4-Cell Li-Ion Charger Circuit

flux

0:41

Thinking deeply about your request.

Providing a high-level execution plan.

Your goal is a 4-cell Li-ion 1 A charger circuit based on the current charger project.

I’ve prepared the plan to build it around U.
It covers charger setup, required passives, connectors, protection placeholders, and project metadata.
Click Start on the plan bar to begin execution.

If you want, send the remaining charge parameters and I can revise the plan before you start.

Plan

Goal

Design a 4-cell Li-ion charger circuit using the existing BQ25672RQMR project as a foundation. The charger will be powered by a single 19 V DC input and will manage a 4S battery pack (14.4 V nominal, 16.8 V maximum), delivering a 1 A charge current. The circuit will operate with a 750 kHz switching frequency and will omit a ship FET.

Implementation plan

Project Update and Requirements Documentation
1. Update the project description to include the 4S Li-ion charger requirements.
2. Document the battery pack parameters (14.4 V nominal, 16.8 V maximum) and the 19 V DC input requirement.
3. Record design goals: 1 A pack charge current and 750 kHz switching.
Review Existing Project Scaffold
1. Examine the current schematic for the BQ25672RQMR and identify available pins and nets.
2. Determine adjustments to incorporate the charger circuitry within the current design framework.
Charger Schematic Development
1. Develop the input power stage to adapt the 19 V DC source for the charging circuit.
2. Incorporate the charger power stage using the BQ25672RQMR, ensuring compatibility with 4S Li-ion charging.
3. Place and configure necessary supporting components (inductors, capacitors, resistors) for regulation at 750 kHz.
4. Ensure the design supports a 1 A charge current and excludes the ship FET feature.
Schematic Connectivity and Integration
1. Establish connections between the input power stage, charger controller, and battery terminals.
2. Update net connections to ensure proper signal path and power management for 4S configuration.
3. Verify that all new design elements integrate cleanly with the existing project structure.
**Validation and Documentation
1. Review the schematic for completeness and correct electrical connections.
2. Update project properties and documentation reflecting the revised design intent and parameters.

Success criteria

The updated schematic meets 4-cell (4S) Li-ion charging requirements with 14.4 V nominal and 16.8 V maximum conditions.
The input 19 V DC is correctly handled by the charger power stage.
All components support the target 1 A charge current and are tuned for 750 kHz switching frequency.
The design successfully integrates into the existing BQ25672RQMR project without the ship FET component.
Project documentation is updated to reflect the new design parameters and schematic changes.

39 days

johannf

single Input is 19V DC, battery is 4S Li-ion 14.4V nominal, 16.8V max, and 1A is pack charge current. switching frequency is 750khz, no shipfet needed

39 days

flux

1:05

Thinking deeply about your request.

Drafting an execution plan.

Creating an execution plan.

Drafting project context.

Working on your request.

Analyzing the schematic.

Reviewing the bill of materials.

Creating execution plan.

Working on your request.

Crafting a concise plan.

Your goal is a 4-cell Li-ion charger in this U project with 19 V input, 16.8 V max charge voltage, 1 A charge current, 750 kHz switching, and no ship FET.

The plan is now updated and ready to execute.
It will document the requirements, build the charger schematic, connect the power/battery paths, and validate completeness.

Click Start on the plan bar to begin.

Plan

Goal

Design a 4-cell Li-ion charger circuit using the existing BQ25672RQMR project as a foundation. The charger will be powered by a single 19 V DC input and will manage a 4S battery pack (14.4 V nominal, 16.8 V maximum), delivering a 1 A charge current. The circuit will operate with a 750 kHz switching frequency and will omit a ship FET.

Implementation plan

Project Update and Requirements Documentation
1. Update the project description to include the 4S Li-ion charger requirements.
2. Document the battery pack parameters (14.4 V nominal, 16.8 V maximum) and the 19 V DC input requirement.
3. Record design goals: 1 A pack charge current and 750 kHz switching.
Review Existing Project Scaffold
1. Examine the current schematic for the BQ25672RQMR and identify available pins and nets.
2. Determine adjustments to incorporate the charger circuitry within the current design framework.
Charger Schematic Development
1. Develop the input power stage to adapt the 19 V DC source for the charging circuit.
2. Incorporate the charger power stage using the BQ25672RQMR, ensuring compatibility with 4S Li-ion charging.
3. Place and configure necessary supporting components (inductors, capacitors, resistors) for regulation at 750 kHz.
4. Ensure the design supports a 1 A charge current and excludes the ship FET feature.
Schematic Connectivity and Integration
1. Establish connections between the input power stage, charger controller, and battery terminals.
2. Update net connections to ensure proper signal path and power management for 4S configuration.
3. Verify that all new design elements integrate cleanly with the existing project structure.
**Validation and Documentation
1. Review the schematic for completeness and correct electrical connections.
2. Update project properties and documentation reflecting the revised design intent and parameters.

Success criteria

The updated schematic meets 4-cell (4S) Li-ion charging requirements with 14.4 V nominal and 16.8 V maximum conditions.
The input 19 V DC is correctly handled by the charger power stage.
All components support the target 1 A charge current and are tuned for 750 kHz switching frequency.
The design successfully integrates into the existing BQ25672RQMR project without the ship FET component.
Project documentation is updated to reflect the new design parameters and schematic changes.

Add battery connector

Review BQ25672 limits

Check input protection

Run review next

39 days

SW2

SYS

GND

SW1

VAC1

~CE

REGN

SCL

~QON

BTST2

BTST1

BAT

SDRV

~INT

BATP

VBUS

PMID

ACDRV2

VAC2

SDA

ILIM_HIZ

STAT

PROG

D+

ACDRV1

VBUS

D-

Reviews

Ground
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Net Portal
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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
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Generic Resistor
A generic fixed resistor ideal for rapid circuit topology development. Its footprint automatically adapts based on the selected package case code—supporting 0402, 0603, 0805, 1203, and many other standard SMD packages, as well as axial horizontal and vertical configurations. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard resistor values: 1.0 ohm, 10 ohm, 100 ohm, 1.0k ohm, 10k ohm, 100k ohm, 1.0M ohm 1.1 ohm, 11 ohm, 110 ohm, 1.1k ohm, 11k ohm, 110k ohm, 1.1M ohm 1.2 ohm, 12 ohm, 120 ohm, 1.2k ohm, 12k ohm, 120k ohm, 1.2M ohm 1.3 ohm, 13 ohm, 130 ohm, 1.3k ohm, 13k ohm, 130k ohm, 1.3M ohm 1.5 ohm, 15 ohm, 150 ohm, 1.5k ohm, 15k ohm, 150k ohm, 1.5M ohm 1.6 ohm, 16 ohm, 160 ohm, 1.6k ohm, 16k ohm, 160k ohm, 1.6M ohm 1.8 ohm, 18 ohm, 180 ohm, 1.8K ohm, 18k ohm, 180k ohm, 1.8M ohm 2.0 ohm, 20 ohm, 200 ohm, 2.0k ohm, 20k ohm, 200k ohm, 2.0M ohm 2.2 ohm, 22 ohm, 220 ohm, 2.2k ohm, 22k ohm, 220k ohm, 2.2M ohm 2.4 ohm, 24 ohm, 240 ohm, 2.4k ohm, 24k ohm, 240k ohm, 2.4M ohm 2.7 ohm, 27 ohm, 270 ohm, 2.7k ohm, 27k ohm, 270k ohm, 2.7M ohm 3.0 ohm, 30 ohm, 300 ohm, 3.0K ohm, 30K ohm, 300K ohm, 3.0M ohm 3.3 ohm, 33 ohm, 330 ohm, 3.3k ohm, 33k ohm, 330k ohm, 3.3M ohm 3.6 ohm, 36 ohm, 360 ohm, 3.6k ohm, 36k ohm, 360k ohm, 3.6M ohm 3.9 ohm, 39 ohm, 390 ohm, 3.9k ohm, 39k ohm, 390k ohm, 3.9M ohm 4.3 ohm, 43 ohm, 430 ohm, 4.3k ohm, 43K ohm, 430K ohm, 4.3M ohm 4.7 ohm, 47 ohm, 470 ohm, 4.7k ohm, 47k ohm, 470k ohm, 4.7M ohm 5.1 ohm, 51 ohm, 510 ohm, 5.1k ohm, 51k ohm, 510k ohm, 5.1M ohm 5.6 ohm, 56 ohm, 560 ohm, 5.6k ohm, 56k ohm, 560k ohm, 5.6M ohm 6.2 ohm, 62 ohm, 620 ohm, 6.2k ohm, 62K ohm, 620K ohm, 6.2M ohm 6.8 ohm, 68 ohm, 680 ohm, 6.8k ohm, 68k ohm, 680k ohm, 6.8M ohm 7.5 ohm, 75 ohm, 750 ohm, 7.5k ohm, 75k ohm, 750k ohm, 7.5M ohm 8.2 ohm, 82 ohm, 820 ohm, 8.2k ohm, 82k ohm, 820k ohm, 8.2M ohm 9.1 ohm, 91 ohm, 910 ohm, 9.1k ohm, 91k ohm, 910k ohm, 9.1M ohm #generics #CommonPartsLibrary
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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, 10000uF 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, 220pF, 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
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Project Name

BQ25672RQMR

Description

Charger IC Lithium Ion/Polymer I2C Controlled, 1- to 4-Cell, 3-A Buck Battery Charger with Dual-Input Selector, MPPT for Solar Panels and Integrated ADC 29-VQFN-HR (4x4)

Properties

Part Type

Integrated Circuit

Manufac…er Name

Texas Instruments

Manufac… Number

BQ25672RQMR

Datasheet URL

ti.com/lit/ds/symlink/bq25672.pdf

Designator Prefix

Pricing & Availability

Distributor	Qty 1

Controls

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