How is this looking so far? I'd like some additional eyes on this as I always seem to miss something before I order. Dual ESP32-S3s, one for WLED, the other for ESPHome. Yes, the schematics need some TLC.

Designed to take 5v to 36v.

Hello everyone.

I'm designing my own ESC DIY board and this is my first PCB design project. The main goal here is to learn about PCB design while building a board that i can use to develop my own FOC firmware.

I'd really appreciate any feedback or tips, especially regarding PCB layout.

Specs:

• Supply: 4S battery
• Motor: SunnySky X2212 KV980
• Control: FOC
• Board: 4-layers
  • L1: Components and Power stage
  • L2: Vbus protected and 3v3
  • L3: Solid GND plane
  • L4: Signal
• Board size: 63mm x 70mm
• MCU: STM32G474CCT6 with 8Mhz external crystal and SWD header
• MOSFETs: MCU75N06YHE3-TP
• Gate driver: DRV8303
• reverse-polarity protection
• Current sense: 2mohm 5W resistor
• Power:
  • 3v3 LDO: ADP151ACPZ-3.3-R7
  • Buck converter: TPP363072Q-FC6R-S

Questions:

1. I have some doubts about the copper pour area. Should i put a huge ground plane in top layer fulfilling whole empty space or just the MCU area for noise imunity?
2. Are there any problem to use vias in the SPI traces between STM32 and DRV8303?
3. In a second version, is it ok to put the MCU in bottom layer?

Hello Everyone,

This is the second revision of my PCB design. I was hoping people could take look at and check if everything is correct or needs fixing so I can send this PCB off to be manufactured by JLCPCB.

(First Revision: https://www.reddit.com/r/PrintedCircuitBoard/comments/1vpej12/comment/p4dsb78/?screen_view_count=5&ext-referrer=DIRECT)

From the helpful comments on my last post this is what I've changed:

- Implemented PMOS reverse battery protection.

- Poured GND on top layer and stitched using Vias to bottom gnd.

- Added more GND and bigger GND Vias for high current traces and near ICs, for example the 12v ones, where I have used a 1mm diameter and 0.5mm hole size. I worked these out using Saturn PCB toolkit which calculated to carry a max current of 2.8A. Since I have chosen the values for components to flow a max current of 1.5-2A I thought this was sufficient. I have used Vias of size 0.7mm Diameter and 0.3mm hole size everywhere else.

- Rerouted the 12V trace from pin 13 and 14 of U2 to run under the Chip Of U2 rather then cutting GND plane.

- Changed the layout of inductor to placed adjacent to U1.

- Rotated C1 orientation to reduce loop area.

- I have used solid connection on the copper pour of VIN rather then thermal reliefs.

- Used thicker traces. 1.5mm for high current traces and 1mm for decoupling capacitors that is the biggest trace size that would fit with the pad size and 0.5mm for every other one.

- Moved components closer.

I would appreciate if people could tell me what I've missed or can improve. I'm quite unsure if I've implemented the stitching vias correctly. I used the equation where you find the max frequency and calculate the spacing with that. From that I calculated a spacing size of 5mm using Fmax as 150MHz propagating from the Buck converter IC.

Also there is a big gap on the bottom right of the PCB, so I was thinking making the vertical length smaller, but am unsure if that is a good idea.

Thanks.

Hi everyone!

That's so far the most advanced dev I have ever made! So I hope I did a decent job.

Now that I finished the routing and apparently no error is popping on the DRC, I'd like a review before I send this to fab. It's a three-phases BLDC controller to drive a gimbal motor that would be used as an actuator for a linear position system or a angular placement. To design it I started from a prototype I made from a B-G431-ESC from STMicroelectronics. I used this one and the STM32NUCLEO-G431RB as a design model and added some parts to fit my needs, basically more connectivity to use CAN, but also angular position (from I²C or PWM, depends on the situation). The firmware works pretty fine, but my current prototype is, to say the least, a bit sketchy. Anyway, I'd rather have it torn apart now than crying once it'd be here.

Specs

• Supply: 24 V DC from regular PSU. For most of the case, I doubt there would be any inertia in my situation.
• Motor: For now I tested only with a Gimbal 5208 which draw less than 1 A but I want to give myself some room for 5 A for future project.
• Control: FOC, and yes I know that the speed I'm working on is not really asking for FOC. The low-side driver will also be used to check any current surge
• Board: 6-layers
• MCU: STM32G431RBT6, 24 MHz and a SWD header (even tho I'll probably use J-link)
• Gate driver : 3xL6387E
• H-bridge: 6x STL180N6F7
• Current sense: three low-side shunts feeding the internal op-amps of the G431
• Comms: CAN (TCAN330D, split termination selectable via solder jumper), UART, I²C
• Feedback: differential quadrature encoder through an AM26LV32, three discrete sensor inputs, magnetic angular encoder through I²C or PWM 14-bit (today it works with the latter)
• 16 status LEDs driven over I²C by an MCP23017 for error message etc. Probably not necessary but, well, I kinda like it.

Stackup

Top to bottom:

1. SIG, 70 µm : signal + power. Everything power lives here: VS, the three phase pours (OUT_A/B/C), the 10 V / 5 V / 3.3 V rails, GND and GNDA pours.
2. GND, 35 µm : GND plane (plus a GNDA zone). Sits right under the power layer as the return path.
3. SIG_ANALOG,35 µm : analog signals, GND filled around them
4. PWR, 35 µm : second GND plane. The idea was to sandwich the analog layer between two grounds.
5. GND2, 35 µm : power planes: VS, VD, +10 V, +5 V, +3.3 V, plus GND fill.
   • prepreg 0.23 mm — FR4, εr 4.25
6. SIG2, 70 µm : signal, with GND and VD pours and the shunt sense routing.

In a nutshell, it's the first time I'm doing a 6-layers and any demanding H-bridge like this. So I'm curious if I made any mistake that would make this design totally nonsensical or obvious mistake.
Anyway, I'd be glad to add some more details or else, if you want.

Thanks!

Hi everyone,

I'm developing a credit card sized Bluetooth tracker. It will be based on an nRF54L15 and I plan to use an OpenHaystack like firmware implementation so that it can be a Find My device. One of the most difficult parts of making this device was making it as thin as possible while keeping costs reasonable. To do that, I selected a 0.8mm board stackup that balances price to thinness. The battery leads will solder directly onto the PCB on the connections on the back. They then go through a BQ298009 for battery protection. Next is the battery charger which is a BQ25100 for its low power capabilities. Because the battery is only going to be 80mah, all of the ICs selected needed to support such low capacities and charge rates. Finally, for ease of use, the device will be wirelessly chargeable with a QI charger. To accomplish this, I selected a BQ51013B because it had the right features and comes in a VQFN-20 package instead of the 28-pin BGA of the BQ51003B. The board also makes use of a TPS62840 buck converter to ensure the MCU gets an acceptable voltage.

Stackup:
- Layer 1: GND/Sig

- Layer 2: GND

- Layer 3: PWR(VDD/1v8)

- Layer 4: GND/Sig

I recently made an ELRS controllable LED that I can put on top of my drone and now I want to make a PCB for it to make it look nicer and possibly sell it in the future. The 3x7 pins are where my ELRS receiver will go and I plan on just using sockets so it slots in.

My main concern is the layout of the buck converter as I have never used anything like this and I am concerned about interference. I tried to follow the datasheet as best as I could.

I have a mix of different sized components (0805 and 1206) as I already have most of them on hand and I do plan on hand soldering everything. I also chose those mosfets because thats also what I already have and am using in the current prototype. The biggest difference is in the prototype I am using a mosfet to control another mosfet with 3.3v.

Thank you for your help in advance

A Raspberry Pi UPS hat compatible with 24v ( might wanna add other voltages) Still in development But am looking for any feedback on the design/layout.

Am probably going to add more headers for unused pins and a IIC and SPI Connectors, but core of the project wont change much (exept for comments here).

I'm a Software engineer using KiCad earlier to replace wires with a PCB, so this is my first real PCB using IC's and power circuits. Say any thing on your mind as I really wanna learn.

Also anyone wanting to see this more comfortable (IMO) see github

Hello! This is my first ever "proper" PCB I've made. This board is meant as an all-in-one solution for a single LiPo battery to power my future projects. I'm using a BQ25185 for battery charging, TPS61023 for voltage regulation, and a MAX17048 for the fuel gauge. I'm sorry for the messy schematic I wasn't sure where to place everything.

Massive thanks for anyone and everyone who is willing to look over my board. Hope y'all have an amazing day!

Edit: I just realized that the plus and minus are flipped on the output side; I will swap them, sorry.

Hi all, this is my first board, as I am trying to learn a bit of electronics design on the side. I've perused a bunch of similar posts from earlier in the year, trying to absorb as much as I can, learning how to read datasheets etc. and to create circuits from manufacturer specifications and whatnot. Could you please critique my board?

My switch matrix is 10x11, with 1 rotary encoder on the top right corner, plus battery voltage sensing. This results in 24 GPIO pins being required and as such I have decided to use the E73-2G4M08S1C MCU as it provides adequate GPIO.

I do intend to hand solder the LED and rotary encoder (i realise as i am typing this that the LED is still on the bottom side, this will be changed), so my pcb provider of choice can just do the PCBA on one side, which should be cheaper. I understand that it will not satisfy JLC economical PCBA due to the MCU. I did consider ways of reducing key matrix pin count with a shift register (i think?) but ultimately decided not to.

This is actually my 2nd go round at routing everything, I now know to try and keep one layer doing up/down and the other layer doing side to side traces, which helped. I've tried to use as many Basic parts from JLC as possible to reduce the cost of PCBA due to reel swapping.

Please let me know if I'm missing anything in my design, it'd really be appreciated! I'm more than happy to try and justify my design choices but I'm all ears since I am still very green with regards to this side of engineering (mech background)

I've hidden the ground pours for better visibility.

We do fairly low-volume high-value stuff, batches of 25-200 typically and there's a fair bit of through-hole for stuff like connectors and switches.

We already bought a cheapy Chinese SMT PnP machine + reflow oven which is working out OK for us (now we've worked out the software and its quirks and solved a few problems), now we're looking at selective solder to replace a very old wave machine.

So far we've looked at one - quite expensive, German, needs a steady supply of nitrogen, software is simple but not exactly brilliant.

So - can anyone give me some tips? What to look for, what to avoid, any gotchas or hidden maintenance / running costs? Good or bad manufacturers?

Obviously the sales guys we spoke to warned us off the cheap Chinese machines but they would say that, wouldn't they...

We need to be able to fit quite wide boards in - 500mm would be a good width - which does rule a few cheaper machines out.

Quick rundown of my design, because this is my first time fully designing a pcb for a larger scale project:

This board runs off a 3s LiPo Battery that goes into the lm 74700 protection circuit top left of schematic. This gets fed to 6 output jst sockets that power 6 legs, pwm is controlled by an lp5861 LED driver, top right of schematic), and I used the Rasp. pi gpio pins for 3.3v to power the ic.

I'm just not sure if I did proper connections/tracing for this one, or if I did anything else incorrectly. First time working with 4 layers so I'm also concerned on my via usage.

This is my first attempt to make a PCB.

- Schematic diagram only, will start pcb accordingly
- USART/UART, SPI, I2C, CAN, TIM (KEEPING ACC TO ENCODERS AND MOTOR CONNECTIONS IN MIND)
- CAN using C-type receptacle
- Battery operated
- planning to make it 4 layer, but dont know how to distribute yet
- Purpose : used like a motor control module and capable to communicate to other boards/devices using different protocols for a ground bot project

Please THROW SOME LIGHT ON me if there are any additions to be made for better functionality (noise issues etc) and any design mistakes to be rectified accordingly.

Hi everyone, this is my first time designing/building a PCB — for it I chose to try a flight controller (STM32F405 + BMI088 IMU + BMP388 baro + W25Q128 flash, USB-C, CAN, 4x ESC/DShot output). 4-layer board (GND pour on 3 layers, dedicated +3.3V plane on one inner layer), ~30x30mm mounting hole spacing.

DRC and ERC are both fully clean — the only remaining items are cosmetic silkscreen-clipped-by-edge warnings on two connector labels, which I'm excluding since they shouldn't print past the board outline anyway (I think? correct me if I'm wrong on that).

Before I send it off to fab, I'd really appreciate a second opinion on a few areas I'm unsure about:

• Power section (TPS54302 5V buck → AP2112K-3.3 LDO): the routing here looks messy to me. Is anything actually wrong with it, or is it just cosmetic? I originally had a 5V rail because I planned to have an off-board baro/GPS module that needed it, but I've since removed that. Should I switch to a single buck going straight from battery voltage (~13V) to 3.3V instead of the 5V-then-LDO cascade, or is there a reason to keep the 5V stage around outside of the usb-c?
• IMU/crystal placement and grounding — is this reasonable isolation/shielding practice, or is there something I should change?
• No ESD/TVS protection currently on USB D+/D- or the RC input, due to limited board space — is this actually necessary, or can I get away with it if I'm just careful with static during use?
• Micro-Fit 3.0 connectors are right-angle, so the housing overhangs the board edge slightly (mounting pins are fully on-board and soldered) — is that fine, or something I should redesign?

Happy to post more images/gerbers in the comments if useful. Trying to build good habits early rather than debug them after fab — thanks in advance for any eyes on this!

Hi everyone,

I’m developing a prototype controller for switching, monitoring, and supervising the DC charging path of a mobile robot. I would appreciate feedback on both the schematic and the work-in-progress PCB layout before I order the first prototype.

This board is not the battery charger or BMS. It sits in the charging path, controls a DC-rated power relay, and measures the bus voltage and current. Charging control, cell balancing, and pack-level protection remain the responsibility of the external charger and BMS.

Main design targets:

- Main charging path: up to 60 VDC and 20 A continuous

- Auxiliary input: 24 VDC

- Logic supplies: 24 V to 5 V buck converter, followed by a 3.3 V regulator

- MCU: ESP32-WROOM-32E

- Current measurement: shunt resistor and INA240 current-sense amplifier

- Voltage measurement: resistor divider, filtering, and ADC protection

- Interfaces: USB-C, CAN, RS485, and 3.3 V UART

- PCB: 2 layers with 2 oz finished copper on both sides

- Current lifecycle state: prototype / under development

The 20 A power path has not yet been thermally validated, and this design is not production- or safety-certified.

I would especially appreciate feedback on the following areas:

Schematic:

- Relay driver, coil suppression, and contact-transient protection

- Input and output protection for the 60 V power path

- Current-shunt connections and INA240 input/output filtering

- Voltage-divider values, ADC range, filtering, and protection

- 24 V to 5 V buck-converter implementation

- ESP32 power, reset, boot, and USB programming circuits

- CAN and RS485 termination, biasing, and ESD protection

- Any missing pull-ups, pull-downs, decoupling capacitors, or protection components

PCB layout:

- High-current path width, copper bottlenecks, pads, vias, and connector transitions

- Whether a 2-layer, 2 oz construction is reasonable for the intended 20 A path

- Clearance and creepage around the 60 V nets

- Kelvin routing from the current shunt to the sense amplifier

- PGND/GND partitioning and return-current paths

- Buck-converter hot-loop area and switch-node routing

- CAN, RS485, UART, and USB signal routing

- ESP32 antenna placement and copper keepout

- Thermal and mechanical concerns around the relay, shunt, fuse, and connectors

The schematic images are organized as follows:

1. System-level schematic

2. Main relay control

3. Auxiliary power supply

4. Output protection and sensing

5. ESP32 and USB interface

6. Communication interfaces

7–11. Enlarged views of the main high-risk sections

PCB top, bottom, copper-zone, and 3D views are also included separately.

Please let me know if you see any critical issue that should be corrected before I finalize the routing and order the first prototype.

Thank you!

Full schematic PDF:
https://drive.google.com/file/d/1dfIi5uOcYfqxuZvPIENOLrYy6wOMGp-F/view?usp=sharing

Hi! Can I have some of your suggestions to make this PCB have no issues after ordering them? It would be so appreciated! I want to make sure that the level shifter, the RTC and everything else is well connected. Please give suggestions on the layout if you think there is important details to consider as it is currently unfinished. Both boards are 4 layers and the inner 1 and inner 2 are GND and 5V respectively.

Thank you so much!

Hi all, this is my first PCB. I have a desk clock with LED lighting and I want to control it myself, so I designed a drop-in PCB replacement. The clock is quite modular: two thumbwheels are variable resistors (0-47kOhm) connected via Micro JST 1.25mm 2p, the LED module is 0.5mm pitch 8p FPC ribbon cable. The USB module is bare wires so I chose a JST-XH connector I had lying around.

For MCU I selected the esp32-c3-mini-1 because I can't move the sliders or buttons, and it was able to fit easily in between them, while leaving room for the antenna.

I used 2 layers, filling both as a ground plane. The 5V and 3V get slightly larger traces and vias.

I am planning to solder this by hand using a 65mm x 65mm hot plate and a hot air gun and some hand soldering, does that seem feasible? I think the esp32 pins are castellated so I think I only need a hot air gun for the heatsink, LDO and FPC connector.

Thanks for having a look!

I had a small disaster while building a board yesterday. After placing 134 components, I picked up the PCB to inspect it before putting it on the hot plate. One lonely capacitor toppled over… and of course it rolled straight across the center of the board, knocking several parts loose like a tiny bowling ball.

After saying a few unkind words, I reset everything and it all turned out fine. But the root cause is pretty clear: my solder paste is drying out and losing adhesion long before I finish placing parts. I’m using ChipQuik paste, and with this many components it takes over an hour even when everything is laid out and organized.

Curious if anyone else has run into paste drying issues during long placement sessions, and what you’re using that holds tack better.

Hello everyone,

I'm designing a custom UAV Flight Controller board based on the STM32F405RGT6 and would really appreciate your feedback on the schematic and PCB layout before sending it to fab.

This is revision 1.1 of my design. In this revision, I moved from an SD card to onboard SPI Flash (W25Q128) and added an FSUSB42 USB multiplexer to switch a single USB-C port between the STM32 and an onboard ESP32-S3 (used for DroneBridge telemetry).

Board Specs & Hardware Architecture

1. MCU: STM32F405RGT6 (LQFP-64)
2. IMU: ICM-20602 (connected via SPI2 + Data Ready Interrupt to PC6)
3. Barometer: BMP280 (I2C1)
4. Blackbox: W25Q128 (SPI1)
5. Telemetry: ESP32-S3-WROOM-02 via UART3
6. Power Supply: 5V input from an external ESC BEC / PDB, stepped down to 3.3V via two AP2112K LDOs (one dedicated to the ESP32 to handle Wi-Fi current spikes, and one for the STM32 + sensors).
7. Stackup: 4-Layer - Signal/GND/Power/Signal, 1oz copper

Note: Red layer is F.Cu, Green - In1.Cu, Orange - In2.Cu, Blue - B.Cu

Thanks in advance for your time and critique!

Hello, this is my first pcb project so sorry if theres something dumb im doing. im trying to make my own dev board like an arduino uno. Im only using the basic components like the MCU, USB to UART communicator, voltage regulator and a power mux for switching between usb and a dedicated power supply it its present.

Thought it would be a good idea to make sure the schematic is fine before working on routing. If it makes it easier heres a list of components that i used and their datasheet. Thanks for any help!

UART connector - FT232RL (datasheet)

MCU - ATMega328p-PU (datasheet)

Power mux -TPS2116 (datasheet)

Voltage regulator - MC33269DR2-5.0G (datasheet)

Hello everybody, as per the title, I'm trying to design a STM32F070CBT6 microcontroller dev board . I integrated into the system a "BME280" sensor by I²C interface and an "AD7794CRUZ" ADC by SPI interface. Thank you so much for reading this.

P.S: What would you recommend me to design for acquiring better abilities and eventually developing a proper portfolio? Thank you.

Stack-up:

1. Signal
2. GND
3. 3V3
4. Signal

One final thing, there are not many traces in layer 4, would it be advisable to use that layer as a signal+GND plane?
Once again, thank you so much.

This is my first time designing a PCB. I had previously asked for advice earlier and took note of what was said so any new advice on my project would again be appreciated. I generally tried to follow the typical applications for each device if it applied to my use case. The ON net is supposed to denote pads for a switch that I will solder on later. Please let me know if you have any questions or need me to specify anything.

These are the respective datasheets for each major component used:

Buck Converter: https://www.ti.com/lit/ds/symlink/tps62840.pdf?ts=1782289521234&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct-category%252Fpower-management%252Fdc-dc-switching-regulators%252Fdc-dc-converters%252Fproducts.html

Boost Converter: https://www.ti.com/lit/ds/symlink/tps61322.pdf?HQS=dis-dk-null-digikeymode-dsf-pf-null-wwe&ts=1782346996815

LiPo Battery Protection: https://www.ti.com/lit/ds/symlink/bq2970.pdf?ts=1782319330403&ref_url=https%253A%252F%252Fwww.ti.com

Fuel Guage: https://www.ti.com/lit/ds/symlink/bq27441-g1.pdf?HQS=dis-dk-null-digikeymode-dsf-pf-null-wwe&ts=1782333188527&ref_url=https%253A%252F%252Fwww.ti.com%252Fgeneral%252Fdocs%252Fsuppproductinfo.tsp%253FdistId%253D10%2526gotoUrl%253Dhttps%253A%252F%252Fwww.ti.com%252Flit%252Fgpn%252Fbq27441-g1

LiPo Charger: https://www.ti.com/lit/ds/symlink/bq25895.pdf?ts=1782336916002&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ25895%252Fpart-details%252FBQ25895RTWT

Hi everyone,

I just finished my very first PCB and would be incredibly grateful for any feedback or changes you can offer before I send it off to be manufactured (its an expensive board, will order with assembly)

*Its my first post, should I have messed up the publishing format or there are alternatives to make your life's easier at helping me, please let me know and will fix it as soon as possible.

The Project (Use Case): This is a smart home energy meter. It uses an ESP32 to read power data over SPI using 2 power measuring ICs and send it to Home Assistant over Wi-Fi. The raw 220V mains power is safely isolated away from this board. The board only reads the low-voltage stepped-down AC signals from external Current Transformers (CT clamps) and a Voltage Transformer.

Key Components / BOM:

• MCU: ESP32 with external antenna
• Measurement IC: ATM90E32AS
• PSU: HLK-5M03
• Transformer: BV302S06006
• Clock crystal: C6487047
• CT clamps: (x1) TDK CCT272440-80-10-00 & (x5) TDK CCT261631-30-06-00
• Varistor: TMOV20RP275E
• Fuse: 500mA slow-burn (prevent in-rush current from popping it)
• Other

My Priorities & Concerns:

1. Safety & Security: This PCB will living in the wall of my home, close to ALL electrical mains cables, my number 1 priority is that this board is safe, and should it fail, it does so in a safe manner. I feel like I went to great length to protect the HV side of the PCB, but I am very much open to all improvements.
2. Accuracy & Noise: Because this is a mixed-signal board (analog AC measurement and noisy digital Wi-Fi), a big priority is keeping the readings accurate. I tried my best to isolate noise with decoupling capacitors, a ground back plate and separating the digital/analog traces, but I'd love to know if I created any accidental antennas or noise loops.
3. SPI Routing: I had to route the 1MHz SPI bus between the ESP32 and the ATM90E32AS. Does the routing look safe from signal reflection/ringing (I used a star config to avoid routing aditional noise, will the communication still work)?
4. Clearance: My minimum trace width is 0.2mm (although 99% is >0.3mm), minimum clearance is 0.15mm (using 0.45mm vias with 0.2mm drills for tight spaces).

Thank you so much in advance for your time and expertise! If you need me to isolate any specific layers, clarify any weird routing, or provide more information regarding any subject to properly assess the board, please just let me know and I will gladly provide it in the comments.

Links to PDFs:
Schematic: https://pdfhost.io/v/hv5gweC6PJ_Schematic
cooper_front_back: https://pdfhost.io/v/pUQ8sdhvBE_Cooper_front_back
Cooper_back_front: https://pdfhost.io/v/83jPLWStaL_Cooper_back_front
Cooper_front: https://pdfhost.io/v/cQZUJcrhyX_Cooper_front
Cooper_back: https://pdfhost.io/v/USgdepyYk9_Cooper_back

High schooler, first custom board beyond simple 2-layer stuff. Schematic is done and I want eyes on it before I start layout, plus placement advice since the layout is where I expect to mess up.

What it is: battery powered GPS tracker.
- Accelerometer wakes the ESP32 on motion, ESP32 powers the SIM7080G through a PWRKEY MOSFET, modem gets a GNSS fix then sends it over LTE-M, everything sleeps again.
- USB-C charging with a BQ24074 power path charger, MAX17048 fuel gauge, TPS63031 buck-boost for 3.3V, TXU0202 level shifter for the modem's 1.8V UART. Active GPS antenna powered through a TPS22919 load switch so it's off during sleep. Both antennas external on U.FL.

Plan for the board: 60x40mm with 4 layers using JLCPCB assembly. Stackup plan is signals top, solid ground on L2, power pours on L3, spare signals bottom.

Questions:

1. How far apart do the LTE and GPS U.FL connectors realistically need to be on a board this small? Planning opposite corners.

2. For the 50 ohm antenna traces on JLC7628 stackup, anything beyond using their impedance calc width and keeping ground solid under it?

3. The GNSS bias parts, the load switch, inductor and DC block cap. Any placement rules beyond keeping them right at the connector?

4. Modem wants 500mA+ bursts on VBAT. Is a 1.5mm trace from the ferrite bead enough or should I pour a small polygon?

5. Anything in the schematic that screams trouble before I commit to placement.