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4/05 2. A secondary output of 5 V with a Schottky rectifier diode. 3. Assumed efficiency of 77% (TNY267 & TNY268), 75% (TNY265 &TNY266)and 73%(TNY263 &TNY264). 4. The parts are board mounted with SOURCE pins soldered to sufficient area of copper to keep the die temperature at or below 100 °C. In addition to the thermal environment (sealed enclosure, ventilated, open frame, etc.), the maximum power capability of TinySwitch-II in a given application depends on transformer core size and design (continuous or discontinuous), efficiency, minimum specified input voltage, input storage capacitance, output voltage 更多：https://www.bmcx.com/ , output diode forward drop, etc., and can be different from the values shown in Table 1. Audible Noise The TinySwitch-II practically eliminates any transformer audio noise using simple ordinary varnished transformer construction. No gluing of the cores is needed. The audio noise reduction is accomplished by the TinySwitch-II controller reducing the current limit in discrete steps as the load is reduced. This minimizes the flux density in the transformer when switching at audio frequencies. Worst Case EMI & Efficiency Measurement Since identical TinySwitch-II supplies may operate at several different frequencies under the same load and line conditions, care must be taken to ensure that measurements are made under worst case conditions. When measuring efficiency or EMI verify that the TinySwitch-II is operating at maximum frequency and that measurements are made at both low and high line input voltages to ensure the worst case result is obtained. Layout Single Point Grounding Use a single point ground connection at the SOURCE pin for the BYPASS pin capacitor and the Input Filter Capacitor (see Figure 17). Primary Loop Area The area of the primary loop that connects the input filter capacitor, transformer primary and TinySwitch-II together should be kept as small as possible. Primary Clamp Circuit A clamp is used to limit peak voltage on the DRAIN pin at turn-off. This can be achieved by using an RCD clamp (as shown in Figure 14). A Zener and diode clamp (200 V) across the primary or a single 550 V Zener clamp from DRAIN to SOURCE can also be used. In all cases care should be taken to minimize the circuit path from the clamp components to the transformer and TinySwitch-II. TNY263-268 Thermal Considerations Copper underneath the TinySwitch-II acts not only as a single point ground, but also as a heatsink. The hatched areas shown in Figure 17 should be maximized for good heat sinking of TinySwitch-II and the same applies to the output diode. EN/UV pin If a line under-voltage detect resistor is used then the resistor should be mounted as close as possible to the EN/UV pin to minimize noise pick up. The voltage rating of a resistor should be considered for the undervoltage detect(Figure 15: R2, R3)resistors. For 1/4 W resistors, the voltage rating is typically 200 V continuous, whereas for 1/2 W resistors the rating is typically 400 V continuous. Y-Capacitor The placement of the Y-capacitor should be directly from the primary bulk capacitor positive rail to the common/return terminal on the secondary side. Such placement will maximize the EMI benefit of the Y-capacitor and avoid problems in common-mode surge testing. Optocoupler It is important to maintain the minimum circuit path from the optocoupler transistor to the TinySwitch-II EN/UV and SOURCE pins to minimize noise coupling. The EN/UV pin connection to the optocoupler should be kept to an absolute minimum (less than 12.7 mm or 0.5 in.), and this connection should be kept away from the DRAIN pin (minimum of 5.1 mm or 0.2 in.). Output Diode