38-V, 10-A rugged step-down uModule regulator features fail safe load protection

October 18, 2012 // By Paul Buckley
Linear Technology Corporation introduces the LTM4641, a 4.5 V to 38 V input, 0.6 V to 6 V output, 10 A 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 500 ns 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.

When any trip threshold is exceeded, the LTM4641’s protection circuitry classifies the fault in one of two categories, latching or non-latching. Normal voltage regulation will automatically resume once a non-latching fault such as input undervoltage, bias input undervoltage or input overvoltage has cleared. For latching faults such as an output overvoltage or a second input overvoltage threshold, the system must cycle the input power or supply a logic level signal to the LTM4641 in order to resume normal operation. An overtemperature fault can be classified by the user as a latching or non-latching fault by setting a logic level pin. The LTM4641 can be configured to autonomously restart after latchoff fault conditions have cleared.

The output voltage is user adjustable from 0.6 V to 6 V with ±1.5% total accuracy over line, load and temperature. Additional features include output current sharing for loads requiring more than 10 A, externally adjustable soft start, output overcurrent protection, switching frequency and output voltage tracking.

Availability and Pricing

The LTM4641 is