LT1245CS8#PBF | Linear Technology

High Speed Current Mode Pulse Width Modulator, LT1245CS8#PBF, Linear Technology

The LT1245CS8#PBF is an 8-pin, fixed-frequency, current-mode, pulse width modulator. It is an improved plug-compatible version of the industry standard UC1842. The LT1245CS8#PBF has both improved speed and lower quiescent current. It is optimized for off-line and DC/DC converter applications. The device contains a temperature-compensated reference, high-gain error amplifier, current-sensing comparator, and a high-current totem-pole output stage ideally suited to driving power MOSFETs.

Cross-conduction current spikes in the output stage of the LT1245CS8#PBF have been eliminated, making 500kHz operation practical. Several new features have been incorporated. Leading-edge blanking has been added to the current-sense comparator. Trims have been added to the oscillator circuit for both frequency and sink current, and both of these parameters are tightly specified. The output stage is clamped to a maximum VOUT of 18V in the on state. The output and the reference output are actively pulled low during undervoltage lockout.

Features

• Undervoltage Lockout with Hysteresis
• No Cross-Conduction Current
• Trimmed Bandgap Reference
• Trimmed Oscillator Frequency and Sink Current
• Active Pull-Down on Reference and Output During Undervoltage Lockout
• Current Sense Leading Edge Blanking

Applications

• Off-Line Converters
• DC/DC Converters