ESP32-S3 PLC Architecture Discussion

Worked for 15 mins 44 sec

Completed the final schematic-gate pass and updated Schematic Review Before Layout. D29 is verified, L2 is now a confirmed shielded Sumida inductor, and U8/U9 FAULT is routed to ESP32 GPIO15 with a 10kΩ pull-up; ERC remains clean.

Open items:

Layout is still not approved: HR911105A symbol-footprint mapping remains Must Fix because the Flux symbol/footprint readout is ambiguous versus the datasheet.

Suggested next steps:

Replace HR911105A with a clearly numbered MagJack part/footprint, or manually verify its symbol-footprint mapping.
After that, update the approval table to “Pass” and proceed to PCB placement.

nuvologic

HOW TO DOWNLOAD SCHEMATIC AS PDF OR AS A ALTIUM PROJECT?

Thought for 8 sec

flux

In Flux, use the Export options from the project UI:

Open your project.
Click Export / download from the top toolbar or project menu.
Choose:
- PDF for schematic/documentation output.
- Altium if available in your export list; otherwise export standard manufacturing/interchange formats such as Gerber, ODB++, IPC-2581, BOM, and Pick-and-Place.

If you don’t see an Altium export option, Flux may not support direct Altium project export for this project. For help from Flux support, use: https://docs.flux.ai/Introduction/getting-support.

Export and verify files

Export schematic PDF

Export BOM files

Generate manufacturing files

Create export checklist

Thought for 3 sec

Files

Schematic

Layout

Preview

ESP32-S3 Industrial PLC Controller — Final Power Budget Before Schematic Capture

Purpose

This file locks the pre-schematic power budget required before drawing the detailed schematic. It verifies whether the selected TI LMR51610XDBVR/XFDBVR 1 A buck regulator has at least 30% output-current margin for the +5V rail.

Locked architecture for this budget

+24V_PROT → buck regulator → +5V
+5V → +3V3 regulator → ESP32-S3, W5500, logic
+5V → Mornsun B0505S-1WR3 → ISO_5V / ISO_GND
ISO_5V powers the ISO1410 isolated RS485 field side.
ISO_GND remains isolated from normal GND.

Datasheet/current assumptions used

Table

Load / item	Source basis	Current used
ESP32-S3-WROOM-1 peak current	ESPressif datasheet search: Wi-Fi TX peak, 802.11b 1 Mbps @ 20.5 dBm	355 mA @ 3.3 V
W5500 current	WIZnet W5500 datasheet search: normal operation at 3.3 V	132 mA @ 3.3 V
ISO1410 isolated field side	TI ISO1410 datasheet search: 500 kbps, 54 Ω load, 50 pF, 5 V	160 mA @ ISO_5V
B0505S-1WR3 input current	Mornsun datasheet search: full-load input current max	257 mA @ +5V
TPS4H160 logic-side GPIO drive	TI datasheet search: no separate VDD logic rail; logic pins use pulldowns	~2 mA @ 3.3 V allowance
8 DI optocoupler logic outputs	Conservative pull-up/pull-down and GPIO leakage allowance	8 mA @ 3.3 V
LEDs and test circuits	Prototype indicator/test allowance	40 mA @ +5V / +3V3 combined allowance
Miscellaneous 3.3 V logic margin	Pullups, reset circuits, level/control signals	25 mA @ 3.3 V

Rail budget

+3V3 rail loads

Table

+3V3 load	Peak current
ESP32-S3-WROOM-1-N16R8	355 mA
W5500 Ethernet controller	132 mA
8 DI logic-side opto outputs	8 mA
TPS4H160 control/diagnostic GPIO allowance	2 mA
Miscellaneous pullups/control logic	25 mA
Status LEDs allocated to 3.3 V side	20 mA
Total +3V3 peak	542 mA

If +3V3 is generated by an LDO from +5V, input current is approximately equal to output current:

I_+5V_for_3V3 ≈ 542 mA

LDO thermal note:

P_LDO ≈ (5.0 V − 3.3 V) × 0.542 A = 0.92 W

That is too high for a small SOT-23/SOT-223 class regulator without substantial copper and thermal review. A 3.3 V buck or high-current thermal-capable regulator should be considered for production reliability.

Direct +5V loads

Table

+5V load	Peak current
Mornsun B0505S-1WR3 input at worst-case ISO1410 load/full load	257 mA
+5 V status/test allowance	20 mA
USB/power-path/control overhead allowance	10 mA
Direct +5V peak excluding +3V3 regulator	287 mA

Total +5V buck output current

Assuming a 5 V to 3.3 V LDO:

I_+5V_total_peak = 542 mA + 287 mA = 829 mA

LMR51610 margin check

LMR51610 rating: 1 A continuous output current.

Required 30% current margin means the design load must be no more than:

1.0 A / 1.30 = 0.769 A

Calculated peak load:

0.829 A

Actual margin:

(1.0 A − 0.829 A) / 0.829 A = 20.6%

Decision

LMR51610 does not meet the requested 30% current margin under this conservative budget.

Do not start schematic capture with LMR51610 as the locked buck unless one of these changes is made:

Replace the +5 V buck with a higher-current 60–65 V industrial buck, or
Reduce the +5 V load by using a more efficient rail plan and re-running the budget, or
Accept less than 30% margin, which is not recommended for this PLC prototype.

Recommended higher-current buck alternatives

Table

Candidate	Rating	Why it fits	Notes
TI LMR51625	4.3–60 V, 2.5 A synchronous buck	Same modern family direction; enough current margin for +5 V rail	Preferred next candidate if library/sourcing available.
TI LMR51635	4.3–60 V, 3.5 A synchronous buck	Large margin; closer replacement for TPS54360 current capability but newer/synchronous	Use if added loads or high thermal margin desired.
TI LMR16020 / LMR16030 class	60 V, 2–3 A class	Older but suitable 24 V industrial buck family	Backup if LMR51625/635 unavailable.
Original TPS54360DDA	60 V, 3.5 A	Electrically safe current margin	Cost/size overkill, but acceptable fallback.

Preferred pre-schematic decision

Use TI LMR51625 as the new preferred 24 V-to-5 V buck candidate, pending datasheet/library confirmation. It gives:

2.5 A / 0.829 A = 3.0× load capacity

Equivalent current margin:

(2.5 A − 0.829 A) / 0.829 A ≈ 202%

This comfortably exceeds the required 30% margin while avoiding the original oversized/costly TPS54360DDA direction.

Schematic capture impact

Before drawing the power tree, update the locked component list:

Replace LMR51610XDBVR/XFDBVR with LMR51625 unless sourcing/library checks fail.
Keep Mornsun B0505S-1WR3, ISO1410, W5500, 8× PC817, and 2× TPS4H160BQPWPRQ1 unchanged.
Consider a 3.3 V buck or thermally robust 3.3 V regulator because the estimated 3.3 V load can make a 5 V-to-3.3 V LDO dissipate about 0.92 W at peak.

Purpose
Locked architecture for this budget
Datasheet/current assumptions used
Rail budget
+3V3 rail loads
Direct +5V loads
Total +5V buck output current
LMR51610 margin check
Decision
Recommended higher-current buck alternatives
Preferred pre-schematic decision
Schematic capture impact