Core Implementation Conditions for Both 12V 6A DC Output and t60W Bidirectional Interface
1. 12V 6A DC Output (Easy to Implement): Only Needs "Unidirectional Stable Power Supply"
No complex design is required; core conditions are as follows:
Topology & Chips: Adopt a simple "AC-DC rectification + Buck step-down topology" with mature fixed-output chips (e.g., LM2596, XL4015). The chip integrates constant voltage/constant current (CV/CC) control to directly output 12V/6A.
Component Specifications:
Power Components: Diodes (voltage resistance ≥20V, current ≥10A), MOSFETs (on-resistance Rds(on) ≤50mΩ) to meet 72W power redundancy;
Filter Components: Electrolytic capacitors (capacity ≥1000μF, voltage resistance ≥25V), inductors (saturation current ≥8A) to ensure output ripple ≤100mV (meeting DC device requirements).
Protection Functions: Series fuse (8A), overvoltage detection chip (e.g., TL431), short-circuit protection circuit (cuts off the circuit by detecting output current feedback)—no need for reverse protection.
Cost & Maturity: Mature solution with core chips priced ≤5 yuan, low overall BOM cost, and high mass production yield (≥99%), suitable for general power supply devices (e.g., router power supplies, small appliance adapters).
2.60W Bidirectional Interface (Difficult to Implement): Requires "Bidirectional Switching + Protocol Adaptation + High-Precision Control"
The core is solving three key issues: "direction recognition, dynamic control, and protocol compatibility." Specific conditions are as follows:
Topology & Control Architecture:
Must adopt a "bidirectional LLC topology" or "bidirectional Buck-Boost topology" to ensure bidirectional current flow (from port to device during charging, from device to port during discharging);
Equipped with a dedicated bidirectional controller (e.g., TI’s UCC28950, ST’s STM32G4 series) that supports real-time detection of port voltage/current and dynamic switching between charging/discharging modes.
Protocol Support (Key Condition):
For fast charging (e.g., mobile phones, tablets), must be compatible with the USB PD protocol (Power Delivery 3.0/3.1). A protocol chip (e.g., Cypress CYPD3177) communicates with external devices to negotiate output power (e.g., 5V/3A, 9V/3A, 15V/4A, 20V/3A) for 0-60W adaptation.
Component Specifications (High-Performance Requirements):
Power Components: Silicon Carbide (SiC) or Gallium Nitride (GaN) MOSFETs (Rds(on) ≤10mΩ, switching frequency ≥1MHz) to reduce losses during bidirectional switching and ensure efficiency ≥90% (otherwise, heat dissipation cannot be sustained);
Control & Communication: MCU (e.g., ESP32, STM32) for direction recognition and mode switching, and a protocol chip for power negotiation with external devices—both requiring real-time communication (I2C/SPI interface).
Protection & Thermal Design:
Protection Functions: Bidirectional overcurrent protection (cuts off when charging/discharging current ≥8A), reverse connection protection (no output if port polarity is reversed), overheating protection (reduces power when PCB temperature ≥85℃), surge protection (TVS tube voltage resistance ≥30V);
Thermal Design: PCB with 2oz copper thickness, heat sinks attached to key components (MOSFETs, inductors), and a fan (wind speed ≥3000rpm) for small devices to avoid power surge-induced heating during switching.
Compatibility Requirements: Must adapt to various devices (compatible with chargers (5V-20V) during charging, and mobile phones, tablets, small appliances during discharging). Requires USB-IF certification (for USB interfaces) to ensure uninterrupted protocol communication.
3. Application Scenario Verification: Why Is 60W Bidirectional Interface Less Popular?
12V 6A DC Output: Common in router power supplies, car chargers, and small LED power supplies. Mature products are available for tens of yuan with low technical barriers;
60W Bidirectional Interface: Found in high-end power banks (e.g., Anker bidirectional fast-charging power banks), laptop adapters (supporting "charging + reverse power supply"), and low-power bidirectional interfaces in new energy vehicles. Products are usually 2-3 times more expensive than unidirectional ones, with stable mass production limited to top brands.
Summary
12V 6A DC Output: Core is "unidirectional stable power supply," relying on mature step-down topology and basic components—low cost, low difficulty, suitable for fixed power supply scenarios of general electronic devices;
60W Bidirectional Interface: Core is "bidirectional dynamic adaptation," requiring solutions for topology switching, protocol negotiation, and bidirectional protection—high cost, high difficulty, suitable for flexible scenarios needing "self-charging + external device power supply" (e.g., power banks, portable devices).
For product design selection: If only powering external devices is needed, prioritize the 12V 6A DC output (low cost, high reliability); if both "self-charging and external power supply" are required, the 60W bidirectional solution is necessary, requiring more R&D resources to address compatibility and stability issues.
