BLDC Motor Control Design Considerations

flux

0:54

General
Project
Here’s a concise technical overview and critique tailored to your stated goals.
Project intent
  • Three-phase BLDC/FOC inverter around the TMC9660, operating from 24 V with up to 4 A phase current, PWM at 25 kHz.
  • Power stage uses three discrete half-bridges based on Infineon IAUC45N04S6L063H MOSFETs (60 V class, very low Rds(on)).
Key functions to implement
  • TMC9660 supplies the FOC control, gate driving, current/voltage sensing, SPI/UART control, protections, and integrated multiphase buck resources.
  • Power stage: 3 half-bridges, phase current shunts or in-package sensing (depending on measurement topology), DC link input and bulk decoupling.
  • Control and comms: SPI/UART to host, fault/wake/enable lines, GPIOs for diagnostics or peripheral features.
Potential challenges
  • Gate drive and switching behavior
    • 25 kHz with low-Rds(on) MOSFETs yields steep di/dt and dv/dt; careful gate resistor sizing, split turn-on/turn-off resistors, and snubbing may be required to control ringing/EMI without adding too much switching loss.
    • Ensure TMC9660 gate drive voltage, peak source/sink current, and Miller clamp behavior are compatible with the IAUC45N04S6L063H’s total gate charge and reverse recovery of the body diode.
    • Dead time: tune for your MOSFETs to avoid shoot-through while minimizing body-diode conduction time.
  • Current sensing accuracy
    • At only 4 A peak and 25 kHz, shunt placement and amplifier bandwidth/noise are critical. Verify the TMC9660 ADC/sample-and-hold timing vs the PWM blanking window to avoid desaturation/diode recovery artifacts.
    • Kelvin routing from shunts, matched differential traces, and low-inductance return paths are essential.
  • Supply and decoupling
    • DC link: low-ESR bulk plus high-frequency ceramics (MLCCs) directly across each half-bridge (HS to LS FET supply) to contain loop current at ns edges.
    • Gate-driver supply decoupling near the TMC9660 pins; observe datasheet-recommended local caps for charge pump/boost pins.
  • Layout/EMI
    • Minimize high di/dt loops: half-bridge switch node, gate loops, and shunt loops. Keep switch-node copper compact; avoid running signals under it.
    • Provide a solid ground reference with star-point strategy between power and signal grounds at the sense/ADC reference node per datasheet guidance.
    • Plan for common-mode filtering at the DC input and shielding/grounding strategy for encoder/sensor I/O.
  • Thermal performance
    • Even at 4 A, continuous conduction plus switching losses and diode conduction during dead time can heat devices, especially in small PCBs. Validate thermal via arrays under FET pads and the TMC9660 exposed pad, and consider copper pours/planes as heat spreaders.
  • Protection features
    • Ensure overcurrent thresholding, desaturation detection (if applicable), VDS monitoring, and fault handling in TMC9660 are configured. Add TVS on the 24 V bus and input reverse-polarity protection.
  • MOSFET selection/capability
    • IAUC45N04S6L063H is a 40–60 V class automotive device family variant. Check its exact VDS rating, Qg, Qgd, tr/tf, Rds(on) at operating temperature, and avalanche robustness vs your 24 V bus and expected transients. For a 24 V system that can see >35–45 V spikes, a solid 60 V margin is common.
Performance considerations
  • Efficiency
    • At 25 kHz and 4 A, conduction loss will be modest with low Rds(on); switching losses likely dominate. Gate drive tuning and dead-time optimization have outsized impact.
  • Control fidelity
    • 25 kHz is a reasonable PWM for acoustic/torque ripple vs switching loss. Verify the TMC9660 FOC timing, ADC sampling synchronization, and current loop bandwidth relative to your motor electrical time constants.
  • Acoustic/EMI
    • 25 kHz is above most audible ranges, but mechanical resonances can still excite noise. Consider experimenting with random PWM or slight frequency dithering if EMI/tonal noise becomes an issue.
  • Start-up and transients
    • Pre-charge or soft-start on DC link; inrush limiting; verified bootstrap pre-charge for high-side drivers before initial PWM.
Real-world applications
  • Compact robotics actuators, AGVs/AMRs, pumps, fans, gimbals, and light e-mobility subsystems requiring tight torque control and good efficiency on 24 V rails.
  • Any system seeking integrated FOC with reduced firmware burden and SPI configurability.
Areas for improvement
  • Documented sensing topology
    • Decide between low-side, phase, or inline shunt sensing, and match it to TMC9660’s recommended circuits. Inline sensing improves dynamic accuracy but raises common-mode demands; low-side is simpler but can reduce observability.
  • Gate network refinement
    • Provide pads for separate turn-on/turn-off resistors and optional series ferrite beads; footprint an R-C snubber per phase (unpopulated by default) to tune in validation.
  • Robust power input
    • Add transient suppression (SM8S or SMBJ 33–36 V TVS typical), reverse-polarity protection (ideal diode or FET-based), and input LC/π filtering to reduce conducted EMI.
  • Thermal headroom
    • Heatsinking strategy through copper planes and vias under FETs; consider thermistor near the power stage feeding TMC9660/host for derating.
  • Safety/protections
    • Add desat/VDS monitoring if supported; overcurrent fast-trip path, overtemperature monitoring, fault-latching behavior verified.
  • Connectors and serviceability
    • Clear phase outputs, hall/encoder input, and 24 V power connector choices with current ratings; include test points for phase currents, DC bus, 1V8/IO rails, and scope-friendly ground.
  • Documentation and bring-up
    • Include jumpers or zero-ohm links for measurement modes (e.g., isolate current sense, swap to external op-amp if needed), and SWD/UART access for diagnostics.
Scalability and future enhancements
  • Higher current variants
    • Parallel MOSFETs per switch with careful gate-drive layout and small series gate resistors; move to 2–3 oz copper; consider 4-layer with heavy copper on power planes.
  • Higher bus voltage
    • For 48 V systems, choose 80–100 V MOSFETs and re-validate gate charge/switching losses; strengthen input TVS and creepage/clearance.
  • Integrated sensing
    • Migrate to inline shunts with differential amplifiers for improved FOC at higher speeds; add sigma-delta isolated sensing if required in noisy environments.
  • Functional safety
    • Add redundant current sense or cross-check mechanisms, independent watchdog, and safe torque off (STO) design patterns depending on application.
  • Firmware/controls
    • Add field-weakening, sensorless startup, and advanced observers; log telemetry over UART/SPI; implement auto-tuning routines for new motors.
Practical next steps
  • Confirm the IAUC45N04S6L063H exact ratings (VDS, Qg, Rds(on) at temperature) versus the TMC9660 gate drive capability; choose initial gate resistor values and provision variants for tuning.
  • Define and freeze the current sense topology and shunt values for 4 A max with adequate headroom and ADC range; plan blanking timing.
  • Allocate PCB real estate: tight half-bridge loops, local ceramics at each half-bridge, star ground at sense reference, and short, symmetric sense routing.
  • Add input protections and measurement/test points to streamline bring-up and EMI debugging.
If you want, I can review or help draft the schematic power stage and sensing network around the TMC9660 and the IAUC45N04S6L063H, and propose concrete component values plus layout guidance.
Share design constraints
Pick sensing topology
Gate resistor values
Protection and input stage
Future 48V scalability
72 days

Ready.

Sign up to send
  • Ground
    Ground
    A common return path for electric current. Commonly known as ground.
    jharwinbarrozo
    20.5M
  • Net Portal
    Net Portal
    Wirelessly connects nets on schematic. Used to organize schematics and separate functional blocks. To wirelessly connect net portals, give them same designator. #portal
    jharwinbarrozo
    43.0M
  • Power Net Portal
    Power Net Portal
    Wirelessly connects power nets on schematic. Identical to the net portal, but with a power symbol. Used to organize schematics and separate functional blocks. To wirelessly connect power net portals, give them the same designator. #portal #power
    jharwinbarrozo
    11.4M
  • Generic Resistor
    Generic Resistor
    A generic fixed resistor for rapid developing circuit topology. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard resistor values: 1.0Ω 10Ω 100Ω 1.0kΩ 10kΩ 100kΩ 1.0MΩ 1.1Ω 11Ω 110Ω 1.1kΩ 11kΩ 110kΩ 1.1MΩ 1.2Ω 12Ω 120Ω 1.2kΩ 12kΩ 120kΩ 1.2MΩ 1.3Ω 13Ω 130Ω 1.3kΩ 13kΩ 130kΩ 1.3MΩ 1.5Ω 15Ω 150Ω 1.5kΩ 15kΩ 150kΩ 1.5MΩ 1.6Ω 16Ω 160Ω 1.6kΩ 16kΩ 160kΩ 1.6MΩ 1.8Ω 18Ω 180Ω 1.8KΩ 18kΩ 180kΩ 1.8MΩ 2.0Ω 20Ω 200Ω 2.0kΩ 20kΩ 200kΩ 2.0MΩ 2.2Ω 22Ω 220Ω 2.2kΩ 22kΩ 220kΩ 2.2MΩ 2.4Ω 24Ω 240Ω 2.4kΩ 24kΩ 240kΩ 2.4MΩ 2.7Ω 27Ω 270Ω 2.7kΩ 27kΩ 270kΩ 2.7MΩ 3.0Ω 30Ω 300Ω 3.0KΩ 30KΩ 300KΩ 3.0MΩ 3.3Ω 33Ω 330Ω 3.3kΩ 33kΩ 330kΩ 3.3MΩ 3.6Ω 36Ω 360Ω 3.6kΩ 36kΩ 360kΩ 3.6MΩ 3.9Ω 39Ω 390Ω 3.9kΩ 39kΩ 390kΩ 3.9MΩ 4.3Ω 43Ω 430Ω 4.3kΩ 43KΩ 430KΩ 4.3MΩ 4.7Ω 47Ω 470Ω 4.7kΩ 47kΩ 470kΩ 4.7MΩ 5.1Ω 51Ω 510Ω 5.1kΩ 51kΩ 510kΩ 5.1MΩ 5.6Ω 56Ω 560Ω 5.6kΩ 56kΩ 560kΩ 5.6MΩ 6.2Ω 62Ω 620Ω 6.2kΩ 62KΩ 620KΩ 6.2MΩ 6.8Ω 68Ω 680Ω 6.8kΩ 68kΩ 680kΩ 6.8MΩ 7.5Ω 75Ω 750Ω 7.5kΩ 75kΩ 750kΩ 7.5MΩ 8.2Ω 82Ω 820Ω 8.2kΩ 82kΩ 820kΩ 8.2MΩ 9.1Ω 91Ω 910Ω 9.1kΩ 91kΩ 910kΩ 9.1MΩ #generics #CommonPartsLibrary
    jharwinbarrozo
    1.5M
  • Generic Capacitor
    Generic Capacitor
    A generic fixed capacitor ideal for rapid circuit topology development. You can choose between polarized and non-polarized types, its symbol and the footprint will automatically adapt based on your selection. Supported options include standard SMD sizes for ceramic capacitors (e.g., 0402, 0603, 0805), SMD sizes for aluminum electrolytic capacitors, and through-hole footprints for polarized capacitors. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard capacitor values: 1.0pF 10pF 100pF 1000pF 0.01uF 0.1uF 1.0uF 10uF 100uF 1000uF 10,000uF 1.1pF 11pF 110pF 1100pF 1.2pF 12pF 120pF 1200pF 1.3pF 13pF 130pF 1300pF 1.5pF 15pF 150pF 1500pF 0.015uF 0.15uF 1.5uF 15uF 150uF 1500uF 1.6pF 16pF 160pF 1600pF 1.8pF 18pF 180pF 1800pF 2.0pF 20pF 200pF 2000pF 2.2pF 22pF 20pF 2200pF 0.022uF 0.22uF 2.2uF 22uF 220uF 2200uF 2.4pF 24pF 240pF 2400pF 2.7pF 27pF 270pF 2700pF 3.0pF 30pF 300pF 3000pF 3.3pF 33pF 330pF 3300pF 0.033uF 0.33uF 3.3uF 33uF 330uF 3300uF 3.6pF 36pF 360pF 3600pF 3.9pF 39pF 390pF 3900pF 4.3pF 43pF 430pF 4300pF 4.7pF 47pF 470pF 4700pF 0.047uF 0.47uF 4.7uF 47uF 470uF 4700uF 5.1pF 51pF 510pF 5100pF 5.6pF 56pF 560pF 5600pF 6.2pF 62pF 620pF 6200pF 6.8pF 68pF 680pF 6800pF 0.068uF 0.68uF 6.8uF 68uF 680uF 6800uF 7.5pF 75pF 750pF 7500pF 8.2pF 82pF 820pF 8200pF 9.1pF 91pF 910pF 9100pF #generics #CommonPartsLibrary
    jharwinbarrozo
    1.5M
  • Generic Inductor
    Generic Inductor
    A generic fixed inductor for rapid developing circuit topology. *You can now change the footprint and 3D model at the top level anytime you want. This is the power of #generics
    jharwinbarrozo
    15.1k
  • Terminal
    Terminal
    An electrical connector acting as reusable interface to a conductor and creating a point where external circuits can be connected.
    natarius
  • RMCF0805JT47K0
    RMCF0805JT47K0
    47 kOhms ±5% 0.125W, 1/8W Chip Resistor 0805 (2012 Metric) Automotive AEC-Q200 Thick Film #forLedBlink
    jharwinbarrozo
    1.2M
  • 875105359001
    875105359001
    10uF Capacitor Aluminum Polymer 20% 16V SMD 5x5.3mm #forLedBlink #commonpartslibrary #capacitor #aluminumpolymer #radialcan
    jharwinbarrozo
    1.2M
  • CTL1206FYW1T
    CTL1206FYW1T
    Yellow 595nm LED Indication - Discrete 1.7V 1206 (3216 Metric) #forLedBlink
    jharwinbarrozo
    1.1M

Inspect

TMC9660ATB+

TMC9660ATB+
Description

Created
Last updated by adrian95
1 Contributor(s)
adrian95

Controls

Properties

Manufacturer Name
https://www.analog.com/
Designator Prefix
IC
Manufacturer Part Number
TMC9660ATB+
Package or Case Code
QFN50P900X900X80-65N
Part Type
Integrated Circuit

Availability & Pricing

DPNStockQty 1
20–1$10.654–$12.373
10$27.3481
1525$19.10
21–229$9.8521–$12.373

Assets