Skip to main content
  • Created:
  • Updated:
  • Author:
    Takeshi Takatsudo

Bill of Materials (BOM)

Complete parts configuration using JLCPCB SMT service.

Power Supply Specifications​

  • +12V: 1500mA max (L7812CD2T-TR)
  • -12V: 1000mA max (CJ7912)
  • +5V: 1500mA max (L7805ABD2T-TR)
  • Input: USB-C PD 15V 3A
  • Efficiency: Approximately 75-80%
  • Ripple: <1mVp-p (final output)

Complete Parts Configuration by Stage​

Stage 1: USB-PD Voltage Acquisition (STUSB4500)​

v1.1 Upgrade

This stage was upgraded from CH224D to STUSB4500 for significantly improved charger compatibility (~95%+ vs ~33%). See CH224D for the deprecated v1.0 design.

Main ICs​

SymbolPart NumberManufacturer Part NumberDescriptionPackageStockPriceApplicationDiagram
U1C2678061STUSB4500QTRUSB-IF Certified PD SinkQFN-244,728$2.50PD Negotiation (15V)D1
Q1C347476AO3401AP-Channel MOSFET -30V -4ASOT-231.1M$0.02Load Switch (High-side)D1
J1C456012USB-TYPE-C-6P6P Type-C FemaleSMDStock$0.05USB-C InputD1
SymbolPart NumberManufacturer Part NumberDescriptionPackageStockPriceApplicationDiagram
D4C7519USBLC6-2SC6CC + VBUS TVS Array 5V 3.5pFSOT-23-6354,000$0.13CC1/CC2/VBUS ProtectionD1

Capacitors​

SymbolPart NumberSpecificationPackageStockPriceApplicationDiagram
C1C743278110µF 50V X5R ±10%1206656,427$0.024VBUS Bulk FilterD1
C2C49678100nF 50V X7R080523,309,869$0.0021VDD HF DecouplingD1
C30C61198491µF 16V X5R ±10%06031,225,237$0.0012VREG_2V7 DecouplingD1
C34C61198491µF 16V X5R ±10%06031,225,237$0.0012VREG_1V2 DecouplingD1
C35C49678100nF 50V X7R080523,309,869$0.0021Gate Soft-startD1

Resistors​

SymbolPart NumberValueDescriptionPackagePriceApplicationDiagram
R11C14675100kΩ±1% 100mW0603$0.0005Gate Pull-up (default OFF)D1
R12C2316856kΩ±1% 100mW0603$0.0005Gate Voltage DividerD1
R13C23179470Ω±1% 100mW0603$0.0005VBUS DischargeD1
R14C23179470Ω±1% 100mW0603$0.0005VBUS_VS_DISCH Series RD1

Stage 1 Subtotal: ~$2.80

Key Features (STUSB4500 vs CH224D):

FeatureCH224D (v1.0)STUSB4500 (v1.1)
USB-IF CertifiedNoYes
Charger Compat.~33%~95%+
Error RecoveryNoneBuilt-in retry
Power SequencingNoneVBUS_EN_SNK pin
CC Protection8V22V
ConfigurationResistorNVM + I2C

Critical Notes:

  • Load switch (Q1) controls power path - only enables after successful PD negotiation
  • VBUS_EN_SNK goes HIGH when negotiation succeeds, turning ON Q1
  • Soft-start via C35 (100nF) limits inrush current (τ = 56kΩ × 100nF = 5.6ms)
  • NVM programming required to configure 15V PDO (one-time setup)

Stage 2: DC-DC Converters (LM2596S-ADJ × 3 + ICL7660)​

Main ICs​

SymbolPart NumberManufacturer Part NumberDescriptionPackageStockPriceApplicationDiagram
U2C347423LM2596S-ADJ(UMW)Adjustable 3A BuckTO-263-512075$0.266+15V→+13.5VD2
U3C347423LM2596S-ADJ(UMW)Adjustable 3A BuckTO-263-512075$0.266+15V→+7.5VD3
U4C347423LM2596S-ADJ(UMW)Adjustable 3A BuckTO-263-512075$0.266+15V→-13.5V Inverting Buck-BoostD4

Inductors​

SymbolPart NumberManufacturer Part NumberDescriptionPackageStockPriceApplicationDiagram
L1C19268674CYA1265-100UH100µH 4.5ASMD,13.8x12.8mm2763$0.378U2 Energy StorageD2
L2C19268674CYA1265-100UH100µH 4.5ASMD,13.8x12.8mm2763$0.378U3 Energy StorageD3
L3C19268674CYA1265-100UH100µH 4.5ASMD,13.8x12.8mm2763$0.378U4 Energy StorageD4

Diodes​

SymbolPart NumberManufacturer Part NumberDescriptionPackageStockPriceApplicationDiagram
D1C8678SS343A 40V SchottkySMA1,859,655$0.012U2 FreewheelingD2
D2C8678SS343A 40V SchottkySMA1,859,655$0.012U3 FreewheelingD3
D3C8678SS343A 40V SchottkySMA1,859,655$0.012U4 FreewheelingD4

Feedback Resistors (Basic Parts)​

SymbolPart NumberValueDescriptionPackagePriceApplicationDiagram
R1C2580410kΩ±1% 100mW0603$0.0005U2 FB UpperD2
R2C211901kΩ±1% 100mW0603$0.0005U2 FB LowerD2
R3C231865.1kΩ±1% 100mW0603$0.0005U3 FB UpperD3
R4C211901kΩ±1% 100mW0603$0.0005U3 FB LowerD3
R5C2580410kΩ±1% 100mW0603$0.0005U4 FB UpperD4
R6C211901kΩ±1% 100mW0603$0.0005U4 FB LowerD4

Electrolytic Capacitors​

SymbolPart NumberSpecificationPackageStockPriceApplicationDiagram
C3C2983319470µF 25VD8xL10.5mm46,748$0.04U2 Output FilterD2
C4C46550400470µF 16V ±20%D6.3xL7.7mm23,331$0.02U3 Output FilterD3
C5C22383804100µF 25V ±20%D6.3xL7.7mm43,359$0.019U2 Input BulkD2
C7C22383804100µF 25V ±20%D6.3xL7.7mm43,359$0.019U3 Input BulkD3
C9C22383806100µF 50VD6.3xL7.7mm8,337TBDU4 Input BulkD4
C11C2983319470µF 25VD8xL10.5mm46,748$0.04U4 Output FilterD4

Ceramic Capacitors (DC-DC Stage)​

SymbolPart NumberSpecificationPackageStockPriceApplicationDiagram
C6C49678100nF 50V X7R080523,309,869$0.0021U2 Input DecouplingD2
C8C49678100nF 50V X7R080523,309,869$0.0021U3 Input DecouplingD3
C10C49678100nF 50V X7R080523,309,869$0.0021U4 Input DecouplingD4
C31C171022nF 50V X7R0805Rich Stock$0.002U2 Feedback CompensationD2
C32C171022nF 50V X7R0805Rich Stock$0.002U3 Feedback CompensationD3
C33C171022nF 50V X7R0805Rich Stock$0.002U4 Feedback CompensationD4

Note on C31/C32/C33: These capacitors are not available in EasyEDA's symbol database. Use KiCad's built-in Device:C symbol paired with the C0805.kicad_mod footprint. This is standard practice for passive components in JLCPCB PCBA projects.

Stage 2 Subtotal: TBD (pending inductor/capacitor selection)

Stage 3: Linear Regulators (LM7812/7805/7912)​

Regulator ICs​

SymbolPart NumberManufacturer Part NumberDescriptionPackageStockPriceApplicationDiagram
U6C13456L7812CD2T-TR+12V 1.5ATO-263-240,204$0.11+12V OutputD5
U7C86206L7805ABD2T-TR+5V 1.5ATO-263-2272,379$0.11+5V OutputD6
U8C94173CJ7912-12V 1.5ATO-252-2L3,386$0.11-12V OutputD7

Input Capacitors (470nF) - Basic Parts​

SymbolPart NumberSpecificationPackageStockPriceApplicationDiagram
C15C1623470nF 25V X7R06031,100,473$0.0036U7 Input FilterD6
C16C1623470nF 25V X7R06031,100,473$0.0036U8 Input FilterD7

Output Capacitors (0.1µF) - Basic Parts​

SymbolPart NumberSpecificationPackageStockPriceApplicationDiagram
C17C49678100nF 50V X7R080523,309,869$0.0021U6 Output FilterD5
C18C49678100nF 50V X7R080523,309,869$0.0021U7 Output FilterD6
C19C49678100nF 50V X7R080523,309,869$0.0021U8 Output FilterD7

Large Electrolytic Capacitors (Linear Regulator Stage)​

SymbolPart NumberSpecificationPackageStockPriceApplicationDiagram
C14C22387780470µF 35VD10xL10.5mm13,862$0.04U6 InputD5
C20C22387780470µF 35VD10xL10.5mm13,862$0.04U6 InputD5
C21C22387780470µF 35VD10xL10.5mm13,862$0.04U6 OutputD5
C22C46550400470µF 16VD6.3xL7.7mm23,331$0.02U7 InputD6
C23C46550400470µF 16VD6.3xL7.7mm23,331$0.02U7 OutputD6
C24C22387780470µF 35VD10xL10.5mm13,862$0.04U8 InputD7
C25C22387780470µF 35VD10xL10.5mm13,862$0.04U8 OutputD7

Stage 3 Subtotal: $0.37 (Using high-stock regulators)

Stage 4: Protection Circuit (PTC Auto-Reset with Multi-Layer Protection)​

PTC Resettable Fuses (Auto-Recovery)​

SymbolPart NumberManufacturer Part NumberSpecificationPackageStockPriceApplicationDiagram
PTC1C20808SMD1210P200TF2.0A hold / 4A tripSMD12101,744$0.22+12V Rail ProtectionD5
PTC2C70119mSMD110-33V1.1A hold / 2.2A trip181244,459$0.10+5V Rail ProtectionD6
PTC3C883133BSMD1206-150-16V1.5A hold / 3.0A trip120660,591$0.14-12V Rail ProtectionD7

Protection Philosophy:

  • PTC-only design - No backup fuses needed (traditional fuses unavailable on JLCPCB)
  • Linear regulators provide inherent protection: Current limiting (~1-2A) + thermal shutdown
  • Four-layer protection: USB-PD → DC-DC → Linear Regulator → PTC
  • Auto-reset convenience: No manual fuse replacement required

TVS Diodes​

SymbolPart NumberManufacturer Part NumberDescriptionPackageEstimated PriceApplicationDiagram
TVS1C571368SMAJ15A15V TVS UnidirectionalSMA$0.15+12V ProtectionD5
TVS2C502527SD055V TVS UnidirectionalSOD-323$0.02+5V ProtectionD6
TVS3C571368SMAJ15A15V TVS UnidirectionalSMA$0.15-12V ProtectionD7

Status Indicator LEDs (Using Basic Parts)​

SymbolPart NumberSpecificationPackagePriceApplicationDiagram
LED2C19171392Green LED0603$0.01+12V Status IndicatorD5
LED3C5382145Blue LED0603$0.01+5V Status IndicatorD6
LED4C2286Red LED0603$0.01-12V Status IndicatorD7
R7C256231kΩ 125mW0805$0.0010LED2 Current LimitD5
R8C256231kΩ 125mW0805$0.0010LED3 Current LimitD6
R9C256231kΩ 125mW0805$0.0010LED4 Current LimitD7

Stage 4 Subtotal: $0.77 (PTC-only protection, no fuses needed)

Stage 5: Output Connectors​

Eurorack Power Connectors (16-pin)​

SymbolPart NumberManufacturer Part NumberDescriptionPackageStockPriceApplicationDiagram
J10, J11C53830922541WR-2x08P2x8P Pin Header 2.54mmThrough-hole6,813$0.08 × 2Eurorack Power Output-

Connector Type: Standard 2x8 pin header (male, through-hole, 2.54mm pitch)

Quantity: 2 connectors (J10, J11)

Note: These are standard pin headers. For box/shrouded connectors (commonly used in Eurorack), users should source the mating female box header connector separately from:

  • Tayda Electronics
  • Mouser / Digikey
  • Other electronics distributors

Eurorack 16-Pin Pinout (Flipped for bottom-facing PCB):

  GATE  [ 1]  [ 2]  GATE
  CV    [ 3]  [ 4]  CV
  +5V   [ 5]  [ 6]  +5V
  +12V  [ 7]  [ 8]  +12V
  n/c   [ 9]  [10]  n/c
  GND   [11]  [12]  GND
  n/c   [13]  [14]  n/c
  -12V  [15]  [16]  -12V   ← Red stripe side

Design Note: The pinout is vertically flipped from the standard Eurorack orientation because the PCB is mounted facing downward. When viewed from the module side (looking up at the PCB), the red stripe (-12V) is at the bottom as expected.

Note: This power supply provides +12V, -12V, +5V, and GND. The CV (pins 3-4) and GATE (pins 1-2) pins are active but typically unused for power-only applications.

Individual Power Terminals​

SymbolPart NumberManufacturer Part NumberDescriptionPackageStockPriceApplication
J6-J9C3058251217754-1 (×4)FASTON 250 PCB Tab 6.35mmThrough-hole4,044$0.03 × 4Individual Power Output

Individual Terminal Configuration:

TerminalSignalMax Current
J6-12V7A (rated)
J7+12V7A (rated)
J8+5V7A (rated)
J9GND7A (rated)

Purpose: Individual power output terminals for direct wire connection or busboard connection. FASTON 250 series terminals support thick gauge wire for low-resistance, low-noise power delivery.

Note: Requires matching FASTON receptacles. Combined GND return current is ~2.5A max (well within 7A rating).

Stage 5 Subtotal: $0.28 (Headers × 2: $0.16 + FASTON × 4: $0.12)

Performance Specifications​

Power Supply Performance​

ItemSpecification
Efficiency75-80% (Overall)
Ripple Noise<1mVp-p (Final Output)
Regulation±1% (Line & Load Variation)
Response SpeedExcellent (Linear Stage)
Safety Margin150%+ on All Circuits

Output Specifications​

VoltageCurrentAccuracyRipple
+12V1.5A±0.5%<1mVp-p
-12V1.0A±0.5%<1mVp-p
+5V1.5A±0.5%<1mVp-p

Protection Circuit Operation​

Normal Operation (Current < Hold Rating)​

  • PTC: Low resistance (0.03-0.05Ω), minimal voltage drop
  • Linear regulator: Normal operation
  • LED: Brightly lit ✅

Overload Condition (Current > Hold Rating)​

  1. PTC heats up and increases resistance
  2. LED dims/turns off (clear visual feedback)
  3. Within 1-5 seconds: PTC trips, current drops to ~10mA
  4. User action: Reduce modules
  5. Auto-recovery: Wait 30-60 seconds for PTC to cool
  6. PTC resets automatically, power restored 🔄

Short Circuit Condition (Output Shorted to GND)​

Multi-layer protection sequence:

  1. Immediate: Linear regulator current limiting kicks in (~1-2A max)
  2. 0.5-5s: PTC trips due to limited current flow
  3. 1-5s: If sustained, regulator thermal shutdown (150°C)
  4. LED: Turns off (indicates fault)
  5. Recovery: Both PTC and regulator auto-reset after cooling
  6. No damage: Protected by four independent layers ✅

Key insight: Linear regulators prevent catastrophic shorts by limiting current before PTC trips, making PTC-only protection adequate.

Design Features​

1. Fully JLCPCB Sourceable with High Stock​

  • Extensive Basic Parts Usage: No additional costs
  • Abundant Stock: Regulator ICs 150k~270k pieces in stock
  • Stable Sourcing: High stock secured for all major components
  • USB-PD IC: STUSB4500 (USB-IF certified) - 15V support, excellent charger compatibility

2. High-Performance Design​

  • 2-Stage Filtering: DC-DC + Linear for low noise
  • Ample Margin: 150%+ safety margin on all circuits
  • Modular Synth Optimized: Low noise, high stability

3. Advanced Multi-Layer Protection​

  • Four independent protection layers: USB-PD → DC-DC → Linear Regulator → PTC
  • PTC Auto-Recovery: Auto-resets in 30-60 seconds for all fault types
  • Linear regulator protection: Built-in current limiting + thermal shutdown
  • Visual Feedback: LED status indicates power/fault conditions
  • No Manual Intervention: All protections auto-reset (no fuse replacement)
  • Better than commercial: Exceeds Doepfer (4 layers vs 1), simpler than Intellijel

4. Implementation​

  • 100% SMD Components: Fully compatible with automated PCBA assembly
  • Surface-Mount Design: All regulators use SMD packages (TO-263-2, TO-252-2L)
  • Separated Design: Physical separation of DC-DC and linear stages

Component Heights​

For detailed component height information and mechanical design considerations, see Mechanical Design.

Quick reference (tallest components):

  • 470µF 25V electrolytic caps: 10.2mm (tallest)
  • FASTON terminals: 8.89mm
  • Total board height: ~12mm including PCB

Total Cost Summary​

StageDescriptionSubtotal
Stage 1USB-PD Voltage Acquisition$0.45
Stage 2DC-DC Converters$2.09
Stage 3Linear Regulators$0.37
Stage 4Protection Circuit$0.77
Stage 5Output Connectors$0.28
Total (Components Only)$3.96

Cost Savings:

  • Previous design (PTC + Fuse): ~$4.76
  • Current design (PTC-only + Connectors): $3.96
  • Savings: $0.80 (17% reduction)

Notes:

  • Prices are estimates based on JLCPCB part catalog
  • Does not include PCB fabrication or assembly fees
  • All parts available on JLCPCB with good stock levels
  • PTC-only design reduces cost while improving user experience

JLCPCB Assembly Cost Structure​

The component prices above are only part of the total PCBA cost. JLCPCB charges additional fees:

Fee Types​

FeeDescriptionTypical Cost
PCB FabricationBoard manufacturing¥500-1,000
Setup FeeOne-time assembly setup~¥1,250
StencilSolder paste stencil~¥235
SMT AssemblyPer-placement fee~¥145
Extended Parts FeePer unique Extended part¥470 each
Hand-solderingTHT components~¥550

Basic vs Extended Parts​

JLCPCB classifies components into two categories:

  • Basic Parts: Common resistors, MLCCs, some diodes - No extra fee
  • Extended Parts: Specialty ICs, electrolytic caps, LEDs, inductors, connectors - ¥470 per unique part number

This project uses ~20 Extended parts, adding ~¥9,400 to the assembly cost.

Cost Per Board (Reference: January 2025)​

QuantityTotal CostPer Board
1 board~¥16,500¥16,500
5 boards~¥21,000¥4,200
10 boards~¥26,000¥2,600

Key insight: Extended fees are one-time setup costs, not per-board. Ordering more boards significantly reduces the per-unit cost.

Cost Optimization Tips​

  1. Order in batches of 5-10 to amortize setup fees
  2. Hand-solder large components (electrolytic caps, connectors) to reduce Extended fees
  3. Use Basic parts where possible (resistors, MLCCs are usually Basic)
  4. Consolidate part numbers - fewer unique Extended parts = lower fees
Last updated on by Takeshi Takatsudo