UC2842-UC3842 Fast Delivery |IC PHOENIX CO.,LIMITED

UC2842 ,CURRENT MODE PWM CONTROLLERapplications The correspondingnecessary
UC2842A ,Linear High-Performance Current Mode ControllerUC284XAUC384XAHIGH PERFORMANCE CURRENT MODE PWM CONTROLLERNOT FOR NEW DESIGN1
UC2842A ,Linear High-Performance Current Mode ControllerElectrical Characteristics....... 711.4 Receiving Notification of Documentation Updates 256.6 Typic ..
UC2842A ,Linear High-Performance Current Mode ControllerBlock Diagram (toggle flip flop used only in UC3844A and UC3845A)7ViUVLO34V85VVREF5 S/RREFGROUND 5V ..
UC2842A ,Linear High-Performance Current Mode ControllerFEATURESFigure 1. Package■ TRIMMED OSCILLATOR DISCHARGE CURRENT■ CURRENT MODE OPERATION TO 500kHz A ..
UC2842A ,Linear High-Performance Current Mode Controller SLUS224F–SEPTEMBER 1994–REVISED OCTOBER 20174 Revision HistoryNOTE: Page numbers for previous revi ..
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UC2842-UC3842
SMPS Controller
UC2842/3 /4/5
UC3842/3 /4/5
October 1998
CURRENT MODE PWM CONTROLLER OPTIMIZED FOR OFF-LINE AND DCTODC
CONVERTERS. LOW START-UP CURRENT(<1 mA). AUTOMATIC FEED FORWARD COMPENSA-
TION. PULSE-BY-PULSECURRENT LIMITING. ENHANCED LOAD RESPONSE CHARAC-
TERISTICS. UNDER-VOLTAGE LOCKOUTWITH HYSTER-
ESIS. DOUBLE PULSE SUPPRESSION. HIGH CURRENT TOTEM POLE OUTPUT. INTERNALLY TRIMMED BANDGAP REFER-
ENCE. 500 KHz OPERATION. LOWRO ERROR AMP
DESCRIPTION
TheUC3842/3/4/5familyof controlICsprovidesthe
necessary featuresto implement off-lineorDCto fixed frequencycurrent mode controlschemes
witha minimalexternalpartscount.Internallyimple-
mentedcircuitsincludeundervoltagelockout featur-
ing start-up current less than1 mA,a precisionref-
erencetrimmedfor accuracyat theerrorampinput,
logicto insure latchedoperation,a PWM compara-
torwhichalsoprovidescurrentlimitcontrol,andato-
tem pole output stage designedto sourceor sink
high peak current. The output stage, suitablefor
drivingN-ChannelMOSFETs, islowin theoff-state.
Differencesbetween membersofthis familyarethe
under-voltage lockout thresholds and maximum
duty cycle ranges. The UC3842 and UC3844 have
UVLO thresholdsof 16V (on) and 10V (off), ideally
suited off-line applications The corresponding
thresholdsforthe UC3843 and UC3845are8.5V
and7.9V. The UC3842 and UC3843can operate duty cycles approaching 100%.A rangeofthe
zeroto<50%is obtainedbythe UC3844 and
UC3845by theadditionof aninternaltoggleflipflop
which blanksthe outputoff every other clock cycle.
BLOCK DIAGRAM (toggleflip flop used onlyin U3844 and UC3845)
Minidip SO14
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All voltagesare withrespecttopin 5,allcurrentsare positiveintothe specifiedterminal.PIN CONNECTIONS (top views)
SO14 Minidip
ORDERING NUMBERS
Type Minidip SO14
UC2842
UC3843
UC2844
UC2845
UC2842N
UC2843N
UC2844N
UC2845N
UC2842D
UC2843D
UC2844D
UC2845D
UC3842
UC3843
UC3844
UC3845
UC3842N
UC3843N
UC3844N
UC3845N
UC3842D
UC3843D
UC3844D
UC3845D
ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Value Unit Supply Voltage(low impedance source) 30 V Supply Voltage(Ii< 30mA) Self Limiting Output Current ±1 A Output Energy (capacitive load) 5 μJ
Analog Inputs (pins2,3) –0.3to6.3 V
ErrorAmplifier Output Sink Current 10 mA
Ptot Power Dissipationat Tamb≤50°C (minidip, DIP-14) 1W
Ptot Power Dissipationat Tamb≤25°C (SO14) 725 mW
Tstg Storage Temperature Range –65to150 °C Lead Temperature (soldering 10s) 300 °C
THERMAL DATA
Symbol Description Minidip SO14 Unit
Rthj-amb Thermal Resistance Junction-ambient. max. 100 165 °C
UC2842/3/4/5-UC3842/3/4/5
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ELECTRICAL CHARACTERISTICS (Unless otherwise stated,these specifications applyfor-25< Tamb<
85°Cfor UC2824X;0< Tamb <70°Cfor UC384X;Vi= 15V (note5);RT= 10K;CT= 3.3nF)
Symbol Parameter Test Conditions UC284X UC384X Unit
Min. Typ. Max. Min. Typ. Max.
REFERENCE SECTION
VREF Output Voltage Tj =25°CIo= 1mA 4.95 5.00 5.05 4.90 5.00 5.10 V
ΔVREF Line Regulation 12V≤Vi≤ 25V 620 6 20 mV
ΔVREF Load Regulation 1≤Io≤ 20mA 625 6 25 mV
ΔVREF/ΔT Temperature Stability (Note2) 0.2 0.4 0.2 0.4 mV/°C
Total Output Variant Line, Load, Temperature(2) 4.9 5.1 4.82 5.18 V Output Noise Voltage 10Hz≤f≤ 10KHzTj =25°C
(2) 50 μV
Long Term Stability Tamb= 125°C, 1000Hrs(2) 525 5 25 mV
ISC Output Short Circuit -30 -100 -180 -30 -100 -180 mA
OSCILLATOR SECTION Initial Accuracy Tj =25°C(6) 47 52 57 47 52 57 KHz
Voltage Stability 12≤Vi≤ 25V 0.2 1 0.2 1 %
Temperature Stability TMIN≤ Tamb≤ TMAX(2) 55 % Amplitude VPIN4 Peakto Peak 1.7 1.7 V
ERROR AMP SECTION Input Voltage VPIN1= 2.5V 2.45 2.50 2.55 2.42 2.50 2.58 V Input Bias Current -0.3 -1 -0.3 -2 μA
AVOL 2≤Vo≤4V 65 90 65 90 dB Unity Gain Bandwidth (2) 0.7 1 0.7 1 MHz
SVR Supply Voltage Rejection 12V≤Vi≤ 25V 60 70 60 70 dB Output Sink Current VPIN2= 2.7V VPIN1= 1.1V 2 6 2 6 V Output Source Current VPIN2= 2.3V VPIN1=5V -0.5 -0.8 -0.5 -0.8 mA
VOUT High VPIN2= 2.3V;= 15KΩto Ground 5 6 V
VOUTLow VPIN2= 2.7V;= 15KΩtoPin8
0.7 1.1 0.7 1.1 V
CURRENT SENSE SECTION Gain (3&4) 2.85 3 3.15 2.8 3 3.2 V/V Maximum Input Signal VPIN1=5V(3) 0.9 1 1.1 0.9 1 1.1 V
SVR Supply Voltage Rejection 12≤Vi≤25V(3) 70 70 dB Input Bias Current -2 -10 -2 -10 μA
Delayto Output 150 300 150 300 ns
OUTPUT SECTION
IOL OutputLow Level ISINK= 20mA 0.1 0.4 0.1 0.4 V
ISINK= 200mA 1.5 2.2 1.5 2.2 V
IOH Output High Level ISOURCE= 20mA 13 13.5 13 13.5 V
ISOURCE= 200mA 12 13.5 12 13.5 V Rise Time Tj =25°CCL=1nF(2) 50 150 50 150 ns Fall Time Tj =25°CCL=1nF(2) 50 150 50 150 ns
UC2842/3/4/5-UC3842/3/4/5
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Notes:2. Theseparameters, although guaranteed,arenot 100% testedin production. Parameter measuredat trippointoflatchwithVPIN2=0. Gaindefinedas:VPIN1A= ;0≤VPIN3≤0.8VΔVPIN3 AdjustVi abovethe startthreshold before settingat15V. Outputfrequency equalsoscillator frequencyforthe UC3842and UC3843.
Outputfrequencyis onehalfoscillator frequencyforthe UC3844and UC3845.
ELECTRICAL CHARACTERISTICS (continued)
Symbol Parameter Test Conditions UC284X UC384X Unit
Min. Typ. Max. Min. Typ. Max.
UNDER-VOLTAGE LOCKOUT SECTION
Start Threshold X842/4 15 16 17 14.5 16 17.5 V
X843/5 7.8 8.4 9.0 7.8 8.4 9 V
Min Operating Voltage
After Turn-on
X842/4 9 10 11 8.5 10 11.5 V
X843/5 7.0 7.6 8.2 7.0 7.6 8.2 V
PWM SECTION
Maximum Duty Cycle X842/3 93 97 100 93 97 100 %
X844/5 46 48 50 47 48 50 %
Minimum Duty Cycle 0 0 %
TOTAL STANDBY CURRENT
Ist Start-up Current 0.5 1 0.5 1 mA Operating Supply Current VPIN2 =VPIN3 =0V 11 20 11 20 mA
Viz Zener Voltage Ii= 25mA 34 34 V
UC2842/3/4/5-UC3842/3/4/5
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Figure1: ErrorAmp Configuration.
Erroramp cansourceor
sinkupto 0.5mA
Figure2: UnderVoltage Lockout.
During Under-Voltage Lockout,the output driveris
biasedto sink minor amountsof current. Pin6
shouldbe shuntedto groundwitha bleederresistor preventactivatingthe power switch with extrane-
ous leakage currents.
Figure3: Current SenseCircuit.
Peak current(is)is determinedbythe formula
1.0VISmax≈ RS smallRC filter maybe requiredto suppress switch transients.
UC2842/3/4/5-UC3842/3/4/5
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Figure4. Figure5: Deadtimevs.CT(RT >5KΩ).
1.72forRT >5KΩf= RTCT
Figure7: OutputSaturation Characteristics.Figure6: Timing Resistancevs. Frequency.
Figure8: Error Amplifier Open-loop Frequency
Response.
UC2842/3/4/5-UC3842/3/4/5
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Partno	Mfg	Dc	Qty	Available	Descript
UC3842	LMI	N/a	1	avai	SMPS Controller
UC2842	ST	N/a	250	avai	CURRENT MODE PWM CONTROLLER