LinkSwitch-TN
20Pages

Cost Effective Linear/Cap Dropper Replacement Ε Lowest cost and component count buck converter solution Fully integrated auto-restart for short-circuit and open loop fault protection Ֆ saves external component costs LNK302 uses a simpli ed controller without auto-restart for very low system costՕ 66 kHz operation with accurate current limit allows low cost off-the-shelf 1 mH inductor for up to 120 mA output current֕ Tight tolerances and negligible temperature variation High breakdown voltage of 700 V provides excellent input surge withstandՕ Frequency jittering dramatically reduces EMI (~10 dB) minimizes EMI lter cost֕ High thermal shutdown temperature (+135 > FBBPSD + + LinkSwitch-TN DC OutputWide RangeHV DC Input C minimum) > PI-3492-111903 Figure 1. Typical Buck Converter Application (See Application Examples Section for Other Circuit Con gurations). Much Higher Performance over Discrete Buck and Passive Solutions Е Supports buck, buck-boost and yback topologies System level thermal overload, output short-circuit and open control loop protectionՕ Excellent line and load regulation even with typical con guration High bandwidth provides fast turn-on with no overshoot Օ Current limit operation rejects line ripple Universal input voltage range (85 VAC to 265 VAC) Օ Built-in current limit and hysteretic thermal protection Higher ef ciency than passive solutionsՕ Higher power factor than capacitor-fed solutions Entirely manufacturable in SMD EcoSmart OUTPUT CURRENT TABLE > 1 230 VAC ձ15%85-265 VACMDCM PRODUCT > 4 2 CCM > 3 MDCM > 2 CCM > 3 LNK302P/G/D63 mA80 mA63 mA80 mALNK304P/G/D120 mA170 mA120 mA170 mA LNK305P/G/D175 mA280 mA175 mA280 mA LNK306P/G/D225 mA360 mA225 mA360 mA > Table 1. Output Current Table. Notes: 1. Typical output current in a non-isolated buck converter. Output power capability depends on respective output voltage. See Key Applications Considerations Section for complete description of assumptions, including fully discontinuous conduction mode (DCM) operation. 2. Mostly discontinuous conduction mode. 3. Continuous conduction mode. 4. Packages: P: DIP-8B, G: SMD-8B, D: SO-8C. Ζ Extremely Energy Ef cient Consumes typically only 50/80 mW in self-powered buck topology at 115/230 VAC input with no load (opto feedback)Օ Consumes typically only 7/12 mW in yback topology with external bias at 115/230 VAC input with no load Meets California Energy Commission (CEC), Energy Star, and EU requirements 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 start- up 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 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. Applications Օ Appliances and timers LED drivers and industrial controls > LinkSwitch-TN is speci 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 ef ciency. > November 2008 size="-2">

BYPASS(BP) DRAIN(D) REGULATOR5.8 VBYPASS PINUNDER-VOLTAGECURRENT LIMITCOMPARATOR FEEDBACK(FB)Q +- 5.8 V4.85 V SOURCE(S) 6.3 V +- VI LIMIT CLOCKJITTEROSCILLATOR MAX THERMALSHUTDOWN 1.65 V -V T SRQDC LEADINGEDGEBLANKING PI-3904-020805 BYPASS(BP)FAULTPRESENT DRAIN(D) REGULATOR5.8 VBYPASS PINUNDER-VOLTAGECURRENT LIMITCOMPARATOR FEEDBACK(FB)Q > +- CLOCK 5.8 V4.85 V SOURCE(S) RESETAUTO-RESTARTCOUNTER 6.3 V > +- VI > LIMIT CLOCKJITTEROSCILLATOR > MAX THERMALSHUTDOWN 1.65 V -V > T SRQDC LEADINGEDGEBLANKING > PI-2367-021105

LinkSwitch-TN . When the MOSFET is on, the LinkSwitch-TN F is suf cient for both high frequency decoupling and energy storage.In addition, there is a 6.3 V shunt regulator clamping the BYPASS pin at 6.3 V when current is provided to the BYPASS pin through an external resistor. This facilitates powering of LinkSwitch-TN runs off of the energy stored in the bypass capacitor. Extremely low power consumption of the internal circuitry allows the 5.8 V Regulator and 6.3 V Shunt Voltage Clamp to operate continuously from the current drawn from the DRAIN pin. A bypass capacitor value of 0.1 The 5.8...

High-Side Buck Direct Feedback 1. Output referenced to input2. Positive output (V > O ) with respect to -V > IN FBBPSD 3. Step down ֖ V > O < V > IN 4. Low cost direct feedback (10% typ.)High-SideBuck і Optocoupler Feedback1. Output referenced to input2. Positive output (V > + + V LinkSwitch-TN IN V O PI-3751-121003 BPFBDS O ) with respect to -V > IN 3. Step down V > O < V > IN + + 4. Optocoupler feedback - Accuracy only limited by reference choice - Low cost non-safety rated opto - No pre-load required 5. Minimum no-load consumptionLow-SideBuck ֖ Optocoupler Feedback1. Output referenced to...

Low-SideBuck Boost Optocoupler Feedback 1. Output referenced to input2. Positive output (V provides the lowest cost and highest ef ciency converter. CCM designs require a larger inductor and ultra-fast (t > + O ) with respect to +V > IN 3. Step up/down ֖ V > O > V > IN or V > O < V > IN LinkSwitch-TN 4. Optocoupler feedback - Accuracy only limited by reference choice - Low cost non-safety rated opto - No pre-load required 5. Fail-safe output is not subjected to input voltage if the internal MOSFET fails > V IN V O BPFBDS + PI-3756-111903 Feedback Diode D2 LinkSwitch-TN design spreadsheet...