Kestrel esc

Kestrel 4in1: 6S 4-in-1 ESC

Four STM32G071s running stock AM32, twelve half-bridge drivers and twenty-four 60 V FETs stacked through a 48 x 52 mm board, with battery current sensing for the flight controller.

The Kestrel 4in1 is the ESC of Kestrel. Each motor has its own STM32G071 wired to AM32's HARDWARE_GROUP_G0_H pin map, the group of the Mamba F55 G071 build, so it runs a stock AM32 release: firmware/am32/README.md maps every pin and walks through the first flash. Each half bridge is stacked through the board, the high-side FET on the top face over its low side on the bottom, joined by the motor wire soldered through a plated hole.

Not fabricated, assembled, powered or flown yet. Every number on this page is measured by KiCad 10.0.6 on the files in this repository (report.json, fab/erc.json, fab/drc.json) or read from the live JLC/LCSC catalogue (bom_cost.md: parts only, at a 10-board build's price tier with JLC's Extended-part fee; the bare PCB and assembly are quoted at order time). The 4 ERC warnings are KiCad's pin-type check on a pin the design ties to a rail on purpose: AM32's per-motor current input, tied to GND: the board measures battery current once, for the FC.

What's on it

• Motor control: 4 x STM32G071G8U6N, AM32 HARDWARE_GROUP_G0_H (the MAMBA_F55_G071 build).
• Gate drive: 12 x LM5109B (WSON-8), 1 A peak, internal bootstrap diode, from an always-on 10 V LMR51430 rail.
• Power stage: 24 x CSD18540Q5B (60 V, SON 5 x 6), high side on the top face over its low side on the bottom.
• Back-EMF: 20k / 2.2k per phase against a 20k x 3 / 750 ohm virtual neutral.
• Battery sense: 2 x 0.5 mOhm 2512 low-side shunts and an INA180A2: 12.5 mV/A on CURR (Betaflight ibata_scale 125).
• Telemetry: all four MCUs' USART1 TX (open drain) on one TLM wire.
• Protection: SMAJ30A on VBAT and six 10 uF / 50 V on the bus; solder a 1000 uF / 35 V low-ESR capacitor across the battery pads.
• Harness: JST-SH 8 in the Kestrel H7's order: VBAT, GND, CURR, TLM, M1-M4.
• Current rating: not measured. At 30 A a motor's two conducting FETs dissipate about 3.2 W before switching loss; a bench thermal run with one motor comes before the first flight (SPEC.md).

Ordering

6 layers, 1.6 mm, 2 oz outer copper recommended; parts on both faces. Upload fab/kestrel_esc_gerbers.zip, fab/kestrel_esc_bom.csv and fab/kestrel_esc_cpl_jlc.csv to JLCPCB: every part has an LCSC number. Bring-up, one board at a time, is in the hub's BUILD.md.

How it was made

Designed with the HeyPCB method on KiCad 10.0.6, headless, by the heypcb-kicad pipeline: a written brief composed from reusable circuit blocks, every pin from KiCad's own symbol library, every part bound to an LCSC number from a dated catalogue read, then ERC, a netlist round trip, locked placement, Freerouting 2.4.1, pours and stitching, silkscreen, DRC with schematic parity, DFM and a fab gate, each stage gated by a measurement. design/make_brief.py regenerates the brief (outline, part locks, net classes) from code.

Part of Kestrel, a 5-inch 6S FPV quad's electronics.

License

Hardware: CERN-OHL-S v2. KiCad's symbol, footprint and 3D libraries used in the design are CC-BY-SA 4.0 with the KiCad library exception.