IRAC1166-100W International Rectifier, IRAC1166-100W Datasheet - Page 3

• Manufacturer Part Number: IRAC1166-100W
• Description: BOARD DEMO 100W FOR IR1166
• Manufacturer: International Rectifier

Specifications of IRAC1166-100W

• Main Purpose: AC/DC, Secondary Side
• Outputs And Type: 1, Isolated
• Power - Output: 100W
• Voltage - Output: 16V
• Current - Output: 6.25A
• Voltage - Input: 90 ~ 264VAC
• Regulator Topology: Flyback
• Board Type: Fully Populated
• Utilized Ic / Part: IR1166S, IRF7853
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Frequency - Switching: -

1.0 INTRODUCTION
Generally, Schottky diodes are traditional devices use in passive rectification in order to
have low conduction loss in secondary side for switching power supplies. The
proliferations of synchronous rectification (SR) idea - which is mostly use in buck-derive
topologies - have reached the domain of flyback application in recent years. The use of
low-voltage-low-Rdson mosfet has become so attractive to replace the Schottky rectifiers
in high current applications because it offers several system advantages such as
dramatic decrease in conduction loss and better thermal management of the whole
system by reducing the cost investment in heat sink and PCB space.
A number of techniques in the implementation of SR in flyback converters are
continuously growing from a simple self-driven (secondary winding voltage detection) to
a more complex solution using “current transformer sensing” or combinations of both to
improve the existing technology. The idea has become quite complicated though and
additional discrete devices have made the cost and part counts issue even worse.
Moreover, the issue of reverse current conduction (-due to the delay in sensing the sharp
drop of secondary current during turn-off phase of the SR) still lingers on in different input
line/ output load conditions. The use of a simple fast-rate-direct-sensing of voltage drop
across the mosfet (Vsd) using integrated solution has pave the way for a much simpler
and effective means of controlling the SR mosfets as well as alleviating the reverse
current and multiple-pulse gate turn-ON issues.
The objective of this user guide is to show the advantages of SR application using
integrated IC approach and study the practical limits of the efficiency improvements vs.
the normal rectification method.
2.0 GENERAL DESCRIPTION
The IRAC1166-100W demo board is a universal-input flyback converter with single DC
output capable of delivering continuous 100W (@ +16V x 6.25A) during active
rectification mode.
This demo board is primarily designed to study synchronous
rectification using IR1166 in low-side configuration to take advantage of simpler
derivation of Vcc supply from converter’s output. It is equipped with necessary jumpers to
ease exploring the conduction behavior of synchronous rectifiers SRs in quasi-resonant
mode, so discussion would be confined to variable frequency switching in Critical
Conduction Mode.
It features the fast Vsd sensing of the IR1166 Smart Rectifier Control IC with gate output
drive capability of 1.5Apk. It drives 2 pcs. of SRs in parallel (100V N-ch mosfet IRF7853
in SO-8 package with very low Rdson in its class : 18 mΩ max). This had greatly
simplified the overall mechanical design for not having those bulky and heavy heat sinks
normally seen in high current flyback design using passive rectification.
Rev.1A
18 August 2006
RD#0618
Page 3 of 24
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http://www.irf.com/ Data and specifications subject to change without notice.