Description
This is a DC-DC step-up converter based on LM2585-ADJ regulator manufactured by Texas Instruments. This IC was choosen for it's simplicity of use, requiring minimal external components and for it's ability to control the output voltage by defining the feedback resistors (R1, R2). NPN switching/power transistor is integrated inside the regulator and is able to withstand 3A maximum current and 65V maximum voltage. Switching frequency is defined by internal oscillator and it's fixed at 100KHz.
Additional features include soft-start circuit to eliminate current spikes during start-up and internal current limit. Output voltage regulation is 4% within input voltage and load specifications.
Schematic
Specifications
Vin 10-15V DC
Vout 24V
Iout 1A
frequency 100KHz
Schematic is a simple boost topology arrangement based on datasheet. Input capacitors and diode should be placed close enough to the regulator to minimize inductance effects of pcb traces. IC1, L1, D1, C1, C2 and C5, C6 are the main parts used in voltage conversion. Capacitor C3 is a high frequency bypass capacitor and should be placed as close to IC1 as possible.
All components are selected for their low loss characteristics. So capacitors selected have low ESR and inductor selected has low DC resistance.
At maximum output power there is significant heat produced by IC1 and for that reason we mounted it directly on the ground plane to achieve maximum heat radiation.
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