Conceptual Distinction
Built-in Driver:
Refers to an independent driver module embedded within the fixture’s structure. It features its own PCB, housing (typically aluminum or plastic), complete I/O ports, electrical isolation (usually), and a self-contained package. This module connects to the light source board via wires.
DOB (Driver-on-Board):
Involves mounting/soldering critical driver components (especially the power stage and rectification/filtering circuits) directly onto the same PCB as the light source board (COB or MCPCB). This eliminates the need for a separate driver housing and output wiring, as power conversion occurs directly on the light source board.
1. DOB (Driver on Board)
Essence:
High Integration: Core driver components (AC-DC rectification/filtering, primary-side power switches, control ICs, passive components like capacitors/inductors) are laid out on the light source substrate (e.g., MCPCB or COB aluminum board).
No Independent Housing: No physical "driver module" enclosure exists.
Circuit Fusion: Driver and light source circuits share a common ground (unless isolated at added cost).
Simplified Structure: Eliminates housings, I/O connectors (e.g., Dupont wires, sockets), wiring between driver and light source, and mounting brackets.
Advantages:
Lower Costs (Materials/Production): Saves materials (housing, connectors, wires) and assembly labor.
Thermal Management Potential (in specific designs): Heat from driver components conducts directly to the substrate and fixture housing, potentially reducing hotspots.
Compactness: Slimmer profile, smaller size, higher design flexibility.
Simplified Supply Chain: Easier component procurement (chips, capacitors, resistors) and reduced module inventory/QC.
Challenges:
Thermal Stress: Critical components (e.g., electrolytic capacitors) degrade rapidly under high temperatures near the light source, shortening lifespan. Requires careful component selection, layout optimization, and thermal design.
Design Complexity: Demands strict high/low-voltage zoning, safety clearances, thermal management, and EMI control. Requires dual expertise in driver and light source design.
Reliability Risks: Single component failure may scrap the entire board. Vibration and thermal cycling stress solder joints.
Stricter Certification (e.g., UL/IEC): Safety clearances and creepage distances are harder/expensive to certify (full fixture required).
EMI/EMC Vulnerability: High-voltage circuits near light sources raise interference risks.
Limited Light Source Flexibility: Best suited for single-color-temperature, fixed-voltage setups. Multi-color, full-voltage, or advanced dimming (e.g., 0-10V/DALI) support is costly and rare.
Poor Maintainability: Driver failure requires full board replacement.
2. Traditional Built-in Driver (Independent Module)
Essence:
Physical Separation: Driver is a self-contained, fully packaged module.
Functional Isolation: Module handles AC-DC conversion, constant current/voltage control, protection (OVP/OCP/OTP), and electrical isolation. Light source board emits light.
Standard Interfaces: Connects via I/O ports (AC/DC wires or connectors).
Advantages:
High Reliability: Components operate within certified temperature limits (e.g., Ta≤50°C, Tc≤85°C), ensuring longevity (>5 years/100k hours). Resilient to shock/vibration.
Thermal Isolation: Driver heat dissipates independently, avoiding light source heat impacts.
Standardization: Modules are swappable based on power, voltage, dimming protocols, etc. Light source/driver are designed/tested separately.
Easier Maintenance: Only the driver module needs replacing during failures.
Streamlined Certification: Modules pre-certified (UL/TUV/CE/CB) simplify fixture compliance.
Feature-Rich: Supports high PF (>0.9), high efficiency (>90%), low THD (<20%), multi-channel outputs, dimming protocols (TRIAC/0-10V/DALI), and global voltage ranges.
Controllable EMI/EMC: Shielded housing simplifies interference mitigation.
Reduced Thermal Pressure: Fixture design focuses solely on light source cooling.
Disadvantages:
Higher Costs (Materials/Production): Added expenses for housing, connectors, wires, and assembly labor.
Space Constraints: Occupies physical space, limiting fixture slimness.
Complex Supply Chain: Dual procurement for modules and light source boards.
Connection Failure Risks: Potential I/O wiring/solder joint failures.
Potential Overkill: Less cost-effective for ultra-low-power, basic applications.
Additional Insights
Use Cases:
DOB: Low-cost, compact, fixed-color applications (e.g., budget bulbs, candles, downlights).
Built-in Driver: High-reliability, versatile fixtures (e.g., commercial/industrial luminaires, streetlights).
Trends:
DOB: Improving via high-temp capacitors, thermal designs, and IC integration. Targets mid-low-end markets.
Built-in Driver: Dominates mid/high-end with innovations like GaN/SiC, miniaturization, and smart controls.
Hybrids: "Quasi-DOB" designs partition components between board and micro-modules.
Selection Criteria:
Lifespan: >5 years → Built-in driver; ≤3 years → DOB (with robust design).
Cost Sensitivity: Extreme → DOB; Moderate → Built-in driver.
Features: Dimming/wide voltage → Built-in driver only.
Space/Heat Constraints: Ultra-slim → Assess DOB viability (thermal risks first).
Certification: Strict markets → Built-in driver for easier compliance.
Summary
Core Distinction: DOB integrates drivers directly onto the light source board; built-in drivers use physical modules within fixtures.
DOB: Maximizes cost/compactness; battles thermal/reliability hurdles.
Built-in Driver: Prioritizes reliability/performance/longevity; trades off cost/space.
Neither is universally superior – the choice hinges on product goals, cost targets, performance needs, lifespan expectations, and certification demands.