometer then we can decrease R20 value to realize dimming.
In
In real application, component can be more or less than
Other controllers without PFC function can be used in power supply without PFC based on Flyback converter (such as Iw1688). Components, connection way or components value may be different from
The AC input is rectified by D1 to D4 (as Rectifier block 203 in schematic 7) and filtered by the bulk storage capacitors C1 and C2.
Resistor RF1 is a fuse, PTC or NTC thermistor, or inrush current limiter or other over current protection. (As RF1 block 201 in schematic 7).
Together with the π filter formed by C1, C2, L1 and L2, differential mode noise attenuator. (as Filter block 202 in schematic 7) Other type of filter can also be used here.
Resistor R1 damps ringing caused by L1 and L2.
The rectified and filtered input voltage is applied to the primary winding of T1.
The other side of the primary is driven by the integrated MOSFET in U1. The secondary of the flyback transformer T1 is rectified by D5, and filtered by C4. (All these are as block 204 in schematic 7). U1,T1,D5,C4 compose a flyback converter as 206 in
The combined voltage drop across VR1, R4, R5 and the LED of U2 determines the output voltage. R4 and R5 are as Sample block 207 in schematic 7.
VR1, R2, R3, U2, R4, R5 and C3 are Feedback and Dimmer block 205 in schematic 7.
Suppose VR1 rating voltage=Vzener. Vr2 is voltage across resistor R2. Vu2led is voltage across LED in opto-coupler U2.
Vo=[Vzener+Vr2+Vu2led]*(R4+R5)/R5=[Vzener+Vr2+Vu2led]*(1+R4/R5)
Vr2<<Vzener, VU2LED<<Vzener, So Vo≈Vzener*(1+R4/R5)
We can increase R5 to decrease Vo to realize dimming. If R4 is a potentiometer, we can decrease R4 to decrease Vo for dimming.
In one implementation, when the output voltage exceeds this level, current will flow through the LED of U2. As the LED current increases, the current fed into the FEEDBACK pin of U1 increases until the turnoff threshold current is reached, disabling further switching cycles, and at very light loads, almost all the switching cycles will be disabled, giving a low effective frequency and providing high light load efficiency and low no-load consumption. Resistor R2 provides 1 mA through VR1 to bias the Zener closer to its test current. Resistor R3 allows the output voltage to be adjusted to compensate for designs where the value of the zener may not be ideal, as they are only available in discrete voltage ratings. For higher output accuracy, the Zener may be replaced with a reference IC such as the TL431. The LinkSwitch-XT is completely self-powered from the DRAIN pin, requiring only a small ceramic capacitor C3 connected to the BYPASS pin. No auxiliary winding on the transformer is required.
Several implementations are listed in
In real application, component can be more or less than
Other controllers with switch integrated into the controller can also be used in power supply based on Flyback converter with switch integrated in controller.
As above part1, power supply for lamp can be realized by flyback converter with or without PFC and can use all kinds of controllers with any kind of control method or algorithm for controller 209 in
Vo=(n2/n1)*D*Vg,
Any Full-bridge controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=0.5*(n2/n1)*D*Vg,
Any Half-bridge controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=(n3/n1)*D*Vg,
Any Forward controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=(n2/n1)*D*Vg,
Any two-transistor Forward controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=(n2/n1)*D*Vg,
Any two-transistor Forward controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
(
Vo=(n2/n1)*(2D−1)Vg/D,
Any Push-pull converter based on Watkins-Johnson controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=(n2/n1)*D*Vg/D′,
Any Isolated SEPIC controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=(n2/n1)*D*Vg/D′,
Any Isolated Inverse SEPIC controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=(n2/n1)*D*Vg/D′,
Any Cuk controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=Vg*D*(n2/n1)/D′
Any Two-transistor flyback controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
As above, components can be more or less than
Buck converter is shown in
Transistor Q1 on, 0<t<DTs, voltage on point A equals to Vg, diode D1 is off, voltage on point A is positive with respect to point B on inductor L1, VA=Vg;
Transistor Q1 off, DTs<t<Ts, polarity of inductor change, voltage on point A is negative with respect to point B on inductor L1, diode D1 turns on, VA=0.
Output voltage is average value of VA for the filter composed of L1, C1. So Vo=(Vg*DTs+0*D′Ts)/Ts=DVg.
The circuits shown in
The input stage comprises fusible resistor RF1 (as RF1201 block in
Diodes D3 and D4 work as Rectifier 203 in
Capacitors C4 and C5, and inductor L2 (as Filter block 202 in
The power processing stage is formed by the LinkSwitch-TN, freewheeling diode D1, Controller U1, output choke L1, and the output capacitor C2 compose Buck converter (as converter 206 in
The LNK302/304-306 was selected for U1 as controller 209 in
(controller U1 with switch integrated into, diode D1, inductor L1 and capacitor C2 become a buck converter as block 204 in schematic 7)
Active startup circuit 208 and main switch are integrated in IC controller U1.
To a first order, the forward voltage drops of D1 and D2 are identical. Therefore, the voltage across C3 tracks the output voltage. The voltage developed across C3 is sensed and regulated via the resistor divider R1 and R3 (R1 or R3 is a potentiometer) connected to U1's FB pin. The values of R1 and R3 are selected such that, at the desired output voltage, the voltage at the FB pin is 1.65v. So Vout·R3/(R1+R3)=1.65v, Vout=1.65*(1+R1/R3).
If R3 is a potentiometer, we can increase R3 to decrease output voltage for dimming;
If R1 is a potentiometer, we can decrease R1 to decrease output voltage for dimming.
Main switch is integrated in IC LNK302/304-306.
D2, become sample block 207 in
C3, R1, R3 work as Feedback and dimmer block 205 in
In one implementation, Regulation is maintained by skipping switching cycles. As the output voltage rises, the current into the FB pin will rise. If this exceeds Ifb then subsequent cycles will be skipped until the current reduces below Ifb. Thus, as the output load is reduced, more cycles will be skipped and if the load increases, fewer cycles are skipped. To provide overload protection if no cycles are skipped during a 50 ms period, LinkSwitch-TN will enter auto-restart (LNK304-306), limiting the average output power to approximately 6% of the maximum overload power. Due to tracking errors between the output voltage and the voltage across C3 at light load or no load, a small pre-load may be required (R4). For the design in
Feedback can be realized by opto-coupler as in
Output voltage is set by voltage divider composed of potentiometer R3 and resistor R1. Voltage of reference Z1 is Vz. Vo=Vz*(1+R1/R3). Dimming can be realized by increasing R3. If R1 is potentiometer, dimming can be realized by decreasing R1 value.
Connection or component values can be changed in application. Components can be more or less than
As above in Part 2, we can use any buck controller with any kind of control way or algorithm which can convert DC sinusoidal voltage to DC constant voltage with switch or without switch integrated in power supply for lamp with PFC or without PFC.
Buck-Boost converter is shown in
Transistor Q1 on, 0<t<DTs, voltage across L1 equals to Vg, diode D1 is off, voltage on point A is positive with respect to point B on inductor L1, VA=Vg;
Transistor Q1 off, DTs<t<Ts, polarity of inductor change, voltage on point A is negative with respect to point B on inductor L1, diode D1 turns on, VL=−Vo.
For steady state, the average of voltage across inductor L1 should be 0. So 0=(Vg*DTs+Vo*D′Ts)/Ts; Vo=−Vg*D/D′, Vo had opposite polarity as Vg.
The circuits shown in
Feedback can be realized by opto-coupler as in
Output voltage is set by voltage divider composed of potentiometer R3 and resistor R1. Voltage of reference Z1 is Vz. Vo=Vz*(1+R1/R3). Dimming can be realized by increasing R3. If R1 is potentiometer, dimming can be realized by decreasing R1 value.
Connection or component values can be changed in application. Components can be more or less than
As above in II-2 Part 2, we can use any buck-boost controller with any kind of control way or algorithm which can convert DC sinusoidal voltage to DC constant voltage with switch or without switch integrated in power supply for lamp.
Vo=Vg/D′,
Any Boost controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=Vg*D/D′,
Any noninverting Buck-Boost controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=Vg*(2D−1),
Any H-bridge controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=Vg*(2D−1)/D,
Any Watkins-Johnson controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=Vg/(2D−1),
Any current-fed bridge controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=Vg*D/(2D−1),
Any Inverse of Watkins-Johnson controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=−Vg*D/D′,
Any Cuk controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=Vg*D/D′,
Any SEPIC controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Vo=Vg*D/D′,
Any Inverse of SEPIC controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
VO=D*D
Any Buck square controller with any control way that can convert DC sinusoidal voltage to DC constant voltage can be used as controller 209.
Other non-isolated topology controller with any control which can convert DC sinusoidal voltage to DC constant voltage can also be used as controller 209.
Controller 209 can use all kinds of control method such as digital control, analog control, DSP, SmartSkip Mode, LinkSwitch-XT or LinkSwtich-TN mode etc.
A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Moreover, the converter topologies discussed above can be used within power supplies to supply power to devices other than lamps—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 output voltage Battery charger, Power tool charger, Electronic ballast, Video game power supply.
The present application claims priority to U.S. Patent Application No. 11/204,307, filed on Aug. 15, 2005, which is incorporated herein by reference in its entirety.