IO-Link transceiver integrates step-down regulator & LDO

July 02, 2014 // By Graham Prophet
LT3669 is 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, making it suitable for industrial sensor applications. The LT3669's internal switching regulator can deliver up to 100 mA of load current, whereas the LT3669-2 delivers up to 300 mA. 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 additional design flexibility while maintaining high efficiency. Both versions feature constant frequency/synchronisable operation with programmable switching frequencies between 250 kHz and 2.2 MHz. This enables the use of small external components, which combined with the 4 x 5mm QFN-28, offer a highly compact solution footprint for industrial IO-Link sensor applications.

The LT3669/-2 feature rugged line drivers with adjustable slew rates and current limit which are externally adjustable to optimise EMC performance. The line drivers can source/sink up to 250 mA of current each or 500 mA 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 configurable as push-pull, pull-up or pull-down to maximise system flexibility. Other features include current limit detection and thermal shutdown. The LT3669EUFD and LT3669EUFD-2 are both in a 28-pin thermally enhanced 4 x 5mm QFN package from $3.55 (1000). Industrial grade versions, the LT3669IUFD and LT3669IUFD-2, are guaranteed to operate over the -40°C to +125°C operating junction temperature range and the high temperature grade versions, the LT3669HUFD and LT3669HUFD-2 are guaranteed to operate over the -40°C to +150°C.

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