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UC3842AN datasheet & circuit | pdf onsemi

Discover the UC3842AN Reference Manual for comprehensive details on its schematic, pinout, and equivalent circuits. This document is essential for understanding its application in power supply designs and various circuits. Access the UC3842AN Reference Manual in PDF format for all technical specifications.

Brands: onsemi

Download: UC3842AN Datasheet PDF

Price: inquiry

In Stock: 25,614

Output Type: Transistor Driver

Function: Step-Up, Step-Up/Step-Down

Output Configuration: Positive, Isolation Capable

Package: 8-DIP (0.300, 7.62mm)

UC3842AN Pinout Equivalent

1：Overview of the UC3842AN：

UC3842AN is a high-performance fixed-frequency current mode controller chip with a low pin count and simple external components, enabling precise duty cycle control. It operates over a wide voltage range and is commonly used in switch-mode power supplies to provide stable drive signals and protection features such as overcurrent and undervoltage protection, ensuring reliable system operation.

2：UC3842AN Important pin function definition:

No.	Name	Symbol	Description
1	Compensation	COMP	Error amplifier compensation pin. Connect external compensation components to this pin to modify the error amplifier output.
2	Voltage Feedback	V_FB	Inverting input to the internal error amplifier. VFB is used to control the power converter voltage-feedback loop for stability.
3	Current Sense	I_SENSE	Primary-side current sense pin. Connect to current sensing resistor. The PWM uses this signal to terminate the OUTPUT switch conduction.
4	Oscillator	R_T / C_T	Connect timing resistor, RRT, to VREF and timing capacitor, CCT, to GROUND from this pin to set the switching frequency and maximum output ratio. Maximum frequency can up to 500kHz.
5	Ground	GND	Ground
6	Output	OUTPUT	OUTPUT is the gate drive for the external MOSFET. Peak currents of up to 1 A are sourced and sunk by this pin.
7	Power Supply	V_CC	Provides power to the device.
8	Reference Voltage	V_REF	VREF is used to provide charging current to the oscillator timing capacitor through the timing resistor.

3：Alternative model recommendation

UC3845：Similar to the UC3842AN, it has a maximum duty cycle of 100%, whereas the UC3842AN’s maximum duty cycle is approximately 50%. This makes it suitable for switch-mode power supply designs that require a higher duty cycle.

SG3842：It is a direct replacement for the UC3842AN, produced by a different manufacturer, with identical pin configurations and functions, offering excellent compatibility and widely used in switch-mode power supplies.

TL494：This is a versatile PWM control chip that supports dual-output functionality. It can operate in either push-pull mode or half-bridge mode, offering flexible features. Besides switching power supplies, it can also be used in motor control and other applications.

KA3842：Similar to the UC3842AN in terms of functionality and pin configuration, it is a common current-mode PWM controller that provides precise pulse-width modulation control and can be used in various switching power supply circuits.