Board Redesign Specifications

devells

Focus only on the power-input and protection stage.
From a 12 V motorcycle battery, design:
  • automotive TVS diode,
  • reverse-polarity protection (P-MOS ideal diode preferred),
  • input LC or π filter,
  • wide-input buck converter that generates 3.3 V @ 100 mA, with properly sized capacitors and resistors.
Show this as a separate block that feeds a clean 3.3 V rail.
65 days

flux

1:29

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Planning response strategy.

Using Knowledge Base Tool.

Executing design queries.

I’ll add a standalone 12 V→3.3 V power-input block with TVS, P‑MOS reverse protection, LC/π filter, and a wide‑input buck, then feed a clean 3.3 V rail.
  • Add and wire: TVS Diode at VIN, P-Channel MOSFET ideal‑diode stage, Inductor + Capacitor LC/π filter, and a Buck Converter with inductor, Cin/Cout, and feedback resistors. Use AEC‑Q200 passives, size L for 20–40% ripple, select Cout by ΔV = ΔI·ESR + ΔI/(8·fSW·Cout), and pick TVS Vbr just above max battery while clamping spikes.
  • Create nets: VIN_BATT → VIN_PROT → VIN_FILT → 3V3_CLEAN; isolate as a module and connect 3V3_CLEAN to board 3V3 after review. Run ERC/DRC and availability checks.
Before I start, a couple quick choices:
  1. Automotive transients to design for (e.g., ISO 7637-2/16750 load‑dump level)?
  2. Prefer LC or full π filter? Any EMI target/class to hit?
  3. Buck preference: synchronous and/or spread‑spectrum switching?
65 days

Started implementing a plan

# Goal

- Create a standalone automotive 12 V input power block that delivers a clean 3.3 V @ 100 mA output. This block will incorporate automotive-grade protection and filtering including a TVS diode, reverse-polarity protection with a P‑channel MOSFET ideal-diode arrangement, an LC/π EMI filter, and a wide-input buck converter with properly sized support components. The output will feed the board's 3V3 rail.

# Implementation plan

1. **Input Protection Stage**

1. Add the automotive TVS diode after the 12 V motorcycle battery connection. Ensure the clamping voltage is selected appropriately for automotive transients.

2. Add the reverse-polarity protection stage using a P‑channel MOSFET in an ideal-diode configuration. Select a MOSFET with adequate V_DS and I_D ratings for automotive applications.

2. **EMI Filtering**

1. Design and add an LC or π filter stage after the protection circuitry to attenuate EMI. Choose automotive AEC‑Q200 rated passive components (inductor and capacitor) and calculate values based on the input frequency range and transient suppression requirements.

3. **Buck Converter Stage**

1. Add a wide‑input buck converter IC capable of handling the 12 V input and regulating down to 3.3 V @ 100 mA.

2. Add and size the buck converter’s inductor, input/output capacitors, and feedback resistor divider network appropriately per the datasheet guidelines. Include any necessary compensation components to ensure stable regulation.

3. Connect the output of the buck converter to the clean 3.3 V rail (3V3).

4. **Integration and Verification**

1. Wire the stages in sequence: 12 V Battery → TVS Diode → P‑MOS reverse-polarity protection → EMI filter → Buck Converter → 3V3 rail.

2. Verify component ratings and connections against automotive standards and datasheet recommendations.

3. Run ERC/DRC checks to ensure compliance with design rules and connectivity requirements.

# Success criteria

- The 12 V input is properly safeguarded against voltage transients and reverse polarity.

- EMI filtering effectively attenuates high-frequency noise.

- The buck converter properly regulates the input to provide a stable 3.3 V @ 100 mA output.

- The design meets automotive reliability requirements with AEC‑Q200 rated passives and is verified via ERC/DRC checks.

62 days

Stopping...

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what does this pin do?
mirceadaneliuc

mirceadaneliuc

@copilot what does this pin do?
11mo

copilot

Could you please specify which pin you're referring to? There are several pins listed in your project description, and I'll provide details on the functionality or common usage of the pin you mention.
11mo
mirceadaneliuc

mirceadaneliuc

D10_MOSI pin
11mo

copilot

The D10_MOSI_P1.15 pin serves as the Master Output Slave Input (MOSI) pin in the Serial Peripheral Interface (SPI) communication protocol. Here's a bit more detail:
  • MOSI (Master Output Slave Input): This line carries data sent from the master device to the slave device in an SPI setup. When the microcontroller is configured as an SPI master, MOSI is used to transmit data to peripherals, such as slaves. When the microcontroller acts as a slave, it receives data on this pin.
If you need more information on using this pin in your specific project, feel free to ask!
11mo
Someone is typing...
is the 5V an output pin?
mirceadaneliuc

mirceadaneliuc

@copilot is the 5V an output pin?
11mo

copilot

In the context of the Seeed Studio XIAO nRF52840, the 5V pin is typically used as a power input. It allows you to power the board using an external 5V power source. This pin is often used to supply power to the board from sources like USB power.
If you intended to use the 5V pin as an output, it's important to consult the specific documentation or datasheets for the Seeed Studio XIAO nRF52840 to confirm its capabilities. However, in typical scenarios for microcontroller boards, the 5V pin is primarily an input. If you have a specific use case in mind, feel free to share it!
11mo
Someone is typing...
4
is this an output pin?
mirceadaneliuc

mirceadaneliuc

@copilot is this an output pin?
11mo

copilot

You've shared a project with various pins, but without specifying which pin you're referring to, it's challenging to determine if a particular pin is an output. Output pins are typically labeled according to their function in the microcontroller's datasheet or pinout specification.
If you're asking about a specific pin from the Seeed Studio XIAO nRF52840, typically pins with designations like TX, MISO, or MOSI are output pins in specific modes (UART, SPI, etc.). For instance:
  • P1.11_TX_D6 could be configured as a transmitter (TX) in UART mode.
To provide a definitive answer, I would need to know the specific pin you are referring to and the intended configuration or mode of operation. Let me know which pin you're curious about!
11mo
Someone is typing...
3
U2 GND - GND GND
GND
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Inspect

Seeed Studio XIAO nRF52840

Seeed Studio XIAO nRF52840
Description

Created
Last updated by gokux
2 Contributor(s)
jharwinbarrozo
gokux

Controls

Properties

Outline Width
17.8 mm
Manufacturer Part Number
102010448
Part Type
Microcontroller
Designator Prefix
U
Board Center
[0 mm, 0 mm]
Outline Height
20.95 mm
System Architecture
```mermaid graph LR MCU[nRF52840 MCU] --> ACC[Accelerometer] MCU --> BATT[Battery Connector] MCU --> MOUNT[Mounting Holes] ```
Board Center
[-0.05 mm, -0.075 mm]

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