Product Summary

The UC3843 is a high performance fixed frequency current mode controller. It is specifically designed for Off-Line and DC-DC converter applications offering the designer a cost-effective solution with minimal external components. This UC3843 feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totem pole output ideally suited for driving a power MOSFET. The feature of UC3843 included are protective features consisting of input and reference undervoltage lockouts each with hysteresis, cycle by cycle current limiting, programmable output deadtime, and a latch for single pulse metering.

Parametrics

UC3843 absolute maximum ratings: (1)Bias and Driver Voltages (Zero Series Impedance, see also Total Device spec), VCC, VC: 30V; (2)Total Power Supply and Zener Current (ICC + IZ): 30mA; (3)Output Current, Source or Sink, IO: 1.0A; (4)Output Energy (Capacitive Load per Cycle), W: 5.0μJ; (5)Current Sense and Voltage Feedback Inputs, Vin: -0.3 to +5.5V; (6)Error Amp Output Sink Current, IO: 10mA; (7)Maximum Power Dissipation @ TA = 25℃, PD: 862mW

Features

UC3843 features: (1)Trimmed Oscillator for Precise Frequency Control; (2)Oscillator Frequency Guaranteed at 250 kHz; (3)Current Mode Operation to 500 kHz; (4)Automatic Feed Forward Compensation; (5)Latching PWM for Cycle By Cycle Current Limiting; (6)Internally Trimmed Reference with Undervoltage Lockout; (7)High Current Totem Pole Output; (8)Undervoltage Lockout with Hysteresis; (9)Low Startup and Operating Current; (10)Pb?Free Packages are Available.

Diagrams

UC3843 Internal Block Diagram

Image Part No Mfg Description Data Sheet Download Pricing
(USD)		 Quantity
UC3843
UC3843
Other

Data Sheet
Negotiable 
UC3843A
UC3843A
Other

Data Sheet
Negotiable 
UC3843AD
UC3843AD
Texas Instruments
Current Mode PWM Controllers Current Mode
Data Sheet
0-1: $0.85
1-25: $0.76
25-100: $0.67
100-250: $0.59
UC3843AD1
UC3843AD1
ON Semiconductor
Other Power Management 52kHz 1A Current PWM
Data Sheet
Negotiable 
UC3843AD1013TR
UC3843AD1013TR

IC REG CTRLR BST FLYBK ISO 8SOIC
Data Sheet
Negotiable 
UC3843AD1G
UC3843AD1G
ON Semiconductor
Other Power Management 52kHz 1A Current PWM w/96% Duty Cycle Max
Data Sheet
Negotiable 
UC3843AD1R2
UC3843AD1R2
ON Semiconductor
Other Power Management 52kHz 1A Current PWM
Data Sheet
Negotiable 
UC3843AD1R2G
UC3843AD1R2G
ON Semiconductor
Other Power Management 52kHz 1A Current PWM w/96% Duty Cycle Max
Data Sheet
Negotiable