adafruit wrote:1. please do not call it mintyboost 3.0 - it will confuse folks since we do not offer a SMD version (yet) - SMDboost or something would be more appropriate.
adafruit wrote:2. the forum photos are gigantic, you might want to resize them before posting.
The high speed, high current switching associated with the LT1302 mandates careful attention to layout.
...High current functions are separated by the package from sensitive control functions. Feedback resistors R1 and R2 should be close to the feedback pin (pin4). Noise can easily be coupled into this pin if care is not taken. A small capacitor (100pF to 200pF) from FB to ground provides a high frequency bypass.
...The 0.1µF ceramic bypass capacitor C3 (use X7R, not Z5U) should be mounted as close as possible to the package.
...Grounding should be segregated as illustrated. C3’s ground trace should not carry switch current. Run a separate ground trace up under the package as shown. The battery and load return should go to the power side of the ground copper.
...For surface mount devices heat sinking is accomplished by using the heat spreading capabilities of the PC board and its copper traces. Experiments have shown that the heat spreading copper layer does not need to be electrically connected to the tab of the device. The PCB material can be very effective at transmitting heat between the pad area attached to pins 1 and 8 of the device, and a ground or power plane layer either inside or on the opposite side of the board. Although the actual thermal resistance of the PCB material is high, the length/area ratio of the thermal resistance between the layer is small. Copper board stiffeners and plated through holes can also be used to spread the heat generated by the device.
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