Abstract: FM2822 is section of adjustable photoelectron ballast ASIC which the Shanghai Second dawn Micro electron Company promotes. Introduced that this electric circuit’s characteristic, the pin function and the electrical specification, give its model application electric circuit and the principle of work.
Key word: FM2822; Adjustable light; Ballast; TF8/36W
1 introduction
Under the energy short situation, conserves energy the green illumination electro-optic light and the electronic ballast highly effective day by day receives people’s favor more and more. After the electronic ballast is published in the 20 remaining years of life. The domestically produced electron ballast uses the controller to rely on the import completely. The Shanghai second dawn micro electron Limited liability company, the Shanghai Beiling Limited liability company promoted separately recently has independent property right FM2811/FM2822 and BL8301 fluorescent lamp electron ballast specific IC (ASIC), in the performance-to-price ratio aspect definitely may with the world advanced similar products setoff.
FM2822 is the Shanghai Second dawn Micro electron Company adjustable light fluorescent lamp electron ballast ASIC which researches and develops in the FM2811 foundation. With IR, Fairchild, ST and IJnear and so on overseas company’s similar IC compares. Has the unique merit in the design, may simplify the peripheral circuit design, increases the periphery design greatly the flexibility.
The fluorescent lamp and the incandescent lamp compare, its characteristic is completely different. Therefore, 
the fluorescent lamp cannot continue to use the incandescent lamp to adjust the light plan. At present uses the electronic ballast the fluorescent lamp to adjust the light plan mainly to have frequency modulation (FM) and the phase modulation (PM) two kinds, sometimes two kind of plans may concurrently use. The fluorescent lamp adjusts the light in fact adjusts the lamp power, adjusts the light the goal is for the electricity saving. The incandescent lamp adjusted the light technology already to apply for several dozens years, but in our country, the adjustable light fluorescent lamp’s application was actually rare. FM2822 being published. Solved has realized the stepless regulation technical difficult problem through the ordinary thyristor light modulator to the fluorescent lamp brightness.
2 FM2822 seals and pin function
FM2822 uses 16 pin DIP seal, pin arrangement as shown in Figure 1. Various pins function as follows states:
Foot l(CRECT): This pin output current high frequency ingredient anti- is accommodated by exterior the filter circuit filtration, the output current size decision lamp electric current and the lamp voltage product signal, thus the exchange light control realizes the lamp power closed loop feedback.
Foot 2(VL): Lamp voltage sampled signal/overvoltage protection signal input. Enters this pin the electric current to take an internal multiplier’s input. If on this foot’s electric current IvL>Ivu(stop) (120μA), on CP foot condenser charge time delay. After passing through 0.5s the detention, if has pressed the condition still to exist, IC enters waits for an opportunity the pattern. Otherwise, component normal work. If electric current IⅥ- is bigger than serious excess current IvL (hissing sound c) (approximately 240txA), the component enters directly waits for an opportunity the pattern.
Foot 3(DIM): The closed loop adjusts the light control signal input end, uses in establishing the lamp brightness. This foot already may realize the control by a thyristor out-port signal conversion average voltage signal, may also through the potentiometer or the special-purpose light modulator control. On this foot’s input voltage scope is 0~4VDC.
Foot 4(RIND): Half bridge output current phase examination input, internal two comparator examination different phase relation. And through the logic circuit judges whether to present the capacitive character pattern. If presents the capacitive character working pattern, protects the condition after the time delay less advanced person.
Foot 5(CF): The external connection pressure controls the oscillator (VCO) electric capacity, on when initial electricity this electric capacity charges to the interior voltage reference value.
Foot 6(RP): External connection preheating frequency hypothesis resistance. On the preheating when this foot’s voltage charge to 4V, after preheating had ended, on this foot’s voltage drops 0V.
Foot 7(CP): External connection preheat interval establishment electric capacity.
Foot 8(FAULT): This foot when preheating or the system is at the abnormal state outputs the high level control signal, but uses in each kind of control nimbly.
Foot 9/1l(G1/G2): Half height/low end driver outputs, between two driving signal’s non-overlap time fixes in 1.3μs typical value, thus may avoid in half bridge two MOSFET occurrences “the penetration”.
Foot 10(GND): Ground terminal.
Foot 12(VDD): The power line voltage exerts the end.
Foot 13(RF): This foot reference voltage is 2.4v, the external connection resistance or the materials for internal reference current supply, the external connection resistance resistance number and the CF foot exterior electric capacity decides the oscilation frequency together the bound.
Foot 14(EOL): Lamp life end examination input end, so long as on this foot’s voltage outside ±1V the window level, the blocking of oscillator, IC enters waits for an opportunity the pattern. If does not need this foot also to be possible to earth.
Foot 15/16(ITl/IT2): Lamp electric current sampled signal input, in interior after full-wave rectification inputs the multiplier. As a result of after internal rectification and enlargement, can therefore to the small signal accurate sampling.
3 characteristics and main electrical parameter
3.1 main features
The FM2822 electron ballast controls IC the main feature to be as follows:
* adjusts the light scope l%~100%, entire journey adjusts the light to dodge without the frequency;
* lamp electric current closed loop regulating control, built-in lamp electric current sampled signal full-wave rectification electric circuit;
* the preheat interval and the preheat current may adjust;
* provided half bridge capacitive character pattern protection, the lamp dies of old age the (EOL) valve effect protection and the overvoltage protection;
* suits actuates each kind of model the tube.
Figure 2
3.2 main electrical parameters
The F:M2822 main electrical specification parameter typical value is as follows:
●VDD foot breakover threshold voltage VDD(on) is 11V, stepping down of voltage shutdown threshold level VDD(off) is 8V, the clamp voltage is 16.2V, starting current Istart is 1.2mA;
●RF the foot materials for internal reference level is the 2.4V, RP foot materials for internal reference level is 4V;
* preheat interval tpre is ls, triggering time tipn is 0.2s (@Cp=0.33μF), preheating and ratio of the triggering time is 5:1;
●DIM the foot adjusts the light control input voltage scope is 0V~4V;
* capacitive character/near capacitive character protects the RIND foot quite low level is 150 mV, the high level is 50mV:
* the overvoltage protection VL foot current input clamp electric current for 80μA, the slight excess current, IVL(stop) is 120txA, serious excess current IVL(penic) is 240μA;
* the lamp died of old age (EOL) to protect EOI. The foot high threshold examination level is 1V, the low threshold examination level is 1V.
4 model application electric circuit and principle of work
Based on FM2822 36W, T8 energy conservation lamp electron ballast electric circuit as shown in Figure 2. In the chart, Cl, L1 and C2 compose the EMI filter, D1 D4 are the bridge-type rectifier, RPl are adjust the light resistance. V1 and V2 are half bridge switch, L3-1 and C15 compose the LC series resonance circuit, the L4 two windings and the R7 composition lamp electric current sampling circuit, composition current phase sampling circuits and so on R12 and R24, R11, R14, R15, D10 and the C13 composition lamp voltage and the pressure have examined the electric circuit.
4.1 electric circuit starts
After putting through the AC power source, the bridge-type rectifier outputs after starting resistance R1, R2 and D5 to IC (F’M2822) on the foot VDD electric capacity C6 charge. When on the C6 voltage achieves above 11V, IC starts, the oscillating circuit starting of oscillation, half bridge invertor starts to work. Once half bridge has the output, composition and so on C5, D5 and D6 electric charge pump electric circuits are the IC VDD foot provide the operating current.
4.2 preheating with open the splendor (triggering)
The filament preheating goal is to lengthen the tube life. Simultaneously reduces the lamp trigger voltage. Once the electric circuit starts, the oscillator produces high frequency fpre to the filament preheating, when IC on the foot CP electric capacity C11 voltage climbs to 4V, the preheat interval ended. When C11 takes 0.331μF, preheat interval tpre=1s. Preheating frequency fpre mainly establishes by IC foot RP non-essential resistance R18. The R18 resistance number is bigger, the oscilation frequency is lower. Usually the preheating frequency establishment is 50-60kHz.
After preheating conclusion, on the C11 voltage starts from 4V to the 0V scanning, the oscilation frequency from preheating frequency fDre to the work (i.e. stable state work) the frequency frun scanning, as shown in Figure 3. When frequency close L3-1 and C15 natural frequency, then has the LC series resonance, produces a high pressure on C15 to lighten the lamp. The triggering time is 0.2s, for the preheat interval 20%, after the lamp lightens, under the frun frequency works. Operating frequency fru namely for lowest oscilation frequency. Usually its establishment is 35-45kHz, makes concrete resistance R5 and foot CF’SHANG electric capacity C16 decided together by foot RF on.
4.3 adjust the light
IC on the foot DIM accent light signal and the foot 1 on signal does compares, the internal error amplifier produces the corresponding erroneous electric current to deliver to the pressure controls the oscillator to have some frequency. Causes the invertor to work under this frequency, and has an impedance on resonant inductance L3-1 (ZL=2μfL), this impedance decision lamp electric current and lamp power, thus decision lamp brightness.
IC foot 15 and foot 16 receive lamp electric current sampled signal, after internal full-wave rectification inputs the multiplier. Foot 2(VL) receive lamp voltage sampled signal, and as multiplier’s another input. On the foot l output current (multiplier outputs) anti- accommodates the filter circuit filtration high frequency ingredient after exterior, decides the lamp electric current and the lamp voltage product signal, thus the exchange light control realizes the power closed loop feedback. On the foot DIM input DC voltage is 0V~4V, the corresponding lamp power regulation scope is 1102%.
4.4 fail safes
FM2822 was provides the overvoltage protection, the capacitive character pattern protection and the lamp dies of old age the (EOL) protection.
If presents the tube to leak air or the negative pole de-excitation enables the lamp to trigger lightens, half bridge will have the high voltage to be very big and the electric current. Foot VL serves as the examination over-voltage condition. Once presents the serious overvoltage, the oscillator the failure of oscillations, causes the system to enter the low power immediately to wait for an opportunity the pattern.
If the lamp is unable to lighten or in the tube the overtension, the ballast half bridge inversion electric circuit possibly enters the capacitive character working pattern. Once has this kind of situation, (V1 and V2) on will have the very big loss in MOSFET, will be serious when will cause MOSFET to burn down. When the IC 4 feet (the RIND foot) examines to half bridge current phase in advance in the voltage, then determines as the capacitive character pattern, the system the failure of oscillations enters the readiness for action immediately.
When the lamp died of old age (EOI), the tube will present the valve effect, the filament presents the extremely high hot spot. Serious when will cause the tube electrode nearby glass melting. The IC EOL foot may examine the EOL condition, once on this foot the voltage surpasses the window scope (±1V) the system to meet the failure of oscillations, enters waits for an opportunity the pattern. In Figure 2 in the electric circuit, the foot EOL earth, the EOL protection function has not used.
