Compact 20A hot-swap controller integrates MOSFET and current sensing

New from Linear Technology, the LTC4234, a 20A hot-swap controller with integrated MOSFET and current sensing, provides a small footprint hot-plug solution for high-density circuit boards. The LTC4234 ensures safe board insertion and removal from live 2.9V to 15V backplanes by controlling an internal N-channel power MOSFET to gently power up bulk capacitors, avoiding sparks, connector damage and system glitches. By integrating the two most critical and largest Hot Swap components-power MOSFET and sense resistor-the LTC4234 reduces design time and saves valuable board area. The internal MOSFET’s safe operating area (SOA) is production tested and specified to ensure a rugged hot-plug solution, especially for space-constrained boards and cards in servers, network routers and switches, solid state drives and industrial systems. Upon insertion, the LTC4234 waits for connector contact bounce to finish before soft-starting the output. A ground-referenced signal proportional to the load current is provided for monitoring with an external analog-to-digital converter (ADC). The current limit can be reduced from its 22.5A default with a single resistor, affording quick adjustment for dynamic load changes and various applications. For higher current applications, two LTC4234s are easily paralleled for a 40A solution. During overcurrent conditions, the controller limits MOSFET power dissipation by folding back its current limit for an adjustable timeout period. Under-voltage and overvoltage thresholds protect downstream loads against voltages outside a valid window, preventing circuit malfunction and damage. Specified over the 0C to 70C commercial, -40C to 85C industrial and -40C to 125C automotive temperature ranges, the LTC4234 is offered in a 38-pin 5mm x 9mm QFN package. Device samples and evaluation circuit boards are available, says the company.