Design of 28V-25V voltage converter based on LM1575-5.0 chip

LM1575 is a 1A step-down monolithic switching regulator produced by NS Company. LM1575 is a military-grade product. LM1575 contains a 52 kHz oscillator, reference circuit, thermal shutdown circuit, current limit circuit, amplifier, comparator and internal voltage stabilizing circuit. It only requires a few peripheral components to form an efficient voltage stabilizing circuit. And it has a complete protection circuit inside, making it an ideal substitute for traditional three-terminal voltage stabilizing integrated circuits. Each product in the LM1575 series can provide products with multiple voltage levels such as 3.3 V, 5V, 12V, 15V and l(ADJ) (the number in the model suffix is ​​the rated output voltage). The main parameters of the LM1575 series switch integrated circuit are as follows: maximum output current: 1 A; maximum input voltage: LM1575 is 45 V; oscillation frequency: 54 kHz; maximum voltage stabilization error: 4%; conversion efficiency: 75%--88% (Different voltages have different output efficiencies);
Because LM1575 has a series of advantages such as high efficiency and fewer external components, it is widely used in CRT monitors, LCD monitors, televisions, power adapters, automatic control equipment power supplies, and standby power supplies. etc. in the circuit.
This circuit uses National Semiconductor's LM1575-5.0, which forms a very simple switching regulator that converts 28Vdc from the voltage bus into 5Vdc with 80% efficiency. This voltage is used as a 5V, 1A power supply to power other circuits. .