Schematic Symbol for 480W, 48V Buck Boost: 99% Efficient 480W, 48V...

Variable Output Voltage Design

flux

2:14

General

Project

BOM

Datasheet

File

Knowledge Base

Evaluating design adjustments.

Confirming voltage specifications.

Discussing component linking.

Confirming LTC3779 specifications.

Using Knowledge Base Tool.

Using BOM Tool.

Looking for "VFB reference voltage" in ltc3779.pdf

Looking for "Output voltage setting equation VOUT VFB resistive divider" in ltc3779.pdf

Looking for "VFB pin description" in ltc3779.pdf

Looking for "Loop compensation ITH component selection guidelines" in ltc3779.pdf

Looking for "PGOOD threshold relative to VFB regulation" in ltc3779.pdf

Looking for "SS pin soft-start description" in ltc3779.pdf

Looking for "VOUTSENSE pin function and remote sensing guidance" in ltc3779.pdf

Looking for "Output voltage range limitations and minimum on/off-time constraints" in ltc3779.pdf

Looking for "VFB reference voltage" in ltc3779.pdf

Looking for "Output voltage programming equation VOUT" in ltc3779.pdf

Looking for "VFB pin description" in ltc3779.pdf

Looking for "ITH compensation selection" in ltc3779.pdf

Looking for "PGOOD threshold" in ltc3779.pdf

Looking for "SS soft-start" in ltc3779.pdf

Looking for "VOUTSENSE pin function" in ltc3779.pdf

Looking for "minimum on-time off-time output voltage range" in ltc3779.pdf

Exploring adjustable output options.

Yes. This design can be made variable by changing the feedback divider around U1. Per best practice, the output voltage is set by the feedback resistors, so making one leg adjustable will vary VOUT.

Practical options:

Front-panel potentiometer:
- Keep R10 fixed and replace R11 with a series fixed resistor plus a multi-turn pot to the output. Add “stopper” resistors to enforce safe min/max VOUT. This is the simplest way to vary VOUT.
MCU/DAC control:
- Inject a controlled voltage/current into the FB node with a DAC (through a resistor or small summing amp). This avoids a mechanical pot and enables profiles/limits in firmware.

What to watch:

Compensation: Varying VOUT changes plant gain. You may need to retune the ITH network (R9, C11) for stability across the range.
Status thresholds: PGOOD/OV/UV thresholds track the FB ratio, so they will shift with adjustable VOUT.
Remote sense: Keep VOUT sense wiring as-is; do not route the divider wiper through long runs.
Range limits: Define hard min/max with fixed resistors so the pot/DAC cannot drive VOUT into unsafe regions.
Power/train limits: Ensure the chosen VOUT range stays within controller minimum on/off-time limits, inductor ratings, and MOSFET/diode voltage stress.

If you share:

Desired VOUT range (min/max)
Adjustment method (pot vs MCU/DAC)
Load current over that range

I can put together a concrete change proposal (values for R10/R11, pot value and end-stops, and any ITH tweaks), and then implement it in the project for you.

Give target range

Prefer potentiometer

Ask compensation impact

MCU/DAC control

Check controller limits

60 days

Ready.

SW1

Resistance

10k Ω

BOTB_DRAIN

FREQ

R10

Resistance

12.1k Ω

BOOST2

TOPD_SOURCE

Resistance

100 Ω

Inductance

15u H

RUN

BOTC_SOURCE

SENSEN

Resistance

4m Ω

C444

Capacitance

10n F

BG2

PGOOD

BOTC_DRAIN

I_AVGSNSN

R13

Resistance

4m Ω

BOOST2

C25

Capacitance

10u F

V_FB

BOOST1

Capacitance

.22 u F

I_AVGSNSP

C16

Capacitance

4.7µ F

TOPA_SOURCE

Resistance

100 Ω

MODE

C12

Capacitance

10u F

C14

Capacitance

220p F

SW2

BOTB_SOURCE

C11

Capacitance

100p F

Manufacturer Part Number

GRM033R60J224KE15D

Designator Prefix

Capacitance

.22 u F

PGND

SENSEP

R19

Resistance

100 Ω

R12

Resistance

100 Ω

ITH

SGND

PILLIN

C10

Capacitance

10u F

SW2

V_OUTSNS

TG2

TOPD_DRAIN

Reviews

Electrical Rule Checks

Missing Footprints

Reports parts that have no footprint.

Design Rule Checks

Overlapping Copper • 2

	Des	Net	Des	Net	...
	Q4:D_2	Net 33	Q4:9	None
	Q4:9	None	Q4:D_1	Net 33

Invalid Layer

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

Component Overrides • 55

	Designator	Ruleset
	＊｀REF｀＊	Override rule for ＊｀REF｀＊
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	＊｀REF｀＊	Override rule for ＊｀REF｀＊
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	＊｀REF｀＊	Override rule for ＊｀REF｀＊
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	＊｀VALUE｀＊	Override rule for ＊｀VALUE｀＊
	＊｀VALUE｀＊	Override rule for ＊｀VALUE｀＊
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	＊｀VALUE｀＊	Override rule for ＊｀VALUE｀＊
	＊｀VALUE｀＊	Override rule for ＊｀VALUE｀＊
	＊｀VALUE｀＊	Override rule for ＊｀VALUE｀＊
	＊｀VALUE｀＊	Override rule for ＊｀VALUE｀＊
	＊｀VALUE｀＊	Override rule for ＊｀VALUE｀＊
	＊｀VALUE｀＊	Override rule for ＊｀VALUE｀＊
	＊｀VALUE｀＊	Override rule for ＊｀VALUE｀＊
	＊｀VALUE｀＊	Override rule for ＊｀VALUE｀＊
	＊｀VALUE｀＊	Override rule for ＊｀VALUE｀＊
	＊｀VALUE｀＊	Override rule for ＊｀VALUE｀＊
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	C＊＊	Override rule for C＊＊
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	Q＊＊	Override rule for Q＊＊
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	R＊＊	Override rule for R＊＊
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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

Reports layers that have multiple copper fills of different nets. Make sure the Connected Layers rule value of nets with fills is valid.

Floating Copper • 7

	Name
	Via
	Via
	Via
	Via
	Trace a24f
	Trace 6bf5
	Trace 6b9f

Protected Intrusions

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

Manufacturing

Manufacturer Part Number • 4

	Designator	MPN
	M1	None
	M2	None
	M3	None
	M4	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.

Learn more

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
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1.2M
875105359001
10uF Capacitor Aluminum Polymer 20% 16V SMD 5x5.3mm #forLedBlink #commonpartslibrary #capacitor #aluminumpolymer #radialcan
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1.2M
CTL1206FYW1T
Yellow 595nm LED Indication - Discrete 1.7V 1206 (3216 Metric) #forLedBlink
jharwinbarrozo
1.1M

Inspect

480W, 48V Buck Boost

Controls

Properties

Availability & Pricing

Distributor		Qty 1
	Digi-Key	$28.96–$35.90
	LCSC	$61.99
	Mouser	$25.22

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