1FEATURES

• QML-V Qualified, SMD 5962-87681

• Rad-Tolerant: 30 kRad (Si) TID (1)

• Compatible With Voltage- or Current-Mode

Topologies

• Practical Operation Switching Frequencies to

1 MHz

• 50-ns Propagation Delay-to-Output

• High-Current Dual Totem Pole Outputs

(1.5 A Peak)

• 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 (1.1 mA)

DESCRIPTION

The UC1825 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 current-mode 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.