The LT1952/LT1952-1 are current mode PWM controllers optimized to control the forward converter topology, using one primary MOSFET. The LT1952/LT1952-1 provide synchronous rectifier control, resulting in extremely high efficiency. A programmable Volt-Second clamp provides a safeguard for transformer reset that prevents saturation. This allows a single MOSFET on the primary side to reliably run at greater than 50% duty cycle for high MOSFET, transformer and rectifier utilization. The devices include soft-start for controlled exit from shutdown and undervoltage lockout. A precision 107mV current limit threshold, independent of duty cycle, combines with softstart to provide hiccup short circuit protection. The LT1952EGN-1 is optimized for micropower bootstrap startup from high input voltages. The LT1952-1 allows startup from lower input voltages. Programmable slope compensation and leading edge blanking allow optimization of loop bandwidth with a wide range of inductors and MOSFETs. Each device can be programmed over a 100kHz to 500kHz frequency range and the part can be synchronized to an external clock. The error amplifier is a true op amp, allowing a wide range of compensation networks. The LT1952/LT1952-1 are available in a small 16-pin SSOP package.
Feature
- Synchronous Rectifier Control for High Efficiency
- Programmable Volt-Second Clamp
- Output Power Levels from 25W to 500W
- Low Current Start-Up(LT1952: 460µA; VIN On/Off = 14.25V/8.75V)(LT1952-1: 400µA; VIN On/Off = 7.75V/6.5V)
- True PWM Soft-Start
- Low Stress Short Circuit Protection
- Precision 107mV Current Limit Threshold
- Adjustable Delay for Synchronous Timing
- Accurate Shutdown Threshold with Programmable Hysteresis
- Programmable Slope Compensation
- Programmable Leading Edge Blanking
- Programmable Frequency (100kHz to 500kHz)
- Synchronizable to an External Clock up to 1.5 • fOSC
- Internal 1.23V Reference
- 2.5V External Reference
- Current Mode Control
- Small 16-Pin SSOP Package
Applications
- Telecommunications Power Supplies
- Industrial and Distributed Power
- Isolated and Non-Isolated DC/DC Converters
(Picture: Pinout)
