UC3845A STMicroelectronics, UC3845A Datasheet
UC3845A
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UC3845A Summary of contents
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... DUTY CYCLE CONTROL under voltage lock- outfeaturingstart-up current less than0.5mA,a pre- cision reference trimmed for accuracy at the error amp input, logicto insure latched operation,a PWM BLOCK DIAGRAM (toggle flip flop used only in UC3844A and UC3845A 34V 5 ...
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... C (SO8) Minidip/SO8 REF OUTPUT 4 5 GROUND D95IN332 Description to ground. Operation to 500kHz is possible. T UC2842AN; UC3842AN UC2843AN; UC3843AN UC2844AN; UC3844AN UC2845AN; UC3845AN 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 UC284XA; 0 < T amb Symbo l Parameter REFERENCE SECTION ...
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UC2842A/3A/4A/5A - UC3842A/3A/4A/5A 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: Oscillator ...
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UC2842A/3A/4A/5A - UC3842A/3A/4A/5A 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: Current Sense Input Threshold vs. Er- ror Amp ...
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Figure 9: Output Saturation Voltage vs. Load Current. V sat (V) Source Saturation V i (Load to Ground = =- =15V Pulsed Load 120Hz Rate 3 T =-40 ...
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... D95IN347 Peak current ( determined by the formula s 1 max small RC filter may be required to suppress switch transients. 8/15 2. COMP <17mA UC3843A UC3845A 8.4V <0.5mA 7.6V Fig.15-UC3842A ERROR AMPL 1mA D95IN345 OFF ON 1V CURRENT SENSE COMPARATOR ...
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Figure 17 : Slope Compensation Techniques. V REG UC3842A SLOPE SENSE Figure 18 : Isolated MOSFET Drive and Current Transformer Sensing. ...
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UC2842A/3A/4A/5A - UC3842A/3A/4A/5A Figure 19 : 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 21: 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 22: External ...
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UC2842A/3A/4A/5A - UC3842A/3A/4A/5A Figure 23: Soft-Start Circuit Figure 24: 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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UC2842A/3A/4A/5A - UC3842A/3A/4A/5A 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 ...