# Smart fan sequencer ## Description Smart fan sequencer for PCs, servers, AV racks, and 3D printers: staggers 12V PWM fans with RPM feedback via I2C, reducing inrush and noise ## Project Details - **Owner:** vasy_skral - **Created:** 12/15/2025 - **Last Updated:** 12/26/2025 - **Visibility:** Public - **Copies:** 1 ## Key Components ### D1 — [SMF6.0CA](https://www.flux.ai/lcsc/smf6p0ca~a4a6.md) - Manufacturer Part Number: SMF6.0CA - Part Type: Diode - Package or Case Code: SOD-123FL_L2.8-W1.8-LS3.7-BI - Manufacturer Name: Liown(里阳半导体) - Forward Voltage: 1V - LCSC Part Number: C2990473 - Diode Type: TVS Diode - Reverse Voltage: 6V - JLCPCB Part Class: Extended Part **Pins:** - 1 [pin 1] - 2 [pin 2] ### D2 — [SMF6.0CA](https://www.flux.ai/lcsc/smf6p0ca~a4a6.md) - Part Type: Diode - Manufacturer Part Number: SMF6.0CA - Package or Case Code: SOD-123FL_L2.8-W1.8-LS3.7-BI - Manufacturer Name: Liown(里阳半导体) - LCSC Part Number: C2990473 - Forward Voltage: 1V - Diode Type: TVS Diode - JLCPCB Part Class: Extended Part - Reverse Voltage: 6V **Pins:** - 1 [pin 1] - 2 [pin 2] ### D3 — [SMF6.0CA](https://www.flux.ai/lcsc/smf6p0ca~a4a6.md) - Reverse Voltage: 6V - JLCPCB Part Class: Extended Part - Diode Type: TVS Diode - Forward Voltage: 1V - LCSC Part Number: C2990473 - Manufacturer Name: Liown(里阳半导体) - Package or Case Code: SOD-123FL_L2.8-W1.8-LS3.7-BI - Part Type: Diode - Manufacturer Part Number: SMF6.0CA **Pins:** - 1 [pin 1] - 2 [pin 2] ### D4 — [SMF6.0CA](https://www.flux.ai/lcsc/smf6p0ca~a4a6.md) - Manufacturer Part Number: SMF6.0CA - Part Type: Diode - Package or Case Code: SOD-123FL_L2.8-W1.8-LS3.7-BI - Forward Voltage: 1V - LCSC Part Number: C2990473 - Manufacturer Name: Liown(里阳半导体) - Reverse Voltage: 6V - JLCPCB Part Class: Extended Part - Diode Type: TVS Diode **Pins:** - 1 [pin 1] - 2 [pin 2] ### D5 — [SMBJ18CA-13-F](https://www.flux.ai/lcsc/smbj18ca-13-f~zots.md) - Manufacturer Part Number: SMBJ18CA-13-F - JLCPCB Part Class: Extended Part - Package or Case Code: SMB_L4.6-W3.6-LS5.3-BI - Product Info Url: https://lcsc.com/product-detail/TVS_DIODES_SMBJ18CA-13-F_SMBJ18CA-13-F_C129585.html - LCSC Part Number: C129585 - Part Type: TVS - Manufacturer Name: DIODES(美台) - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2304140030_Diodes-Incorporated-SMBJ18CA-13-F_C129585.pdf **Pins:** - 1 [pin 1] - 2 [pin 2] ### J1 — [0470531000](https://www.flux.ai/adrian95/0470531000~evc.md) - Part Type: Connector - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://tools.molex.com/pdm_docs/sd/470531000_sd.pdf - Manufacturer Part Number: 0470531000 - Manufacturer Name: Molex **Pins:** - Pin_1 [pin 1] - Pin_2 [pin 2] - Pin_3 [pin 3] - Pin_4 [pin 4] ### J2 — [0470531000](https://www.flux.ai/adrian95/0470531000~evc.md) - Manufacturer Part Number: 0470531000 - Datasheet URL: https://tools.molex.com/pdm_docs/sd/470531000_sd.pdf - Manufacturer Name: Molex - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Connector **Pins:** - Pin_1 [pin 1] - Pin_2 [pin 2] - Pin_3 [pin 3] - Pin_4 [pin 4] ### J3 — [0470531000](https://www.flux.ai/adrian95/0470531000~evc.md) - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: Molex - Manufacturer Part Number: 0470531000 - Datasheet URL: https://tools.molex.com/pdm_docs/sd/470531000_sd.pdf - Part Type: Connector **Pins:** - Pin_1 [pin 1] - Pin_2 [pin 2] - Pin_3 [pin 3] - Pin_4 [pin 4] ### Q1 — [AO3401A](https://www.flux.ai/lcsc/ao3401a~wvl4.md) - Package or Case Code: SOT-23_L2.9-W1.3-P1.90-LS2.4-BR - Continuous Drain Current: 5A at 25°C - Drain to Source Voltage: 30V - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2311091734_UMW-Youtai-Semiconductor-Co---Ltd--AO3401A_C347476.pdf - Manufacturer Name: UMW(友台半导体) - JLCPCB Part Class: Extended Part - Product Info Url: https://lcsc.com/product-detail/Others_Youtai-Semiconductor-Co-Ltd-AO3401A-4-1A_C347476.html - Manufacturer Part Number: AO3401A - Transistor Type: N-channel MOSFET - Part Type: MOSFETs - LCSC Part Number: C347476 **Pins:** - D [pin 3] - G [pin 1] - S [pin 2] ### Q2 — [MMBT3904LT1G](https://www.flux.ai/openpartlist/mmbt3904lt1g~s5.md) - Part Type: Transistor - Manufacturer Name: onsemi - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: MMBT3904LT1G - Datasheet URL: https://www.onsemi.com/pdf/datasheet/mmbt3904lt1-d.pdf **Pins:** - B [pin 1] - C [pin 3] - E [pin 2] ### Q3 — [AO3401A](https://www.flux.ai/lcsc/ao3401a~wvl4.md) - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2311091734_UMW-Youtai-Semiconductor-Co---Ltd--AO3401A_C347476.pdf - Package or Case Code: SOT-23_L2.9-W1.3-P1.90-LS2.4-BR - Continuous Drain Current: 5A at 25°C - Drain to Source Voltage: 30V - Transistor Type: N-channel MOSFET - Manufacturer Part Number: AO3401A - LCSC Part Number: C347476 - Part Type: MOSFETs - JLCPCB Part Class: Extended Part - Manufacturer Name: UMW(友台半导体) - Product Info Url: https://lcsc.com/product-detail/Others_Youtai-Semiconductor-Co-Ltd-AO3401A-4-1A_C347476.html **Pins:** - D [pin 3] - G [pin 1] - S [pin 2] ### Q4 — [MMBT3904LT1G](https://www.flux.ai/openpartlist/mmbt3904lt1g~s5.md) - Part Type: Transistor - Manufacturer Name: onsemi - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: MMBT3904LT1G - Datasheet URL: https://www.onsemi.com/pdf/datasheet/mmbt3904lt1-d.pdf **Pins:** - B [pin 1] - C [pin 3] - E [pin 2] ### Q5 — [AO3401A](https://www.flux.ai/lcsc/ao3401a~wvl4.md) - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2311091734_UMW-Youtai-Semiconductor-Co---Ltd--AO3401A_C347476.pdf - Drain to Source Voltage: 30V - Continuous Drain Current: 5A at 25°C - Package or Case Code: SOT-23_L2.9-W1.3-P1.90-LS2.4-BR - Part Type: MOSFETs - LCSC Part Number: C347476 - Manufacturer Part Number: AO3401A - Transistor Type: N-channel MOSFET - Product Info Url: https://lcsc.com/product-detail/Others_Youtai-Semiconductor-Co-Ltd-AO3401A-4-1A_C347476.html - JLCPCB Part Class: Extended Part - Manufacturer Name: UMW(友台半导体) **Pins:** - D [pin 3] - G [pin 1] - S [pin 2] ### Q6 — [MMBT3904LT1G](https://www.flux.ai/openpartlist/mmbt3904lt1g~s5.md) - Manufacturer Name: onsemi - Part Type: Transistor - Datasheet URL: https://www.onsemi.com/pdf/datasheet/mmbt3904lt1-d.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: MMBT3904LT1G **Pins:** - B [pin 1] - C [pin 3] - E [pin 2] ### Q7 — [AO4485&-20-VB](https://www.flux.ai/lcsc/ao4485and-20-vb~o8rk.md) - Manufacturer Name: VBsemi(微碧半导体) - JLCPCB Part Class: Extended Part - Part Type: MOSFETs - Manufacturer Part Number: AO4485&-20-VB - LCSC Part Number: C557954 - Package or Case Code: SOIC-8_L5.0-W4.0-P1.27-LS6.0-BL **Pins:** - D [pin 8] - D [pin 5] - D [pin 6] - D [pin 7] - G [pin 4] - S [pin 2] - S [pin 1] - S [pin 3] ### U1 — [LM75C](https://www.flux.ai/vasy_skral/lm75c~ovv.md) - Manufacturer Name: Texas Instruments - Manufacturer Part Number: LM75CIM-3/NOPB - Datasheet URL: https://media.digikey.com/pdf/Data%20Sheets/National%20Semiconductor%20PDFs/LM75.pdf - Part Type: Sensor **Pins:** - +Vs [pin 8] - A0 [pin 7] - A1 [pin 6] - A2 [pin 5] - GND [pin 4] - O.S. [pin 3] - SCL [pin 2] - SDA [pin 1] ### U3 — [EMC2303-1-KP-TR](https://www.flux.ai/lcsc/emc2303-1-kp-tr~e4gk.md) - Manufacturer Name: MICROCHIP(美国微芯) - Manufacturer Part Number: EMC2303-1-KP-TR - JLCPCB Part Class: Extended Part - LCSC Part Number: C621414 - Package or Case Code: TQFN-12_L4.0-W4.0-P0.80-BL-EP2.1 **Pins:** - ~{ALERT} [pin 10] - ADDR_SEL [pin 4] - CLK [pin 9] - EP [pin 13] - PWM1 [pin 5] - PWM2 [pin 7] - PWM3 [pin 11] - SMCLK [pin 2] - SMDATA [pin 1] - TACH1 [pin 6] - TACH2 [pin 8] - TACH3 [pin 12] - VDD [pin 3] ### U4 — [TLV76733DRVT](https://www.flux.ai/lcsc/tlv76733drvt~n82q.md) - Package or Case Code: WSON-6_L2.0-W2.0-P0.65-TL-EP - JLCPCB Part Class: Extended Part - Manufacturer Name: TI(德州仪器) - Part Type: Linear Voltage Regulators (LDO) - Manufacturer Part Number: TLV76733DRVT - LCSC Part Number: C2867572 **Pins:** - EN [pin 4] - EP [pin 7] - FB/SNS [pin 2] - GND [pin 3] - GND [pin 5] - IN [pin 6] - OUT [pin 1] ### U5 — [B6B-XH-A(LF)(SN)](https://www.flux.ai/lcsc/b6b-xh-alfsn~oamk.md) - Connector Gender: Male - Connector Positions: 6 - Manufacturer Name: JST - Connector Type: Wire To Board Connector - Manufacturer Part Number: B6B-XH-A(LF)(SN) - Connector Rows: 1 - LCSC Part Number: C144397 - Product Info Url: https://lcsc.com/product-detail/XH-Connectors_JST-Sales-America_B6B-XH-A-LF-SN_JST-Sales-America-B6B-XH-A-LF-SN_C144397.html - Connector Pitch: 2.5mm - Part Type: Wire To Board / Wire To Wire Connector - Package or Case Code: CONN-TH_6P-P2.50_B6B-XH-A-LF-SN - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2304140030_JST-B6B-XH-A-LF-SN_C144397.pdf - JLCPCB Part Class: Extended Part **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] - 5 [pin 5] - 6 [pin 6] ### VIN — [430450412](https://www.flux.ai/lcsc/430450412~z9nu.md) - JLCPCB Part Class: Extended Part - Product Info Url: https://lcsc.com/product-detail/Others_MOLEX_430450412_MOLEX-430450412_C277721.html - Package or Case Code: CONN-TH_4P-P3.00-S3.00_L7.4-W9.7-EH9.0 - Datasheet URL: https://assets.lcsc.com/datasheet/szlcsc/Download-ISO9001-Certification.pdf - Part Type: Wire To Board / Wire To Wire Connector - Manufacturer Part Number: 430450412 - Manufacturer Name: MOLEX - LCSC Part Number: C277721 **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 43] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/vasy_skral/smart-fan-sequencer~g1](https://www.flux.ai/vasy_skral/smart-fan-sequencer~g1).* --- *Generated from [https://www.flux.ai/vasy_skral/smart-fan-sequencer~g1](https://www.flux.ai/vasy_skral/smart-fan-sequencer~g1)*