UC3842 Philips Current-mode PWM controller Data Sheet

Download Datasheet for Philips Semiconductors UC3842 Current-mode PWM controller [8 pages 853-0614 13721 1998 pdf/zip]

SKU: UC3842PHILIPSDS1994 Category: Brand:

Description

The UC3842 is available in an 8-Pin mini-DIP the necessary features to implement off-line, fixed-frequency current-mode control schemes with a minimal external parts count. This technique results in improved line regulation, enhanced load response characteristics, and a simpler, easier to design control loop. Topological advantages include inherent pulse-by-pulse current limiting.
Protection circuitry includes built-in undervoltage lock-out and current limiting. Other features include fully-latched operation, a 1% trimmed bandgap reference, and start-up current less than 1mA.
These devices feature a totem-pole output designed to source and sink high peak current from a capacitive load, such as the gate of a power MOSFET. Consistent with N-channel power devices, the output is low in the OFF-state.

FEATURES
– Low start-up current (<=31mA) - Automatic feed-forward compensation - Pulse-by-pulse current limiting - Enhanced load response characteristics - Undervoltage lock-out with hysteresis - Double pulse suppression - High current totem-pole output - Internally-trimmed bandgap reference - 400kHz operation, guaranteed min DATASHEET CONTAINS: PIN CONFIGURATIONS (UC3842 PINOUT) APPLICATIONS - Off-line switched mode power supplies - DC-to-DC converters UC3842 BLOCK DIAGRAM ORDERING INFORMATION ABSOLUTE MAXIMUM RATINGS DC AND AC ELECTRICAL CHARACTERISTICS - Reference section - Oscillator section - Error amp section - Current sense section - Output section - Undervoltage lockout section - PWM section - Total standby current - Maximum operating frequency section UNDERVOLTAGE LOCKOUT ERROR AMP CONFIGURATION CURRENT SENSE CIRCUIT TYPICAL PERFORMANCE CHARACTERISTICS - Output Saturation Characteristics - Error Amplifier Open-Loop Frequency Response OPEN-LOOP LABORATORY TEST FIXTURE SHUTDOWN TECHNIQUES OFF-LINE FLYBACK REGULATOR SPECIFICATIONS SYNCHRONIZATION AND MAXIMUM DUTY CYCLE CLAMP