12V to 9V to 5V

Sharing a 12V to 9V to 5V Power Supply Board Solution
Background
: Our lab is currently working on a dexterous hand system with six miniature servo cylinders. Each cylinder operates at 9V with a peak current of 1.5A, so we need to find a DC-DC step-down chip with strong output current capability. Additionally, the power supply board requires 5V to power the CAN chip on the communication board. These requirements were ultimately placed on a circular PCB with a radius of 24mm.
Design Process:


For the 12V to 9V conversion, we used the XL6016E1.

Here's the description from its datasheet: Referring to the design in the datasheet, the schematic is as follows: Here, the reference voltage for the FB pin is 1.25V, and the output voltage is calculated as $1.25*(1+R1/R2)$.



9V to 5V conversion, using LM2596SX-5.0.

Here's the datasheet description: Refer to the design in the datasheet. The schematic is as follows:


PCB layout:

Top layer is the 12V to 9V network; bottom layer is the 9V to 5V network. Follow these rules during layout:
smaller input capacitors are placed closer to the chip; larger output capacitors are placed closer to the chip;
the two resistors connected to the FB (starter circuit) should be placed as close to the FB as possible; traces should be thin and short;
cut out
a window at the bottom of the inductor for high-current networks to facilitate soldering.





Soldering tests

have not yet been conducted to assess the heat generated by continuous high current, but a heatsink can be attached to the XL4016 initially.