The basic design of power supply voltage switch circuit

The so-called power transfer is the input voltage through the pressure circuit to achieve the lift/buck function for the use of other modules, intelligent car production, the input battery voltage of 7.2V, the other modules required voltage as follows: Minimum system board/oled/Eagle Eye camera 3.3V, op amp power supply ±5 V, servo power supply 6V, Drive circuit 12V, ccd/encoder 5V. The following is about the switch circuit to do some related introduction.

Voltage Regulator circuit is mainly divided into the following categories:

1. LM2940 to 5V: LM2940 Series linear voltage regulator circuit (only for buck), this kind of circuit structure is simple, high stability, but large power consumption, large volume, low filtering efficiency, must have a large input and output filter capacitance.

2. LM2663 Turn -5v:

The LM2663 can be used as a simple negative-voltage converter that uses only two external capacitors for the voltage inverter circuit.

3. MC34063 to 12V MC34063 is a switch-type DC voltage regulator chip (available lift/buck), this kind of circuit power consumption is small, high efficiency, small size, light weight, wide voltage regulation range, but its circuit structure is more complex, high failure rate. It works by increasing the internal chip through the switching tube (its frequency and timing capacitance), energy storage inductance and capacitance for a short period of time charge and discharge to the load to provide power (inductor can choose a large point) to output continuous DC voltage, another uo=1.25* (1+R4/R3) (see Manual formula).

4. MIC29302 turn 6V: MIC29302 is a linear adjustable voltage regulator, using the same method as the 34063 circuit, can be used for large current load, the voltage output formula is uo=1.242* (1+R1/R2). In this case, the output 6V is supplied to the rudder.

5.1 5V ext. 3.3v (HT7833)

5.2 (sgm2019-3.3yn5g 5V ext. 3.3V)

Note: Should try to avoid due to manual errors and other reasons caused by the reverse circuit, can add anti-reverse design in the circuit

1. Unidirectional conductivity of the diode (tps73633-5v to 3.3V):

2. MoS Tube Type anti-reverse protection circuit NMOS is connected to the negative of the power supply, gate high-level conduction. The PMOs is connected to the positive of the power supply and the gate is low-level conduction.     (nMOS tube on resistance is smaller than pmos, preferably nMOS) 2. MOS tube Type anti-reverse protection circuit NMOS is connected to the negative of the power supply, gate high-level conduction. The PMOs is connected to the positive of the power supply and the gate is low-level conduction. (nMOS the resistance of the tube is smaller than the PMOs, preferably nMOS)
3. Various anti-reverse connectors