UC3843B STMicroelectronics, UC3843B Datasheet
UC3843B
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UC3843B Summary of contents
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... The UC3842B and UC3844B have UVLO thresholds of 16V (on) and 10V (off), ideally suitedoff-lineapplicationsThecorrespondingthresh- oldsforthe UC3843BandUC3845Bare8.5 V and7.9 V. The UC3842B and UC3843B can operate to duty cycles approaching 100%. A range of the zero to < obtained by the UC3844B and UC3845B by the addition of an internal toggle flip flopwhich blanks the output off every otherclock cycle ...
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... C (SO8) Minidip/SO8 REF OUTPUT / GROUND T D95IN332 Description to ground. Operation to 500kHz is possible. T UC2842BN; UC3842BN UC2843BN; UC3843BN UC2844BN; UC3844BN UC2845BN; UC3845BN Valu Self Limiting – 0 1.25 W 800 mW – 150 C – 150 C ...
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THERMAL DATA Symbo l Description R Thermal Resistance Junction-ambient. th j-amb ELECTRICAL CHARACTERISTICS ( [note 1] Unless otherwise stated, these specifications apply for -25 < T < for UC284XB; 0 < T amb Symbo l Parameter REFERENCE SECTION ...
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UC2842B/3B/4B/5B - UC3842B/3B/4B/5B ELECTRICAL CHARACTERISTICS (continued) Symbo l Parameter OUTPUT SECTION V Output Low Level OL V Output High Level OH V UVLO Saturation OLS t Rise Time r t Fall Time f UNDER-VOLTAGE LOCKOUT SECTION Start Threshold Min Operating ...
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Figure 1: Open Loop Test Circuit. 4.7K 2N2222 100K ERROR AMP. ADJUST 1K I SENSE 4.7K ADJUST 5K D95IN343 High peak currents associatedwith capacitive loads necessitate careful grounding techniques. Timing and bypass capacitors should be connected close Figure 2: Timing ...
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UC2842B/3B/4B/5B - UC3842B/3B/4B/5B Figure 4: Oscillator Discharge Current vs. Tem- perature. I dischg (mA) V =15V i V =2V OSC 8.5 8.0 7.5 7.0 -55 - Figure 6: Error Amp Open-Loop Gain and Phase vs. Frequency. ...
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Figure 10: Output Saturation Voltagevs. Load Current. V sat (V) Source Saturation V i (Load to Ground = =- =15V Pulsed Load 120Hz Rate 3 T =-40 C ...
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... Peak current ( determined by the formula s 1 max small RC filter may be required to suppress switch transients. 8/15 2. COMP <17mA UC3843B UC3845B 8.4V <0.5mA 7.6V D95IN346 ERROR AMPL 1mA D95IN345 OFF ON During UVLO, the Output is low 1V CURRENT ...
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Figure 18 : Slope Compensation Techniques. V REG UC3842B R C SLOPE SENSE Figure 19 : Isolated MOSFET Drive and Current Transformer Sensing. ...
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UC2842B/3B/4B/5B - UC3842B/3B/4B/5B Figure 20 : Latched Shutdown. 2N 3905 SCR must be selected for a holding current of less than 0.5mA at T The simple two transistor circuit can be used in place of the SCR as shown. All ...
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Figure 22: External Clock Synchronization. EXTERNAL SYNC INPUT 0.01 F The diode clamp is required if the Sync amplitude is large enough to cause the bottom side more than 300mV below ground T Figure 23: External ...
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UC2842B/3B/4B/5B - UC3842B/3B/4B/5B Figure 24: Soft-Start Circuit Figure 25: Soft-Start and Error Amplifier Output Duty Cycle Clamp 1mA + BC109 ...
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DIM. MIN. TYP. MAX. MIN. A 1.75 a1 0.1 0.25 0.004 a2 1.65 a3 0.65 0.85 0.026 b 0.35 0.48 0.014 b1 0.19 0.25 0.007 C 0.25 0.5 0.010 c1 45 (typ.) D (1) 4.8 5.0 0.189 E 5.8 ...
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UC2842B/3B/4B/5B - UC3842B/3B/4B/5B mm DIM. MIN. TYP. MAX. MIN. A 3.32 a1 0.51 0.020 B 1.15 1.65 0.045 b 0.356 0.55 0.014 b1 0.204 0.304 0.008 D 10.92 E 7.95 9.75 0.313 e 2.54 e3 7.62 e4 7.62 F 6.6 ...
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... No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specification mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMi- croelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics ...