UC2825ADWTR Integrated Circuits (ICs)

PMIC - Voltage Regulators - DC DC Switching Controllers

The UC2825ADWTR is a high-performance monolithic power switching regulator. It is part of Texas Instruments’ switch mode (SMPS) controller family,and is designed for use in consumer and industrial applications. Unique features of the UC2825ADWTR include programmable PWM frequency, low-side MOSFET sensing, and an over-temperature shut-down protection circuit.

Application Field

The UC2825ADWTR is well suited for a variety of consumer and industrial products, especially those that require cost-sensitivegains in power efficiency. Typical applications include computer power supplies, vehicle audio amplifiers, motor control systems,industrial lighting, and consumer appliances.

Working Principle

The UC2825ADWTR is a discontinuous mode switching regulator that operates by periodically turning ON and OFF the output switch. This ON/OFF cycling is controlled by the Controller ON logic. The Controller ON logic operates in conjunction with an error amplifier to control the average output voltage represented by Vo. It is important to note that the average output voltage is not the actual output voltage seen at the load.

The Controller ON logic is a pulse-width modulator (PWM) circuit that uses a sawtooth ramp voltage to determine the amount of time that the output switch remains ON. The PWM frequency is set by an RC network connected to pins 10 and 7. The duty cycle of this wave is variable and is determined by the amount of voltage that appears at pin 5. The amount of voltage at pin 5 is determined by the relationship between output voltage Vo and an internal reference voltage VP, which is 1.25 V.

If, for example, the output voltage drops below its set point, the error amplifier amplifies the difference between VP and Vo and causes the Controller ON logic to increase the amount of current flowing to the gate of the output switchenabling it to turn on harder, thus increasing the output voltage. This feedback loop continues until the output voltage converges on the set point.

The UC2825ADWTR also contains adjustable short-circuit protection, internal gate drive current limits and an over-temperature shut-down protection circuit.

Conclusion

The UC2825ADWTR is a highly versatile switching regulator designed for consumer and industrial applications wherecost and efficiency are important factors. It is an ideal choice for applications such as computer power supplies, vehicle audio amplifiers, motor control systems, industrial lighting, and consumer appliances.