The UC28023 and UC28025 are fixed-frequency PWM controllers optimized for high-frequency
switched-mode power-supply applications. The UC28023 is a single output PWM for single-ended
topologies while the UC28025 offers dual alternating outputs for double-ended and full bridge
Targeted for cost-effective solutions with minimal external components. UC2802x devices
include an oscillator, a temperature compensated reference, a wide bandwidth error amplifier, a
high-speed current-sense comparator, and high-current, active-high, totem-pole outputs to directly
drive external MOSFETs.
Protection circuitry includes a current limit comparator with a 1-V threshold, a TTL
compatible shutdown port, and a soft-start pin which doubles as a maximum duty-cycle clamp. The
logic is fully latched to provide jitter-free operation and prohibit multiple pulses at an output.
An undervoltage lockout section with 800 mV of hysteresis assures low start-up current. During
undervoltage lockout, the outputs are high impedance. Propagation delays through the comparators
and logic circuitry have been minimized while maximizing bandwidth and slew rate of the error
Devices are available in the industrial temperature range of –40°C to 105°C. Package
offerings are 16-pin SOIC (DW), or 16-pin PDIP (N) packages.
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