12V DC UPS Stabilizer Design

flux

Looks good overall. I checked your actual nets and here’s a focused review with any fixes.
What’s correct
  • Input chain and TVS
    • J1 → F1 → R1 → U1 IN and Q1 S are on U1.
    • D1 is across the input (cathode on J1 P1 via Net 4, anode to GND). Placement is correct.
  • Ideal‑diode stage
    • U1:OUT and Vdd are on the downstream node with Q1:D (NET_OUTPUT). Good.
    • U1:GATE to Q1:G only (Net 5). Correct.
  • Supercap bank and balance
  • Output filter
    • Q1 D → L1 P1; L1 P2 → J2 P1 with C1 220 µF and C2 100 nF to GND (Net 6). Correct.
Required fixes and recommendations
  • TVS part number: You specified 1.5KE18CA (bidirectional). The current device on D1 is 1.5KE18A (unidirectional). Replace it with 1.5KE18CA to match the requirement.
  • LTC4357 VDD decoupling (from the datasheet)
    • The datasheet states: “For applications up to 30 V, bypass the VDD pin with 39 µF; above 30 V use at least 100 µF. If VDD is powered from the output side, one capacitor serves to guard against VDD collapse and also protect OUT from voltage spikes. If OUT is diode-clamped or VDD is powered from input, use a separate 100 Ω, 100 nF filter (increase to 1 µF above 10 A).”
    • Action: Add a local VDD bypass for U1 per the above. In your case, with VDD tied to OUT, place a bypass from VDD/OUT to GND near U1.
  • Supercap properties: Your SC1–SC6 placeholders still say 256 F. Update to 25 F, 3 V and use a polarized footprint/symbol for the final MPN (Eaton TV1625-3R0256-R), since the real parts are polarized.
Want me to:
  • swap D1 to 1.5KE18CA,
  • add the LTC4357 VDD bypass per datasheet,
  • and update SC1–SC6 to 25 F/3 V?
Say “apply those fixes” and I’ll make the edits.
Ask about LTC4357 capacitor value
Supercap balancing check
TVS diode choice
Output LC sizing
Thermal on MOSFET
Sign up to send
J2
SC3
Capacitance
256 F
C2
Capacitance
100 nF
Rbal6
Resistance
1kΩ
Rbal4
Resistance
1kΩ
C1
Capacitance
220 µF
SC1
Capacitance
256 F
Rbal5
Resistance
1kΩ
Rbal3
Resistance
1kΩ
SC2
Capacitance
256 F
Rbal1
Resistance
1kΩ
SC5
Capacitance
256 F
L1
Inductance
47 µH
SC4
Capacitance
256 F
Q1
SC6
Capacitance
256 F
C1 P1 - GND GND
Rbal2
Resistance
1kΩ
D1
R1
Resistance
5 Ω
U1
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12 V Automotive UPS-Style Supercapacitor Power Stabilizer

Properties

Diagram



  
    
  
  
    
  



""Input Protection""















"Input Terminal"
"7.5A Blade Fuse"
"5Ω >15J NTC Thermistor"
"LTC4357 + IPT015N10N5 Ideal-Diode Stage"
"6S1P Supercapacitor Bank\n(Eaton TV1625-3R0256-R x6)"
"Output LC Filter\n(47µH Inductor, 220µF Electrolytic, node_100nF Ceramic)"
"Output Terminal"
"1.5KE18CA TVS Diode"

Pricing & Availability

Distributor

Qty 1

Arrow

$3.35–$4.83

Digi-Key

$5.62

LCSC

$7.06–$7.16

Mouser

$6.18

TME

$0.33

Verical

$11.06–$13.29

Controls