# Swiftlane SRB Lite Relay Board ## Description Swiftlane SRB Lite relay controller layout under production cleanup. Updated board-level rules to conservative manufacturable defaults (0.15 mm min trace and keep out, 0.25 mm board inset, explicit preferred widths) and audited remaining PCB blockers. Current blockers remain concentrated in overlapping copper, floating copper, and unrouted priority nets pending further interactive layout cleanup and re-route passes. ## Project Details - **Owner:** saurabhswiftlane - **Created:** 3/30/2026 - **Last Updated:** 4/8/2026 - **Visibility:** Public - **Manufacturer Part Number:** SRB-Lite-Concept-01 - **Manufacturer Name:** Swiftlane - **Connectivity:** RS-485 half-duplex with firmware update support - **Implementation Details:** 12V_AUX generated by LM5006 buck from RECTIFIED_DC. LM5006 FB reference is 2.5V, so R5=90.9k and R6=10k set VOUT to about 25.2V; current divider must be revised for a true 12V_AUX rail before production release. LD1117S33TR input should remain at or below 15V nominal. - **Operating Voltage:** 36V - **Max Current:** 0.5A - **Software:** Field firmware update uses STM32 system/bootloader-compatible RS-485 protocol via U2; factory programming and recovery use SWD on J4 - **Power Requirements:** 10-26VAC RMS or 10-36VDC input; 10VAC target minimum; 12VDC 500mA always-on output - **Part Type:** Relay Controller - **Stars:** 1 ## Key Components ### D1 — [CD-MMBL110S](https://www.flux.ai/jecstronic/cd-mmbl110s~4ej.md) - Part Type: Bridge Rectifiers - Manufacturer Name: Bourns - Manufacturer Part Number: CD-MMBL110S - Forward Voltage: 900mV - Role Details: Rectifies 12-26VAC or 12-36VDC for internal power while strike path remains pre-bridge - Package: SMD - Role: Input Bridge Rectifier - Datasheet URL: https://www.mouser.ca/datasheet/2/54/Bourns_CD_MMBL110S_datasheet-2586146.pdf **Pins:** - - - + - ~_1 - ~_2 ### D2 — [PMEG4010CEJ,115](https://www.flux.ai/jecstronic/pmeg4010cej115~dcj.md) - Package: SOD-323 - Part Type: Diode - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: Nexperia USA Inc. - Role Details: Used for relay coil flyback and LM5006 bootstrap support - Manufacturer Part Number: PMEG4010CEJ,115 - Role: Schottky Diode - Datasheet URL: https://www.mouser.com/datasheet/2/916/PMEG4010CEH_PMEG4010CEJ-2835951.pdf **Pins:** - A [pin 2] - K [pin 1] ### D3 — [PMEG4010CEJ,115](https://www.flux.ai/jecstronic/pmeg4010cej115~dcj.md) - Manufacturer Name: Nexperia USA Inc. - Part Type: Diode - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: Used for relay coil flyback and LM5006 bootstrap support - Package: SOD-323 - Role: Schottky Diode - Datasheet URL: https://www.mouser.com/datasheet/2/916/PMEG4010CEH_PMEG4010CEJ-2835951.pdf - Manufacturer Part Number: PMEG4010CEJ,115 **Pins:** - A [pin 2] - K [pin 1] ### D4 — [PMEG4010CEJ,115](https://www.flux.ai/jecstronic/pmeg4010cej115~dcj.md) - Datasheet URL: https://www.mouser.com/datasheet/2/916/PMEG4010CEH_PMEG4010CEJ-2835951.pdf - Manufacturer Part Number: PMEG4010CEJ,115 - Manufacturer Name: Nexperia USA Inc. - Part Type: Diode - License: https://creativecommons.org/licenses/by/4.0/ - Role: Schottky Diode - Package: SOD-323 - Role Details: Used for relay coil flyback and LM5006 bootstrap support **Pins:** - A [pin 2] - K [pin 1] ### D5 — [SM712-02HTG](https://www.flux.ai/adrian95/sm712-02htg~cby.md) - Mount: Surface Mount - License: https://creativecommons.org/licenses/by/4.0/ - Package or Case Code: SOT-23 - Datasheet URL: https://www.littelfuse.com/media?resourcetype=datasheets&itemid=a4019802-ff62-41ff-bf66-295f97422f81&filename=littelfuse-tvs-diode-array-sm712-datasheet - Manufacturer Name: Littelfuse - Role: RS485 TVS - Role Details: Protects external A/B lines against ESD and surge transients - Manufacturer Part Number: SM712-02HTG - Part Type: Diodes - Package: SOT-23 **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] ### D6 — [SMBJ36D-M3/H](https://www.flux.ai/adrian95/smbj36d-m3h~rds.md) - Package: DO-214AA - Datasheet URL: https://www.vishay.com/docs/87606/smbj5cdthrusmbj120cd.pdf - Part Type: Diode - License: https://creativecommons.org/licenses/by/4.0/ - Role: Input TVS - Role Details: Clamps industrial input surges across 12-26VAC or 12-36VDC input - Manufacturer Name: Vishay General Semiconductor - Diodes Division - Manufacturer Part Number: SMBJ36D-M3/H **Pins:** - A [pin 2] - K [pin 1] ### F1 — [0ZCF0200AF2C](https://www.flux.ai/adrian95/0zcf0200af2c~eal.md) - Manufacturer Part Number: 0ZCF0200AF2C - Manufacturer Name: BelFuse - Role: PTC Fuse - Role Details: Series input overcurrent protection for board power path - Package: 1812 - Datasheet URL: https://belfuse.com/resources/datasheets/circuitprotection/ds-cp-0zcf-series.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Package or Case Code: FUSC7451X80N - Part Type: Fuse **Pins:** - ~ [pin 2] - ~ [pin 1] ### J1 — [DG250-3.5-02P-11-00A(H)](https://www.flux.ai/adrian95/dg250-3p5-02p-11-00ah~77l.md) - Role: Input Power Terminal - License: https://creativecommons.org/licenses/by/4.0/ - Pin Description: Pin 1=FIELD_IN_1, Pin 2=FIELD_IN_2 - Connector Type: Terminal Block - Datasheet URL: https://www.tme.com/Document/74a50bb60bd70b3c953bc54e89073085/DG250-3.5.pdf - Package: THT - Manufacturer Name: Degson - Manufacturer Part Number: DG250-3.5-02P-11-00A(H) - Part Type: Connector - Connector Positions: 2 - Role Details: Installer-facing field input terminal for 12-26VAC or 12-36VDC board power **Pins:** - 1 [pin 1] - 2 [pin 2] ### J2 — [DG250-3.5-02P-11-00A(H)](https://www.flux.ai/adrian95/dg250-3p5-02p-11-00ah~77l.md) - License: https://creativecommons.org/licenses/by/4.0/ - Pin Description: Pin 1=RS485_A, Pin 2=RS485_B - Datasheet URL: https://www.tme.com/Document/74a50bb60bd70b3c953bc54e89073085/DG250-3.5.pdf - Role Details: Installer-facing RS-485 A/B communications terminal - Connector Positions: 2 - Role: RS-485 Terminal - Part Type: Connector - Manufacturer Name: Degson - Manufacturer Part Number: DG250-3.5-02P-11-00A(H) - Package: THT - Connector Type: Terminal Block **Pins:** - 1 [pin 1] - 2 [pin 2] ### J3 — [DG250-3.5-02P-11-00A(H)](https://www.flux.ai/adrian95/dg250-3p5-02p-11-00ah~77l.md) - Datasheet URL: https://www.tme.com/Document/74a50bb60bd70b3c953bc54e89073085/DG250-3.5.pdf - Connector Positions: 2 - Role: Aux Output Terminal - License: https://creativecommons.org/licenses/by/4.0/ - Pin Description: Pin 1=STRIKE_NO_OUT, Pin 2=AUX_SW_OUT - Package: THT - Manufacturer Part Number: DG250-3.5-02P-11-00A(H) - Part Type: Connector - Role Details: Installer-facing switched auxiliary/strike output terminal - Manufacturer Name: Degson - Connector Type: Terminal Block **Pins:** - 1 [pin 1] - 2 [pin 2] ### J4 — [ARM JTAG SWD 10Pin 0.1" Connector](https://www.flux.ai/vasy_skral/arm-jtag-swd-10pin-01-connector~wke.md) - Connector Positions: 10 - Connector Type: SWD Header - Manufacturer Part Number: 61201021621 - Part Type: Connector - Datasheet URL: https://www.we-online.com/components/products/datasheet/61201021621.pdf - Role: SWD Header - Pin Description: 1=VTref 3V3, 2=SWDIO, 3=GND, 4=SWCLK, 5=GND, 6=SWO, 10=NRST - Manufacturer Name: Wurth Elektronik - Package: THT - Role Details: Provides SWD debug and recovery access alongside RS-485 firmware update support **Pins:** - ~RESET~ [pin 10] - GND [pin 5] - GND [pin 3] - GNDDetect [pin 9] - NC [pin 7] - NC/TDI [pin 8] - SWDCLK/TCK [pin 4] - SWDIO/TMS [pin 2] - SWO/TDO [pin 6] - VTref [pin 1] ### J5 — [61300411121](https://www.flux.ai/adrian95/61300411121~pw9.md) - Package: THT - Role Details: 1x4 UART/service header carrying 3V3, GND, RS485_TX, RS485_RX for direct bring-up and recovery - Manufacturer Part Number: 61300411121 - Role: Service Header - Package or Case Code: HDRV4W95P0X254_1X4_1016X254X854P - Manufacturer Name: Wurth Elektronik - Datasheet URL: https://www.we-online.com/components/products/datasheet/61300411121.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Connector **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] ### K1 — [Relay-12VDC-SL-C](https://www.flux.ai/deadzerok/relay-12vdc-sl-c~zh.md) - Package: THT - Datasheet URL: https://datasheet.lcsc.com/lcsc/2304140030_Ningbo-Songle-Relay-SRD-12VDC-SL-C_C30431.pdf - Part Type: Relay - Implementation Details: NC contact is intentionally used as auxiliary switched output; relay symbol/library pin type should not be treated as no-connect for this design. - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: Ningbo Songle Relay - Manufacturer Part Number: SRD-12VDC-SL-C - Role Details: Form C relay for raw strike path switching ahead of the bridge rectifier; NC contact intentionally used for auxiliary switched output - Role: Power Relay **Pins:** - Coil-1 [pin COIL1] - Coil-2 [pin COIL2] - Com-3 [pin COM] - NC [pin NC] - NO [pin NO] ### K2 — [Relay-12VDC-SL-C](https://www.flux.ai/deadzerok/relay-12vdc-sl-c~zh.md) - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: Ningbo Songle Relay - Role: Power Relay - Manufacturer Part Number: SRD-12VDC-SL-C - Role Details: Form C relay for raw strike path switching ahead of the bridge rectifier; NC contact intentionally used for auxiliary switched output - Implementation Details: NC contact is intentionally used as auxiliary switched output; relay symbol/library pin type should not be treated as no-connect for this design. - Package: THT - Datasheet URL: https://datasheet.lcsc.com/lcsc/2304140030_Ningbo-Songle-Relay-SRD-12VDC-SL-C_C30431.pdf - Part Type: Relay **Pins:** - Coil-1 [pin COIL1] - Coil-2 [pin COIL2] - Com-3 [pin COM] - NC [pin NC] - NO [pin NO] ### LED1 — [HSMA-C190](https://www.flux.ai/adrian95/hsma-c190~1oy.md) - Part Type: LED - Role Details: Dedicated relay activity LED; lights when either relay drive gate is asserted to aid installer diagnostics - Role: Relay Active LED - Datasheet URL: https://docs.broadcom.com/docs/AV02-0112EN - License: https://creativecommons.org/licenses/by/4.0/ - Package: 0603 - Manufacturer Name: Broadcom Limited - Manufacturer Part Number: HSMA-C190 **Pins:** - A [pin 2] - K [pin 1] ### Q1 — [2N7002K](https://www.flux.ai/jecstronic/2n7002k~8y.md) - Role Details: 3.3V GPIO-controlled low-side switch for 12V relay coil - Manufacturer Part Number: 2N7002K - Role: Relay Driver MOSFET - Package: SOT-23 - Manufacturer Name: MDD - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Transistor - Datasheet URL: https://www.infineon.com/dgdl/Infineon-2N7002-DS-v02_04-en.pdf **Pins:** - D [pin 3] - G [pin 1] - S [pin 2] ### Q2 — [2N7002K](https://www.flux.ai/jecstronic/2n7002k~8y.md) - Role: Relay Driver MOSFET - Role Details: 3.3V GPIO-controlled low-side switch for 12V relay coil - Manufacturer Part Number: 2N7002K - Manufacturer Name: MDD - Package: SOT-23 - Datasheet URL: https://www.infineon.com/dgdl/Infineon-2N7002-DS-v02_04-en.pdf - Part Type: Transistor - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - D [pin 3] - G [pin 1] - S [pin 2] ### U1 — [STM32F205RBT6](https://www.flux.ai/vasy_skral/stm32f205rbt6~21g.md) - Implementation Details: Datasheet-audited bring-up: all VDD pins tied to 3V3 with local decoupling; VDDA/VSSA tied to 3V3/GND with local 1uF + 10nF support; VBAT tied to 3V3 and decoupled when no backup source is used; VCAP1/VCAP2 each use 2.2uF ceramic capacitors with ESR below 2 ohms; BOOT0 defaults low for boot from user flash; PB2/BOOT1 held in defined state; NRST uses external pull-up and capacitor; SWD pins retained; no external HSE/LSE fitted so PH0/PH1 and PC14/PC15 reserved unless firmware later enables crystals; unused GPIO shall be configured as analog/no-pull in firmware at startup. - Role Details: Manages RS-485 communications, firmware update path, relay timing, dry-contact monitoring, and supervisory logic - Part Type: Microcontroller - Manufacturer Part Number: STM32F205RBT6 - Manufacturer Name: STMicroelectronics - Datasheet URL: https://www.st.com/resource/en/datasheet/stm32f205vg.pdf - Role: Main MCU - Software: Primary field update via RS-485 bootloader protocol; factory programming and recovery via SWD header J4 - Package: LQFP-64 **Pins:** - BOOT0 [pin 60] - NRST [pin 7] - PA0 [pin 14] - PA1 [pin 15] - PA10 [pin 43] - PA11 [pin 44] - PA12 [pin 45] - PA13 [pin 46] - PA14 [pin 49] - PA15 [pin 50] - PA2 [pin 16] - PA3 [pin 17] - PA4 [pin 20] - PA5 [pin 21] - PA6 [pin 22] - PA7 [pin 23] - PA8 [pin 41] - PA9 [pin 42] - PB0 [pin 26] - PB1 [pin 27] - PB10 [pin 29] - PB11 [pin 30] - PB12 [pin 33] - PB13 [pin 34] - PB14 [pin 35] - PB15 [pin 36] - PB2 [pin 28] - PB3 [pin 55] - PB4 [pin 56] - PB5 [pin 57] - PB6 [pin 58] - PB7 [pin 59] - PB8 [pin 61] - PB9 [pin 62] - PC0 [pin 8] - PC1 [pin 9] - PC10 [pin 51] - PC11 [pin 52] - PC12 [pin 53] - PC13 [pin 2] - PC14 [pin 3] - PC15 [pin 4] - PC2 [pin 10] - PC3 [pin 11] - PC4 [pin 24] - PC5 [pin 25] - PC6 [pin 37] - PC7 [pin 38] - PC8 [pin 39] - PC9 [pin 40] - PD2 [pin 54] - PH0 [pin 5] - PH1 [pin 6] - VBAT [pin 1] - VCAP_1 [pin 31] - VCAP_2 [pin 47] - VDD [pin 64] - VDD [pin 48] - VDD [pin 19] - VDD [pin 32] - VDDA [pin 13] - VSS [pin 63] - VSS [pin 18] - VSSA [pin 12] ### U2 — [THVD1451D](https://www.flux.ai/kicad-part-library/thvd1451d~z1b.md) - Package or Case Code: SOIC-8_3.9x4.9mm_P1.27mm - Datasheet URL: http://www.ti.com/lit/ds/symlink/thvd1451.pdf - Role Details: UART-to-RS-485 physical layer for command/status traffic and bootloader firmware updates - Manufacturer Part Number: THVD1451D - Manufacturer Name: Texas Instruments Inc. - Allow Substitutes: Yes - Role: RS-485 Transceiver - Package: SOIC-8 **Pins:** - A [pin 8] - B [pin 7] - D [pin 3] - GND [pin 4] - R [pin 2] - VCC [pin 1] - Y [pin 5] - Z [pin 6] ### U3 — [LM5006MM](https://www.flux.ai/kicad-part-library/lm5006mm~q29.md) - Allow Substitutes: Yes - Package or Case Code: MSOP-10_3x3mm_P0.5mm - Role Details: Generates always-on 12V rail from rectified input with margin for 12VAC minimum operation - Manufacturer Name: Texas Instruments Inc. - Manufacturer Part Number: LM5006MM - Role: 12V Buck Regulator - Datasheet URL: http://www.ti.com/lit/ds/symlink/lm5006.pdf - Package: MSOP-10 **Pins:** - BST [pin 2] - FB [pin 7] - LG [pin 3] - RT/SD [pin 8] - RTN [pin 4] - SW [pin 1] - UV [pin 5] - UVO [pin 6] - VCC [pin 9] - VIN [pin 10] ### U4 — [LD1117S33TR](https://www.flux.ai/adrian95/ld1117s33tr~s0.md) - Manufacturer Part Number: LD1117S33TR - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Integrated Circuit - Manufacturer Name: STMicroelectronics - Role Details: Generates MCU and transceiver logic rail from the 12V intermediate rail - Package: SOT-223 - Role: 3.3V LDO - Datasheet URL: https://www.st.com/content/ccc/resource/technical/document/datasheet/99/3b/7d/91/91/51/4b/be/CD00000544.pdf/files/CD00000544.pdf/jcr:content/translations/en.CD00000544.pdf - Allow Substitutes: Yes **Pins:** - GND [pin 1] - IN [pin 3] - OUT [pin 2] - OUT [pin 4] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/saurabhswiftlane/swiftlane-srb-lite-relay-board~5w](https://www.flux.ai/saurabhswiftlane/swiftlane-srb-lite-relay-board~5w).* --- *Generated from [https://www.flux.ai/saurabhswiftlane/swiftlane-srb-lite-relay-board~5w](https://www.flux.ai/saurabhswiftlane/swiftlane-srb-lite-relay-board~5w)*