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High Performance Current Mode Pwm Controller


The UC384xB family of control ICs provides the necessary features to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal external parts count. Internally implemented circuits include a trimmed oscillator for precise DUTY CYCLE CONTROL under voltage lockout featuring start-up current less than 0.5mA, a precision reference trimmed for accuracy at the error amp input, logic to insure latched operation, a PWM comparator which also provides current limit control, and a totem pole output stage designed to source or sink high peak current. The output stage, suitable for driving N-Channel MOSFETs, is low in the offstate.


UC3843 Features


• Trimmed oscillator for precise frequency control 
• Oscillator frequency guaranteed at 250khz 
• Current mode operation to 500khz 
• Automatic feed forward compensation 
• Latching pwm for cycle-by-cycle current limiting 
• Internally trimmed reference with undervoltage lockout 
• High current totem pole output 
• Undervoltage lockout with hysteresis 
• Low start-up and operating current


Switching Frequency500 kHz
Rise Time50 ns
Fall Time50 ns
Operating Supply Voltage30 V
Number of Outputs1
Maximum Operating Temperature+ 150 C
Mounting StyleThrough Hole
Package / CasePDIP-8
Minimum Operating Temperature- 40 C
Output Current1000 mA
Output Voltage4.90 V to 5.10 V
Factory Pack Quantity50
TopologyBoost, Flyback, Forward
UC3843 Replacement Parts
UC3843 Price
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