UC3842AN PWM Controller[FAQ+Video]: UC3842AN VS UC3842N, Circuit, Equivalent, Datasheet, and Pinout

The UC3842AN is a Current Mode PWM Controller optimized for off-line and DC to DC converters. The internal circuits include UVLO, low start-up current circuit, temperature compensated reference, high gain error amplifier, current sensing comparator, and high current totem-pole output for driving a POWER MOSFET. Also, UC3842A provides a low start-up current below 0.3mA and a short shutdown delay time typ. 100ns. The UC3842A has a UVLO threshold of 16V(on) and 10V(off). The UC3842A can operate within a 100% duty cycle. 

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3D Models

• Optimized for Off-Line and DC-DC Converters

• Low Start-Up Current (< 0.5 mA)

• Trimmed Oscillator Discharge Current

• Automatic Feedforward Compensation

• Pulse-by-Pulse Current Limiting

• Enhanced Load Response Characteristics

• Undervoltage Lockout With Hysteresis

• Double Pulse Suppression

• High-Current Totem Pole Output

• Internally-Trimmed Bandgap Reference

• Up to 500-kHz Operation

• Create a Custom Design Using the UCx84xA With the WEBENCH® Power Designer

• Switch Mode Power Supplies (SMPS)

• DC-DC Converters

• Power Modules

• Industrial PSU

• Battery Operated PSU

Texas Instruments Inc. (TI) is an American technology company that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globally. Its headquarters are in Dallas, Texas, United States. TI is one of the top ten semiconductor companies worldwide, based on sales volume. Texas Instruments's focus is on developing analog chips and embedded processors, which account for more than 80% of its revenue. TI also produces TI digital light processing (DLP) technology and education technology products including calculators, microcontrollers, and multi-core processors.

The UC3842AN IC is a current Mode PWM Controller, which means it can change the output voltage to the load to provide a constant current. A trimmed oscillator, a temperature corrected reference, a high gain error amplifier, a current detecting comparator, and a high current totem pole output for driving a Power MOSFET are all included in this IC.

In applications such as SMPS, RPS, DC-DC Converters, Line voltage regulators, and so on, the UC3842AN can be used to regulate or limit current. So, if you're looking for an IC that can generate PWM signals to control a power switch based on the current flowing through the circuit, this IC would be a good fit.

The use of the UC3842 in a circuit is fairly straightforward because it only requires a few components. The following is a sample application circuit taken from the UC3842 datasheet.

The VCC pin's input voltage should be between 12 and 28 volts. The IC's output pin is connected to the gate driver circuit of the to-be-switched Power switch. The VFB (Voltage feedback) pin serves as feedback for controlling the PWM signal. The feedback pin receives the difference voltage across the shunt resistor, which is used to monitor the change in current in the circuit. Through the timing resistor, VREF is utilized to deliver the charging current to the oscillator timing capacitor. VREF must be bypassed to GROUND with a ceramic capacitor attached as close to the pin as possible for reference stability.