Power boards

Selectable USB-C PD trigger

Circuit review & bench-test guide →

Components#

Every placed component, with the reason it is on the board. Extracted directly from the schematic, so this cannot drift from the design.

Signals#

Net labels used in the schematic, which are also the names the HDL top level should use.

CC1 CC2 DEBUG_N EFUSE_DVDT EFUSE_FLT_N EFUSE_ILM EFUSE_ITIMER EFUSE_LED_A EFUSE_OVLO EN_HVDCP EN_UVLO GND HUSB_EN_N HUSB_GATE HUSB_VDD PD_FAULT PD_FAULT_LED_A PD_VBUS PMOS_GATE SNK_ISET SNK_VSET USB_DM USB_DP USB_SHIELD VBUS_RAW VOUT VOUT_LED_A VOUT_SENSE VSET_12 VSET_15 VSET_20 VSET_5 VSET_9

Production status#

Source: boards/usb-c-pd-trigger

Status#

Revision 0.1 is an actively generated KiCad design. It is a 60 W-class, power-only USB-C Power Delivery sink with a five-position voltage selector, contract-controlled disconnect, protected 3 A output, terminal output, and a light-load breadboard interface.

The design sources and generated artifacts all live in this folder. The routed usb-c-pd-trigger.kicad_pcb is the controlled production source. Run generate_design.py to rebuild the schematic and project libraries; generate_pcb.py creates an explicitly named unrouted placement/plane foundation for routing experiments and will not overwrite the reviewed board without --force. finalize_routing.py reapplies the reviewed footprints, qualified metadata, and plane transfers to the controlled routed PCB.

Run the complete release gate with:

python3 boards/usb-c-pd-trigger/qa/run_release_qa.py --refresh --strict
python3 boards/usb-c-pd-trigger/qa/validate_report.py

The generated HTML QA report is the release index for CAD, analysis, simulation, manufacturing, bench, and certification evidence.

Electrical architecture#

USB-C receptacle
  |-- CC1/CC2, D+/D- --> HUSB238A-BB001 autonomous PD sink
  |                         |-- SNK_VSET <- fail-safe 2-pole selector
  |                         |-- SNK_ISET = 21.0 kOhm (3 A request)
  |                         `-- GATE --> 40 V P-MOSFET contract switch
  |
  `-- VBUS_RAW --> TVS2200 --> contract PMOS --> TPS259470A eFuse --> VOUT
                                                         |        |-- terminal
                                                         |        `-- light-load header
                                                         `-- current limit, inrush,
                                                             UVLO/OVLO, reverse block

HUSB238A-BB001 is frozen because Hynetek identifies it as the no-SOP-prime orderable variant. The board only uses conventional SPR fixed PDOs up to 20 V. PPS, AVS, EPR, and 5 A operation are intentionally out of scope.

Fail-safe selector#

A simple one-pole rotary is not acceptable here: HUSB238A interprets an open SNK_VSET as its highest voltage code. Revision 0.1 therefore uses a break-before-make 2-pole, 5-position selector:

• pole A selects one of the five precision SNK_VSET resistors;
• pole B connects EN_N to ground at every valid detent;
• between detents, pole B opens, the controller's internal pull-up disables the controller, and GATE turns the external P-MOSFET off;
• after the switch reaches a detent, the controller reinitializes and samples the now-stable resistor before reconnecting the output.

SNK_ISET uses 21.0 kOhm, 1%, for a preferred 3 A request. The knob is a ceiling, not a voltmeter: HUSB238A searches downward for the highest source PDO that does not exceed the selected voltage and can supply the requested current. If no source PDO meets both requirements, it reports a capability mismatch. Always measure VOUT before connecting a voltage-sensitive load.

Selector interfaces#

• J2 is the production SMT harness connector (JST SM12B-SRSS-TB). The frozen panel switch is Grayhill 56A36-01-2-05N, whose manufacturer listing explicitly specifies two poles, five positions, and non-shorting contacts. Any alternate must have documented break-before-make contacts and must pass the harness continuity/interlock test in the QA report.
• J3 is an optional 2x6, 2.54 mm development header carrying the same nets. It is DNP in the core SMT build and is intended for a breadboard selector or continuity testing.

The panel switch/harness is a mechanical subassembly rather than a reflowed component. This keeps the core PCB compatible with automated SMT assembly and lets the rotary control mount to an enclosure without stressing the PCB.

Protection and operating limits#

• Input target: USB PD SPR, 5 V through 20 V, 3 A maximum.
• TVS2200DRVR: 22 V standoff flat-clamp protection at the USB-C input.
• DMP4015SSS-13: 40 V P-channel contract switch driven by HUSB238A GATE, with a 10 V gate clamp.
• TPS259470ARPWR: true reverse-current blocking eFuse with controlled output slew, active current limiting, short-circuit fast trip, thermal shutdown, UVLO, OVLO, and fault indication.
• The 976 Ohm ILM resistor is chosen so the low tolerance corner remains approximately 3 A; the nominal current limit is intentionally above 3 A to avoid nuisance limiting.
• A 470 kOhm pull-up enables the eFuse as documented by TI for input rails above 5 V; the lower divider leg is intentionally omitted, so the internal 2.44-2.64 V input UV protection is used without overdriving the 6.5 V-rated EN/UVLO pin. The OVLO divider is designed to pass a 20 V PDO at its allowed high corner while cutting off before prolonged operation above the eFuse's recommended 23 V input limit.
• The high-current path targets 3 A. The 2.54 mm breadboard output is explicitly limited to 0.5 A; use the Micro-Fit J4 harness for load and thermal testing. Do not route 3 A through a solderless breadboard.
• D2 is the exact SMA B340A-13-F 40 V / 3 A negative-input clamp. D5 is the exact SOD123F PMEG4010EH,115 40 V / 1 A negative-output clamp. These orderable/package pairs replace the mismatched provisional review values.
• The module is SELV-side only. It provides no mains isolation and is not a certified power supply.

Outputs and measurements#

• J4: tape-and-reel Molex 43650-0210 Micro-Fit 3.0 full-load output (VOUT, GND). Use mating housing 43645-0200, appropriate female crimp contacts, and 18-20 AWG wire for the 3 A test harness.
• J5: duplicated 2.54 mm light-load output (VOUT, VOUT, GND, GND).
• J6: status/measurement header (VOUT_SENSE, PD_FAULT, EFUSE_FLT_N, GND). EFUSE_FLT_N is an open-drain debug output: use an external pull-up to 5 V or less. R16, R21, and D7 are mandatory DNP because the eFuse FLT pin is only 5 V recommended / 6.5 V absolute maximum; the protected output can be 20 V.
• Test points: raw VBUS, contract-switched VBUS, protected output, divided output sense, CC1, CC2, ground, selector voltage, enable, and PMOS gate.
• The VOUT_SENSE divider is 187 kOhm / 33 kOhm. It produces 3.00 V at 20 V nominal and remains below 3.21 V at 21 V with 1% resistor tolerance. The receiving ADC must still be rated for at least 3.3 V and share board GND.
• The green LED means only that protected output voltage is present. It does not prove that the knob voltage or 3 A capability was obtained.

Assembly variants#

• CORE_SMT: populate all SMT electronics, selector connector J2, and the full-load Micro-Fit output J4; DNP the breadboard/debug headers and test points. R16, R21, and D7 are also mandatory DNP to keep high voltage away from EFUSE_FLT_N. Both production connectors are supplied in tape-and-reel packaging.
• MIXED_PROTOTYPE: add J3, J5, J6, and the plated test points. The pin headers require a mixed-technology or hand-finish assembly operation.
• The external DP5T rotary switch and harness are always a separate mechanical assembly.

Release status#

The automated QA report distinguishes CAD/analysis evidence from physical evidence. The current rev-0.1 release has 41 PASS, 5 CONDITIONAL, 18 OPEN, and 0 FAIL results. Passing ERC, DRC, corner calculations, simulations, BOM/PnP parity, and fabrication-file checks does not constitute USB-IF, FCC, CE, UL, or other certification. Hardware remains prototype-only until every required bench and certification item in the HTML report is closed.

Primary references#

• Hynetek HUSB238A product page and Rev. 0.1 full data sheet; the current product page identifies HUSB238A-BB001 and HUSB238A-BB002.
• Texas Instruments TPS25947 Rev. C data sheet.
• Texas Instruments TVS2200 Rev. C data sheet.
• Diodes Incorporated DMP4015SSS data sheet.
• GCT USB4105 product page and B4 mechanical drawing.
• Grayhill Series 56 selector data and 56A36-01-2-05N product record.
• Molex 43650-0210 Micro-Fit 3.0 product record and drawing.
• USB Type-C and USB Power Delivery specifications; formal compliance testing requires access to the licensed specifications and an authorized test setup.