LTM4600

The Module power technology enables very dense power design for 14A peak, and 10A continuous loads in the LTM4600 device. The Module has two voltage options: 20V maximum for the LTM4600EV and 28V maximum for the LTM4600HVEV. The small 15mm * 15mm * 2.8mm LGA surface mount package has specific load current derating curves in the datasheet for input voltage, output voltage, and ambient temperature with air flow. These derating curves provide guidelines for using the LTM4600 in ambient environments with regard to safe-operating-area (SOA). Also there are efficiency curves in the datasheet that are used to extrapolate the power loss curves used in this thermal application note. The purpose of this thermal application note is to provide a guideline for using the Module in ambient environments with and without air flow. The goal is to be able to take measured temperature data on a design and derive the junction-to-ambient thermal resistance (_JA) in units of °C/W with and without a heatsink under air flow conditions. The required data includes power loss curves, safe operating curves (SOA), thermal camera images, current de-rating curves verses ambient temperature with and without a heatsink. Also air flow will be included in the de-rating curves. The 24V designs are analyzed for a worse case temperature rise due to the lower efficiency exhibited in these higher input voltage designs. The 12V designs are characterized for this common input voltage.