AP63203 datasheet(12/18 Pages) DIODES

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AP63200/AP63201/AP63203/AP63205

Application Information (continued)

Power Derating Characteristics

To prevent the regulator from exceeding the maximum junction temperature, some thermal analysis is required. The temperature rise is given by:

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Eq. 4

Where PD is the power dissipated by the regulator and

θJA is the thermal resistance from the junction of the die to the ambient temperature.

The junction temperature, TJ, is given by:

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Eq. 5

Where TA is the ambient temperature of the environment. For the TSOT26 package, the θJA is 89°C/W. The actual junction temperature should not

exceed the absolute maximum junction temperature of +125°C when considering the thermal design. A typical derating curve versus ambient

temperature is shown in Figure 24.

Figure 24. Output Current Derating Curve vs. Temperature, VIN = 12V

Setting the Output Voltage

The AP63203 and AP63205 have fixed output voltages of 3.3V and 5V, respectively. The AP63200 and AP63201 have adjustable output

voltages starting from 0.8V using an external resistive divider. An optional in Figure 20, of 10pF to 220pF is used to improve the transient

response. Resistor R2 is selected based on a design tradeoff between efficiency and output voltage accuracy. There is less current consumption

in the feedback network for high values of R2. R1 can be determined by the following equation:

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��

−��)

Eq. 6

AP63200/AP63201/AP63203/AP63205

Document number: DS41326 Rev. 2 - 2

12 of 18

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January 2019

AP63203 датащи(PDF) 12 Page - Diodes Incorporated