Electronics Schematic Design for Product

Project Title: Economical SMD Power Management & Protection Circuit for 2x18650 / 12V USB Source with Isolation

Description:

We are seeking a skilled electronics engineer to design a reliable and compact power management and protection circuit using widely available SMD components (easily sourced in India). The design should support:
• Primary Power: 2x18650 Li-ion batteries
• Secondary Power: 12V USB adapter
• If batteries are low/dead, the adapter should charge the batteries and power the PCB simultaneously.

Design Requirements:
• Output regulated and protected 3.3V and 5V rails for sensitive components.
• Provide isolated and stable 3V–6V, 1A for a motor driver.
• Ensure isolation where needed between motor, logic, and power lines..

Protection Features:
• Over-voltage / under-voltage
• Over-current / under-current
• Reverse polarity & reverse current
• ESD, surge, and voltage spike protection
• Power rail isolation and noise suppression

Component Guidelines:
• Use only SMD components
• Use commonly available, economical, and reliable parts from Indian suppliers (e.g., Robu, Mouser India, LCSC India, etc.)
• Avoid rare, expensive, or long lead-time components

Deliverables:
• Circuit schematic in KiCad/Eagle/Altium
• Complete BOM with sourcing links (India preferred)
• Design explanation and protection logic flow
• PCB layout (preferred)

Ideal Expertise:
• Power electronics
• Battery charge/discharge handling with auto switch-over
• Isolation design and protection circuits
• Embedded system hardware design

We are focused on simplicity, economy, reliability, and local component availability