Layout is a critical portion of good power supply design. Figure 55 shows the recommended PCB layout configuration. A list of PCB layout considerations using these devices are listed below.
Proper mounting technique adequately covers the exposed thermal tab with solder. Excessive heat during the reflow process can affect electrical performance. Figure 56 shows the recommended reflow oven thermal profile. Proper post-assembly cleaning is also critical to device performance. See SLUA271 for more information.
|RAMP UP AND RAMP DOWN|
|rRAMP(up)||Average ramp-up rate, TS(max) to TP||3||°C/s|
|rRAMP(down)||Average ramp-down rate, TP to TS(max)||6||°C/s|
|tS||Pre-heat time, TS(min) to TS(max)||60||180||s|
|tL||Time maintained above liquidus temperature, TL||60||150||s|
|tP||Time maintained within 5 °C of peak temperature, TP||20||40||s|
|t25P||Total time from 25 °C to peak temperature, TP||480||s|