Datasheet LT8309 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Secondary-Side Synchronous Rectifier Driver |
| Pages / Page | 14 / 1 — FEATURES. DESCRIPTION. Works with DCM and BCM/CrCM Conduction Mode. … |
| Revision | B |
| File Format / Size | PDF / 604 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Works with DCM and BCM/CrCM Conduction Mode. Flyback Topologies. VCC: 4.5V to 40V
Model Line for this Datasheet
Text Version of Document
LT8309 Secondary-Side Synchronous Rectifier Driver
FEATURES DESCRIPTION
n
Works with DCM and BCM/CrCM Conduction Mode
The LT®8309 is a secondary-side synchronous rectifier
Flyback Topologies
driver that replaces the output rectifier diode in a flyback n
VCC: 4.5V to 40V
topology. By replacing the diode with a N-channel MOSFET, n
Supports Up to 150V MOSFETs
applications are no longer restricted by the heat constraints n
26ns Turn-Off Propagation Delay
of the output diode. The IC replicates the behavior of a n
Accurate Minimum On and Off Timers for Reliable
diode by sensing the drain-to-source voltage to determine
Operation
when the current becomes negative. The LT8309's low n Adjustable and Accurate Trip Point: +5mV to –30mV minimum on- and off-times help improve noise immunity. n 1Ω Gate Driver Pull-Down The fast propagation delay of 26ns allows applications to n SOT-23 5-Lead Package operate in discontinuous conduction mode (DCM) and critical conduction mode (CrCM). The gate driver features
APPLICATIONS
a 0.8Ω pull-down device for fast turn-offs. The 40V VCC n rating allows the part to be driven from the output volt- High Output Current Flybacks n age or the rectified drain voltage of the MOSFET. A low High Efficiency Flybacks quiescent current of 400µA maximizes efficiency at low output currents. All registered trademarks and trademarks are the property of their respective owners.
TYPICAL APPLICATION 40W, 5V Isolated Telecom Supply Efficiency vs Load Current
5.33:1 V 100 IN VOUT+ 36V TO 10µF 412k • 5V, 8A 72V 60Ω 400µF 95 EN/UVLO VIN 100pF • 10Ω LT8309 VIN = 48V WITH LT8309 15.4k VCC 90 LT3748 147k R 1µF FB 85 RREF 6.2V 6.04k 2.2k VIN = 48V WITH PDS760 DIODE DRAIN 80 INTVCC EFFICIENCY (%) TC GATE GATE 75 GND SS SENSE 30.9k V 70 C GND INTVCC 4.7µF 12mΩ 12.1k VOUT– 0.1µF 65 4.7µF 8309 TA01a 0 1 2 3 4 5 6 7 8 15nF LOAD CURRENT (A) 8309 TA01b Rev. B Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Typical Applications Package Description Revision History Typical Application Related Parts
FEATURES DESCRIPTION
n
Works with DCM and BCM/CrCM Conduction Mode
The LT®8309 is a secondary-side synchronous rectifier
Flyback Topologies
driver that replaces the output rectifier diode in a flyback n
VCC: 4.5V to 40V
topology. By replacing the diode with a N-channel MOSFET, n
Supports Up to 150V MOSFETs
applications are no longer restricted by the heat constraints n
26ns Turn-Off Propagation Delay
of the output diode. The IC replicates the behavior of a n
Accurate Minimum On and Off Timers for Reliable
diode by sensing the drain-to-source voltage to determine
Operation
when the current becomes negative. The LT8309's low n Adjustable and Accurate Trip Point: +5mV to –30mV minimum on- and off-times help improve noise immunity. n 1Ω Gate Driver Pull-Down The fast propagation delay of 26ns allows applications to n SOT-23 5-Lead Package operate in discontinuous conduction mode (DCM) and critical conduction mode (CrCM). The gate driver features
APPLICATIONS
a 0.8Ω pull-down device for fast turn-offs. The 40V VCC n rating allows the part to be driven from the output volt- High Output Current Flybacks n age or the rectified drain voltage of the MOSFET. A low High Efficiency Flybacks quiescent current of 400µA maximizes efficiency at low output currents. All registered trademarks and trademarks are the property of their respective owners.
TYPICAL APPLICATION 40W, 5V Isolated Telecom Supply Efficiency vs Load Current
5.33:1 V 100 IN VOUT+ 36V TO 10µF 412k • 5V, 8A 72V 60Ω 400µF 95 EN/UVLO VIN 100pF • 10Ω LT8309 VIN = 48V WITH LT8309 15.4k VCC 90 LT3748 147k R 1µF FB 85 RREF 6.2V 6.04k 2.2k VIN = 48V WITH PDS760 DIODE DRAIN 80 INTVCC EFFICIENCY (%) TC GATE GATE 75 GND SS SENSE 30.9k V 70 C GND INTVCC 4.7µF 12mΩ 12.1k VOUT– 0.1µF 65 4.7µF 8309 TA01a 0 1 2 3 4 5 6 7 8 15nF LOAD CURRENT (A) 8309 TA01b Rev. B Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Typical Applications Package Description Revision History Typical Application Related Parts
