LNK302/304-306

LinkSwitch-TN Family

Lowest Component Count, Energy-Effi cient Off-Line Switcher IC

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

Applications

• Appliances and timers

• LED drivers and industrial controls

Description

LinkSwitch-TN is specifi cally 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 effi ciency. ® 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.

Figure 1. Typical Buck Converter Application.

ABSOLUTE MAXIMUM RATINGS(1,5)

DRAIN Voltage .................................. ............... -0.3 V to 700 V

Peak DRAIN Current (LNK302) ................. 200 mA (375 mA)⁽²⁾

Peak DRAIN Current (LNK304) ................. 400 mA (750 mA)⁽²⁾

Peak DRAIN Current (LNK305) ................. 800 mA (1500 mA)⁽²⁾

Peak DRAIN Current (LNK306).................1400 mA (2600 mA)⁽²⁾

FEEDBACK Voltage .........................................-0.3 V to 9 V

FEEDBACK Current.............................................100 mA

BYPASS Voltage ..........................................-0.3 V to 9 V

Storage Temperature .......................................... -65 °C to 150 °C

Operating Junction Temperature(3) ..................... -40 °C to 150 °C

Lead Temperature(4) ........................................................260 °C

Notes:

1. All voltages referenced to SOURCE, TA = 25 °C.

2. The higher peak DRAIN current is allowed if the DRAIN to SOURCE voltage does not exceed 400 V.

3. Normally limited by internal circuitry.

4. 1/16 in. from case for 5 seconds.

5. Maximum ratings specifi ed may be applied, one at a time, without causing permanent damage to the product. Exposure to Absolute Maximum Rating conditions for extended periods of time may affect product reliability.

Figure 2a. Functional Block Diagram (LNK302).

Figure 2b. Functional Block Diagram (LNK304-306).

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