# Mini UPS 42V to 12V ## Description Mini UPS PCB for a 42 V external adapter and external 10S lithium battery pack. Includes adapter-priority source selection with automatic switchover, input protection, ideal-diode OR-ing, a 30 V to 42 V HV bus, and a regulated 12 V output stage. Includes status LEDs and battery monitor pads. Excludes onboard charger circuitry and excludes adapter or battery source design. ## Project Details - **Owner:** enochaddodjangmah - **Created:** 4/15/2026 - **Last Updated:** 4/18/2026 - **Visibility:** Public - **Operating Voltage:** 30V-42V in, 12V out - **Implementation Details:** HV bus ideal-diode OR-ing with dual LM5050-2 controllers and external N-MOSFETs, followed by a BD9G341EFJ buck stage to 12V - **Power Requirements:** External 42V adapter or external 10S battery, adapter-priority switchover - **Stars:** 1 ## Key Components ### D1 — [SMDJ48CA-HR](https://www.flux.ai/lcsc/smdj48ca-hr~ypu9.md) - Role Details: Clamp input transients on each high-voltage input path - Manufacturer Part Number: SMDJ48CA-HR - Role: TVS Protection - Manufacturer Name: Littelfuse(美国力特) - Part Type: TVS - Package: SMC_L6.9-W5.9-LS7.9-BI - Package or Case Code: SMC_L6.9-W5.9-LS7.9-BI - LCSC Part Number: C1977164 - JLCPCB Part Class: Extended Part **Pins:** - A [pin 2] - K [pin 1] ### D2 — [SMDJ48CA-HR](https://www.flux.ai/lcsc/smdj48ca-hr~ypu9.md) - Manufacturer Part Number: SMDJ48CA-HR - LCSC Part Number: C1977164 - Package or Case Code: SMC_L6.9-W5.9-LS7.9-BI - Role Details: Clamp input transients on each high-voltage input path - Part Type: TVS - Manufacturer Name: Littelfuse(美国力特) - Package: SMC_L6.9-W5.9-LS7.9-BI - Role: TVS Protection - JLCPCB Part Class: Extended Part **Pins:** - A [pin 2] - K [pin 1] ### D3 — [Schottky Diode](https://www.flux.ai/corynrobinson/schottky-diode~hs.md) - Manufacturer Part Number: MBR0520LT1G - Breakdown Voltage: 60V - Manufacturer Name: onsemi - Current: 5A - Purchase Url: https://octopart.com/mbr0520lt1g-onsemi-2933?r=sp - Part Type: Diode - Datasheet URL: https://www.onsemi.com/pdf/datasheet/mbr0520lt1-d.pdf - Package or Case Code: D_SOD-123 **Pins:** - A - K ### F1 — [MF-R050-2](https://www.flux.ai/adrian95/mf-r050-2~y77.md) - Manufacturer Name: Bourns Inc. - License: https://creativecommons.org/licenses/by/4.0/ - Role: Input Fuse - Part Type: Fuse - Manufacturer Part Number: MF-R050-2 - Datasheet URL: https://www.bourns.com/docs/product-datasheets/mf-r.pdf - Role Details: Per-input resettable overcurrent protection - Package: Through Hole **Pins:** - 1 [pin 1] - 2 [pin 2] ### F2 — [MF-R050-2](https://www.flux.ai/adrian95/mf-r050-2~y77.md) - Role: Input Fuse - Part Type: Fuse - Manufacturer Part Number: MF-R050-2 - Datasheet URL: https://www.bourns.com/docs/product-datasheets/mf-r.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Package: Through Hole - Role Details: Per-input resettable overcurrent protection - Manufacturer Name: Bourns Inc. **Pins:** - 1 [pin 1] - 2 [pin 2] ### H1 — [MountingHole 7.4mm Pad 3.2mm drill](https://www.flux.ai/adrian95/mountinghole-74mm-pad-32mm-drill~7o1.md) - Manufacturer Part Number: MountingHole_Pad **Pins:** - 1 ### H2 — [MountingHole 7.4mm Pad 3.2mm drill](https://www.flux.ai/adrian95/mountinghole-74mm-pad-32mm-drill~7o1.md) - Manufacturer Part Number: MountingHole_Pad **Pins:** - 1 ### H3 — [MountingHole 7.4mm Pad 3.2mm drill](https://www.flux.ai/adrian95/mountinghole-74mm-pad-32mm-drill~7o1.md) - Manufacturer Part Number: MountingHole_Pad **Pins:** - 1 ### H4 — [MountingHole 7.4mm Pad 3.2mm drill](https://www.flux.ai/adrian95/mountinghole-74mm-pad-32mm-drill~7o1.md) - Manufacturer Part Number: MountingHole_Pad **Pins:** - 1 ### J1 — [PJ-037A](https://www.flux.ai/vasy_skral/pj-037a~6cq.md) - Manufacturer Part Number: PJ-037A - Datasheet URL: https://www.cuidevices.com/product/resource/pj-037a.pdf - Manufacturer Name: CUI Devices - Package: Through Hole - Part Type: Connector - Role Details: One jack for 42V adapter input and one jack for regulated 12V output - Role: Power Connector **Pins:** - Center pin [pin 1] - Terminal [pin 2] ### J2 — [PJ-037A](https://www.flux.ai/vasy_skral/pj-037a~6cq.md) - Manufacturer Part Number: PJ-037A - Datasheet URL: https://www.cuidevices.com/product/resource/pj-037a.pdf - Role Details: One jack for 42V adapter input and one jack for regulated 12V output - Role: Power Connector - Manufacturer Name: CUI Devices - Part Type: Connector - Package: Through Hole **Pins:** - Center pin [pin 1] - Terminal [pin 2] ### J3 — [XT60PW-M](https://www.flux.ai/chisf/xt60pw-m~tj.md) - Role: Battery Connector - Manufacturer Part Number: XT60PW-M - Manufacturer Name: AMASS - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.snapeda.com/parts/XT60PW-M/AMASS/datasheet/ - Package: Through Hole - Role Details: External 10S lithium battery pack input **Pins:** - Neg [pin 2] - Pos [pin 1] ### J4 — [XY301V-A-5.0-2P](https://www.flux.ai/jharwinbarrozo/xy301v-a-50-2p~u6.md) - Manufacturer Part Number: XY301V-A-5.0-2P - Manufacturer Name: Ningbo Xinlaiya Elec. **Pins:** - PIN1 [pin 1] - PIN2 [pin 2] ### LED1,RED — [LTST-C190KRKT](https://www.flux.ai/adrian95/ltst-c190krkt~3pw.md) - Manufacturer Part Number: LTST-C190KRKT - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: Lite-On Inc. - Role: Status LED - Part Type: LED - Datasheet URL: https://optoelectronics.liteon.com/upload/download/DS-22-99-0151/LTST-C190KRKT.pdf - Package: 0603 - Role Details: Red LED to indicate adapter path active **Pins:** - A [pin 2] - K [pin 1] ### LED2,GREEN — [LTST-C190GKT](https://www.flux.ai/adrian95/ltst-c190gkt~hjc.md) - Part Type: LED - Datasheet URL: https://media.digikey.com/pdf/Data%20Sheets/Lite-On%20PDFs/LTST-C190AKT.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: Green LED to indicate battery path active - Role: Status LED - Manufacturer Part Number: LTST-C190GKT - Manufacturer Name: Lite-On Inc. - Package: 0603 **Pins:** - A [pin 2] - K [pin 1] ### Q1 — [NCEP0178AK](https://www.flux.ai/lcsc/ncep0178ak~yy56.md) - Power: 125W - Package: TO-252-2_L6.5-W6.1-P4.58-LS10.0-TL - Operating Temperature: -55℃~+175℃ - Package or Case Code: TO-252-2_L6.5-W6.1-P4.58-LS10.0-TL - Transistor Type: 1 N-channel - Continuous Drain Current: 78A - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/1810010234_Wuxi-NCE-Power-Semiconductor-NCEP0178AK_C216784.pdf - Manufacturer Part Number: NCEP0178AK - JLCPCB Part Class: Extended Part - LCSC Part Number: C216784 - Drain to Source Voltage: 100V - Role Details: One MOSFET per source path, driven by LM5050-2 ideal diode controller - Role: OR-ing MOSFET - Part Type: MOSFETs - Manufacturer Name: NCE(无锡新洁能) - Product Info Url: https://lcsc.com/product-detail/MOSFET_Wuxi-NCE-Power-Semiconductor-NCEP0178AK_C216784.html **Pins:** - D [pin 4] - G [pin 1] - S [pin 3] ### Q2 — [NCEP0178AK](https://www.flux.ai/lcsc/ncep0178ak~yy56.md) - Operating Temperature: -55℃~+175℃ - Power: 125W - Package: TO-252-2_L6.5-W6.1-P4.58-LS10.0-TL - Role: OR-ing MOSFET - Manufacturer Part Number: NCEP0178AK - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/1810010234_Wuxi-NCE-Power-Semiconductor-NCEP0178AK_C216784.pdf - Transistor Type: 1 N-channel - Continuous Drain Current: 78A - Package or Case Code: TO-252-2_L6.5-W6.1-P4.58-LS10.0-TL - Role Details: One MOSFET per source path, driven by LM5050-2 ideal diode controller - Drain to Source Voltage: 100V - LCSC Part Number: C216784 - JLCPCB Part Class: Extended Part - Product Info Url: https://lcsc.com/product-detail/MOSFET_Wuxi-NCE-Power-Semiconductor-NCEP0178AK_C216784.html - Manufacturer Name: NCE(无锡新洁能) - Part Type: MOSFETs **Pins:** - D [pin 4] - G [pin 1] - S [pin 3] ### Q3 — [MMBT3904LT1G](https://www.flux.ai/openpartlist/mmbt3904lt1g~s5.md) - Manufacturer Part Number: MMBT3904LT1G - Part Type: Transistor - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.onsemi.com/pdf/datasheet/mmbt3904lt1-d.pdf - Manufacturer Name: onsemi **Pins:** - B [pin 1] - C [pin 3] - E [pin 2] ### Q4 — [MMBT3904LT1G](https://www.flux.ai/openpartlist/mmbt3904lt1g~s5.md) - Datasheet URL: https://www.onsemi.com/pdf/datasheet/mmbt3904lt1-d.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: onsemi - Manufacturer Part Number: MMBT3904LT1G - Part Type: Transistor **Pins:** - B [pin 1] - C [pin 3] - E [pin 2] ### U1 — [LM5050-2](https://www.flux.ai/kicad-part-library/lm5050-2~os.md) - Role Details: One controller per source path for automatic switchover into HV bus - Package: TSOT-23-6 - Manufacturer Part Number: LM5050-2 - Role: Ideal Diode Controller - Manufacturer Name: Texas Instruments Inc. - Datasheet URL: http://www.ti.com/lit/ds/symlink/lm5050-2.pdf - Package or Case Code: TSOT-23-6 **Pins:** - ~{FGD} [pin 1] - GATE [pin 5] - GND [pin 2] - IN [pin 4] - OFF [pin 3] - OUT [pin 6] ### U2 — [LM5050-2](https://www.flux.ai/kicad-part-library/lm5050-2~os.md) - Datasheet URL: http://www.ti.com/lit/ds/symlink/lm5050-2.pdf - Package or Case Code: TSOT-23-6 - Manufacturer Part Number: LM5050-2 - Role Details: One controller per source path for automatic switchover into HV bus - Manufacturer Name: Texas Instruments Inc. - Package: TSOT-23-6 - Role: Ideal Diode Controller **Pins:** - ~{FGD} [pin 1] - GATE [pin 5] - GND [pin 2] - IN [pin 4] - OFF [pin 3] - OUT [pin 6] ### U3 — [BD9G341EFJ](https://www.flux.ai/kicad-part-library/bd9g341efj~bm.md) - Manufacturer Part Number: BD9G341EFJ - Datasheet URL: https://media.digikey.com/pdf/Data%20Sheets/Rohm%20PDFs/BD9G341EFJ.pdf - Role: Buck Regulator - Role Details: Convert 30V-42V HV bus to regulated 12V output - Package or Case Code: HTSOP-8-1EP_3.9x4.9mm_P1.27mm_EP2.4x3.2mm_ThermalVias - Package: HTSOP-8 **Pins:** - BST [pin 7] - EN [pin 6] - FB [pin 4] - GND [pin 2] - LX [pin 1] - RT [pin 5] - VC [pin 3] - VCC [pin 8] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/enochaddodjangmah/mini-ups-42v-to-12v](https://www.flux.ai/enochaddodjangmah/mini-ups-42v-to-12v).* --- *Generated from [https://www.flux.ai/enochaddodjangmah/mini-ups-42v-to-12v](https://www.flux.ai/enochaddodjangmah/mini-ups-42v-to-12v)*