Negative voltage design has a lot of different plan according to different load current, it is to give out below a few kinds of negative voltage plan with at present commonner market, can use proper program according to different situation.

 

One, output of labour frequency transformer is losing voltage

 

Graph transformer of 1 labour frequency is losing output power source

 

Each engineer sees a picture whether does the circuit of 1 have very strong friendly feeling, whether can you remember to the scene when is the electron designed is contacted when the university? This classical circuit advantage is clearer, circuit structure is extremely simple, low interference noise, stability is good; This circuit is faulty also at the same time, range of input alternating current is narrow (it is 220VAC±5% commonly) , bulk weight is great; Although this circuit defect still has a few application at present apparently,use this plan to design. This plan basically is to use transformer to produce negative voltage to be in through linear manostat 7905 undertake stabilized voltage.

 

2, output of power source module loses voltage

 

Because technology of electronic component workmanship is better and better, energy loss is smaller and smaller, come so more and more those who be helpful for power source is modular development. And also can accomplish miniaturization on the design, light-duty change a design.

 

1, output of blame segregation negative pressure loses voltage

 

Graph stabilized voltage of 2 blame segregation outputs module

 

Graph of module of 3 blame segregation output and negative output receive a standard

 

If the graph is shown 3 times, application of module of this power source and commonly used LM7805 are similar, and do not need to install carbon fin. As above graph, we need to losing voltage to be put to carry when waiting for power supply, need two E78xxOS-500 power source to be able to come true only.

 

2, output of module of segregation power source is losing voltage

 

Graph module of 4 segregation power source is losing two-way output

 

Representative application of power source of graph 5 E_URADD-6W

 

Taller to demand of interference rejection performance circumstance waits in electric power, industry, communication, general need undertakes to power source processing will keep apart the interference that carries from total power supply keeping apart. When this kind of application if need to use negative tension, can use module of segregation power source directly direct output is losing voltage to give a system power supply.

 

3, Buck-Boost develop attacks design output loses voltage

 

Besides adopt segregation module plan, we still can choose him chip to design negative pressure circuit, the blame that we introduce here to be designed more easily keeps apart negative pressure to output Buck-Boost circuit. If pursue,6 this circuit need only advocate dominate the chip, chip such as inductance, capacitance, at present the chip of DC-DC power source of MPS supports the design construction of Buck-Boost, can choose appropriate model according to different output electric current.

 

Develop of graph 6 Buck-Boost attacks principle

 

From the graph the develop of 6 attacks in can seeing input voltage and output voltage polarity is contrary, because this Buck-Boost develop attacks structure abbreviation attacks to pour photograph develop. Graph 7 it is to use what MP2359DT designs – circuit of 15V power source, MP2359DT is those who use SOT23-6 enclose, whole circuit takes up PCB area is lesser.

 

Graph 7 MP2359 negaive electricity presses output circuit

 

4, summary

 

Program of negative voltage design is varied, which plan suits your design, still need to consider integratedly to differ to application, different technique asks and be decided.