LT4321 Datasheet | Linear Technology

LT4321 Po E Ideal Diode Bridge Controller Features n n n n Description The LT®4321 is a dual ideal diode bridge controller that enables a Power over Ethernet (Po E) powered device (PD) to receive power in either voltage polarity from RJ-45 data pairs, spare pairs, or both. The LT4321 and eight N-channel MOSFETs replace the eight diodes in a passive Po E rectifier bridge. The LT4321 eases thermal design and increases delivered power. An internal charge pump allows an all-NMOS bridge eliminating larger and more costly PMOS switches. The LT4321 works with 2-pair and 4-pair applications. High impedance input sense pins prevent reverse current on unused pairs. If the power source fails or is shorted, a fast turn-off minimizes reverse current transients. Unlike discrete ideal bridge solutions, the LT4321 will operate through transients without enabling the MOSFETs on unpowered pairs. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Power Path and LTPo E++ are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Reduces Heat, Eliminates Thermal Design Problems Maximizes Power Efficiency Less than 800µA Quiescent Operating Current Fully patible with IEEE 802.3 Detection and Classification n IEEE 802.3 pliant When Paired with a Powered Device (PD) Controller n Works with 2-Pair and 4-Pair Po E Applications n patible with Po E, Po E+, and LTPo E++™ n100V Absolute Maximum Voltage n H-Grade Version Operates Up to 125°C n16-Lead 4mm × 4mm QFN Package Applications n n Po E/Po E+/ LTPo E++ Powered Devices DC Polarity Correction and Ideal Diode-ORing of Tele Supplies Typical Application Powered Device for Po E (to 13W), Po E+ (to 25.5W), or Linear LTPo E++ (to 90W) Systems 1 0.1µF DATA PAIRS 2 3 IN12 6 IN36 IN45 4 IN78 5 7 BG45 TG45 TG78 BG78 OUTN LT4321 EN PWRGD GND TG12 BG12 BG36 TG36 OUTP EN LT4275 SMAJ60A VPORT HSGATE HSSRC + 10µF ISOLATED POWER SUPPLY...