Datasheet LT3753 (Analog Devices) - 2

LT3753
TABLE OF CONTENTS Features ... 1
DVSEC Open Loop Control: No Opto-Coupler,
Applications .. 1
Error Amplifier or Reference ... 19
Typical Application .. 1
RIVSEC: Open Pin Detection Provides Safety ... 19
Description.. 1
Transformer Reset: Active Clamp Technique ...20
Table of Contents .. 2
LO Side Active Clamp Topology (LT3753)...20
Absolute Maximum Ratings .. 3
HI Side Active Clamp Topology (LT3752-1) ...22
Order Information .. 3
Active Clamp Capacitor Value and Voltage
Pin Configuration .. 3
Ripple ...22
Electrical Characteristics ... 4
Active Clamp MOSFET Selection ..23
Typical Performance Characteristics ... 7
Programming Active Clamp Switch Timing:
Pin Functions ..10
AOUT to OUT (tAO) and OUT to AOUT (tOA)
Block Diagram ...11
Delays ... 24
Timing Diagrams ...12
Programming Synchronous Rectifier Timing:
Operation...14
SOUT to OUT (tSO) and OUT to SOUT (tOS) Introduction ... 14 Delays ... 24 Part Start-Up .. 14 Soft-Start (SS1, SS2) ...25
Applications Information ..15
Soft-Stop (SS1) ..25 Programming System Input Undervoltage Hard-Stop (SS1, SS2) ...26 Lockout (UVLO) Threshold and Hysteresis ... 15 OUT, AOUT, SOUT Pulse-Skipping Mode ..27 Soft-Stop Shutdown ... 15 AOUT Timeout ..27 Micropower Shutdown ... 15 Main Transformer Selection ...27 Programming System Input Overvoltage Generating Auxiliary Supplies ...28 Lockout (OVLO) Threshold ... 15 Primary-Side Auxiliary Supply ..29 Programming Switching Frequency .. 16 Secondary-Side Auxiliary Supply ...29 Synchronizing to an External Clock .. 16 Primary-Side Power MOSFET Selection ...30 INTVCC Regulator Bypassing and Operation .. 16 Synchronous Control (SOUT) ...31 Adaptive Leading Edge Blanking Plus Output Inductor Value ...32 Programmable Extended Blanking.. 17 Output Capacitor Selection ...32 Current Sensing and Programmable Slope Input Capacitor Selection ...32 Compensation .. 18 PCB Layout/Thermal Guidelines ..33 Overcurrent: Hiccup Mode .. 18
Package Description ...35
Programming Maximum Duty Cycle Clamp:
Revision History ..35
DVSEC (Volt-Second Clamp) .. 18
Typical Application ...36 Related Parts ..36
Rev. B 2 For more information www.analog.com Document Outline Features Applications Typical Application Description Table of Contents Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Timing Diagrams Operation Applications Information Package Description Revision History Typical Application Related Parts