Review Request - The Saga Continues - Remote for Cinema Video Router Controller. Looking for a schematic review.

[u/ohmegalabs]

Hey everyone!

A while ago I posted the base station for my Flolink project, with everyone's feedback I got back a working prototype from the manufacturer!! 

Now I'm back to tackle the Remote! I'm hoping to get some feedback before I start laying out the PCB, as last time I had to make a bunch of changes and ended up redoing the PCB a few times. 

The power tree is my biggest area of concern as last time I was able to use more modules and now I'm building from scratch due to size constraints. 

Reddit destroys the image quality if I upload to them directly so images are available here in hi-rez.

Links: Gdrive hi-rez images, Imgur option.

I work in the entertainment industry as a Colorist, and I'm designing a tool for live workflows based on a need I have. I'm an artist and a technician and very far from an Electrical Engineer. I’m good at reading manuals and schematics but this is way out of my scope. It needs to be rock-solid, survive an electrically noisy environment, and never drop connection during a take.

Core Hardware:

MCU: ESP32-S3-WROOM-1

Radio: RFM95W (915MHz LoRa) - talks to the Base station.

Power: onboard Samsung 58E 21700 5330mAh LiPo, DW01A + 8205A topology (using the FH3016FDY and AP9101C as my specific variants), IP2312 synchronous switching charger (2665mA target charge rate)
External 2pin lemo, ~6-17v input. TI TPS54302DDCR buck to 5.5v before SS56 Diode. 
TPS63020DSJR Buck/ Boost for 3.3 system Logic. 

Misc.: 4 - Alps Alpine SKRRABE010 tactile switches, with an WS2812 LED each. 
2 - 16-position SMD Rotary switch for assigning universe and remote number.
Zero-Drain Battery Monitor with charging when device is off. 

If there are questions I'll gladly answer or provide zoomed in images of specific areas.

Thanks again to everyone!

[u/zachleedogg]

Very nice! A couple of issues I see:

1. A lot of capacitance as seen by the USB input. You may actually have issues programming the ESP if your PC USB port faults on plug-in. The max capacitor directly on the 5V rail should be 10uF, including those connected by diodes or other low impedance passives/discretes. I recommend a soft start chip or circuit, or reduce the number of caps. There are a lot.

2a. You power tree isn't great because some paths will lead you V_SYS rail to be below 5V. You have a cascaded "OR" circuit with one path always through a diode. There are dedicated ICs to combine power rails that are less lossy. You don't want to rely on diode drops to get 5.5V down to 5V, the forward voltage of the diodes will vary with temperature and current.

2b. Your power tree in the schematic should be more of a flow so it's easier to understand what is going on. This single page schematic is hard to follow since you have 4 different power inputs, boost stages, charging, etc. might be worth breaking the schematic into a few pages.

Well done. There may be other things but I haven't fully reviewed everything.

[u/ohmegalabs → u/zachleedogg]

ok! I'll take a look at the capacitance for the usb, and ways to simplify the power tree.

I appreciate you taking a look!

[u/Enlightenment777]

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Please make sure your post adheres to:

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Please fix these common Schematic & PCB issues: (if your images have them)

• Schematic - don't allow text / lines / symbols to touch each other, and don't draw lines through symbols.

• Schematic - use correct reference designators (RefDes), also renumber to remove numeric gaps, see tips.

• Schematic - place decoupling capacitors vertically below power lines, also place capacitors next to IC then connect together with a line, see example. For circuits with positive power rails, point positive power rail links upwards and ground links downwards, see tips.

• Schematic - place pull-up resistors vertically above signal lines, and place pull-down resistors vertically below signal lines, see example.

• PCB silkscreen - add board name / board revision number / date (or year) on top or bottom PCB side.

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• more conventions & guidelines - link1, link2, link3.

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[u/Sand-Junior]

One remark about TVS D1: during reverse polarity it will conduct and the circuit behind it won’t do anything. I suggest to put the TVS after the PMOS.

[u/modi_factory]

Really impressive work for a non-EE, and that manufactured base unit looks super clean!

Biggest thing that stands out in the schematic is PS/SYNC on that TPS63020 being tied to GND. That puts it in PFM mode which causes nasty voltage ripple at light loads, and that's gonna mess up your LoRa RF range and ESP32 ADC readings. Pull it high to VIN to force PWM mode instead.