1FEATURES
• Rad-Tolerant: 30 kRad (Si) TID (1)
• Compatible With Voltage- or Current-Mode
Topologies
• Practical Operation Switching Frequencies
• 50-ns Propagation Delay-to-Output
• High-Current Dual Totem Pole Outputs
• Wide Bandwidth Error Amplifier
• Fully Latched Logic With Double-Pulse
Suppression
• Pulse-by-Pulse Current Limiting
• Soft Start/Maximum Duty-Cycle Control
• Undervoltage Lockout With Hysteresis
• Low Start-Up Current

DESCRIPTION
The UC1825-DIE PWM control device is optimized for high-frequency switched mode power supply applications.
Particular care was given to minimizing propagation delays through the comparators and logic circuitry while
maximizing bandwidth and slew rate of the error amplifier. This controller is designed for use in either currentmode
or voltage mode systems with the capability for input voltage feed-forward.
Protection circuitry includes a current limit comparator with a 1-V threshold, a TTL compatible shutdown port, and
a soft start pin which will double 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.
This device features totem pole outputs designed to source and sink high peak currents from capacitive loads,
such as the gate of a power MOSFET. The on state is designed as a high level.