Overview
Features and Benefits
- 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
Product Details
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 LT1952 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.
Applications
- Telecommunications Power Supplies
- Industrial and Distributed Power
- Isolated and Non-Isolated DC/DC Converters
Product Lifecycle
Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (14)
Documentation
Reliability Data (1)
Evaluation Kit Manuals (14)
Tools & Simulations
LTspice
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.
Models for the following parts are available in LTspice:
Reference Materials
Design Resources
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Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.
