LinkSwitch-TNZ
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LNK33x2-7D LinkSwitch-TNZ Family Energy Efficient Off-line Switcher IC with Best-in-Class Light Load Efficiency and Lossless AC Zero-Cross Detection Product Highlights Highest Performance and Design Flexibility • • • • • Lossless zero cross signal generation Supports buck, buck-boost and flyback topologies Enables ±3% regulation across line and load Selectable device current limit 66 kHz operation with accurate current limit • Allows the use of low-cost off-the-shelf inductors • Reduces size and cost of magnetics and output capacitor • Frequency jittering reduces EMI filter complexity • X capacitor discharge function (LNK331x only) Enhanced Safety and Reliability Features • • • • • • Soft-start limits system component stress at start-up Auto-restart for short-circuit and open loop faults Output overvoltage protection (OVP) Line input overvoltage protection (OVL) Hysteretic over-temperature protection (OTP) Extended creepage between DRAIN pin and all other pins improves field reliability • 725 V MOSFET rating for excellent surge withstand • Nemko (EN62368-1) and CB (IEC62368-1) certifications EcoSmart™– Extremely Energy Efficient • • • • IC standby supply current <100 mA On/Off control provides constant efficiency over a wide load range Easily meets all global energy efficiency regulations No-load consumption <30 mW with external bias Home and building automation Dimmers, switches and sensors with and w/o Neutral wire Appliances IoT and industrial controls Description The LinkSwitch™-TNZ family of ICs combine power conversion with lossless generation of AC zero crossing signal used typically for system clock and timing functions. Designs using the highly integrated LinkSwitch-TNZ ICs are more flexible than discrete implementations reducing component count by 40% or higher. Besides enabling 80+ efficiencies in low power flyback designs, very low consumption at light loads enabled by On/Off control allow for more functions (display, wireless connectivity, sensors etc.) to be active during system standby. The device family supports buck, buck-boost and flyback converter topologies. Each device incorporates a 725 V power MOSFET, oscillator, a high-voltage switched current source for self-biasing, frequency jittering, fast (cycle-by-cycle) current limit, hysteretic thermal shutdown, and output and input overvoltage protection circuitry onto a monolithic IC. LinkSwitch-TNZ ICs consume <100 mA current in standby resulting in power supply designs that can meet no-load and standby regulations worldwide. MOSFET current limit modes can be selected through the BYPASS pin capacitor value. The high current limit level provides maximum continuous output current while the low level permits using very low-cost and small surface mount inductors. A full suite of protection features enables safe and reliable power supplies protecting the device and the system against input and output overvoltage faults, device over-temperature faults, lost regulation, and power supply output overload or short-circuit faults. www.power.com + Zero Cross Signal PI-9175-060820 Figure 1. Typical Buck Converter Application (See Application Examples Section for Flyback and other Circuit Configurations). Output Current in Buck Table1 Product LNK33x2D Table 1. Output Power Table. Notes: 1. Typical output current in a non-isolated buck converter with devices operating at default current limit and adequate heat sinking. Output power capability depends on respective output voltage and thermal requirements. 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. Output Power in Flyback Table6 Product Table 2. Output Power Table. Notes: 4. Maximum practical continuous power in an open frame design with adequate heat sinking, measured at 25 °C ambient. 5. LNK33x6 is recommended in Flyback for highest efficiency. 6. See Key Application Considerations section for complete description of assumptions. This Product is Covered

FAULT PRESENT BYPASS PIN CAPACITOR DETECT AUTO-RESTART COUNTER CLOCK RESET CURRENT LIMIT COMPARATOR + JITTER CLOCK ISUPPLY ZERO-DETECT 2 (Z2) THERMAL SHUTDOWN LEADING EDGE BLANKING Figure 3. Functional Block Diagram. Pin Functional Description Z1 and Z2 Pins • Z1 and Z2 are used in combination for zero cross detect (ZCD) signal generation, X capacitor discharge or both. • For zero crossing, Z1 is connected to one of the input AC lines through an external resistor while Z2 forms the ZCD signal output. • For X capacitor discharge (LNK331x only), Z1 is connected to one AC line input through an...

LinkSwitch-TNZ LinkSwitch-TNZ Functional Description Oscillator The typical oscillator frequency is internally set to an average of fOSC (66 kHz). Two signals are generated from the oscillator: the maximum duty cycle signal (DC(MAX)) and the clock signal that indicates the beginning of each cycle. The LinkSwitch-TNZ oscillator incorporates circuitry that introduces a small amount of frequency jitter, typically 4 kHz peak-to-peak, to minimize EMI emission. The modulation rate of the frequency jitter is set to 1 kHz to optimize EMI reduction for both average and quasipeak emissions. The...

LinkSwitch-TNZ Hysteretic Output Overvoltage Protection The output overvoltage protection provided by the LinkSwitch-TNZ IC uses auto-restart that is triggered by a current >IBPSD into the BYPASS pin. In addition to an internal filter, the BYPASS pin capacitor forms an external filter providing noise immunity from inadvertent triggering. For the bypass capacitor to be effective as a high frequency filter, the capacitor should be located as close as possible to the SOURCE and BYPASS pins of the device. The OVP function can be realized in a flyback converter by connecting a Zener diode from...