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LT1963AEST-1.8 数据表(PDF) 19 Page - Linear Technology |
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LT1963AEST-1.8 数据表(HTML) 19 Page - Linear Technology |
19 / 28 page LT1963A Series 19 1963aff For more information www.linear.com/LT1963A applicaTions inForMaTion The following tables list thermal resistance for several different board sizes and copper areas. All measurements were taken in still air on 1/16" FR-4 board with one ounce copper. Table 3. Q Package, 5-Lead DD COPPER AREA THERMAL RESISTANCE TOPSIDE* BACKSIDE BOARD AREA (JUNCTION-TO-AMBIENT) 2500mm2 2500mm2 2500mm2 23°C/W 1000mm2 2500mm2 2500mm2 25°C/W 125mm2 2500mm2 2500mm2 33°C/W *Device is mounted on topside Table 4. S0-8 Package, 8-Lead SO COPPER AREA THERMAL RESISTANCE TOPSIDE* BACKSIDE BOARD AREA (JUNCTION-TO-AMBIENT) 2500mm2 2500mm2 2500mm2 55°C/W 1000mm2 2500mm2 2500mm2 55°C/W 225mm2 2500mm2 2500mm2 63°C/W 125mm2 2500mm2 2500mm2 69°C/W *Device is mounted on topside Table 5. SOT-223 Package, 3-Lead SOT-223 COPPER AREA THERMAL RESISTANCE TOPSIDE* BACKSIDE BOARD AREA (JUNCTION-TO-AMBIENT) 2500mm2 2500mm2 2500mm2 42°C/W 1000mm2 2500mm2 2500mm2 42°C/W 225mm2 2500mm2 2500mm2 50°C/W 100mm2 2500mm2 2500mm2 56°C/W 1000mm2 1000mm2 1000mm2 49°C/W 1000mm2 0mm2 1000mm2 52°C/W *Device is mounted on topside T Package, 5-Lead TO-220 Thermal Resistance (Junction-to-Case) = 4°C/W Calculating Junction Temperature Example: Given an output voltage of 3.3V, an input volt- age range of 4V to 6V, an output current range of 0mA to 500mA and a maximum ambient temperature of 50°C, what will the maximum junction temperature be? The power dissipated by the device will be equal to: IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX)) where, IOUT(MAX) = 500mA VIN(MAX) = 6V IGND at (IOUT = 500mA, VIN = 6V) = 10mA So, P = 500mA(6V – 3.3V) + 10mA(6V) = 1.41W Using a DD package, the thermal resistance will be in the range of 23°C/W to 33°C/W depending on the copper area. So the junction temperature rise above ambient will be approximately equal to: 1.41W(28°C/W) = 39.5°C The maximum junction temperature will then be equal to the maximum junction temperature rise above ambient plus the maximum ambient temperature or: TJMAX = 50°C + 39.5°C = 89.5°C Protection Features The LT1963A regulators incorporate several protection featureswhichmakethemidealforuseinbattery-powered circuits. In addition to the normal protection features associated with monolithic regulators, such as current limiting and thermal limiting, the devices are protected against reverse input voltages, reverse output voltages and reverse voltages from output to input. Current limit protection and thermal overload protection are intended to protect the device against current overload conditions at the output of the device. For normal opera- tion, the junction temperature should not exceed 125°C. The input of the device will withstand reverse voltages of 20V. Current flow into the device will be limited to less than 1mA (typically less than 100µA) and no negative voltage will appear at the output. The device will protect both itself and the load. This provides protection against batteries that can be plugged in backward. |
类似零件编号 - LT1963AEST-1.8 |
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类似说明 - LT1963AEST-1.8 |
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