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поискавой системы для электроныых деталей |
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поискавой системы для электроныых деталей |
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LTM8049 датащи(PDF) 11 Page - Linear Technology |
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LTM8049 датащи(HTML) 11 Page - Linear Technology |
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11 / 20 page  LTM8049 11 8049fa For more information www.linear.com/LTM8049 APPLICATIONS INFORMATION circuit they may have only a small fraction of their nominal capacitance resulting in much higher output voltage ripple than expected. A final precaution regarding ceramic capacitors concerns the maximum input voltage rating of the LTM8049. A ceramic input capacitor combined with trace or cable inductance forms a high Q (underdamped) tank circuit. If the LTM8049 circuit is plugged into a live supply, the input voltage can ring to twice its nominal value, possi- bly exceeding the device’s rating. This situation is easily avoided; see the Hot-Plugging Safely section. Programming Switching Frequency TheLTM8049hasanoperationalswitchingfrequencyrange between 200kHz and 2.5MHz. The free running frequency is programmed with an external resistor from the RT pin to ground. Do not leave this pin open under any condition. When the SYNC pin is driven low (<0.4V), the frequency of operation is set by a resistor from RT to ground. The RT value is calculated by the following equation: RT = 81.6 fOSC – 1, where fOSC is in MHz and RT is in kΩ Switching Frequency Trade-Offs It is recommended that the user apply the optimal RTvalue given in Table 1 for the corresponding input and output operating condition. System level or other considerations, however, may necessitate another operating frequency. While the LTM8049 is flexible enough to accommodate a wide range of operating frequencies, a haphazardly chosen one may result in undesirable operation under certain operating or fault conditions. A frequency that is too high can reduce efficiency, reduce the usable input voltage range, generate excessive heat or even damage the LTM8049 in some fault conditions. A frequency that is too low can result in a final design that has too much output ripple or too large of an output capacitor. Note that the Maximum Output Current vs Input Voltage curves given in the Typical Characteristics section are for the recommended operating conditions in Table 1. Using a different operating frequency may result in a different maximum output current. Table 1. Recommended Component Values and Configuration (TA = 25°C) VIN RANGE (V) VOUT (V) CIN COUT RFB (Ω) fOPTIMAL RTOPTIMAL (Ω) fMAX RTMIN (Ω) 2.6V to 11.5V 2.5V 4.7µF 25V 0603 X5R 100µF 4V 0805 X5R 15.4k 600kHz 137k 2MHz 38.3k 2.6V to 9.5V –2.5V 4.7µF 25V 0603 X5R 100µF 4V 0805 X5R + 47µF 6.3V 0805 X5R 30.1k 600kHz 137k 2MHz 38.3k 2.6V to 18V 3.3V 4.7µF 25V 0603 X5R 100µF 4V 0805 X5R 25.5k 650kHz 124k 2.3MHz 33.2k 2.6V to 12V –3.3V 4.7µF 25V 0603 X5R 100µF 4V 0805 X5R + 47µF 6.3V 0805 X5R 39.2k 650kHz 124k 2.3MHz 33.2k 2.7V to 20V 5V 4.7µF 25V 0603 X5R 47µF 6.3V 0805 X5R 45.3k 750k 107k 2.5MHz 31.6k 2.7V to 15V –5V 4.7µF 25V 0603 X5R 100µF 6.3V 1206 X5R + 47µF 10V 1206 X5R 60.4k 750k 107k 2.5MHz 31.6k 2.7V to 20V 8V 4.7µF 25V 0603 X5R 22µF 10V 1206 X5R 82.5k 1MHz 80.6k 2.5MHz 31.6k 2.7 to 18.5V –8V 4.7µF 25V 0603 X5R 2x 47µF 10V 1206 X5R 95.3k 1MHz 80.6k 2.5MHz 31.6k 2.7V to 20V 12V 4.7µF 25V 0603 X5R 22µF 16V 1210 X5R 130k 1MHz 80.6k 2.5MHz 31.6k 2.7V to 20V –12V 4.7µF 25V 0603 X5R 47µF 16V 1210 X5R 143k 1MHz 80.6k 2.5MHz 31.6k 2.7V to 20V 15V 4.7µF 25V 0603 X5R 22µF 16V 1210 X5R 165k 1.1MHz 73.2k 1.9MHz 41.2k 2.7V to 20V –15V 4.7µF 25V 0603 X5R 47µF 16V 1210 X5R 178k 1.1MHz 73.2k 1.9MHz 41.2k 3V to 20V 18V 4.7µF 25V 0603 X5R 22µF 16V 1210 X7R 200k 1.5MHz 53.6k 1.8MHz 45.3k 3V to 20V –18V 4.7µF 25V 0603 X5R 22µF 16V 1210 X7R 215k 1.5MHz 53.6k 1.8MHz 45.3k 3.7V to 18V 24V 4.7µF 25V 0603 X5R 22µF 25V 1206 X5R 274k 1.5MHz 53.6k 1.8MHz 45.3k 3.7V to 18V –24V 4.7µF 25V 0603 X5R 22µF 25V 1206 X5R 287k 1.5MHz 53.6k 1.8MHz 45.3k Note: An input bulk capacitor is required. |
Аналогичный номер детали - LTM8049 |
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Аналогичное описание - LTM8049 |
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