BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO GENERAL DESCRIPTION

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BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO GENERAL DESCRIPTION

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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO GENERAL DESCRIPTION
CM6802 green PFC/PWM. generation ML4802, ML4841, ML4801 ML4824-2. system clock frequency generated external then frequency clock frequency clock. CM6802 designed pin-pin compatible with CM6800 family, ML4800 family ML4824 family. section) easily configured Voltage Mode Current Mode. green mode function easily designed during load condition, input power less than 0.75Watt without shutting PFC. green mode threshold green mode threshold separately selecting proper filter ISENSE (pin3) RAMP (pin Power Factor Correction (PFC) allows smaller, lower cost bulk capacitors, reduces power line loading stress switching FETs, results power supply that fully compiles with IEC-1000-3-2 specifications. Intended BiCMOS version industry-standard CM6800, CM6802 includes circuits implementation leading edge, average current, "boost" type power factor correction trailing edge, pulse width modulator (PWM). Both Gate-driver with 0.5A capabilities minimizes need external driver circuits. power requirements improve efficiency reduce component costs. over-voltage comparator shuts down section event sudden decrease load. section also includes peak current limiting input voltage brownout protection. section operated current voltage mode, 250kHz, includes accurate duty cycle limit prevent transformer saturation. When RAMP1 280KHz, fpfc 70KHz fpwm 140KHz.
Patent Number #5,565,761, #5,747,977, #5,742,151, #5,804,950, #5,798,635 fosc=2 fpwm fpfc bleed resistor required Before chip wakes start Compatible with CM6800, ML4824 ML4800 needs modify values external component work properly). User Program automatic green mode threshold (patented) User Program automatic green mode threshold (patented) Input power less than 0.75Watt without shutting load condition. Additional folded-back current limit section. Bi-CMOS process pulse keeping green mode guaranteed turn 2.5V instead 1.5V Internally synchronized leading edge trailing edge Slew rate enhanced transconductance error amplifier ultra-fast response start-up current (30µA typ.) operating current (3.0mA type.) total harmonic distortion, high Reduces ripple current storage capacitor between sections Average current, continuous discontinuous boost leading edge Comparator will turn both Power Detect Comparator Tri-Fault detect meet UL1950 configurable current mode voltage mode operation Current gain modulator improved noise immunity Brown-out control, over-voltage protection, UVLO, soft start, Reference
Hours Technical Support-WebSIM
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO APPLICATIONS
Desktop Power Supply Internet Server Power Supply Power Supply Battery Charger Motor Power Supply Monitor Power Supply Telecom System Power Supply Distributed Power
ISENSE LIMIT
CONFIGURATION
SOP-16 (S16) PDIP-16 (P16) View
DESCRIPTION
Symbol
IEAO
Description
transconductance current error amplifier output
Min.
Operating Voltage Typ. Max. Unit
4.25
gain control reference input. Before chip wakes connected VCC. After chip wakes connected AGC.
ISENSE
Current sense input current limit comparator
VRMS
Input line voltage compensation
Connection point soft start capacitor
voltage feedback input
RAMP (RTCT)
Oscillator timing node; timing
RAMP
When current mode, this functions current sense input; when voltage mode, input from (PWM RAMP) output (feed forward ramp). ILIMIT current limit comparator input
Ground
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO
driver output
driver output
Positive supply
VREF
Buffered output internal 7.5V reference
transconductance voltage error amplifier input transconductance voltage error amplifier output
VEAO
BLOCK DIAGRAM
VEAO IEAO
19.4V
7.5V REFERENCE
VREF
VRMS ISENSE
2.5V
GAIN MODULATOR 3.5K
RAMP1
DUTY CYCLE
SPST
RAMP2
20uA
SPST SPST SPST
VREF
ILIMIT
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2.45V
1.5V
0.5V
POWER DETECT 3.5K
2.75V
POWER FACTOR CORRECTOR
MPPFC
ILIMIT
MNPFC
OSCILLATOR
DUTY
PFCOUT PWMOUT
LIMIT
MPPWM
MNPWM
1.0V
ILIMIT
PULSE WIDTH MODULATOR
UVLO fosc=2xfpwm=4xfpfc
Page
CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO ORDERING INFORMATION
Part Number CM6802IP CM6802IS Temperature Range Package 16-Pin PDIP (P16) 16-Pin (S16)
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum ratings those values beyond which device could permanently damaged.
Parameter
IEAO ISENSE Voltage PWMOUT Voltage Other IREF Input Current Peak Current, Source Sink Peak Current, Source Sink OUT, Energy Cycle Junction Temperature Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering, sec) Thermal Resistance (JA) Plastic Plastic SOIC
Min.
Max.
VREF
Units
ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply Vcc=+15V,
5.0k, 1.0nF, TA=Operating Temperature Range (Note CM6802 Min. VNONINV VINV, VEAO 3.75V Note 2.45 -1.0 VEAO 1.5V, VEAO 1.5V 16.5V Current Error Amplifier (gmi) Input Voltage Range Transconductance Input Offset Voltage VNONINV VINV, VEAO 3.75V -1.5 µmho -0.5 Typ. Max. 2.55
Symbol
Parameter
Test Conditions Voltage Error Amplifier (gmv)
Unit
Input Voltage Range Transconductance Feedback Reference Voltage Input Bias Current Output High Voltage Output Voltage Sink Current Source Current Open Loop Gain Power Supply Rejection Ratio
µmho
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO ELECTRICAL CHARACTERISTICS (Conti.) Unless otherwise stated, these specifications apply
Vcc=+15V, 5.0k, 1.0nF, TA=Operating Temperature Range (Note CM6802 Min. -1.0 ISENSE +0.5V, IEAO 4.0V ISENSE -0.5V, IEAO 1.5V 16.5V Comparator Threshold Voltage Hysteresis Power Detect Comparator Threshold Voltage Hystersis Comparator Threshold Voltage Hysteresis ILIMIT Comparator Threshold Voltage (PFC ILIMIT Gain Modulator Output) Delay Output (Note Threshold Voltage Delay Output (Note Threshold Voltage Hysteresis GAIN Modulator 100µA, VRMS Gain (Note 100µA, VRMS 1.1V, 150µA, VRMS 1.8V, 300µA, VRMS 3.3V, Bandwidth Output Voltage 3.5K*(ISENSE-IOFFSET) Initial Accuracy Voltage Stability Temperature Stability 100µA 250µA, VRMS 1.1V, Oscillator 16.5V 0.70 0.59 1.47 0.66 0.21 0.80 0.90 0.81 2.03 0.92 0.29 Overdrive Voltage 100mV Comparator 2.35 2.45 2.55 Overdrive Voltage -100mV ILIMIT Comparator 0.95 1.05 -1.10 -1.00 -0.90 1.40 19.4 1.65 0.25 2.70 2.77 2.85 Typ. -0.5 4.25 0.65 Max.
Symbol
Parameter Input Bias Current Output High Voltage Output Voltage Sink Current Source Current Open Loop Gain Power Supply Rejection Ratio
Test Conditions
Unit
75.5
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO ELECTRICAL CHARACTERISTICS
(Conti.) Unless otherwise stated, these specifications apply
Vcc=+15V, 5.0k, 1.0nF, TA=Operating Temperature Range (Note CM6802 Min. VRAMP2 VRAMP1 2.5V Reference Output Voltage Line Regulation Load Regulation Temperature Stability Total Variation Long Term Stability Minimum Duty Cycle Maximum Duty Cycle Output Rdson Output Voltage Output High Rdson Output High Voltage Rise/Fall Time (Note Duty Cycle Range Output Rdson Output Voltage Output High Rdson Output High Voltage Rise/Fall Time (Note Start-Up Current Operating Current Undervoltage Lockout Threshold Undervoltage Lockout Hysteresis IOUT 100mA, room temp 1000pF Supply 12V, 14V, CM6802 CM6802 14.7 4.85 15.3 5.15 13.5 IOUT -100mA room temp IOUT -10mA, room temp IOUT 100mA, room temp 1000pF 0-49.5 14.2 0-50 22.5 13.5 IOUT -100mA room temp IOUT -10mA, room temp Line, Load, Temp 125, 1000HRs VIEAO 4.0V VIEAO 1.2V 14.2 22.5 7.35 I(VREF) 16.5V I(VREF) 7mA; 0~70 I(VREF) 5mA; -40~85 7.65 10.5 Typ. Max.
Symbol
Parameter Total Variation Ramp Valley Peak Voltage Dead Time (Note Discharge Current
Test Conditions Line, Temp
Unit
Note Limits guaranteed 100% testing, sampling, correlation with worst-case test conditions. Note Includes bias currents other circuits connected pin. Note Gain 5.375V; (ISENSE IOFFSET) [IAC (VEAO 0.625)] VEAOMAX Note Guaranteed design, 100% production test.
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO TYPICAL PERFORMANCE CHARACTERISTIC
Transconductance (umho)
Transconductance (umho)
-500 -400 -300 -200 -100
ISENSE (mV)
Voltage Error Amplifier (gmv) Transconductance
Current Error Amplifier (gmi) Transconductance
Variable Gain Block Constant 0.35 0.25 Gain VRMS 0.15 0.05
VRMS
Gain Modulator Transfer Characteristic
Gain
IGAINMOD IOFFSET 0.625)
Gain
ISENSE IOFFSET
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO
Functional Description
CM6802 consists average current controlled, continuous boost Power Factor Correction (PFC) front synchronized Pulse Width Modulator (PWM) back end. used either current voltage mode. voltage mode, feedforward from output buss used improve PWM's line regulation. either mode, stage uses conventional trailing edge duty cycle modulation, while uses leading edge modulation. This patented leading/trailing edge modulation technique results higher usable error amplifier bandwidth, significantly reduce size buss capacitor. synchronized with simplifies compensation controlled ripple output capacitor (the input capacitor). section CM6802 runs same frequency PFC. addition power factor correction, number protection features have been built into CM6802. These include soft-start, overvoltage protection, peak current limiting, brownout protection, duty cycle limiting, under-voltage lockout.
Green Mode Function
Both Green Mode Green Mode separately selecting proper external value external components. These external components RAMP1 filter resistor ISENSE pin. Both Blue Angel Energy Star spec. easily without shutting because CM6802, both green mode thresholds. Once green mode threshold triggered, section will pulse skipping mode. Disable Green Mode, Mega resistor needed between IEAO(pin1) VREF(pin14).
Green Mode Threshold
During light load, VEAO voltage will reduce. When VEAO less than 0.5V, will turn PFC. 0.25V hysteresis. light load condition continues, section will stay pulse skipping condition without audible noise since input power minimal because VEAO around 0.75V. Green Mode Threshold selecting proper which resistor filter Isense pin. typical value from ohm. value below ohm, Mega resistor needed between IEAO(pin1) VREF(pin14), will pulse skipping. During pulse skipping, reading power meter trust. will need integrate real power than average with time average power. further reduce power improve light load efficiency, values resistor dividers VRMS need doubled tripled. However, will increase layout sensitivity. Disable Green Mode, Mega resistor needed between IEAO(pin1) VREF(pin14).
Oscillator (RAMP1)
oscillator frequency determined values which determine ramp off-time oscillator output clock:
which internal clock tRAMP tDEADTIME frequency, fosc=2 fpwm= fpfc
fOSC Clock period oscillator derived from following equation: tRAMP VREF 1.25 VREF 3.75 VREF 7.5V: tRAMP 0.51 dead time oscillator determined using: tDEADTIME
2.5V 5.5mA
Green Mode Threshold
During light load, section duty cycle also reduces. When section duty cycle less than internal clock duty cycle which RAMP1, section will start pulse skipping. selecting proper user program Green Mode Threshold. Usually, 1nF.
EXAMPLE: application circuit shown datasheet, with oscillator running fOSC 280kHz
Power Factor Correction
Power factor correction makes nonlinear load look like resistive load line. resistor, current drawn from line phase with proportional line voltage, power factor unity (one). common class nonlinear load input most power supplies, which bridge rectifier capacitive input filter from line. peak-charging effect, which occurs input filter capacitor these supplies, causes brief high-amplitude pulses current flow from power line, rather than sinusoidal current phase with line voltage.
tRAMP
fpwm fpfc. Here, fpwm
=140KHz fpfc=70KHz. Selecting standard components values, 1.0nF, 5.0k
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO
Such supplies present power factor line less than (i.e. they cause significant current harmonics power line frequency appear their input). input current drawn such supply other nonlinear load) made follow input voltage instantaneous amplitude, will appear resistive line unity power factor will achieved. hold input current draw device drawing power from line phase with proportional input voltage, must found prevent that device from loading line except proportion instantaneous line voltage. section CM6802 uses boost-mode DC-DC converter accomplish this. input converter full wave rectified line voltage. bulk filtering applied following bridge rectifier, input voltage boost converter ranges twice line frequency) from zero volts peak value input back zero. forcing boost converter meet simultaneous conditions, possible ensure that current drawn from power line proportional input line voltage. these conditions that output voltage boost converter must higher than peak value line voltage. commonly used value 385VDC, allow high line 270VACrms. other condition that current drawn from line given instant must proportional line voltage. Establishing suitable voltage control loop converter, which turn drives current error amplifier switching output driver satisfies first these requirements. second requirement using rectified line voltage modulate output voltage control loop. Such modulation causes current error amplifier command power stage current that varies directly with input voltage. order prevent ripple, which will necessarily appear output boost circuit (typically about 10VAC 385V level), from introducing distortion back through voltage error amplifier, bandwidth voltage loop deliberately kept low. final refinement adjust overall gain such proportional 1/VIN2, which linearizes transfer function system input voltage varies. Since boost converter topology CM6802 current-averaging type, slope compensation required. current representing instantaneous input voltage (amplitude waveshape) PFC. rectified input sine wave converted proportional current resistor then into gain modulator IAC. Sampling current this minimizes ground noise, required high power switching power conversion environments. gain modulator responds linearly this current. voltage proportional long-term line voltage, derived from rectified line voltage after scaling filtering. This signal presented gain modulator VRMS. gain modulator's output inversely proportional VRMS (except unusually values VRMS where special gain contouring takes over, limit power dissipation circuit components under heavy brownout conditions). relationship between VRMS gain called illustrated Typical Performance Characteristics. output voltage error amplifier, VEAO. gain modulator responds linearly variations this voltage. output gain modulator current signal, form full wave rectified sinusoid twice line frequency. This current applied virtual-ground (negative) input current error amplifier. this gain modulator forms reference current error loop, ultimately controls instantaneous current draw form power line. general output gain modulator IGAINMOD
VEAO VRMS2
More exactly, output current gain modulator given IGAINMOD (VEAO 0.625V) Where units
Note that output current gain modulator limited around 228.47µA maximum output voltage gain modulator limited 228.47uA 3.5K=0.8V. This 0.8V also will determine maximum input power. However, IGAINMOD cannot measured directly from ISENSE. ISENSE IGAINMOD-IOFFSET IOFFSET only measured when VEAO less than 0.5V IGAINMOD Typical IOFFSET around 60uA. Typically, feedforward resistor, RAC, less than 500K resistor connected between this rectified line input voltage. During startup condition, supplies startup current; therefore, system does require additional bleed resistor start chip.
Section
Gain Modulator Figure shows block diagram section CM6802. gain modulator heart PFC, this circuit block which controls response current loop line voltage waveform frequency, line voltage, output voltages. There three inputs gain modulator. These are:
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO
Selecting input gain modulator. also current mirror input requires current input. selecting proper resistor RAC, will provide good sine wave current derived from line voltage also helps program maximum input power minimum input line voltage. RAC=Vin peak 7.9K. example, minimum line voltage 80VAC, RAC=80 1.414 7.9K=894Kohm. Current Error Amplifier, IEAO current error amplifier's output controls duty cycle keep average current through boost inductor linear function line voltage. inverting input current error amplifier, output current gain modulator summed with current which results from negative voltage being impressed upon ISENSE pin. negative voltage ISENSE represents currents flowing circuit, typically derived from current sense resistor series with negative terminal input bridge rectifier. higher power applications, current transformers sometimes used, monitor boost diode. stated above, inverting input current error amplifier virtual ground. Given this fact, arrangement duty cycle modulator polarities internal PFC, increase positive current from gain modulator will cause output stage increase duty cycle until voltage ISENSE adequately negative cancel this increased current. Similarly, gain modulator's output decreases, output duty cycle will decrease, achieve less negative voltage ISENSE pin. Disable Green Mode, Mega resistor needed between IEAO(pin1) VREF(pin14). This Mega resistor will reduce gain will impact performance. Cycle-By-Cycle Current Limiter Selecting ISENSE pin, well being part current feedback loop, direct input cycle-by-cycle current limiter section. Should input voltage this ever more negative than -1V, output will disabled until protection flip-flop reset clock pulse start next power cycle. sensing resistor boost converter. During steady state, line input current IGAINMOD 3.5K. Since maximum output voltage gain modulator IGAINMOD 3.5K= 0.8V during steady state, line input current will limited below 0.8V well. Therefore, choose following equation: =0.7V Vinpeak/(2x Line Input power) example, minimum input voltage 80VAC, maximum input power 200Watt, (0.7V 1.414)/(2 200) 0.197 ohm. CM6802, comparator serves protect power circuit from being subjected excessive voltages load should suddenly change. resistor divider from high voltage output VFB. When voltage exceeds 2.75V, output driver shut down. section will continue operate. comparator 250mV hysteresis, will restart until voltage drops below 2.50V. power components CM6802 within their safe operating voltages, interfere with boost voltage regulation loop. Also, served redundant PFCOVP protection. threshold 19.4V with 1.5V hysteresis.
Figure Section Block Diagram
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO
Error Amplifier Compensation loading modeled negative resistor; increase input voltage causes decrease input current. This response dictates proper compensation transconductance error amplifiers. Figure shows types compensation networks most commonly used voltage current error amplifiers, along with their respective return points. current loop compensation returned VREF produce soft-start characteristic PFC: reference voltage comes from zero volts, creates differentiated voltage IEAO which prevents from immediately demanding full duty cycle boost converter. Voltage Loop There major concerns when compensating voltage loop error amplifier, VEAO; stability transient response. Optimizing interaction between transient response stability requires that error amplifier's open-loop crossover frequency should that line frequency, 23Hz 47Hz line (lowest anticipated international power frequency). gain input voltage CM6802's voltage error amplifier, VEAO specially shaped non-linearity such that under steady-state operating conditions transconductance error amplifier local minimum. Rapid perturbation line load conditions will cause input voltage error amplifier (VFB) deviate from 2.5V (nominal) value. this happens, transconductance voltage error amplifier will increase significantly, shown Typical Performance Characteristics. This raises gain-bandwidth product voltage loop, resulting much more rapid voltage loop response such perturbations than would occur with conventional linear gain characteristics. Voltage Loop Gain voltage amplifier, prevent interaction with voltage loop. should also limited less than 1/6th that switching frequency, e.g. 16.7kHz 100kHz switching frequency. Current Loop Gain
VISENSE DOFF IEAO DOFF IEAO ISENSE VOUTDC 2.5V
ZCI: Compensation Work Current Loop GMI: Transconductance IEAO VOUTDC: Boost Output Voltage; typical designed value 380V worst condition calculate Sensing Resistor Boost Converter 2.5V: Amplitude Leading Modulation Ramp Boost Inductor There modest degree gain contouring applied transfer characteristic current error amplifier, increase speed response current-loop perturbations. However, boost inductor will usually dominant factor overall current loop response. Therefore, this contouring significantly less marked than that voltage error amplifier. This illustrated Typical Performance Characteristics. ISENSE Filter, filter between ISENSE There purposes filter ISENSE pin: Protection: During start inrush current conditions, will have large voltage cross which sensing resistor boost converter. requires ISENSE Filter attenuate energy. reduce Boost Inductor: ISENSE Filter also reduce Boost Inductor value since ISENSE Filter behaves like integrator before going ISENSE which input current error amplifier, IEAO. selecting proper change Green Mode threshold. Typical value from Skipping) ohm. ISENSE Filter filter. resistor value ISENSE Filter between because IOFFSET resistor generate offset voltage IEAO. selecting RFILTER equal will keep offset IEAO less than 5mV. Usually, design pole ISENSE Filter fpfc/6, sixth switching frequency. Therefore, boost inductor reduced times without disturbing stability. Therefore, capacitor ISENSE Filter, CFILTER, will around 283nF.
VOUT VEAO VEAO VOUT 2.5V VOUTDC VEAO
ZCV: Compensation Work Voltage Loop GMv: Transconductance VEAO PIN: Average Input Power VOUTDC: Boost Output Voltage; typical designed value 380V. CDC: Boost Output Capacitor Current Loop current amplifier, IEAO compensation similar that voltage error amplifier, VEAO with exception choice crossover frequency. crossover frequency current amplifier should least times that
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO
Section
Pulse Width Modulator section CM6802 straightforward, there several points which should noted. Foremost among these inherent synchronization section device, from which also derives basic timing. capable current-mode voltage-mode operation. current-mode applications, ramp (RAMP2) usually derived directly from current sensing resistor current transformer primary output stage, thereby representative current flowing converter's output stage. DCILIMIT, which provides cycle-by-cycle current limiting, typically connected RAMP2 such applications. voltage-mode, operation certain specialized applications, RAMP2 connected separate timing network generate voltage ramp against which will compared. Under these conditions, voltage feedforward from buss assist line regulation accuracy response. current mode operation, ILIMIT input used output stage overcurrent protection. voltage error amplifier included stage CM6802, this function generally performed output side PWM's isolation boundary. facilitate design optocoupler feedback circuitry, offset been built into PWM's RAMP2 input which allows command zero percent duty cycle input voltages below 1.25V.
Current Limit ILIMIT direct input cycle-by-cycle current limiter section. Should input voltage this ever exceed output flip-flop reset clock pulse start next power cycle. Beside, cycle-by-cycle current, when ILIMIT triggered cycle-by-cycle current, also softly discharge voltage soft start capacitor. will limit duty cycle mode. Therefore, power dissipation will reduced during dead short condition. Comparator comparator monitors output inhibits this voltage less than nominal 2.45V. Once this voltage reaches 2.45V, which corresponds output capacitor being charged rated boost voltage, soft-start begins. Control (RAMP2) When section used current mode, RAMP2 generally used sampling point voltage representing current primary PWM's output transformer, derived either current sensing resistor current transformer. voltage mode, input ramp voltage generated second timing components (RRAMP2, CRAMP2), that will have minimum value zero volts should have peak value approximately voltage mode operation, feedforward from output buss excellent derive timing ramp stage.
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO
Soft Start Start-up controlled selection external capacitor current source 20µA supplies charging current capacitor, start-up begins 1.25V. Start-up delay programmed following equation: tDELAY
1.25V
where required soft start capacitance tDEALY desired start-up delay. important that time constant soft-start allow time generate sufficient output power section. start-up delay should least 5ms. Solving minimum value CSS:
Generating After turning CM6802 15V, operating voltage vary from 19.4V. threshold voltage comparator 19.4V. hysteresis 1.5V. When 19.4V, PFCOUT will low, section will disturbed. That's ways generate VCC. auxiliary power supply around 15V, other bootstrap winding self-bias CM6802 system. bootstrap winding either taped from boost choke from transformer stage. ratio winding transformer bootstrap should between 15V. filter network recommended between (pin bootstrap winding. resistor filter following. RFILTER IVCC IVCC (QPFCFET QPWMFET (typ.) anything goes wrong, goes beyond 19.4V, gate (pin drive goes gate drive (pin remains function. resistor's value must chosen meet operating current requirement CM6802 itself (3mA, max.) plus current required gate driver outputs.
80nF 1.25V
Caution should exercised when using this minimum soft start capacitance value because premature charging capacitor activation section result hysteresis band comparator start-up. magnitude start-up related both line voltage nominal output voltage. Typically, 1.0µF soft start capacitor will allow time reach their nominal values prior activation section line voltages between 90Vrms 265Vrms.
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO
EXAMPLE: With wanting voltage called, VBIAS 18V, CM6802 driving total gate charge 90nC 100kHz (e.g. IRF840 MOSFET IRF820 MOSFET), gate driver current required IGATEDRIVE 100kHz 90nC RBIAS
VBIAS
case leading edge modulation, switch turned right leading edge system clock. When modulating ramp reaches level error amplifier output voltage, switch will turned effective duty-cycle leading edge modulation determined during time switch. Figure shows leading edge control scheme. advantages this control technique that required only system clock. Switch 1(SW1) turns switch (SW2) turns same instant minimize momentary "no-load" period, thus lowering ripple voltage generated switching action. With such synchronized switching, ripple voltage first stage reduced. Calculation evaluation have shown that 120Hz component PFC's output ripple voltage reduced much using this method.
RBIAS
Choose RBIAS CM6802 should locally bypassed with 1.0µF ceramic capacitor. most applications, electrolytic capacitor between 47µF 220µF also required across part, both filtering part start-up bootstrap circuitry.
Leading/Trailing Modulation
Conventional Pulse Width Modulation (PWM) techniques employ trailing edge modulation which switch will turn right after trailing edge system clock. error amplifier output then compared with modulating ramp effective duty cycle trailing edge modulation determined during time switch. Figure shows typical trailing edge control scheme.
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO APPLICATION CIRCUIT (Current Mode)
+12V +12V Return +12V D11B RAMP2 R20B R20A RAMP1 PWM-OUT PFC-OUT VEAO VRMS RAMP2 ILIMIT I-SENSE VREF CM6802 IEAO
+382V
D11A
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO APPLICATION CIRCUIT (Voltage Mode)
IVIN_EMC
FILTER
IVIN IVIN PFC_VIN PFC_VIN IBOOT 470p R17A C55A R65A MUR1100 R16A IC10
PFC_Vout
PFC_Vout
100n
Q2N2222 Q2N904
PFC_DC
1N4148
1N4002
1N4002
IEAO CM6802 IEAO VEAO ISENSE VRMS VREF
PWM_OUT VREF
VEAO
I-SENSE VREF VRMS PFC-OUT
VREF 100n
PWM-OUT RAMP1 RAMP2 ILIMIT
ILIMIT ILIMIT
ISO1
PFC_Vout
PWM_IN 100k
IC17 IC18 PWM_Rload 500m PWM_Vout ILOAD CM431
MUR1100 MUR1100
IBIAS 100n Q2N2222 PWM_DC PFC_OUT Q2N904 1N4148 ILIMIT 6.8V R32A
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO PACKAGE DIMENSION
16-PIN PDIP (P16)
16-PIN (S16)
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CM6802
BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO IMPORTANT NOTICE
Champion Microelectronic Corporation (CMC) reserves right make changes products discontinue integrated circuit product service without notice, advises customers obtain latest version relevant information verify, before placing orders, that information being relied current. applications using integrated circuit products involve potential risks death, personal injury, severe property environmental damage. integrated circuit products designed, intended, authorized, warranted suitable life-support applications, devices systems other critical applications. products such applications understood fully risk customer. order minimize risks associated with customer's applications, customer should provide adequate design operating safeguards.
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BLEED RESISTOR GREEN MODE PFC/PWM CONTROLLER COMBO GENERAL DESCRIPTION

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