Datasheet LTC3900 (Analog Devices)
| Hersteller | Analog Devices |
| Beschreibung | Synchronous Rectifier Driver for Forward Converters |
| Seiten / Seite | 20 / 1 — FeaTures. DescripTion. N-Channel Synchronous Rectifier MOSFET Driver. … |
| Dateiformat / Größe | PDF / 288 Kb |
| Dokumentensprache | Englisch |
FeaTures. DescripTion. N-Channel Synchronous Rectifier MOSFET Driver. Programmable Timeout Protection
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LTC3900 Synchronous Rectifier Driver for Forward Converters
FeaTures DescripTion
n
N-Channel Synchronous Rectifier MOSFET Driver
The LTC®3900 is a secondary-side synchronous recti- n
Programmable Timeout Protection
fier driver designed to be used in isolated forward con- n
Reverse Inductor Current Protection
verter power supplies. The chip drives N-channel rectifier n Pulse Transformer Synchronization MOSFETs and accepts pulse sychronization from the n Wide VCC Supply Range: 4.5V to 11V primary-side controller via a pulse transformer. n 15ns Rise/Fall Times at VCC = 5V, CL = 4700pF The LTC3900 incorporates a full range of protection for the n Undervoltage Lockout external MOSFETs. A programmable timeout function is n Small SO-8 Package included that disables both drivers when the synchroniza- tion signal is missing or incorrect. Additionally, the chip
applicaTions
senses the output inductor current through the drain-source resistance of the catch MOSFET, shutting off the MOSFET n 48V Input Isolated DC/DC Converters if the inductor current reverses. The LTC3900 also shuts n Isolated Telecom Power Supplies off the drivers if the supply voltage is too low. n High Voltage Distributed Power Step-Down Converters L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective n Industrial Control System Power Supplies owners. n Automotive and Heavy Equipment
Typical applicaTion
ISOLATION BARRIER L0 VOUT VIN 3.3V 36V TO 72V D3 + 40A COUT
Efficiency
T1 CZ RZ GATE 95 VOUT = 3.3V Q1 R Q CS2 REG RB 90 OUT Q3 RCS1 DZ V CS+ IN = 36V OC VIN = 72V 85 470Ω Q4 CG V I V IN = 48V SENSE CS– CC 80 R 10mΩ CS3 LTC3900 RTMR LT1952 TIMER CVCC C FG EFFICIENCY (%) SG 75 CTMR SOUT SYNC GND GND COMP 70 SG T2 RSYNC 270Ω 65 0 5 10 15 20 25 30 35 40 R1 LOAD CURRENT (A) V OPTO IN LT4430 3900 F10b GND COMP OCI OC FB R2 3900 F01
Figure 1. Simplified Isolated Synchronous Forward Converter
3900fb 1 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
FeaTures DescripTion
n
N-Channel Synchronous Rectifier MOSFET Driver
The LTC®3900 is a secondary-side synchronous recti- n
Programmable Timeout Protection
fier driver designed to be used in isolated forward con- n
Reverse Inductor Current Protection
verter power supplies. The chip drives N-channel rectifier n Pulse Transformer Synchronization MOSFETs and accepts pulse sychronization from the n Wide VCC Supply Range: 4.5V to 11V primary-side controller via a pulse transformer. n 15ns Rise/Fall Times at VCC = 5V, CL = 4700pF The LTC3900 incorporates a full range of protection for the n Undervoltage Lockout external MOSFETs. A programmable timeout function is n Small SO-8 Package included that disables both drivers when the synchroniza- tion signal is missing or incorrect. Additionally, the chip
applicaTions
senses the output inductor current through the drain-source resistance of the catch MOSFET, shutting off the MOSFET n 48V Input Isolated DC/DC Converters if the inductor current reverses. The LTC3900 also shuts n Isolated Telecom Power Supplies off the drivers if the supply voltage is too low. n High Voltage Distributed Power Step-Down Converters L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective n Industrial Control System Power Supplies owners. n Automotive and Heavy Equipment
Typical applicaTion
ISOLATION BARRIER L0 VOUT VIN 3.3V 36V TO 72V D3 + 40A COUT
Efficiency
T1 CZ RZ GATE 95 VOUT = 3.3V Q1 R Q CS2 REG RB 90 OUT Q3 RCS1 DZ V CS+ IN = 36V OC VIN = 72V 85 470Ω Q4 CG V I V IN = 48V SENSE CS– CC 80 R 10mΩ CS3 LTC3900 RTMR LT1952 TIMER CVCC C FG EFFICIENCY (%) SG 75 CTMR SOUT SYNC GND GND COMP 70 SG T2 RSYNC 270Ω 65 0 5 10 15 20 25 30 35 40 R1 LOAD CURRENT (A) V OPTO IN LT4430 3900 F10b GND COMP OCI OC FB R2 3900 F01
Figure 1. Simplified Isolated Synchronous Forward Converter
3900fb 1 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Applications Information Typical Applications Package Description Revision History Typical Application Related Parts