UC3845B STMicroelectronics, UC3845B Datasheet
UC3845B
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UC3845B 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 UC3844B and UC3845B UVLO 34V ...
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... UC2844BD1; UC3844BD1 UC2845BD1; UC3845BD1 2/15 Self Limiting – 0 (SO8) – 150 – 150 Minidip/SO8 REF OUTPUT 4 5 GROUND D95IN332 Description to ground. Operation to 500kHz is possible. T Minidip UC2842BN; UC3842BN UC2843BN; UC3843BN UC2844BN; UC3844BN UC2845BN; UC3845BN Valu 1.25 W 800 300 C through resistor ...
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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 amb Symbo l Parameter REFERENCE ...
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UC2842B/3B/4B/5B - UC3842B/3B/4B/5B ELECTRICAL CHARACTERISTICS (continued) Symbo l Parameter OUTPUT SECTION V Output Low Level I OL SINK I SINK V Output High Level I OH SOURCE I SOURCE V UVLO Saturation VCC = 6V; I OLS t Rise Time ...
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Figure 1: Open Loop Test Circuit. 4.7K R 2N2222 100K COMP ERROR AMP. ADJUST SENSE 4.7K SENSE ADJUST D95IN343 High peak currents associated with capacitive loads necessitate careful grounding techniques. Timing and bypass capacitors ...
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UC2842B/3B/4B/5B - UC3842B/3B/4B/5B Figure 4: Oscillator Discharge Current vs. Tem- perature. I dischg D95IN335 (mA) V =15V i V =2V OSC 8.5 8.0 7.5 7.0 -55 - 100 T Figure 6: Error Amp Open-Loop Gain and ...
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Figure 10: Output Saturation Voltagevs. Load Current. V sat D95IN341 (V) Source Saturation V i (Load to Ground = =- =15V Pulsed Load 120Hz Rate 3 T =-40 ...
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... GND D95IN347 Peak current ( determined by the formula s 1 max small RC filter may be required to suppress switch transients. 8/15 2.5V 1mA + COMP 1 D95IN345 I CC <17mA UC3843B UC3845B 8.4V <0.5mA V V OFF 7.6V During UVLO, the Output is low D95IN346 ERROR AMPL CURRENT SENSE COMPARATOR ...
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Figure 18 : Slope Compensation Techniques. V REG UC3842B R C SLOPE SENSE Figure 19 : Isolated MOSFET Drive and Current Transformer ...
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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. The diode clamp is required if the Sync amplitude is large enough to cause the bottom side more than 300mV below ground T ...
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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 + ...
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DIM. MIN. TYP. MAX. MIN. TYP. 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 ...
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UC2842B/3B/4B/5B - UC3842B/3B/4B/5B mm inch DIM. MIN. TYP. MAX. MIN. TYP. A 3.32 0.131 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 0.100 e3 7.62 ...
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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 ...