April 28, 2015 – Linear Technology Korea (Representative Hong Sa-kwak) announced the launch of a 20A Hot Swap™ controller (product name: LTC4234) that integrates a MOSFET and current sensing. This product provides a compact footprint hot-plug solution suitable for high-density circuit boards. The LTC4234 ensures safe board insertion and enables 2.9V to 15V backplane removal by controlling an integrated N-channel power MOSFET that can gently ramp power to bulk capacitors. Therefore, it can avoid sparks, connector damage, and system glitches. By integrating the two most critical and largest hot-swap components—the power MOSFET and sense resistor—the LTC4234 reduces design time and conserves valuable board area. The safe operating area (SOA) of the integrated MOSFET has been production tested and characterized to provide a robust hot-plug solution for space-constrained boards and cards in servers, network routers and switches, SSDs (solid state drives), and industrial systems.

Upon insertion, the LTC4234 waits for connector contact bounce to settle before soft-starting the output. A ground-referenced signal proportional to load current is monitored and provided to an external ADC (analog-to-digital converter). Current limiting can be adjusted with a single resistor and defaults to 22.5A. For higher current applications, two LTC4234s can be easily paralleled for a 40A solution. During overcurrent conditions, the controller limits MOSFET power dissipation using foldback current limiting during an adjustable timeout period. Undervoltage and overvoltage thresholds protect against voltage falling outside the validation window, preventing downstream load circuit failure and damage.

Specified for commercial temperature range 0°C to 70°C, industrial −40°C to 85°C, and automotive −40°C to 125°C, the LTC4234 is offered in a 38-pin 5mm × 9mm QFN package. Pricing is $4.95 per unit in quantities of 1,000. Device samples and evaluation circuit boards are available online or through Linear Technology's regional sales offices. For more information, refer to www.linear.com/product/LTC4234.

Photo caption: 20A Hot Swap™ Controller with Integrated MOSFET & Sense Resistor

Product Features: LTC4234

·Enables safe board insertion into live backplanes

·Integrates sense resistor and 4mΩ MOSFET

·Guaranteed Safe Operating Area (SOA)

·Wide operating voltage range: 2.9V to 15V

·Current limiting for overcurrent fault protection

o 11% accuracy at 22.5A full scale

o Adjustable with single resistor

o Output voltage dependent foldback

o Adjustable fault timer

·Undervoltage, overvoltage & overtemperature protection

·Current & temperature monitoring, power good & fault outputs

·Output voltage soft-start

·−40°C to 125°C operating temperature range

·38-pin 5mm × 9mm QFN package