UC2844BN(LX)

The UC2842/UC2843/UC2844/UC2845 series are fixed-frequency PWM control circuits designed primarily to provide current-mode control for off-line equipment or DC-DC converters, requiring minimal external components. The internal circuitry includes a trimming-frequency oscillator (for precise duty cycle control), a temperature-compensated precision reference, a high-gain error amplifier, and a current-sense comparator. The output stage employs a push-pull configuration capable of sourcing or sinking large currents, making this series well-suited for driving MOSFET power devices. The circuits incorporate comprehensive protection features, including undervoltage lockout (UVLO) and current-limiting protection. Differences among the variants lie in their UVLO thresholds and maximum allowable duty cycles. For example, the UC2842 and UC2844 have UVLO thresholds of 16V (on) and 10V (off), while the UC2843 and UC2845 have thresholds of 8.8V (on) and 7.6V (off). The UC2842 and UC2843 can operate at duty cycles approaching 100%, whereas the UC2844 and UC2845 are limited to approximately 50%.

Key features

• Low startup current (<0.5mA)
• Maximum duty cycle clamp
• UVLO with hysteresis
• Operating frequency up to 500kHz
• Package: SOP8/DIP8
• Operating temperature range: -40°C~125°C