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.