Tool/software:
Hello Support Team,
I am designing a backlight driver circuit using the TPS61500 and have selected a switching frequency of 1.2 MHz to minimize the power stage components and reduce the physical size of the design. Below are the details of my circuit:
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Input voltage: 3.3V (range: 3.0V to 3.6V)
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Output voltage: 25V (24.8V + 0.2V FB voltage)
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Maximum output current: 200mA
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Switching frequency: 1.2 MHz (range: 1 MHz to 1.4 MHz)
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Maximum ambient temperature: 70-75°C
I have two capacitor options and would like to know which one is more suitable for my design.
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Option 1: 2 x 4.7 µF, 50V, 0805 capacitors
The self-resonant frequency of this option is around 3 MHz, but with DC bias up to 80%, the effective capacitance at 25V will be reduced to 1.88 µF.
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Option 2: 2 x 4.7 µF, 50V, 1206 or 1210 capacitors
This option provides an effective capacitance of 5.17 µF at 25V, but the self-resonant frequency is around 1.8 to 2 MHz.
Given that the recommended operating conditions suggest a minimum output capacitance of 4.7 µF, and the notes on page 15 recommend a capacitance range of 1 µF to 10 µF.
Which option would you recommend for my circuit?
Best regards,
Malek
