UC3842T STMICROELECTRONICS [STMicroelectronics], UC3842T Datasheet
UC3842T
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UC3842T Summary of contents
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... UVLO thresholds of 16V (on) and 10V (off), ideally suited to off-line applications The corresponding thresholds for the UC3843T and UC3845T are 8.5 V and 7.9 V. The UC3842T and UC3843T can operate to duty cycles approaching 100%. A range of zero to < obtained by the UC3844T and UC3845T by the addition of an internal toggle flip flop which blanks the output off every other clock cycle ...
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... UC3842T - UC3843T - UC3844T - UC3845T ABSOLUTE MAXIMUM RATINGS Symbol V Supply Voltage (low impedance source Supply Voltage (Ii < 30mA Output Current O E Output Energy (capacitive load) O Analog Inputs (pins 2, 3) Error Amplifier Output Sink Current P Power Dissipation at T tot P Power Dissipation at Tamb ...
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THERMAL DATA Symbol R Thermal Resistance Junction-ambient. th j-amb ELECTRICAL CHARACTERISTICS ( [note 1] Unless otherwise stated, these specifications apply for 0 < T < 105° 15V (note 5); R amb i Symbol Parameter REFERENCE SECTION Line Regulation ...
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... UC3842T - UC3843T - UC3844T - UC3845T ELECTRICAL CHARACTERISTICS (continued) Symbol 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 Voltage After Turn-on PWM SECTION Maximum Duty Cycle ...
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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 associated with capacitive loads necessitate careful grounding techniques. Timing and bypass capacitors should be connected close Figure 2: ...
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... UC3842T - UC3843T - UC3844T - UC3845T Figure 4: Oscillator Discharge Current vs. Tem- perature. I dischg (mA 8.5 8.0 7.5 7.0 -55 - Figure 6: Error Amp Open-Loop Gain and Phase vs. Frequency. (dB) V =15V Gain -20 10 100 1K 10K 100K Figure 8: Reference Voltage Change vs. ...
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Figure 10: Output Saturation Voltagevs. Load Current. V sat (V) Source Saturation V i (Load to Ground =25˚ =15V Pulsed Load 120Hz Rate 3 T =-40˚ Sink Saturation (Load ...
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... UC3842T - UC3843T - UC3844T - UC3845T Figure 15 : Error Amp Configuration Figure 16 : Under Voltage Lockout. 7 ON/OFF COMMAND V TO REST OFF Figure 17 : Current Sense Circuit . D95IN347 Peak current ( determined by the formula s 1 max small RC filter may be required to suppress switch transients. ...
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... COMP/LATCH U3842T - UC3843T - UC3844T - UC3845T UC3842T GND ISOLATION BOUNDARY D95IN349 V REG UC3842T SLOPE SENSE Waveforms 50 -1.4 (pin GND D99IN1059 ...
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... UC3842T - UC3843T - UC3844T - UC3845T Figure 20 : Latched Shutdown. 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 resistors are 10K. Figure 21: Error Amplifier Compensation From Error Amp compensation circuit for stabilizing any current-mode topology except for boost and flyback converters operating with continuous inductor current ...
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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 of C Figure 23: External Duty Cycle Clamp and Multi Unit Synchronization. V ...
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... UC3842T - UC3843T - UC3844T - UC3845T Figure 24: Soft-Start Circuit Figure 25: Soft-Start and Error Amplifier Output Duty Cycle Clamp BC109 V CLAMP 12/15 R BIAS R OSC + 1mA BIAS - R OSC 1mA V Clamp · = where 0 <V <1V CLAMP ...
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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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... UC3842T - UC3843T - UC3844T - UC3845T mm DIM. MIN. TYP. MAX. 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 I 5.08 L 3.18 3.81 0.125 Z 1.52 14/15 inch MIN. TYP. MAX. 0.131 0.065 0.022 0.012 0.430 0.384 0.100 0.300 0.300 0.260 0.200 0.150 0.060 OUTLINE AND ...
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Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the conse- quences of use of such information nor for any infringement of patents or other rights of third parties which may result from its ...