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Datenblatt-Suchmaschine für elektronische Bauteile |
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Datenblatt-Suchmaschine für elektronische Bauteile |
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LM2853 Datenblatt(PDF) 11 Page - Texas Instruments |
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LM2853 Datenblatt(HTML) 11 Page - Texas Instruments |
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11 / 20 page  Applications Information (Continued) TABLE 3. Recommended Capacitors (Continued) Capacitance (µF) Part Number Chemistry Vendor 220 TPSD227M006#0050 Tantalum AVX 220 NOSD227M0040060 Niobium Oxide AVX SPLIT-RAIL OPERATION The LM2853 can be powered using two separate voltages for AVIN and PVIN. AVIN is the supply for the control logic; PVIN is the supply for the power FETs. The output filter components need to be chosen based on the value of PVIN. For PVIN levels lower than 3.3V, use output filter component values recommended for 3.3V. PVIN must always be equal to or less than AVIN. 20201513 SWITCH NODE PROTECTION The LM2853 includes protection circuitry that monitors the voltage on the switch pin. Under certain fault conditions, switching is disabled in order to protect the switching de- vices. One side effect of the protection circuitry may be observed when power to the LM2853 is applied with no or light load on the output. The output will regulate to the rated voltage, but no switching may be observed. As soon as the output is loaded, the LM2853 will begin normal switching operation. LAYOUT GUIDELINES These are several guidelines to follow while designing the PCB layout for an LM2853 application. 1. The input bulk capacitor, C IN, should be placed very close to the PVIN pin to keep the resistance as low as possible between the capacitor and the pin. High current levels will be present in this connection. 2. All ground connections must be tied together. Use a broad ground plane, for example a completely filled back plane, to establish the lowest resistance possible be- tween all ground connections. 3. The sense pin connection should be made as close to the load as possible so that the voltage at the load is the expected regulated value. The sense line should not run too close to nodes with high dV/dt or dl/dt (such as the switch node) to minimize interference. 4. The switch node connections should be low resistance to reduce power losses. Low resistance means the trace between the switch pin and the inductor should be wide. However, the area of the switch node should not be too large since EMI increases with greater area. So connect the inductor to the switch pin with a short, but wide trace. Other high current connections in the application such as PVIN and V OUT assume the same trade off between low resistance and EMI. 5. Allow area under the chip to solder the entire exposed die attach pad to ground for improved thermal perfor- mance. Lab measurements also show improved regula- tion performance when the exposed pad is well grounded. LM2853 Example Circuit Schematic 20201514 FIGURE 1. www.national.com 10 |
Ähnliche Teilenummer - LM2853 |
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Ähnliche Beschreibung - LM2853 |
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