You can use Dongke DK124 is an off-line switching power supply chip with a maximum output power of 24W.
If the output current is very small, you can build a square wave oscillator (such as 74HC04 inverter and resistor capacitor), and then double the voltage rectification. If the output current is high, it can only be achieved by switching power supply chips.
V boost to 5V should consider using DC conversion integrated circuit! This DC-DC conversion circuit is simpler than that composed of triodesThe voltage circuit is much more efficient. Many dedicated conversion chips can work normally at voltages above 3V.
DC-DC refers to a type of switching power supply, which refers to DC-DC conversion.
A DC-DC power supply is a power supply that converts a DC power supply into another DC power supply. It usually consists of a transformer, a control circuit and an output circuit. The transformer converts the input voltage into another voltage, the control circuit controls the output of the transformer, and the outputThe circuit converts the output of the transformer into the desired voltage.
dc-dc is a newly developed miniaturized power switch module, which uses microelectronics technology to assemble small surface-mounted integrated circuits and micro electronic components into one.
DC-DC power supply is usually a kind of switching voltage regulator power supply. Switching regulated power supply is composed of full wave rectifier, switching tube, excitation signal, continuous current diode, energy storage inductor and filter capacitor. In fact, the core part of the switching regulated power supply is a DC transformer.
The analog signal isolation circuit composed of linear optical coupler has good linearity and simple circuit, which effectively solves the problem of electrical isolation between analog signal and single-chip microcomputer application system. If the driver stage and buffer stage are combined operational amplifiers, the linearity can be improved.
Watchdog: There are many kinds, I commonly used max691/ca1161 and DS18. TPS796** has a fixed output, there are also adjustable output, the range between 2-5V, the market is quite a lot. (but no more than 1117) It is also possible to use 1117, and add a MOS tube control in front of it.
2, the use of switching power supply chip LM2576HVT-5 (with 5-pin patch) as long as 5 devices, 2 input and output filter capacitors, a Schottky diode, an inductor (with patch inductor, pay attention to power capacity). Just use LDO for the rest.
3, the most obvious is the increase of positive and negative 3V and positive 5VStandBy two outputs and a PS-ON signal, and change the power output line to a 20-core power cable to supply power to the motherboard.
4, series three-terminal integrated voltage regulator power supply is a linear voltage regulator power supply, requiring the input voltage is not lower than the output voltage 3V, so the output 5V, the input minimum voltage is 8V, the maximum should not exceed 1 times the output voltage, otherwise the efficiency will decrease. (Up to 32V) If you want to boost the output, you can use a switched voltage regulator power supply.
5, with 12V reduced 5 V, and the output is nearly 10A, 12V power output current, mustMust be greater than 10A. With 7805 three-terminal voltage regulator maximum output 3A, and then with high frequency and high power composite pipe connection, the output current can meet the requirements.
No all I/O are isolated in this design, the need for power isolation is generally external interfaces, such as 485, these interfaces only need a few wires, light coupling isolation can be, 51 MCU here with the original electricitySource, 485 use isolated power. I'd like to show you your picture so that you can have a reference.
MOV P1, #0FEH; Then P7-P1 is the input port and P0 is the output port.
P1, P2, and P3 have internal pull-up two-way output IO ports. P0 port has no internal pull-up resistance and is an open leakage output port. If used as an ordinary IO port, a pull-up resistance is added in addition to P0 port, which has the same function. The P3 port generally has a second function such as an external interrupt, serial port, etc.