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LTM4641 TechClips - Efficiency, Output Overvoltage Protection, Overcurrent Protection and More

Afshin Odabaee - Business Manager - uModule Power Products Feb 6th 2013

The LTM4641 is a 4.5V to 38V input, 0.6V to 6V output, 10A step-down μModule® regulator with comprehensive electrical and thermal protection for loads such as processors, ASICs and high-end FPGAs. The LTM4641 μModule regulator monitors input voltage, output voltage and temperature conditions. If any user-adjustable trip thresholds are exceeded, the LTM4641 responds quickly within 500ns in the case of an output overvoltage fault, ceasing operation, and if necessary, activating external switches. One switch disconnects the input supply rail while the other discharges the output capacitors to protect the load. Additionally, when any trip threshold is exceeded, the LTM4641 will issue a logic level fault signal which may be used to initiate an orderly emergency shutdown sequence in the system. The adjustable trip thresholds are accurate to within ±2.7% over the full operating temperature range. As a μModule regulator, the LTM4641 includes power MOSFETs, DC/DC controller, inductor, compensation and the protection logic circuits in a compact surface mount BGA package. The LTM4641 is designed for point-of-load regulation in robotics and industrial instrumentation, as well as rugged environments such as defense and avionics systems.

The LTM4641 exhibits good efficiency and low thermal rise when delivering a 1V, 10A output from an input voltage of 36V and 24V.

To protect high value loads such as FPGAs, ASICs, and microprocessors, the LTM4641 responds to an output overvoltage condition by immediately disconnecting the input supply and activating a crowbar FET between the output and ground. These actions limit the peak output voltage excursion to 20% of the programmed output voltage under a full load and no load condition.

The LTM4641 includes output overcurrent protection and thermal shutdown. Once the fault condition has cleared the LTM4641 automatically resumes operation. The output voltage stays well controlled in all circumstances.

The LTM4641 can support a load up to 40A by combining the outputs of four devices. Using two LTM4641 µModule regulators in parallel, we demonstrate how well the output currents match even under a load transient.

The LTM4641 can withstand surges at the input of up to 80V