Project Overview: Power Management Board

flux

2:08

Project
Here’s a concise, engineer’s walkthrough of your “BRAVE POWER MANAGEMENT BOARD.”
Purpose and system overview
  • Goal: Provide regulated 12 V, 5 V, and 3.3 V rails for IoT systems from multiple sources: Li-ion battery, solar panel, or USB. Also recharge the battery from solar or USB.
  • Primary functions:
    • Battery charging from solar or USB.
    • Boost conversion from battery to a higher rail (12/5 V).
    • Load switching and 3.3 V regulation for logic/MCUs.
    • Status indication and simple voltage sensing.
Core components and roles
  • Solar input and protection:
    • J3 brings in panel power to VSOLAR.
    • D1 Schottky diode blocks reverse flow, feeding VUSB via the “U4 VIN” net. Large drop-in diode is robust, low Vf.
  • USB input:
    • J4 provides VUSB. D3 isolates and OR’s into charger input (“U4 VIN” net). Simple diode-ORing between USB and solar.
  • Battery charger:
    • U4 is a solar-friendly Li-ion charger IC. Inputs from “U4 VIN”, outputs to VBAT. Charge current set by R8 on U4_ISET. Status outputs CHARG and DONE drive D5 and D2 through R2.
  • Battery connection:
    • J1 connects the Li-ion pack to VBAT and GND.
    • Bulk caps around charger input/output: C1, C9, C3, C4, C7.
  • Boost converter (12/5 V rail generation):
    • IC1 is a 2 A step-up regulator. Input: VBAT. Switching node: SW to L1 and D4. Output appears as 12_5V_OUT.
    • Feedback and output selection: SW1 and divider R6 set IC1_FB, allowing a selectable output target (likely 12 V or 5 V). C10 provides output decoupling.
  • 3.3 V rail and load switch:
    • U1 is a synchronous buck/boost-like naming, but in this schematic it is wired as a regulator using LX, L2, and feedback network R3, R7, C8, producing 3V3. Input is VBAT.
    • U3 high-side power switch gates the +3.3 V rail: VIN and EN controlled locally, output is 3V3 with output caps C5, C6. R5 to Net 2 sets current limit/soft-start depending on variant.
  • Outputs and connectors:
  • Sensing and indicators:
    • Divider networks: R1/R4 create 12V_DIV/12V DIV to SW1, and R9 creates a 5V_DIV sense point. These likely feed a microcontroller elsewhere for telemetry.
    • Charging LEDs: D5, D2 indicate CHARGING and DONE.
How the pieces interact
  • Power path: Solar and USB are diode-ORed to the charger input. The charger manages battery charging and exposes status. VBAT feeds two downstream paths:
    1. Boost to 12/5 V via MT3608 (selectable via SW1 and divider), exported at J2.
    2. Regulate/switch to 3.3 V via RT8059 + SY6280 to power logic loads and provide a clean +3V3 at J2.
  • Control and telemetry: EN pins on U1 and U3 plus sense dividers give simple hooks for MCU control/monitoring.
Design choices, trade-offs, and optimizations
  • Diode OR-ing for input selection:
    • Pros: Simple, robust, no control logic needed, solar-friendly.
    • Cons: Efficiency loss from Schottky forward drop (SS34) especially at higher current; reduces available charge headroom for solar.
  • MT3608 for 12/5 V:
    • Pros: Widely available boost, compact, adequate for IoT loads. SW1 allows quick field selection between 12 V and 5 V profiles.
    • Cons: If loads are heavy at 12 V, input current from VBAT rises quickly; careful inductor/diode/cap selection and thermal design required. Efficiency varies significantly between 5 V vs 12 V settings and load.
  • Separate 3.3 V path with high-side switch:
    • Pros: The U3 isolates +3.3 V rail, supports controlled inrush and current limiting to protect the battery and system.
    • Cons: Additional drop and quiescent consumption versus a bare LDO/switcher straight to the load.
  • Charger choice (CN3063):
    • Pros: Tailored for solar (MPPT-like behavior via VIN regulation on some variants), common topology, status pins for UX.
    • Cons: If true MPPT or dynamic power tracking is desired under varying irradiance, a dedicated solar PMIC might outperform a simple linear/switch charger with fixed ISET.
  • Feedback configurability:
    • The use of SPDT + feedback networks provides flexibility between 12 V and 5 V use cases without rework.
Key technologies and dependencies
  • Switching power conversion (boost and buck/step-down with inductor, diode, LX node).
  • Input power OR-ing with Schottky diodes.
  • Battery charging IC with programmable current and status signaling.
  • High-side load switch for 3.3 V rail management.
  • Standard passives (0603 caps/resistors), SWPA power inductors, through-hole terminal for field wiring.
Performance considerations and challenges
  • Thermal and efficiency:
    • At 12 V output, ensure MT3608 inductor L1 current rating and D4 thermal dissipation are adequate. Output caps C10 should be low ESR and appropriately rated.
    • For +3.3 V, verify the RT8059 switching frequency, inductor L2 saturation current, and compensation (R3/R7/C8) for stability across VBAT range.
  • Input headroom:
    • Schottky drops on solar/USB reduce effective input to the charger; with weak sun or long cables, charging might not start or may be slow.
  • Start-up and inrush:
    • Enabling +3.3 V or a heavy 12/5 V load can cause dips. The SY6280’s ISET and soft-start help; still consider sequencing and bulk capacitance.
  • EMI/layout:
    • Fast LX/SW nodes (IC1, U1) require tight loops and proper grounding. Place C3 close to IC pins, minimize hot-loop areas, and maintain a solid ground reference.
  • Battery safety:
    • Ensure charger parameters (ISET via R8) match the battery’s recommended charge current and that thermal regulation is acceptable in enclosure conditions.
Real-world applications
  • Remote sensors, data loggers, and IoT gateways powered by small solar panels and Li-ion cells.
  • Prototyping boards needing flexible 12 V/5 V plus a clean 3.3 V rail.
  • Educational and lab setups to demonstrate multi-source power management.
Areas for improvement and future enhancements
  • Improve input selection efficiency:
    • Replace diode-OR with an ideal diode controller or power mux to remove Schottky losses while preserving reverse blocking.
  • Smarter solar harvesting:
    • Use a solar-optimized PMIC with true MPPT or programmable VIN regulation for better energy yield in partial shade/temperature variation.
  • Telemetry and protection:
    • Add battery voltage/current sensing (high-side current sense) and NTC input to the charger if supported; expose via MCU for SOC estimation.
    • Add input over-voltage and surge protection (TVS at J4 and J3), and reverse battery protection FET instead of relying solely on system topology.
  • Output configuration:
    • If both 12 V and 5 V are needed simultaneously, consider a dedicated 12 V boost followed by a synchronous buck to 5 V, or two parallel converters from VBAT.
  • Efficiency tuning:
    • Size inductors L1/L2 for peak efficiency at expected load, select low-RDS(on) diode or synchronous converter to reduce losses, and ensure capacitors C5 have appropriate voltage rating and ESR.
  • Control/UX:
    • Bring EN pins of IC1 and U1 to a controller header for software-controlled power domains; add a power-good indicator for each rail.
    • Label terminal J2 clearly for field wiring and consider reverse-polarity keyed connectors.
  • Safety and compliance:
    • Add fusing (polyfuse) on inputs and battery line, and evaluate creepage/clearance where applicable.
Scalability considerations
  • Current scaling: For higher loads, move to synchronous boost/buck regulators with higher efficiency and thermal headroom.
  • Modularization: Break out submodules (charger, 12/5 V, 3.3 V switch) as stackable or swappable modules to tailor to application needs.
  • Manufacturability: Standardize on common footprints, ensure parts are active and multi-sourced; consider DFM: component clearances, test points on VBAT, +3V3, 12/5 V, and GND.
If you’d like, I can review DRC/ERC findings, check component values versus datasheets, or propose concrete parts for L1/L2/Cx and ISET based on your target loads and battery.
Ideal diode replacement
MT3608 thermal dissipation
MT3608 capacitor values
EMI layout guidance
Charge resistor calculation
119 days

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how can i connect u1 and u4
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Iset = 6800 / Rset Iset = 6800 / 6.8k Iset = 1A
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Generate a markdown-formatted table to compare D5, D2. Highlight the main differ...
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explain this project.
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create a high level mermaid block diagram of IC1. Include key component's manufa...
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please explain what U4 does.
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C10? PART NO
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WHAT IS THIS PROJECG ABOUT
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, please perform a Design for Testability (DFT) review on the current schematic....
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how do I change 12v out from boost to 5v
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I\_ch = (V\_set / R\_set) x 900 I\_ch = (2 / 2k) x 900 I\_ch = 900mA
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burada neden 10uH kullanılmış
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MOUNTINT HOLE DIMENTIONS
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C1
Capacitance
10u F
R8
Resistance
2k Ω
U4
D1
R2
Resistance
1k5 Ω
VSOLAR
VUSB
VBAT
D5
Color
Red
D2
Color
Green
C9
Capacitance
100n F
D3
VUSB
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  • Generic Capacitor
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  • Generic Inductor
    Generic Inductor
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  • Terminal
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BRAVE POWER MANAGEMENT BOARD thumbnail
Brave is a versatile and efficient power board that can provide 12v, 5v and 3.3v outputs for various applications. It can be powered by battery or solar panel, and the battery can be recharged by solar energy. It can also be powered by a USB port if needed. This board is ideal for IoT projects that require reliable and stable power supply in different environments. #internetOfThings #IoT #power #management #usb

Properties

Properties describe core aspects of the project.

Pricing & Availability

Distributor

Qty 1

Arrow

$0.81–$2.17

Digi-Key

$0.73–$2.82

LCSC

$1.72–$2.90

Mouser

$3.10–$3.73

Verical

$0.48–$1.96

Assets

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