PDF, 155 Kb, 档案已发布: Sep 5, 1999
The UC1842/3/4/5 family of control ICs can implement off-line or DC-to-DC fixed-frequency current-mode control schemes with a minimal external parts count. This design note describes a circuit with low startup current (less than 0.5mA) MOSFET-compatible undervoltage lockout thresholds programmable restart-delay HICCUP fault protection auxiliary 5V precision reference and overvoltage/overtemper
PDF, 61 Kb, 档案已发布: Mar 23, 2000
The switch-mode power supply primary current is often sensed using a power resistor. Using an op amp to amplify the current-sense signal can reduce cost and improve noise performance and efficiency. This report reviews the advantages of using an op amp circuit and analyzes the design criteria needed to choose the proper op amp.
PDF, 75 Kb, 档案已发布: Sep 5, 1999
Despite the fact that the UC3842 and the UCC3802 PWM Controllers are pin-for-pin compatible, they are not drop-in replacements for each other. Designed as the next generation '42, the UCC3809 also has differences that prevent a simple drop-in substitute. This design note will help the user change from either the UC3842 or the UCC3802 to the UCC3809 in an existing design. A table identifies the mos
PDF, 164 Kb, 档案已发布: Sep 5, 1999
This design note describes a programmable electronic circuit breaker that uses the UC3843A control IC to facilitate a high-speed turnoff following an overcurrent condition. This low-cost industry-standard IC contains the required protection features and drive capability in a single 8-pin device.
PDF, 787 Kb, 档案已发布: Sep 5, 1999
This application note explains the numerous PWM functions and ways to maximize their usefulness. It covers practical circuit design considerations such as slope compensation gate drive circuitry external control functions synchronization and paralleling current-mode controlled modules. Circuit diagrams and simplified equations are included.
PDF, 280 Kb, 档案已发布: Feb 7, 2002
Since their introduction in the mid 1980?s the bipolar UC3842 family of Pulse width modulation (PWM)controllers has grown to become the most widely-used control strategy in the power supply industry. [1] The reasons for success are quite clear the devices feature an elegantly simple yet very effective control architecture they use only 8 pins they can drive MOSFET gates directly and they offer
PDF, 173 Kb, 档案已发布: Mar 4, 1999
A switching power supply consists of the power stage and the control circuit. The power stage performs the basic power conversion from the input voltage to the output voltage and includes switches and the output filter. This report addresses the buck power stage only and does not cover control circuits. Detailed steady-state and small-signal analysis of the buck power stage operating in continuous
PDF, 42 Kb, 档案已发布: Sep 5, 1999
The UCC3802 offers numerous advantages that allow the power supply design engineer to meet requirements for lower power for battery-operated equipment higher switching frequencies for reduced magnetics size higher levels of circuit integration for improved reliability and lower cost. The UCC3802 family of devices is pin-out compatible with the UC3842 and UC3842A families; however it is not plu
PDF, 51 Kb, 档案已发布: Sep 5, 1999
Excessive power dissipation can occur in switch-mode power supplies during startup and overload conditions. Many sophisticated PWM controllers provide the means for protection against these problems; however simple low-cost controllers require additional circuitry. This design note describes a circuit that uses only one additional resistor and transistor to enhance the performance of the UC3842A
PDF, 100 Kb, 档案已发布: Sep 5, 1999
Bipolar linear integrated circuits have been with us for years in the form of PWM and PFC controllers supervisory circuits and other circuits. Since these devices have traditionally used relatively high-voltage (35V) bipolar processes powering was not a concern. In addition many of these ICs contained high-current protection zeners to keep higher voltages from damaging the devices. With a numb
PDF, 21 Kb, 档案已发布: Sep 5, 1999
The UC1842A/3A/4A/5A family of control ICs is a pin-for-pin compatible improved version of the UC3842/3/4/5 family. Providing the necessary features to control current-mode switched-mode power supplies this device has been improved for higher frequency off-line power supplies. This new A series of controllers UC1842A/43A/44A/45A is superior to its predecessors in startup current requirements
PDF, 363 Kb, 修订版: A, 档案已发布: May 28, 2002
PDF, 149 Kb, 档案已发布: Mar 4, 1999
A switching power supply consists of the power stage and the control circuit. The power stage performs the basic power conversion from the input voltage to the output voltage and includes switches and the output filter. This report addresses the boost power stage only and does not cover control circuits. The report includes detailed steady-stage and small-signal analysis of the boost power stage o
PDF, 66 Kb, 档案已发布: Sep 5, 1999
This design note explains the differences between voltage-mode and current-mode switching power supply topologies. It includes a circuit diagram for each mode and suggests criteria for choosing which mode to use.
PDF, 39 Kb, 档案已发布: Sep 5, 1999
This design note details programming frequency and maximum duty cycle using the UC3842 and UC3842-A PWM oscillator ICs. Simplified equations are used to develop obtainable ranges for parameters over IC tolerances.
PDF, 507 Kb, 档案已发布: Sep 5, 1999
The fundamental challenge of power supply design is to realize simultaneously two conflicting objectives: good electrical performance and low cost. The UC3842/3/4/5 control ICs are integrated pulse-width modulators (PWMs). These inexpensive IC controllers provide all the performance advantages of current-mode operation. In addition the UC3842 series is optimized for efficient power-sequencing of
