Linear Technology introduced the LT3669, an IO-Link PHY compatible (COM1/COM2/COM3) industrial transceiver that includes a high efficiency step-down regulator and a low dropout linear regulator. The device offers cable interface protection to ±60V.
Wake-up detect functionality as well as a programmable power-on reset timer are included for system reliability. The LT3669/-2 operates from a 7.5V to 40V input voltage range for industrial sensor applications. The LT3669’s internal switching regulator can deliver up to 100mA of load current, whereas the LT3669-2 delivers up to 300mA.
Both versions can deliver high efficiency at output voltages from 0.8V to 16V. The integrated LDO, powered from the switcher output, provides an additional output to offer design flexibility with high efficiency. Both versions feature constant frequency/synchronizable operation with programmable switching frequencies between 250kHz and 2.2MHz. This enables the use of tiny externals passives, which combined with the 4mm x 5mm QFN-28, offer a highly compact solution footprint .
A typical application block diagram for the 300 mA LT3669-2
The LT3669/-2 features line drivers with adjustable slew rates and current limit which are externally adjustable to optimize EMC performance. The line drivers can source/sink up to 250mA of current each or 500mA when connected together, with a minimal residual voltage of less than 2.1V. An adaptive line driver pulsing scheme safely switches heavy loads. The drivers are easily configurable as push-pull, pull-up or pull-down to maximize system flexibility. Other features include current limit detection and thermal shutdown.
The integrated switching regulator has a catch diode1 (Integrated into the LT3669) and provides a typical 60% efficiency at maximum load current (100 mA) with +24 V industrial supply voltage at the L+ pin and a 5 V output. The LT3669-2 needs an external catch diode, but has increased efficiency of 75% at 300 mA maximum load current. This keeps the current draw low on the +24 V industrial line.
Diodes, Inc. SBR1U40LP or DFLS160, ON Semiconductor MBRM140, and Central Semiconductor CMMSH1-60 are good choices for the catch diode.
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