Order this document AN1682/D AN1682 Using MC33157 Electronic Ball

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SEMICONDUCTOR APPLICATION NOTE
Order this document AN1682/D
AN1682 Using MC33157 Electronic Ballast Controller
Prepared Michael Bairanzade System Engineering Motorola Toulouse
BASIC HALF BRIDGE ELECTRONIC BALLAST
Most European pressure fluorescent lamps powered from mains, using filaments preheat tube. Since this type lamp negative going characteristic, described Figure 1.1, must provide system control start sequence steady state current.
Generally speaking, electronic ballast must fulfill three major functions: Preheat filaments Strike tube Keep steady state current constant course, these characteristics depending upon type lamp, essentially length tube, glass diameter, pressure mixture. Several electronic circuits designed implement functions defined here above, most commonly used one, Europe, built around half bridge series resonant network described Figure 1.3.
+Vcc FLUORESCENT TUBE
Vstrike
Figure Typical Pressure Fluorescent Lamp Characteristic
Figure Basic Half Bridge Electronic Ballast Series Resonant Circuit Capacitors computed handle current flowing into lamp under both start steady state conditions, making sure that voltage Vcc/2. When lamp OFF, series resonant network built with inductor capacitors C1/C2/C3. resonant frequency given equation [1.1]:
simple, cost circuit, built with large inductance wired series with tube, depicted Figure 1.2, neon bulb being used strike lamp. Nowadays, these type circuits longer used more efficient systems designed improve global performances.
BI-METALLIC TRIGGER
C3)])
[1.1]
MAINS 50/60 FLUORESCENT TUBE
However, since C1<< capacitors generally, neglected equation simplified
[1.2]
Figure Typical Cost Fluorescent Circuit
order predict behavior circuit, recommended plot impedance resonant network function frequency. Figure gives example highlighting influence ratio this application.
MOTOROLA Motorola, Inc. 1999
AN1682
turn tube, system must generate strike voltage across electrodes. quality factor parameter used fulfill this function, minimum value depending fluorescent lamp characteristics:
Vstrike)
[1.5]
[1.6]
Figure Typical Resonant Circuit Function this point, value inductance can't freely defined, calculated based several parameters: mains voltage sets value fluorescent tube defines Vstrike frequency defines steady state operating frequency other hand, inductance limits current flowing into tube must designed according expected level power: Ptube
Generally speaking, value resistor comes, mainly, from filaments fluorescent tube, total value might adjusted increase damping impedance. Once parameters identified, resonant network calculated, using operating frequency reference. Although such circuit operate first pass application, three main points make straightforward usable industry: Power Factor well below 0.94 specified regulations. output power varies line voltage varies within 185-265 European span normalization. circuit must fulfill class specification. Consequently, must implement extra circuits, depicted Figure 1.5, make electronic ballast module suitable applications.
Itube
[1.3]
Since input pulse supposed have duty cycle, value inductor calculated using Lentz's law:
[1.4]
MAINS
RECTIFIER
FILTER
POWER FACTOR CORRECTION
ELECTRONIC BALLAST CONTROLLER
FLUORESCENT TUBES OUTPUT NETWORK
Figure Basic Industrial Electronic Ballast
AN1682
MC33157 DESCRIPTION
Since this Application Note focused electronic ballast controller, reader will technical informations related Power Factor circuit Motorola Linear data book (see MC33262 data sheet). purpose MC33157 implement basic functions needed operate electronic ballast. This integrated circuit comes SOIC package 10A/500 power MOSFET operated kHz. simplified internal circuit, depicted Figure 2.1, together with data sheet, useful understand MC33157.
CSWP
+VREF
Ifstrike
BAND REFERENCE +Vref +Vref adjust
Latch ENABLE Dead Time Control Logic Strike Detection Clear INHIBIT
COMPARATOR
UVLO
PREHEAT STRIKE CONTROL
VOUT
+Vref
LEVEL SHIFTER HIGH SIDE BUFFER SIDE BUFFER
Strike Detect Vref/2 RESET
Figure Simplified MC33157 Internal Circuit
Reference Voltage
reference voltage Vref generated internal band gap, yielding 2.0% tolerance over -20°C ambient temperature range. This voltage reference 100% trimmed probe level during manufacturing. MC33157 built circuits derived from this reference. that, reference voltage made available supply external components source Practically, recommended bypass Vref ground with ceramic capacitor. High side side boosters capable handle, respectively, into gate external power MOSFET, with gate source voltage capability. totem pole topology yields current transient fast when loaded rated power MOSFET, with capacitance gate peak current above MC33157 data sheet gives details these circuits.
Power Supply
power supply, connected provides energy controller integrated circuit monitors high voltage input value. operate controller, input supply voltage must rise above dV/dt being important long slower than V/ns. According timing described Figure 2.2, system state until internal functions, except voltage reference, disconnected. When input voltage becomes higher than stays within span, system operates normally internal functions active. other hand, built zener absorb short voltage spikes, designed regulate supply. designer make sure that supply voltage never exceeds, continuously, specified data sheet. soon power supply voltage drops below system stopped internal functions disconnected. resume circuit, must rise power supply minimum again described below.
AN1682
Vzin UVhigh
UVlow Vzin UVhigh UVlow input functions, including Vref disconnected. input functions, including Vref activated operate normally. input functions, including Vref disconnected. Figure Supply Voltage Operation
internal zener circuit clamps input voltage protection must taken, externally MC33157, limit clamp current under worst case condition. This particularly important when wide excursions power supply expected application. this case, recommended connect extra external zener across ground avoid inrush current into internal clamp.
Filaments Preheating
During start sequence fluorescent lamp, must provide power preheat filaments, improving ignition tube increasing expected life time. Beside output boosters, controller takes care timing expected designer. This function achieved current source charging external capacitor depicted Figure 2.4.
+Vref
+Vref +Vdd
BAND
ICPH
5.0V Current Pulse
Iclamp Ground
MC33157DW
MC33157
Figure Preheating Capacitor Current Source Control Resistor internally connected from +Vref ground, setup current through built-in current mirror which, turn, charges capacitor CPH. When voltage across this capacitor reaches comparator flips high state system jumps sweep mode. Figure gives main states MC33157 during start sequence.
Figure Basic Voltage Supply Detection
Most time, +Vdd voltage comes from limited power source capacitor mandatory supply energy output high side boosters. Usually, µF/25 electrolytic large enough fulfill this function.
AN1682
+Vdd Vhigh Vlow +12.0 +8.0 +7.0 Voltage Band +Vref +Vref Voltage Input
VCPH
+5.0
Pre-heating Timing Itube Fsweep Steady State
Figure Electronic Ballast Filament Preheat Timing achieve second long timing with 0.47 polyester capacitor, specific current source topology being used chip. concept charge capacitor with pulsed current, described Figure 2.6, decrease dV/dt across capacitor. Assuming leakage current capacitor lower than system gives expected timing with cost standard electrolytic capacitor. Period
Figure Basic Pulsed Timing Since both period width this current derived from main clock integrated circuit, duty cycle constant: timing Width/Period timing 1/16 other hand, internal comparator flips when VCPH rises above with hysteresis, circuit calculated straightforward. Since current constant, then:
Width
DVcph
CIPH VCPH
[2.1]
rearranging constant values, equation [2.2] used once time defined designer, assuming ICPH peak:
*510
[2.2]
AN1682
course, leakage capacitor together with high quality clad, preferably selected implement when long timing expected. internal logic output boosters. frequency derived from integration external capacitor either current RSWP described Figure 2.7. electronic switches used select current source defined Table below:
Oscillator Operation
oscillator used main clock control both
Table Current Source Selection
Preheat Frequency shift Steady state i4*e-t/T
These switches controlled MC33157 internal logic cannot accessed external circuit. However, possible specific frequency shift, given application,
using different current source supply this case, cares much observed avoid over-voltage over-current integrated circuit inputs.
+Vref
+Vref +Vref
CSWP MB0198
Heat
Clock
MC33157
Figure SimplIfied Frequency Operation Circuit
Strike Operation
already described above, comparator flips high state system jumps sweep mode when voltage reaches this moment, current longer supplied comes from integration capacitor CSWP frequency modulated generate strike voltage across resonant network. Once preheating completed, controller shifts frequency from initial value defined designer. This achieved current modulation coming from CSWP capacitor depicted Figures 2.9. Consequently, frequency always lower
than start frequency other hand, frequency modulation moves operating curve network along resonance, depicted Figure 2.8, yielding high voltage expected ignite lamp. event strike, high voltage collapses immediately, since resonant network damped fluorescent tube impedance, controller jumps steady state mode, forcing frequency value defined designer. lamp does strike, system repeats four time frequency sweep mode comes full stop strike detected after last fourth cycle.
AN1682
Dead Time Typical
Pre-heating Timing Itube
Fsweep
Steady State
lamp does strike, system creates dead time between last frequency sweep next depicted Figure 2.8. Such care mandatory avoid false strike detection when resonant current drops from peak value start condition. other hand, controller
Istart Isteady FILAMENTS PRE-HEATING STEADY STATE
0.01 10000 20000 30000 40000 50000 FREQUENCY (Hz) Figure Resonant Circuit Frequency Modulation Behavior 60000 70000 80000 90000 100000
Figure Preheat Strike Cycles Timing SERIES RESONANT TYPICAL CURVES
Tube Striked Second Cycle First Strike Failed
enables strike detection soon start sequence begins. fact, strike voltage depends upon several parameters (ambient temperature, pressure, life lamp, lamp, fluorescent lamp might jump normal operation time during preheating sequence.
1.50 Pout
AN1682
Beside ignition sequence, system must made aware status lamps. This implemented which provides analog input signal coming from external circuit depicted Figure 2.10. critical parameters threshold levels: Vhigh 4.50 this level preset internal comparator high state Vlow 3.75 this level confirm lamp(s) have struck Vhigh 4.50 3.75 Vlow
Vref
MC33157
Standard using Built-in Vref
External Vref
MC33157
External Voltage Controlled
+Vref
External Iref
Strike Detection
MC33157 MC33157DW
External Current Controlled
Ground
Figure 2.10 Electronic Ballast Typical Strike Voltage Sense Timing internal logic activates controller according signal presents this function being de-asserted soon system operates steady state. dV/dt important when limited kV/µs, cares must observed avoid false detection coming from electrical noise present this kind application.
Vref
External Voltage
MC33157
External Control Loop and/or Modulation
Steady State Operation
When start-up sequence ends, controller forces system into steady state mode. frequency defined designer, using current into that purpose. mean time, strike detection input deactivated signal present sensed controller. timing from keeps going does generate logic analog action within MC33157 chip, except when RESET asserted Since oscillator built with current controlled function, frequency easily modulated controlled external circuit. Figure 2.11 gives typical applications drive Figure 2.11 Electronic Ballast Steady State Typical Controls
power control applied output lamps implemented using loop built with external operational amplifier connected given Figure 2.11. Similar circuit used light fluorescent lamps.
AN1682
Reset Function
fast reset function provided control operation MC33157. This level sensitive, latched, negative logic, with CMOS equivalent input. When RESET activated pulling level, system stops, forcing output power MOSFET state (both gates connected their respective source). When logic level released, RESET deactivated system runs strike sequence depicted Figure 2.12, preheating filament being performed. frequencies defined external resistors ROP) capacitor COP. other hand, since grounded when RESET activated, system generates five ignition sequence, first frequency sweep period being time longer than four following one. must point that necessary internally ground capacitor make sure system will restart from fully defined state when RESET will cleared. built source makes sure RESET high level when left open. This function being latched, combined with external gates complex behavior. evaluation board uses this input force re-lamping depicted Figure 3.1.
RESET SWEEP HIGH SIDE SWEEP
SIDE
STEADY STATE BOTH POWER
GROUNDED WHEN RESET ASSERTED
CHARGED WITH CONSTANT Figure 2.12 RESET Operation
RESET logic trigger voltages have being designed provide strong hysterisis, avoiding uncontrolled function coming from noise. This function uses negative logic:
u1.8
Input
RESET
most critical point probably ground path: there must single return point power ground output power current shall flow same track. evaluation board been designed avoid uncontrolled power loop MC33157DW ground.
Activated :true Deactivated :false
ELECTRONIC BALLAST CONTROLLER APPLICATION
Note: application described here below designed operate dual tube module, powered from nominal line voltage. circuits described here after referenced schematic diagram given Figure 3.1.
recommended minimize pick noise coming from environment entering RESET pin. must design this respect 100nF/ceramic capacitor must used bypass ground.
AN1682
k/0.5
Vz14V 1N4148 1N4148 k/0.5
MUR160 1N4148 1N4148
N2881-A MR856 MTP8N50E
Vref CSWP
VOUT RESET
1500 pF/500
COILCRAFT
Vboot
uF/25
pF/5%
MTP8N50E R11N4148 1N4148
MC33262
1N4148 6800 pF/1000 V/5%
TUBE FLUO TUBE
MC33157DW
MTP8N50E
0.47 R/2W
1N4148
BRIDGE A/800 nF/630 nF/630 nF/630
LINE/P
TUBE FLUO TUBE
1N4148
1N4148
FUSE EARTH nF/630
FILTER SEMAP mH/1
LINE/N
Figure Typical Industrial Application Electronic Ballast
6800 pF/1000 V/5%
nF/450
uF/25
MPSA44
1N4148
Vz15V
nF/450
uF/450V
AN1682
OSCILLATOR CAPACITOR
frequencies used controller (preheating, strike steady state) come from integration accurately controlled current into external capacitor COP. Turn time adjusted externally, either single resistors connected +Vref, means current coming from auxiliary circuit. Figure gives simplified schematic circuit.
+Vref
Timing Calculations
COP**I
(Vth high
[3.1]
Since threshold voltages constant accurately given internal circuit, Vthlow Vthhigh Equation [3.1] simplified
Vthlow)
[3.2] [3.3]
COP**I1.4
10dV6
I=2*1
other hand, since capacitor discharged constant current, derive toff timing: toff [3.4]
threshold voltage being same than timing, then:
CHARGE FROM LOGIC COMPARATOR
DISCHARGE
toff and: toff
101.46
[3.5]
Figure Simplified Operating Circuit Turn time defined internal constant used discharge capacitor COP. This current externally adjustable. Delay Time never exceeds cannot adjusted externally. Toff Delay Time Delay Time
COP* 3500
PRACTICAL NUMERICAL EXAMPLE
[3.6]
Let's define steady state. period time shall
601* 8.33 3500 10*12 3500 1.64
turn time needed discharge toff
turn time same capacitor derived from expected operating frequency turn time calculated here above: toff 8.33 1.64 6.69 external programmed current then calculated rearranging equation [3.3]: 470* *6.69**12 **1.4 49.17
Period
Figure Basic Oscillator Capacitor Timing time, frequency externally programmed cope with specific needs, source current flowing into circuit pins must exceed pin. other hand, designer must take into account stray capacitance presents when calculating oscillator. Typically, parasitic internal capacitance
value resistor ROP, which connected between +Vref, with equal internal thresholds,
Vref
49.170.610*26 89.485
[3.7]
AN1682
select normalized value from E24/ series. calculation frequency adjust resistor value derived from graph given Figure below.
Vref ohms) +Vref
+Vref CSWP +Vref RENDSWP
f(Rop)
LOGIC
MC33157
Figure Preheating Network
Figure Frequency Operation f(Rop) given Oscillator Capacitor
PREHEATING TIMING FREQUENCY ADJUST
preheating time comes integration accurate pulsed current into external capacitor CPH. When voltage across capacitor crosses built-in reference, preheating time completed system jumps frequency sweep state. must point that capacitor connected from ground, preheating time micro second range system goes immediately sweep mode. Assuming leakage current around negligible (below then capacitor derived follows: current internally ratio fixed 1/16 represents constant threshold. expected preheating time then: 0.75 During preheating time, capacitor CSWEEP internally shorted +Vref means impedance MOS, thus connecting resistor +Vref. Consequently, oscillator capacitor charged currents depicted Figure 3.5. other hand, internal turned when preheating time completed, capacitor CSWEEP charged current flowing from Vref through current going will reduce until CSWEEP fully charged. this point, frequency defined solely value current hence value resistor RENDSWP.
simplify analysis circuit, consider sweep period, assuming capacitor CSWEEP fully charged. course, resonant behavior series network connected across supply lamp, must analyzed prior timing frequency calculations here below. particular, designer must accurately define shape resonant curve make sure system will operate safe area together with guaranteed strike lamp under worst case conditions. When capacitor CSWEEP fully charged, current flows into resistor charge capacitor comes from current only. Using equations derived before, calculate value resistor given resonant curve. Since make frequency identical value steady state then: RENDSWP 89.485 kW--> normalized 8.33 toff 1.64 6.69 49.17
[3.8]
Next, calculate value resistor needed frequency during preheating time. Based curve, kHz. Using same method used before, then: 7.69 toff 1.64 6.05 54,38 Since resistor RENDSWP supplies 49,17 resistor must provide rest:
49.17
Then:
844.529
normalized Figure gives typical MOSFET gate voltages current flowing lamp.
AN1682
PRE-HEATING Vline ILamp A/div
MC33157
66.65
Vgs/Q2 Dead Time
V/div
Vgs/Q1
V/div
10.0 20.0
1.00
5.00
Figure Preheat Typical Operation
Although preheating filaments very complex, must avoid large inrush current when filaments cold. Such behavior will significantly reduce expected life time lamp downgrading electrodes. Thanks flexibility MC33157, this mechanism
easily overcome using current modulation during first decades milliseconds preheating sequence. matter fact, since oscillator controlled current, modulate frequency, hence current flowing into external load, depicted Figure 3.7.
CSWP PREHEAT STRIKE CONTROL +Vref
Figure Extra Filament Preheating Prevent Cold Inrush Current
AN1682
frequency sweep function resistor connected series with capacitor When supply turns capacitor charges exponentially, yielding current through into node Consequently, preheating frequency smoothly sweep from high value defined PSPICE equivalent circuit typical behavior given Figure 3.8.
peak peak (L4) Frequency
Figure Typical Extra Filament Preheating Simulation Function frequency sweep calculated next paragraph. sweep. Consequently, current must zero before this timing. Using preheating time defined above, frequency sweep timing will tswp
FREQUENCY SWEEP
When preheating time ends, system automatically activates frequency sweep removing internal short across capacitor CSWP. Consequently, current into decreases capacitor CSWP charges exponentially. Since decreases, frequency decreases well, yielding shift from calculated here above. sweep timing generated forcing current into capacitor CPH, associated with threshold voltages (2.80 low, 4.10 high). Since internal circuits built with controlled current voltages, constant time ratio between preheating sweep maintained system.
0.75 93.7
hence Assuming expect operating time under frequency, then: CSWP (93.7** -u15 normalized
slope depends solely upon value
CSWP
CSWP time constant comes from resistor
pre-heat sweep tswp
Figure Basic Preheating Timing controller provides sweep reach strike point located curve resonant network defined design engineer. Generally speaking, frequency shall activated during last milliseconds frequency
pre-heat sweep
Next Sequence
Note: Curve scale. Figure 3.10 Basic Frequency Sweep Timing
AN1682
this point, oscillators defined calculate rest this circuit. Figure 3.11 gives normal operating waveforms recorded evaluation board. this example, lamps connected load highlight start sequence under fault condition.
MOTOROLA Semiconductor
MC33157
Vgs/Q3
Note: Since impedance probe used record this waveform limited Meg, slope voltage across appears linear depicted here above. purely linear when load connected across capacitor during normal operation, when observed with high impedance buffer.
System STOPS after fourth strike sequence 1.00 10.0
Figure 3.11 Start-up Sequence with Strike Lamp Detected
DEAD TIME
Dead Time depends upon snubber capacitor, hence dV/dt output voltage. dV/dt 2kV/µs, yielding 1500 snubber capacitor, cover range operation. dead time must longer than delay coming from snubber circuit:
CsnubI 1500 101.812 447.3
With dead time value, including safety margin, resistor derived from MC33157 curves provided data sheet, yielding normalized value. Figure 3.12 illustrates dead time used this example.
MOTOROLA Semiconductor
MC33157
High Side
Side 10.0 1.00 12.0
Figure 3.12 Typical Dead Time Under Biases used Evaluation Board
AN1682
LAMP STRIKE LOGIC
internal comparator, associated built-in type flip-flop, takes care detection lamp ignition state. signal forced either analog digital long pulse presents positive slope followed negative slope, both being within threshold depicted Figure 2.10.
+Vcc Lamp
Since heavy noise generated into system, recommended filter between detection network. evaluation board includes such filter with resistor associated capacitor ground. state lamp detected using cost circuit depicted Figure 3.13, other topology being useable long they fulfill trigger voltages defined data sheet.
STRIKE DETECT
MC33157
Lamp
Figure 3.13 Basic Strike Detection Circuit analog gate built with D6/D13 senses voltage across each lamp, providing threshold voltages needed trig MC33157 internal logic described here above. When strike sequence initialized, high voltage across each resonant network generates voltage higher than 4.50 expected internal comparator. When both lamps turn voltage drops below threshold level (3.75 system jumps steady START SEQUENCE Vline ILamp state mode. either lamp does strike, voltage does drop below 3.75 MC33157 repeats ignition sequence four time, then goes full stop lamp strike during these sequence. course, designer define different strategy: system might operate steady state lamp ignited only, depending upon level defined voltage divider associated node.
MOTOROLA Semiconductor
MC33157
Vlamp
5.00
1.00
10.2
Figure 3.14 Typical Start-up Sequence Under Normal Operation
AN1682
strike detection input forced predetermined state using constant timing depicted Figure 3.15. This useful engineering purpose, device under different condition, without using extra component.
Vref
MC33157DW
Figure 3.15 Force Strike Detection Input
RE-LAMPING
re-lamping function achieved using RESET mode provided MC33157 (see Figure 3.16). This logic input (CMOS compatible) turns converter, pulling both output MOSFET zero gate voltage, when voltage zero. This latched system
resumes soon voltage RESET rises one. When RESET released from zero, system generates frequency sweep jumps steady state mode lamps struck. event strike detection, cycle repeats four times, then goes full stop either lamps ignite.
+Vcc
+Vref
Lamp
From Active Half Bridge
RESET 1N4148 Internal RESET logic
MC33157
Lamp
From Active Half Bridge
Figure 3.16 Typical Re-lamping Circuit
order maximize flexibility MC33157, RESET built current source force internal circuit logic left open. This capability used implement extremely cost solution control lamping function. When both lamps connected socket, current coming from Vcc/2 point through each filaments generates voltage across resistor other hand, current coming from RESET adds same resistor. Consequently, voltage higher than zero logic level system operates under normal condition. lamp disconnected, voltage across decreases, pulling below
system stops immediately (within maximum). system will automatically restart when lamp connected socket described here above. Diode mandatory make sure that negative going current will flow into substrate under transient conditions. Since RESET latched, easy built gate take care other safety goals define controller. Moreover, since system derives voltage energy from output transformer circuit, second period (depending upon start resistor reservoir capacitor MC33262 automatically generated there fault presents RESET
AN1682
START CURRENT
Since start current generates significant losses into final module, several techniques have been used improve this behavior. Among these alternatives, solution depicted Figure 3.17 provides cost together with nearly zero watt absorbed when system runs steady state. When line switched transistor supplies current MC33157, voltage being regulated zener diode Resistor sized handle current absorbed around steady state, needed drive A/500 output MOSFET running kHz. Transistor MPSA44 with BVCBO extend mean time, capacitor charged resistor until voltage across MC33262 reaches UVON threshold typical). This delay time defined R1/C1, making sure that extend electronic ballast start sequence timing second range).
Rectified Line Transformer
MPSA44
Fluo lamps start supply
1N4148
1N4148
supplies both MC33157 MC33262
1N4148
MC33262 Power Factor Controller
MC33157 Electronic Ballast Controller
supplies R1/C1 delay
Figure 3.17 Typical Fast Start-up Power Circuit
this moment, activated voltage derived from secondary transformer Note that, case, secondary necessary synchronize boost converter. Diodes provide rectification voltage isolate chips from other. soon voltage MC33157 becomes higher than reference coming from zener transistor turns power dissipated into resistor drops zero. Consequently, there need large wattage resistor since start time limited second, eventually less, surface temperature this resistor stays within maximum rating carbon metal film type component. Using cost mW/5% resistor large enough handle start current, yielding stable operation system. reduce system cost, derive start-up supply from line rectification filtering depicted Figure 3.18. Since industrial ballast uses boost converter front end, it's possible start chip
first, MC33157DW being powered later secondary winding transformer medium value capacitor connected across input bridge rectifier (C1) rapidly charged switch provides path smooth line voltage: this described MC33262 data sheet. this point, there supply coming from mains ballast controller: consequently, this will start until front activated. this moment, MC33157DW will energy from transformer auxiliary secondary. connect input filtering reservoir capacitor connected across ground chip using right ratio between these capacitors input reservoir will very rapidly charge takes around ms). rest supply comes from standard wattage resistor connected mains k/0.250 k/0.330 since need rise turn chip.
AN1682
k/250
1N4148
MAINS
MC33262 Power Factor Controller
MC33157 Electronic Ballast Controller
Figure 3.18 Current Start-up Circuit Using this technique limits delay time maximum chip. user accommodate using resistor will reduce this delay less than maximum. When MC33262 activated, energy transferred auxiliary winding MC33157DW take much current needed from this source. ballast powered within less than couple millisecond time needed light lamp depends mainly preheating time defined given lamp. day, total sequence well within delay expected user when mains turned advantages such approach are: Integral Signal Conditioning There high wattage resistor used circuit. There external high voltage transistor; save MPSA44 zener. used capacitors already exist module; there extra passive component. auxiliary winding already exists supply inductor demagnetization information stand supply
Rectified Line Transformer
1N4002
peripheral circuits. This solution solves start-up current problem. make system more efficient, couple cost diodes 1N4002 equivalent) implemented make sure high frequency current does overheat reservoir capacitor. Resistor recommended avoid latch risk when MC33157 activated might have pretty fast dV/dt here uncontrolled operation occurs). module been implemented with such technique been proven stable MOTOROLA Toulouse laboratory. Another alternative uses passive components only, making cost bottom line, delay generated electronic ballast controller powered transformer. Since this delay depending upon line voltage (ranging from R1/C1 time constant described here above, system cannot start lamp within accurate timing. basic schematic given Figure 3.19, evaluation board been designed accommodate either this solution depicted Figure 3.17.
supply Fluo lamps start
1N4148
1N4148
MC33262
MC33262 Power Factor Controller
MC33157 Electronic Ballast Controller
MC33157 R1/C1 delay supplies both
Figure 3.19 Typical Cost Start-up Circuit Since MC33157 input zero until activated, mandatory force minimum bias condition avoid risk coming from spurious pulse pins this controller when system operates depicted Figure 3.13. Resistor fulfill this function forcing approximately Vdd/pin
LOGIC ANALOG STATES
Although operating conditions described Data Sheet, table below provides summary impact every biases MC33157 function.
AN1682
Table Logic Analog States
OPEN SHORT SHORT CAPACITOR RESISTOR NOTES preheat. System jumps FSWEEP. Runs preheat continuously. preheat. System jumps FSWEEP.
Preheat timing activated
system jumps FSWEEP. system preheat continuously.
This made flexible engineering tests during system development.
RSWP CSWP
Fsweep stable. recommended.
System does start. ALLOWED
Fpreheat unstable. recommended. Fsweep. Start uses only.
Fpreheat modulated.
Normal operation
recommended range operation.
Fsweep. Start jumps straight from clocks cleared.
Fsweep activated. Start uses modulation. clocks activated.
Fsweep. Start jumps straight from clocks cleared.
Connecting ground will destroy built-in Vref source. recommended range operation. recommended range operation.
clocks cleared.
clocks cleared.
steady state clock. Dtime infinite
steady state clock. Dtime zero
steady state clock. Dtime infinite
Steady state clock activated.
Dtime infinite after delay.
steady state clock.
Dtime valid
recommended make
System STOPS
System STOPS Logic System STOPS
System STOPS Logic System active
System STOPS
System STOPS Logic <100 Logic
System validated special pulse: text.
This used gate cope with external logic.
RESET
Logic System active
Create RESET pulse with (CV/I) C*105
Notes: Characters italic indicate standard operation mode Since short ground will definitively damage circuit, CSWEEP shall never connected zero impedance node cares must observed avoid such situation.
Steady State Vline ILamp
MOTOROLA Semiconductor MC33157 123.2
Vlamp
57.2 Freq 60.6300 Signal Aplitude
lamp Vds/Q3 1.00 5.00 Math 5.00
Figure 3.20 Typical Voltage Current Lamp Under Nominal Steady State Operation Table gives typical input power function ambient temperature, system being monitored thermally controlled oven. Table Typical Input Power Function Ambient Temperature
Temperature -20°C +30°C +50°C +75°C +85°C 93,73 92,24 90,20 89,37 87,34 86,9
AN1682
Test condition: Vline 0.97 Load fluorescent lamp current feedback
Pload: Tubes
These results demonstrate stability MC33157: with variation over temperature range, system good enough handle industrial lamp ballast application without need extra current loop regulation. Figure 3.21 gives results coming from evaluation board.
MC33157 EVALUTATION BOARD
Tamb (°C) Figure 3.21 MC33157 Evaluation Board Global Efficiency Function Ambient Temperature
ANNEXES
Since passive components series resonant network have value tolerances, designer must attention behavior network illustrated Figure 4.1.
typical
(L2) (L1) (L4)
Nominal Ignition Peak Current typical
(Pre-heating) (Ignition)
Frequency
50.6
Figure Resonant Network Behavior Function Resonant Capacitor Tolerances
AN1682
Fortunately, tolerances each components have risk same values given module. This analyzed running Monte Carlo simulation tool determine worst case conditions. Leaving aside passive components tolerances assuming, moment, tube characteristic being constant, output power depending upon operating frequency. other hand, this frequency depends upon tolerance reference voltage, particularly when ambient temperature varies from minus 20°C plus 85°C. curve given Figure represents behavior evaluation module under here above defined conditions.
Tamb (°C)
With global tolerance over temperature range, MC33157 makes possible operation without external feedback.
MAXIMUM dV/dt
Since voltage transient limited 5kV/us, recommended protect device against extremely fast dV/dt. most critical transient developed when system starts from zero volt (pin line being applied network. this case, very fast transient voltage exist between Vout (pin ground, controller forced into latch mode. Such very fast dV/dt, 10kV/us range, avoided using network depicted Figure 4.3.
Pout (Tamb)
Vboot
Vgate
1N4148
Vout
MC33157
Figure Protection MC33157 Against Extremely Fast dV/dt
Figure Pout (Tamb) kHz/Vcc
CRITICAL COMPONENTS
Description Value Supplier Line Filter mH/1.0A EUROINDUSTRIE Herbiers Phone: (33) Fax: (33) 25190 NOIREFONTAINE FRANCE VOGT Output Phone: (33) Fax: (33) 007xx d'Aguesseau 92771 BOULOUGNE FRANCE Trans N2881-A COILCRAFT Phone: (44) 1236 Fax: (44) 1236 Napier Place Wardpark North CUMBERNAULD, Scotland
EVALUATION BOARD COMPONENTS LIST
Index 330R 1.2M 820k 100k 2.2M 100k 470k 470k 100nF 22nF 22uF/25V 220nF 100nF 10nF 47nF 100nF 100nF 470pF/5% 22uF/450V 47uF/25V 6800pF/1000V/5% 100nF 100nF 680nF 6800pF/1000V/5% 1500pF/500V 100nF 100nF 100nF/450V 100nF/450V 680nF/630V 100nF 630V 100nF 630V 220nF 47nF/630V Designator Index N2881-A Used 820k 330k/0.5W 330k 100R 100k 100k 2.2M 100k 22k/0.5W MPSA44 MTP8N50E MTP8N50E MTP8N50E FILTER 1.4mH 1.4mH 2A-TD FUSE 1N4148 BRIDGE 2A/800V MUR160 1N4148 1N4148 Vz14V Vz15V 1N4148 1N4148 1N4148 1N4148 MR856 1N4148 1N4148 1N4148 1N4148 Designator
AN1682
Index Designator Index Designator 0.47R/2W TUBE TUBE FLUO_TUBE FLUO_TUBE 1.5M MC34262DW MC33157DW
Motorola reserves right make changes without further notice products herein. Motorola makes warranty, representation guarantee regarding suitability products particular purpose, does Motorola assume liability arising application product circuit, specifically disclaims liability, including without limitation consequential incidental damages. "Typical" parameters which provided Motorola data sheets and/or specifications vary different applications actual performance vary over time. operating parameters, including "Typicals" must validated each customer application customer's technical experts. Motorola does convey license under patent rights rights others. Motorola products designed, intended, authorized components systems intended surgical implant into body, other applications intended support sustain life, other application which failure Motorola product could create situation where personal injury death occur. Should Buyer purchase Motorola products such unintended unauthorized application, Buyer shall indemnify hold Motorola officers, employees, subsidiaries, affiliates, distributors harmless against claims, costs, damages, expenses, reasonable attorney fees arising directly indirectly, claim personal injury death associated with such unintended unauthorized use, even such claim alleges that Motorola negligent regarding design manufacture part. Motorola registered trademarks Motorola, Inc. Motorola, Inc. Equal Opportunity/Affirmative Action Employer. Mfax trademark Motorola, Inc. reach EUROPE Locations Listed: Motorola Literature Distribution; P.O. 5405, Denver, Colorado 80217. 1-303-675-2140 1-800-441-2447 Customer Focus Center: 1-800-521-6274 MfaxTM: RMFAX0@email.sps.mot.com TOUCHTONE 1-602-244-6609 ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; Ping Industrial Park, Motorola Back System Canada ONLY 1-800-774-1848 Ting Road, N.T., Hong Kong. 852-26629298 http://sps.motorola.com/mfax/ HOME PAGE: http://motorola.com/sps/ JAPAN: Nippon Motorola Ltd.; SPD, Strategic Planning Office, 141, 4-32-1 Nishi-Gotanda, Shinagawa-ku, Tokyo, Japan. 81-3-5487-8488
AN1682
AN1682/D

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