# Compressor PCB ## Description Compressor PCB - ESP32-S3 HVAC field sensing (24 VAC + CT + UART) ## Project Details - **Owner:** miquiis - **Created:** 3/15/2026 - **Last Updated:** 3/15/2026 - **Visibility:** Public - **CT Current Sensing:** J3 (blower CT) and J4 (compressor CT) feed U4 (OPA2377) burden/conditioning into ADC nets CT_BLOWER_ADC and CT_COMP_ADC. ADC_BIAS_1V65 mid-bias generated by R9/R10 divider. - **HVAC Field Interface:** J2 provides 24 VAC field inputs VAC_Y, VAC_OB, VAC_LP, VAC_HP with shared reference VAC_C. U5 (PC847) provides isolated detection; outputs are Y_DET, OB_DET, LP_DET, HP_DET to ESP32 GPIO with 4.7k pull-ups to 3V3. - **Power Requirements:** 5 VDC input on J1 -> D1 (PMEG2010AEH) -> V5_PROT; U2 (ME6211C33M5) generates 3V3 rail for U1 (ESP32-S3-WROOM-1U-N8). 3V3 also powers U4 (OPA2377) and opto pull-ups. - **Operating Voltage:** 5V in, 3.3V rail - **Domain:** HVAC compressor controller interface PCB - **Connectivity:** 3-wire UART fallback to air handler (TX, RX, GND) - **System Interfaces:** 24VAC field inputs: Y, O/B, LP, HP with shared 24VAC common; CT inputs: blower/fan CT and compressor CT - **System Architecture:** flowchart TD PWR_IN[5V DC Input] --> PWR_PROT[Input protection and filtering] PWR_PROT --> RAIL_5V[5V rail for relays and local loads] PWR_PROT --> REG_3V3[3.3V regulator] REG_3V3 --> RAIL_3V3[3.3V rail] RAIL_3V3 --> MCU[ESP32-S3-WROOM-1U-N8] VAC_TERM[24 VAC Terminals Y O/B LP HP C] --> VAC_SENSE[24 VAC detection x4] VAC_SENSE --> MCU CT_IN[CT Inputs Blower CT, Compressor CT] --> CT_SENSE[CT burden and conditioning x2] CT_SENSE --> MCU UART_HDR[UART to Air Handler TX RX GND] --> MCU - **Fallback Communication:** J5 3-pin header provides UART_TX_AH, UART_RX_AH, GND for fallback communication between compressor PCB and air handler PCB. - **Connector Type:** Field wiring via screw terminals or locking headers for 24 VAC inputs (Y, O/B, LP, HP, C) and CT inputs (2x channels). ## Key Components ### D1 — [PMEG2010AEH,115](https://www.flux.ai/jecstronic/pmeg2010aeh115.md) - Datasheet URL: https://www.mouser.com/datasheet/2/916/PMEG2010AEH_PMEG2010AET-2909960.pdf - Role Details: Series Schottky on 5V input - Role: Reverse Protection - Part Type: Diode - Package: SOD-123F - Manufacturer Name: Nexperia USA Inc. - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: PMEG2010AEH,115 **Pins:** - A [pin 2] - K [pin 1] ### J1 — [WJ500V-5.08-2P](https://www.flux.ai/adrian95/wj500v-5p08-2p.md) - Package: THT terminal block - Manufacturer Name: Ningbo Kangnex - Role: Power Input - Connector Type: Terminal Blocks - Part Type: Connector - Datasheet URL: https://datasheet.lcsc.com/szlcsc/1912251636_Ningbo-Kangnex-Elec-WJ500V-5-08-2P_C8465.pdf - Manufacturer Part Number: WJ500V-5.08-2P - Role Details: 5V DC input **Pins:** - 1 [pin 1] - 2 [pin 2] ### J2 — [282836-5](https://www.flux.ai/adrian95/282836-5.md) - Manufacturer Part Number: 282836-5 - Datasheet URL: https://www.verical.com/datasheet/te-connectivity-terminal-blocks-282836-5-47342.pdf - Package: THT terminal block - Role Details: 24VAC inputs Y, OB, LP, HP, C - Manufacturer Name: TE Connectivity AMP Connectors - License: https://creativecommons.org/licenses/by/4.0/ - Role: Field Input - Part Type: Connector **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] - 5 [pin 5] ### J3 — [282837-2](https://www.flux.ai/vasy_skral/282837-2.md) - Manufacturer Name: TE Connectivity AMP Connectors - Manufacturer Part Number: 282837-2 - Role Details: CT secondary input (2-wire) - Datasheet URL: https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=282837&DocType=Customer+Drawing&DocLang=English - Package: THT terminal block - Role: Sensor Input - Part Type: Connector **Pins:** - 1 [pin 1] - 2 [pin 2] ### J4 — [282837-2](https://www.flux.ai/vasy_skral/282837-2.md) - Role: Sensor Input - Manufacturer Name: TE Connectivity AMP Connectors - Manufacturer Part Number: 282837-2 - Package: THT terminal block - Datasheet URL: https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=282837&DocType=Customer+Drawing&DocLang=English - Role Details: CT secondary input (2-wire) - Part Type: Connector **Pins:** - 1 [pin 1] - 2 [pin 2] ### J5 — [Pin Header 01x03 2.54mm Vertical](https://www.flux.ai/adrian95/pin-header-01x03-254mm-vertical.md) - Part Type: Connector - Package: THT 2.54mm header - Role: Communication - Role Details: UART fallback header TX/RX/GND **Pins:** - Pin_1 [pin 1] - Pin_2 [pin 2] - Pin_3 [pin 3] ### U1 — [ESP32-S3-WROOM-1U-N8](https://www.flux.ai/lcsc/esp32-s3-wroom-1u-n8.md) - LCSC Part Number: C2980297 - Manufacturer Name: ESPRESSIF(乐鑫) - JLCPCB Part Class: Extended Part - Package or Case Code: WIRELM-SMD_ESP32-S3-WROOM-1U - Manufacturer Part Number: ESP32-S3-WROOM-1U-N8 - Package: Module - Role Details: Main controller ESP32-S3-WROOM-1U-N8 (3.3V) - Role: MCU **Pins:** - 3V3 [pin 11] - EN [pin 12] - GND [pin 2] - GND [pin 1] - GND [pin 12] - IO0 [pin 12] - IO1 [pin 2] - IO10 [pin 9] - IO11 [pin 8] - IO12 [pin 7] - IO13 [pin 6] - IO14 [pin 5] - IO15 [pin 7] - IO16 [pin 6] - IO17 [pin 5] - IO18 [pin 4] - IO19 [pin 2] - IO2 [pin 3] - IO20 [pin 1] - IO21 [pin 4] - IO3 [pin 12] - IO35 [pin 11] - IO36 [pin 12] - IO37 [pin 11] - IO38 [pin 10] - IO39 [pin 9] - IO4 [pin 11] - IO40 [pin 8] - IO41 [pin 7] - IO42 [pin 6] - IO45 [pin 1] - IO46 [pin 11] - IO47 [pin 3] - IO48 [pin 2] - IO5 [pin 10] - IO6 [pin 9] - IO7 [pin 8] - IO8 [pin 3] - IO9 [pin 10] - RXD0 [pin 5] - TXD0 [pin 4] ### U2 — [ME6211C33M5](https://www.flux.ai/kicad-part-library/me6211c33m5.md) - Datasheet URL: https://www.lcsc.com/datasheet/lcsc_datasheet_2304140030_MICRONE-Nanjing-Micro-One-Elec-ME6211C33R5G_C235316.pdf - Package or Case Code: SOT-23-5 - Role: Regulator - Manufacturer Part Number: ME6211C33M5 - Role Details: 5V to 3.3V LDO supply - Manufacturer Name: Micron Technology, Inc. - Package: SOT-23-5 **Pins:** - CE [pin 3] - NC [pin 4] - V_{IN} [pin 1] - V_{OUT} [pin 5] - V_{SS} [pin 2] ### U3 — [SMF5.0A](https://www.flux.ai/lcsc/smf5p0a.md) - LCSC Part Number: C2990427 - Role: ESD Protection - Diode Type: Schottky Diode - Package: SOD-123 - Package or Case Code: SOD-123FL_L2.8-W1.8-LS3.6-RD - Manufacturer Part Number: SMF5.0A - Max Reverse Voltage: 5V - Part Type: TVS - Role Details: TVS clamp on 5V input - Manufacturer Name: Liown(里阳半导体) - JLCPCB Part Class: Extended Part - Forward Voltage: 0.45V to 0.55V (at 1A)V **Pins:** - 1 [pin 1] - 2 [pin 2] ### U4 — [OPA2377AIDR](https://www.flux.ai/jecstronic/opa2377aidr.md) - Datasheet URL: https://www.ti.com/lit/ds/symlink/opa2377.pdf - Role: Analog Front End - Part Type: Operational Amplifier (OP-AMP) - Manufacturer Part Number: OPA2377AIDR - Manufacturer Name: Texas Instruments - License: https://creativecommons.org/licenses/by/4.0/ - Package: SOIC-8 - Role Details: CT burden conditioning amplifier, 2 channels **Pins:** - -IN A [pin 2] - -IN B [pin 6] - +IN A [pin 3] - +IN B [pin 5] - OUT A [pin 1] - OUT B [pin 7] - V- [pin 4] - V+ [pin 8] ### U5 — [PC847](https://www.flux.ai/kicad-part-library/pc847.md) - Manufacturer Part Number: PC847 - Role: Isolation - Role Details: 24VAC detection via optocoupler channels - Package: DIP-16 - Package or Case Code: DIP-16_W7.62mm - Datasheet URL: http://www.soselectronic.cz/a_info/resource/d/pc817.pdf **Pins:** - ~ [pin 1] - ~ [pin 12] - ~ [pin 14] - ~ [pin 13] - ~ [pin 10] - ~ [pin 3] - ~ [pin 4] - ~ [pin 11] - ~ [pin 9] - ~ [pin 2] - ~ [pin 15] - ~ [pin 6] - ~ [pin 16] - ~ [pin 5] - ~ [pin 8] - ~ [pin 7] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/miquiis/compressor-pcb](https://www.flux.ai/miquiis/compressor-pcb).* --- *Generated from [https://www.flux.ai/miquiis/compressor-pcb](https://www.flux.ai/miquiis/compressor-pcb)*