UC3842AN Controller: Symbol, Features, Layout Guidelines and More Details

Ⅰ. What is UC3842AN controller?

Ⅱ. Symbol, footprint and pin configuration of UC3842AN controller

Ⅲ. Technical parameters of UC3842AN controller

Ⅳ. Features of UC3842AN controller

Ⅴ. Layout guidelines for UC3842AN controller

Ⅵ. Absolute maximum ratings of UC3842AN controller

Ⅶ. What are the applications of UC3842AN controller?

Ⅷ. What are the causes of damage to UC3842AN controller?

UC3842AN is a current-controlled pulse width modulation chip with excellent performance. The modulator has a single-ended output and can directly drive bipolar power tubes or field effect tubes. Its single PWM output can produce 1000 (maximum) mA, and its switching frequency is 500 kHz. To ensure parts are not damaged by bulk packaging, the product comes in tube packaging, which adds even more protection by storing loose parts in an outer tube. The current mode controller can function within a temperature range spanning from 0°C to 70°C. It is capable of operating with a maximum duty cycle of 100%, and the device can withstand a maximum voltage of 30 V.

UC3842AN is equipped with a frequency-adjustable oscillator for more precise control of the duty cycle. It also features a temperature compensated reference, high gain error amplifier, a current sense comparator and a high current totem pole output, making it ideal for driving power MOSFETs.

Replacement and equivalent:

• UC3842J

• UC3842AN2

• UC3842NG4

As shown in the figure, UC3842AN has a total of 8 pins, and their pin names and descriptions are as follows:

Pin 1 (COMP): Compensation Pin

Pin 2 (VFB): FeedBack Voltage Pin

Pin 3 (Current Sense): Current Sense Pin

Pin 4 (RT/CT): Timing Resistor / Timing Capacitor

Pin 5 (Ground): Ground Pin

Pin 6 (Output): Output Pin

Pin 7 (Vcc): Supply Voltage Pin

Pin 8 (VREF): Reference Voltage Pin

• UC3842AN has a built-in current comparator that can monitor and adjust the output current in real time, thereby effectively preventing overcurrent conditions.

• When the power supply voltage is lower than a preset threshold, UC3842AN will automatically cut off the output to protect the power system from damage.

• UC3842AN is an integrated circuit with a built-in push-pull amplifier, which can amplify and shape the input signal to generate a stable trigger signal for controlling the opening and closing of the switch tube.

• UC3842AN has a built-in oscillator that can generate pulse signals of a certain frequency to control the switching speed and duty cycle of the switching tube.

• The UC3842AN features a PWM latch protection function that safeguards against overcurrent, overvoltage, and other irregularities, thereby enhancing the stability and dependability of the power system.

• The UC3842AN includes an integrated error amplifier capable of continuously monitoring and regulating the output voltage for reliable stability and precision.

• The UC3842AN incorporates an internal reference voltage generator that delivers a consistent reference voltage to multiple circuits within the chip.

• The capacitor CVREF should be positioned in close proximity to both the VREF and GND pins.

• Resistor Rg and capacitor Ce form a low-pass filter for the current detection signal. Ce must be as close as possible to the Cs and GND pins.

• Current loops should be as short and narrow as possible.

• Star grounding technique must be used.

• A high frequency bypass capacitor (Cvcc1) must be placed between the VCC and GND pins as close as possible to the pins.

• The IC ground and power supply ground must be connected at the return path to the input bulk capacitor. Ensure that high frequencies and high currents from the power stage do not pass through the signal ground path.

    Over operating free-air temperature range (unless otherwise noted)

1. Motor control: It is used to control the speed and direction of motors, such as brushless DC motor drives.

2. Lighting control: UC3842AN can also be used in lighting control, especially the driving of light-emitting diodes. It can adjust the brightness of the light-emitting diode and provide stable current output, thereby ensuring the stable brightness of the light-emitting diode.

3. Switching power supply: UC3842AN is commonly used in the design of switching power supplies, such as switch mode power supplies (SMPS), including switching power adapters, inverters and DC-DC boost/buck converters. It achieves precise voltage and current control by adjusting the duty cycle of the output waveform to provide stable power output.

4. Battery charger: UC3842AN can be used to design battery chargers, such as lead-acid batteries, lithium-ion batteries, etc. By properly configuring the control loop, it enables safe and efficient charging.

5. Inverter: It can also be used in variable frequency speed regulation systems to achieve conversion from DC to AC. This is commonly used in solar inverters and UPS.

• Mechanical damage: If the UC3842AN is subjected to mechanical damage such as shock, vibration, etc., its structure may be damaged and its performance may be affected.

• Aging: UC3842AN is an integrated circuit, and its performance may gradually decline or even malfunction as it is used over time.

• Power supply overload or short circuit: If the power circuit has an overload or short circuit fault, resulting in excessive current, the UC3842AN chip may be damaged.

• Abnormal power supply voltage: In the event that the power supply voltage exceeds the operational limits of the UC3842AN, either by being too high or too low, it could lead to improper functionality or potential damage to the chip. Consequently, when dealing with an unstable power supply voltage, it is imperative to employ an appropriate power management chip or implement voltage stabilization measures to safeguard the UC3842AN.

• Temperature is too high: If the working environment temperature of UC3842AN is too high, or its own heat is too high, causing the chip to overheat, it may also be damaged. We should pay attention to the control of its working temperature and heat generation to ensure its normal operation and extend its service life.

Frequently Asked Questions

1. What is UC3842AN?

The UC3842AN is a Current Mode PWM Controller optimized for off-line and DC to DC converters.

2. What is the operating temperature range of UC3842AN ?

The operating temperature of UC3842AN ranges from -0°C to 70 °C.

3. What is the use of UC3842AN?

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.

4. What is the purpose of a PWM controller like the UC3842AN?

PWM controllers are used to regulate the output voltage of power supplies by controlling the duty cycle of the switching transistor. They are essential for achieving efficient voltage regulation.

5. What are the advantages of using the UC3842AN in power supply designs?

The UC3842AN offers precise voltage regulation, high efficiency, and robust performance in power supply applications. It is also relatively easy to use and integrate into circuits.