Schematic Review and Fixes

flux

Here’s the correct wiring from the DC jack into the board, with both protection options shown. Use ONE of the two “Input protection” cases.
  • Jack polarity
    • J6 tip (center, +6 V) = input positive
    • J6 sleeve = GND
  • Input protection (choose ONE)
    • Case A – PTC
      • [J6]:A -> [F4]:P1 -> [F4]:P2 -> [D1]:A (anode) -> [D1]:K (cathode) -> PiVIN (VIN rail)
    • Case B – eFuse (with reverse blocking)
      • [J6]:A -> eFuse IN (TPS259531) -> eFuse OUT -> PiVIN
      • If eFuse does NOT provide reverse blocking, keep [D1] in series: eFuse OUT -> [D1]:A -> [D1]:K -> PiVIN
  • VIN rail consumers and clamps
    • PiVIN -> U2:VIN, C1:P1, C2:P1
    • TVS on VIN: [D5] K -> PiVIN, [D5] A -> GND
    • Motor supply: PiVIN to motor connectors (VIN side), flyback cathodes D2/D3 -> PiVIN
  • Grounds and decoupling
    • [J6] sleeve -> GND
    • [C1]:P2, [C2]:P2 -> GND (place close to [U2])
  • Buck output to Pi 5 V (for completeness)
    • BUCK_5V (post-[U2] inductor) -> Pi fuse -> H1 Pin_1/Pin_3 (5 V)
    • Pi-side TVS (low profile): D6 K -> H1 Pin_1/Pin_3 net, D6 A -> GND
Notes
  • D1 orientation must be forward from source to PiVIN (A upstream, K on PiVIN).
  • If you upgraded to a 5 A class Schottky (e.g., MBRS540), keep it cool with short, wide copper.
  • Size/widen VIN copper for your worst-case (Pi 3 A + motors up to 2 A); prefer pours and via arrays at layer changes.
emricht32flux18

emricht32flux18

For case A, there is no F4 on the board. What part should I use?

flux

For Case A (PTC on the 6 V input), use a higher-hold, low-profile SMD resettable fuse sized for your combined current. Two practical choices:
  • Recommended for 5 A supply headroom (best margin)
    • 2920, 5.0 A hold:
    • When to use: You expect up to ~5 A steady (Pi ~3 A + motors up to ~2 A) and want to avoid nuisance trips and heating. The larger body also runs cooler.
  • Space-constrained, OK up to ~3.5–4 A steady
    • 1812, 3.0 A hold:
    • When to use: Board space limits you, and your real continuous current stays ≤3–3.5 A with motor duty cycle and inrush under control.
If you’d rather avoid PTC drawbacks (hotter, slower trip, higher drop at current), use the eFuse you already considered:
  • TPS259531DSGT
    • Pros: precise current limit, inrush control, thermal shutdown; optionally reverse blocking (depends on variant/config).
How to wire the PTC (F4) in Case A
  • J6 tip (+6 V) → F4:P1 → F4:P2 → D1:A → D1:K → PiVIN (VIN rail)
  • J6 sleeve → GND
Selection tips
  • Pick Ihold ≥ 1.2–1.5× your worst-case continuous current on VIN (for you, 5.0 A hold is safest).
  • Verify Vmax ≥ 6 V (all parts above meet this).
  • Check cold resistance so the 6 V drop and heating are acceptable at your load.
  • Derate for ambient temperature and enclosure heating.
If you tell me your available footprint area, I can lock in either a 2920 5.0 A part (preferred) or an 1812 3.0 A part and prep the swap.
Sign up to send
F2
R4
GND (common)
GND
VIN
Net1
GND
U1 FB - R6 P2
GND
VIN
GPIO 17
GND
VIN
GPIO 17
U1 FB - R6 P2
GND
GND
VIN
GND
GPIO 10
GND
VIN
VIN
Hole3
C1
Capacitance
10µF
U1
Hole2
J6
Hole4
J1
Hole1
J5
VIN
R7
Resistance
10kΩ
D1
D6
R2
J7
D3
C4
C5
End of Life
Capacitance
0.1uF
C2
End of Life
Capacitance
0.1uF
C3
H1
Manufacturer Part Number
2.54-2*20
L2
R6
Q2
Q1
D5
R9

No results...

Learn to Add a Component
Stuck Cyan Lightcycle thumbnail
Pi Zero 2 W Power HAT – 6 V Input, 5.2 V Buck to Pi 5 V Header via 1.85 A Fuse, Enhanced Input & Pi Rail Protection (TVS + High-Hold PTC + 5 A Schottky)

Properties

Ω
Diagram



  
    
  
  
    
  



InputStage


BuckStage


PiPowerPath


MotorDrivers




















































"Barrel Jack IN"
"Polyfuse F1 (input)"
"Schottky D1"
"TVS D2"
"10uF C1"
"100nF C2"
GND
"TPS56339 U2"
"4.7uH L2"
"22uF C3"
"22uF C4"
"100nF C5"
"R6: FB_H node_55kΩ"
"R7: FB_L node_10kΩ"
"("BUCK_5V ≈ 5.2V")"
"PTC F2 ≈1.85A (A16-185)"
"("PI_5V / H1 pins 2,4")"
H1
"PWM10 from H1"
"100R R1"
"AO3400A Q1"
"PWM17 from H1"
"100R R2"
"AO3400A Q2"
"MBRS540 D3 to VIN"
"MBRS540 D4 to VIN"
V
Diagram



  
    
  
  
    
  



InputStage


BuckStage


USBOutput


MotorDrivers


GPIOBreakouts































































"Barrel Jack IN"
"Polyfuse F1"
"Schottky D1"
"TVS D2"
"10uF C1"
"100nF C2"
GND
"TPS56339 U1"
"4.7uH L1"
"22uF C3 (CC1206KKX5R6BB226)"
"22uF C4 (CC1206KKX5R6BB226)"
"100nF C5"
"R_FB_H"
"R_FB_L"
"30R BOOT RBOOT (ERJ-3GEYJ300V)"
"Polyfuse F2"
"TVS5 SP0502BAHT"
"USB-A J3"
"PWM10"
"100R R1"
"AO3400A Q1"
"PWM17"
"100R R2"
"AO3400A Q2"
"MBR540 D3"
VIN
"MBR540 D4"
"RPi 40 Header (PPPC202LFBN-RC node_2x20 TH)"
"GPIO24 J1"
"GPIO25 J2"
"PWM10 Test T10"
"PWM17 Test T17"
V
Ω

Pricing & Availability

Distributor

Qty 1

Arrow

$2.73–$3.33

Digi-Key

$2.22–$3.61

LCSC

$2.78–$3.40

Mouser

$3.42–$3.76

TME

$2.74

Verical

$1.64–$91.56

Controls