DESCRIPTION

The LT?1241 series devices are 8-pin, fixed frequency, current mode, pulse width modulators. They are improved plug compatible versions of the industry standard UC1842 series. These devices have both improved speed and lower quiescent current. The LT1241 series is optimized for off-line and DC/DC converter applications. They contain 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. Start-up current has been reduced to less than 250μA.

FEATURES

■ Low Start-Up Current: < 250μA

■ 50ns Current Sense Delay

■ Current Mode Operation: To 500kHz

■ Pin Compatible with UC1842 Series

■ Undervoltage Lockout with Hysteresis

■ No Cross-Conduction Current

■ Trimmed Bandgap Reference

■ 1A Totem Pole Output

■ Trimmed Oscillator Frequency and Sink Current

■ Active Pull-Down on Reference and Output During Undervoltage Lockout

■ High Level Output Clamp: 18V

■ Current Sense Leading Edge Blanking

APPLICATIONS

■ Off-Line Converters

■ DC/DC Converters