Schematic for Loyal Yellow T-800: Non-Isolated Synchronous 4-...

PV Optimizer Design Guidance

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1:40

General

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Project

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Knowledge Base

Consulting on MOSFET use.

Calculating current for charging.

Discussing MOSFETs for charging.

Considering thermal and power requirements.

Using Knowledge Base Tool.

Using Calculator Tool.

Outlining recommended topologies.

Short answer: Yes—2 MOSFETs is OK if you use a synchronous buck and your panel voltage stays above the battery voltage during charging.

What that means

Topology: A 2‑MOSFET synchronous buck (high‑side switch + low‑side synchronous rectifier) is appropriate for ~18 V panel -> 12 V lead‑acid charging. If you want to keep charging when panel voltage drops below the battery (e.g., dawn/dusk), you’d need a buck‑boost (4 MOSFETs).
Duty example: With 14.4 V absorb target from an 18 V panel, duty ≈ 0.8.
Power/current: A 500 W panel could deliver up to ≈ 41.7 A at 12 V; your 12 V 15 Ah lead‑acid typically can’t take that. Limit charge current (commonly 0.1C–0.3C ≈ 1.5–4.5 A unless your battery’s datasheet allows more).

Design tips (apply exactly as stated)

Include a switching regulator IC, an inductor, and input/output capacitors to avoid unstable or non‑functional output.
Inductor: ripple target 20–40% of full load; saturation current ≥ 1.2× peak load; low DCR and low core loss.
Example inductor for 5 A bulk at 50 kHz, 30% ripple, 18 V -> 14.4 V: about 38 µH.
MOSFETs: choose adequate VDS margin (for 18 V input, 40–60 V class is typical), low RDS(on), and thermal headroom for your limited charge current.
Lead‑acid charging: implement bulk/absorption/float with temperature compensation; add polarity protection, battery protection, and simple charge status indicators.

If you confirm your intended max charge current (e.g., 3 A, 5 A), I can size the inductor and suggest MOSFET/diode ratings and initial capacitor values accordingly.

20 days

Plan completed.

Show Plan

R20 P2 - Q4 S

R17 P2 - Q1 S

U4 LO - R14 P1

C11 P2 - Q2 D

R18 P2 - Q2 S

U5 LO - R16 P1

Q1 G - R13 P2

R19 P2 - Q3 S

Q2 G - R14 P2

U4 HO - R13 P1

C2 P2 - R6 P2

C13 P2 - Q4 D

U5 HO - R15 P1

C12 P2 - Q3 D

Q3 G - R15 P2

Q4 G - R16 P2

Reviews

Electrical Rule Checks

Missing Footprints

Reports parts that have no footprint.

Design Rule Checks

Overlapping Copper • 7

Des	Net	Des	Net
TP2:1	DIVIDER_MID	Trace cc04	GND
TP2:1	DIVIDER_MID	Trace cc38	GND
Q1:D	GND	Q1:Pad	None
Q2:D	SNUB2_DRAIN	Q2:Pad	None
Q3:D	SNUB3_DRAIN	Q3:Pad	None
Q4:D	SNUB4_DRAIN	Q4:Pad	None
Q2:Pad	None	Trace fded	SNUB2_DRAIN

Invalid Layer

Reports nodes that are assigned to a layer that doesn't exist in the layout stackup.

Component Overrides • 1

	Designator	Ruleset
	＊｀VALUE｀＊	Override rules for ＊｀VALUE｀＊

Airwires

Reports missing routed traces between pads in a net.

Deprecated Rules

Reports nodes that are using rules that are not supported anymore.

Layers with Multiple Fills • 1

	Layer	Net
	All	GND, GND

Floating Copper

Detect any via, trace or copper fill island that is not connected to any net.

Protected Intrusions

Reports intrusions from objects of other nets into polygons or fills that have the Protected layout rule applied.

Manufacturing

Manufacturer Part Number • 38

	Designator	MPN
	C1	None
	C2	None
	C3	None
	C4	None
	C5	None
	C6	None
	C10	None
	C11	None
	C12	None
	C13	None
	Hole1	None
	Hole2	None
	Hole3	None
	Hole4	None
	L1	None
	R1	None
	R2	None
	R3	None
	R4	None
	R5	None
	R6	None
	R7	None
	R8	None
	R9	None
	R10	None
	R11	None
	R12	None
	R13	None
	R14	None
	R15	None
	R16	None
	R17	None
	R18	None
	R19	None
	R20	None
	R23	None
	R24	None
	R25	None

Parts Available

Beta

Checks that all parts have a part number and are available from distributors.

System Checks

Auto-Layout

Beta

Reports issues with Auto-Layout if Flux cannot route something or must ignore a configuration.

Passive Components

Resistor Power Rating

Beta

Checks that the power traveling across a given resistor is under its rating with 50% headroom.

Learn more

Pull Up/Pull Down Presence

Beta

Checks that IC pins that require pull up or pull down resistors have them.

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Capacitor Voltage Rating

Beta

Checks that capacitors have appropriate voltage ratings to prevent overheating and ensure reliable circuit operation.

Ground
A common return path for electric current. Commonly known as ground.
jharwinbarrozo
20.5M
Net Portal
Wirelessly connects nets on schematic. Used to organize schematics and separate functional blocks. To wirelessly connect net portals, give them same designator. #portal
jharwinbarrozo
43.0M
Power Net Portal
Wirelessly connects power nets on schematic. Identical to the net portal, but with a power symbol. Used to organize schematics and separate functional blocks. To wirelessly connect power net portals, give them the same designator. #portal #power
jharwinbarrozo
11.4M
Generic Resistor
A generic fixed resistor for rapid developing circuit topology. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard resistor values: 1.0Ω 10Ω 100Ω 1.0kΩ 10kΩ 100kΩ 1.0MΩ 1.1Ω 11Ω 110Ω 1.1kΩ 11kΩ 110kΩ 1.1MΩ 1.2Ω 12Ω 120Ω 1.2kΩ 12kΩ 120kΩ 1.2MΩ 1.3Ω 13Ω 130Ω 1.3kΩ 13kΩ 130kΩ 1.3MΩ 1.5Ω 15Ω 150Ω 1.5kΩ 15kΩ 150kΩ 1.5MΩ 1.6Ω 16Ω 160Ω 1.6kΩ 16kΩ 160kΩ 1.6MΩ 1.8Ω 18Ω 180Ω 1.8KΩ 18kΩ 180kΩ 1.8MΩ 2.0Ω 20Ω 200Ω 2.0kΩ 20kΩ 200kΩ 2.0MΩ 2.2Ω 22Ω 220Ω 2.2kΩ 22kΩ 220kΩ 2.2MΩ 2.4Ω 24Ω 240Ω 2.4kΩ 24kΩ 240kΩ 2.4MΩ 2.7Ω 27Ω 270Ω 2.7kΩ 27kΩ 270kΩ 2.7MΩ 3.0Ω 30Ω 300Ω 3.0KΩ 30KΩ 300KΩ 3.0MΩ 3.3Ω 33Ω 330Ω 3.3kΩ 33kΩ 330kΩ 3.3MΩ 3.6Ω 36Ω 360Ω 3.6kΩ 36kΩ 360kΩ 3.6MΩ 3.9Ω 39Ω 390Ω 3.9kΩ 39kΩ 390kΩ 3.9MΩ 4.3Ω 43Ω 430Ω 4.3kΩ 43KΩ 430KΩ 4.3MΩ 4.7Ω 47Ω 470Ω 4.7kΩ 47kΩ 470kΩ 4.7MΩ 5.1Ω 51Ω 510Ω 5.1kΩ 51kΩ 510kΩ 5.1MΩ 5.6Ω 56Ω 560Ω 5.6kΩ 56kΩ 560kΩ 5.6MΩ 6.2Ω 62Ω 620Ω 6.2kΩ 62KΩ 620KΩ 6.2MΩ 6.8Ω 68Ω 680Ω 6.8kΩ 68kΩ 680kΩ 6.8MΩ 7.5Ω 75Ω 750Ω 7.5kΩ 75kΩ 750kΩ 7.5MΩ 8.2Ω 82Ω 820Ω 8.2kΩ 82kΩ 820kΩ 8.2MΩ 9.1Ω 91Ω 910Ω 9.1kΩ 91kΩ 910kΩ 9.1MΩ #generics #CommonPartsLibrary
jharwinbarrozo
1.5M
Generic Capacitor
A generic fixed capacitor ideal for rapid circuit topology development. You can choose between polarized and non-polarized types, its symbol and the footprint will automatically adapt based on your selection. Supported options include standard SMD sizes for ceramic capacitors (e.g., 0402, 0603, 0805), SMD sizes for aluminum electrolytic capacitors, and through-hole footprints for polarized capacitors. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard capacitor values: 1.0pF 10pF 100pF 1000pF 0.01uF 0.1uF 1.0uF 10uF 100uF 1000uF 10,000uF 1.1pF 11pF 110pF 1100pF 1.2pF 12pF 120pF 1200pF 1.3pF 13pF 130pF 1300pF 1.5pF 15pF 150pF 1500pF 0.015uF 0.15uF 1.5uF 15uF 150uF 1500uF 1.6pF 16pF 160pF 1600pF 1.8pF 18pF 180pF 1800pF 2.0pF 20pF 200pF 2000pF 2.2pF 22pF 20pF 2200pF 0.022uF 0.22uF 2.2uF 22uF 220uF 2200uF 2.4pF 24pF 240pF 2400pF 2.7pF 27pF 270pF 2700pF 3.0pF 30pF 300pF 3000pF 3.3pF 33pF 330pF 3300pF 0.033uF 0.33uF 3.3uF 33uF 330uF 3300uF 3.6pF 36pF 360pF 3600pF 3.9pF 39pF 390pF 3900pF 4.3pF 43pF 430pF 4300pF 4.7pF 47pF 470pF 4700pF 0.047uF 0.47uF 4.7uF 47uF 470uF 4700uF 5.1pF 51pF 510pF 5100pF 5.6pF 56pF 560pF 5600pF 6.2pF 62pF 620pF 6200pF 6.8pF 68pF 680pF 6800pF 0.068uF 0.68uF 6.8uF 68uF 680uF 6800uF 7.5pF 75pF 750pF 7500pF 8.2pF 82pF 820pF 8200pF 9.1pF 91pF 910pF 9100pF #generics #CommonPartsLibrary
jharwinbarrozo
1.5M
Generic Inductor
A generic fixed inductor for rapid developing circuit topology. *You can now change the footprint and 3D model at the top level anytime you want. This is the power of #generics
jharwinbarrozo
15.1k
Terminal
An electrical connector acting as reusable interface to a conductor and creating a point where external circuits can be connected.
natarius
RMCF0805JT47K0
47 kOhms ±5% 0.125W, 1/8W Chip Resistor 0805 (2012 Metric) Automotive AEC-Q200 Thick Film #forLedBlink
jharwinbarrozo
1.2M
875105359001
10uF Capacitor Aluminum Polymer 20% 16V SMD 5x5.3mm #forLedBlink #commonpartslibrary #capacitor #aluminumpolymer #radialcan
jharwinbarrozo
1.2M
CTL1206FYW1T
Yellow 595nm LED Indication - Discrete 1.7V 1206 (3216 Metric) #forLedBlink
jharwinbarrozo
1.1M

Inspect

Loyal Yellow T-800

Controls

Properties

Testpoint Placement

Desired_Output_Current

Ready for DRC

Clearance_Distance

Switching_Frequency

kHz

Initial Trace Widths - power nets

Panel Datasheet URL

PCB Layout Width (mm)

PCB Layout Height (mm)

Panel_Imp

Kelvin Sense Nets

DRC_airwires_results

Clearance_mm

Manufacturability_Issues

Initial Trace Widths - HV nets

Desired_Output_Voltage

Clearance Rule

Desired_Output_Power

missing_footprints_results

Connector Orientation

Net Classes

BOM_entries

### Bill Of Materials Search Results

Creepage Rule

Panel_Voc

Creepage_Distance

Creepage_mm

DRC_routed_board_issues

Copper Weight

Components_Missing_MPN

Board Size

Placement Guidance

Initial Trace Widths - signal nets

Panel_Vmp

Stackup

PCB Layers

System Architecture

Availability & Pricing

Distributor		Qty 1
	Arrow	$15.09–$52.36
	Digi-Key	$21.59–$86.17
	LCSC	$30.48–$30.73
	Mouser	$42.39–$44.72
	TME	$9.03
	Verical	$15.92–$54.82

Assets

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