"Keywords:
LED, lnk302, powerint, street lamp, lighting
Powerint's 150W LED street lighting reference design (rdr-292) adopts linkswitch TN series lnk302 and hiperpfs and hiperlcs series products, combining PFS power factor stage and LCS output stage. The input voltage is 90 VAC - 265 VAC, and the power factor at 100% load and 50% load is greater than 0.9. This paper introduces the highlights of lnk302 products, Block diagram and 150W LED street lighting reference design, main characteristics and indicators, circuit diagram, bill of materials and PCB layout
Reference Design Report for a 150 W Power Factor Corrected LLC Power Supply for LED Street LighTIng
LinkSwitch-TN is specifically designed to replace all linear and capacitor-fed (cap dropper) non-isolated power supplies in the under 360 mA output current range at equal system cost while offering much higher performance and energy efficiency.
LinkSwitch-TN devices integrate a 700 V power MOSFET, oscillator, simple On/Off control scheme, a high voltage switched current source, frequency jittering, cycle-by-cycle current limit and thermal shutdown circuitry onto a monolithic IC. The startup and operaTIng power are derived directly from the voltage on the DRAIN pin, eliminaTIng the need for a bias supply and associated circuitry in buck or fl yback converters. The fully integrated auto-restart circuit in the LNK304-306 safely limits output power during fault condiTIons such as short-circuit or open loop, reducing component count and system-level load protection cost. A local supply provided by the IC allows use of a non-safety graded optocoupler acting as a level shifter to further enhance line and load regulation performance in buck and buck-boost converters, if required.
Lnk302 product highlights:
Cost Effective Linear/Cap Dropper Replacement
• Lowest cost and component count buck converter solution
• Fully integrated auto-restart for short-circuit and open loop fault protection – saves external component costs
• LNK302 uses a simplifi ed controller without auto-restart for very low system cost
• 66 kHz operation with accurate current limit – allows low cost off-the-shelf 1 mH inductor for up to 120 mA output current
• Tight tolerances and negligible temperature variation
• High breakdown voltage of 700 V provides excellent input surge withstand
• Frequency jittering dramatically reduces EMI (~10 dB) – minimizes EMI fi lter cost
• High thermal shutdown temperature (+135 °C minimum)
Much Higher Performance over Discrete Buck and Passive Solutions
• Supports buck, buck-boost and fl yback topologies
• System level thermal overload, output short-circuit and open control loop protection
• Excellent line and load regulation even with typical confi guration
• High bandwidth provides fast turn-on with no overshoot
• Current limit operation rejects line ripple
• Universal input voltage range (85 VAC to 265 VAC)
• Built-in current limit and hysteretic thermal protection
• Higher effi ciency than passive solutions
• Higher power factor than capacitor-fed solutions
• Entirely manufacturable in SMD
EcoSmart®– Extremely Energy Effi cient
• Consumes typically only 50/80 mW in self-powered buck topology at 115/230 VAC input with no load (opto feedback)
• Consumes typically only 7/12 mW in fl yback topology with external bias at 115/230 VAC input with no load
• Meets California Energy Commission (CEC), Energy Star, and EU requirements
Lnk302 application:
• Appliances and timers
• LED drivers and industrial controls
Uploaded at 13:42:40 on May 3, 2012
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Figure 1. Functional block diagram of lnk302
150W LED street lighting reference design
This engineering report describes a 48 V, 150 W reference design power supply for 90 VAC - 265 VAC LED street lights which can also serve as a general purpose evaluation board for the combination of a PFS power factor stage with an LCS output stage using devices from the Power Integration’s HiperPFS and HiperLCS device families.
The design is based on the PFS708EG IC and LQA05TC600 diode for the PFC front end, with a LNK302 utilized in a non-isolated flyback bias supply. An LCS702HG IC is used for the LLC output stage.
The circuit shown in this report is optimized for >0.9 power factor, over an input voltage range of 90 VAC - 230 VAC, at both 100% load and 50% load. If >0.9 power factor is not required at 50% load, the circuit can be cost reduced by downsizing common mode filter L1 and PFC input capacitor C6. Contact Power Integrations for more details.
This power supply is designed to be mounted inside a grounded enclosure for streetlight service, with the input AC safety ground connected to the chassis. EMI and line surge tests should be performed with the supply screwed down to a ground plane with the input AC safety ground connected to this plane.
Main characteristics of 150W LED street lighting reference design:
Integrated PFC stage using
o PFS708EG from HiperPFS family of ICs
o LQA05TC600 ultrafast soft recovery QSpeed diode
Integrated LLC stage using
o LCS702HG from HiperLCS family of ICs
Simple snubberless bias supply using
o LNK302DG from LinkSwitch-TN family of ICs
CAPZero (CAP002DG) IC used to discharge X capacitors for higher efficiency compared to resistive solution
High frequency (250 kHz) LLC for small transformer size
>95% full load PFC efficiency at 115 VAC
>9
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