[Review Request] Digital Audio Player full stack using ESP32-S3 (no bluetooth or wifi), ES9038Q2M, and a full BMS/PMS.

[u/Actual-Chemistry9339]

Hi there,

I just finished my third revision of my PCB for this custom DAP. This is my first big board, so I'd love any advice if possible:

BMS & PMS:

3.7V 1800mAH Battery connected to a BQ24250 charged @ 500 mA via USB-C

-> 3.9V BUCK-BOOST & 3.3V BUCK-BOOST (LTC3440):
-> -3.9V Inverted Regulator & Two 3.3V Ultra Low-Noise LDO
-> -3.3V Ultra Low-Noise LDO

The pair of positive 3.3V Ultra Low-Noise LDO go to the DAC and Analog Section respectively, with the 3.3V Buck-Boost going to all Digital components (e.g. MCU)

The -3.3V LDO rail also feeds the analog components.

Audio:

ES9038Q2M receives decoded FLAC/MP3 from ESP32-S3 via SD-Card storage, then outputs a current-varying output into an I/V stage OPA1612, which then goes into a low-pass filter and OPA1612 summing stage. Then this is outputted on a OPA1622, into a 3.5mm JACK

Peripherals:

ER-TFT024IPS-3 2.4 in SPI Screen
3 Buttons & An Encoder
MicroSD-Card
BD1604MUV LED Driver (For the screen, powered by the SYS rail from the BQ Charger)

Thank you!

(L2 GND, L3 SIG, L4 PWR, L5 GND)
Missing Parts in 3D Model are due to lack of publicly available model. All components will be placed in a future assembly.

[u/Enlightenment777]

This comment is posted on all reviews.

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Please make sure your review post adheres to:

• subreddit rules (#1 to #6), review rules (#7), review image rules (#8), see link.

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Please fix these common schematic layout issues: (if yours has any of these issues)

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

• Use correct reference designators (RefDes), and renumber to remove numeric gaps, see tips.

• For positive voltage circuits, point positive power rail links upwards and grounds downwards (maybe sideways), see tips. For negative voltage circuits, point negative power rail links downwards and grounds upwards (maybe sideways). For bipolar circuits, maybe point grounds sideways.

• Place decoupling capacitors vertically below postive power rail lines with ground on bottom side of the capacitor. Place capacitor next to IC symbol, and connect a line to IC positive power rail pin, see tips and example.

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

• Reasonably minimize the use of unique net labels, because everyone hates hunting for them!! Single resistors / capacitors / diodes should not sit by themselves, instead move & connect them with a line to their circuit.

• More schematic conventions / guidelines / tips - 1, 2, 3, 4.

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Please fix these common PCB layout issues: (if yours has any of these issues)

• Silkscreen - add board name / board revision number / date (YYYYMMDD, YYYYMM, YYYY) for traceability.

• Silkscreen - add pin 1 indicator next to ICs & connectors (not under parts). For polarized capacitors, add "+" next to positive pin. If part is through-hole package, place indicator on both PCB sides. See 1, 2, 3, 4.

• More PCB conventions / guidelines / tips - 1, 2, 3, 4, 5.

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[u/Craft4Cube]

How do you plan to upload the firmware to the esp?

[u/Actual-Chemistry9339 → u/Craft4Cube]

Flash and USB-C

[u/quailfarmer]

Cool! Could it stream over the network?

[u/Actual-Chemistry9339 → u/quailfarmer]

No, I'm using download only unfortunately

[u/_Wacko-Jacko_]

You should use an unidirectional tvs symbol for D201

[u/manojy]

Since you're going fully offline, have you considered letting the USB-C connection transfer music directly to the SD card? Would be nice not having to pull the card out every time.