[introduction] power source management attacks through certain circuit pictures, the output voltage that different power source the input changes into contented system work to need. Power source is affecting systematic performance directly, and the crucial element that decides power source function is chip of power source government (Power Management Integrated Circuits, PMIC) .

Power source management attacks through certain circuit pictures, the output voltage that different power source the input changes into contented system work to need. Power source is affecting systematic performance directly, and the crucial element that decides power source function is chip of power source government (Power Management Integrated Circuits, PMIC) .

The applied field with the biggest PMIC is electronic consumer goods, telegraphic, labour accuses the domain such as terminal of equipment, car to also have persistent demand to PMIC. All electron equipment has power supply, but different system is different to the requirement of power source. To develop the property of electronic system, the power source that need chooses to suit runs way.

1.What power source changes is basic need to know

The component of power source management with proper choice depends on the input of this application and output condition.

• Is power source input communication (AC) or dc (DC) ?

• Is inputting voltage prep above or the output voltage that need under place?

• How much is needs load current?

• Load is right noise is sensitive, or need constant current (the application that is like LED) , or be the electric current with bigger change?

Each application is based on its special demand, can choose different power source to change element. Next graphs show several application example and its typical and commonly used power source change element;

Graph 1. The applied example of power source management

Can be clear about from afore-mentioned example know, be about to get optimal component to choose to must consider all sorts of parameter. Will introduce these parameter in detail below.

2.Of IC of power source management choose a level

When the design, what consider above all is the voltage difference that inputs output (VIN – VOUT) . When choosing solution of first-rate power source, the special demand of this application, like efficiency, medicinal powder hot limitation, noise, complex degree wait to must consider with cost.

Express 1. Poor manostat of choice low pressure, step-down, step up, rise – the basic standard of step-down converter

3.Framework of main power source and power source manage postmortem component

Be less than VIN when VOUT, what needing to output electric current and VIN / VOUT to compare is consideration choice low pressure poor linear manostat (LDO) or step-down converter (the main factor of Buck) .

Low-pressure poor linear manostat (the application that LDO) suits to need low noise, small electric current and low VIN / VOUT to compare very much. Its are basic circuit graph pursues it is thus clear that 2. Low-pressure poor linear manostat (means of linear of LDO) by means of accuses what control and guide connects component to guide, output voltage in order to adjust. Linear manostat is offerred accurate and the output voltage that does not have noise, the load that because should be outputted,can carry quickly changes. However, linear adjustment mean is worn input-output voltage difference is multiplied on average load current is the power that linear manostat guides place uses up a component, namely Pd = (VIN – VOUT) * ILOAD. Tall VIN / VOUT has caused much more additional power loss than be being met with tall load current.

Graph 2. Low-pressure poor linear manostat (sketch map of LDO) basic circuit

Power uses up taller low-pressure poor linear manostat (LDO) need is bigger enclose dimension, and this meeting increases space of cost, PCB board and heat energy to use up. Exceed ~0.8W when LDO power comsumption so when, more well-advised course of action is to change collect step-down converter to serve as replacement scheme.

When choosing LDO, beard consideration input and the voltaic size that output the limits of voltage, LDO come loose with what enclose heat energy force. LDO voltage difference is to point to inside adjustable limits, the least tension of VIN – VOUT. In small power application, if need the application that relies on single cell power supply a lot of years, IQ of electric current of LDO static state must quite low, use up needlessly in order to reduce batteries; And this kind of application needs special, the low pressure that has IQ of electric current of small static state differs linear manostat (LDO) .

Step-down converter is converter of step-down of type of a kind of switch, it can be under the load current with taller taller than mixing VIN / VOUT, offer efficient the output with tall flexibility. Its basic circuit is shown 3 times like the graph. Most step-down converter includes the MOSFET that high side MOSFET and a low side regard an interior as synchronous commutator, borrowing interior to occupy sky comparing to control circuit to control both leave alternately, close (ON/OFF) outputs voltage on average with adjusting. The noise that switch causes can filter by exterior LC filter.

Graph 3. Converter is basic circuit sketch map

Because two MOSFET are alternant switch (ON or OFF) , so power is used up very small; Control of by means of occupies sky comparing, can generate the output that bigger VIN / VOUT compares. The guides electrify block RDS(ON) decided step-down converter electric current of in-house MOSFET handles ability, and the rated voltage of MOSFET decides voltage of the biggest input. The ripple voltage size that switch switch frequency and component of exterior LC filter decide to output end jointly; The filter wave cell that the step-down converter of frequency of taller switch switch uses but lesser, but the power comsumption that switch switch causes can increase. Have pulse leap pattern (the step-down converter of PSM) can reduce frequency of its switch switch when carrying gently, the efficiency when rising to carry gently thereby, this character is low to needing power comsumption bides his time the application of mode is very important.

Step up converter is the application that is used at VIN of VOUT prep above. If the graph is shown 4 times,basic circuit pursues. Step up converter rises input tension to taller output voltage. Its operation principle is by interior MOSFET charges to inductor, and when MOSFET opens circuit, discharge inductance through the commutator that carries to load. Inductance charges turn to be able to make for discharge inductance voltage turns into retrorse, the prep above VIN that lifts output voltage makes thereby. The ON/OFF of MOSFET switch occupies sky comparing to will decide step up compares VOUT / VIN, and feedback loop also is controlled occupy sky comparing to output voltage steadily in order to maintain. Outputting capacitance is amortize component, with will reduce output voltage Lian Bo.

Absolutely the biggest rating and step up compare MOSFET electric current to decide the biggest load current together, and absolutely the biggest rating decides MOSFET voltage voltage of the biggest output. Converter of some step up is met rectifier with MOSFET conformity at interior, achieve the effect of synchronous commutate.

Graph 4. Step up converter is basic circuit sketch map

Litre – step-down converter is used at inputting voltage to may be changed, but under or the application of voltage of prep above output. Be like what the graph shows 5 times to rise – in step-down converter, when VOUT of VIN prep above, 4 in-house MOSFET switch become automatic configuration step-down converter, and when VIN under turn to operate mode for step up when VOUT. This makes litre – the application that step-down converter suits to serve as power supply with batteries very much, output voltage at adjusting when batteries report depress especially when the value, be able to lengthen batteries to use time. Because four switch rise – the operation mode that step-down converter is complete synchronism, reason can amount to taller efficiency. The capability of output electric current when step-down mode is higher than be when step up mode; Because be below same laden condition, step up mode and step-down mode photograph are compared under, the switch electric current with former taller need.

Absolutely the biggest rating will decide the voltage of MOSFET the biggest input and output voltage limits. In the application that does not need referenced ground connection in output voltage, be like LED driver, can use what have odd switch and commutator only to rise – step-down converter. And fall in most circumstance, outputting voltage is referenced to VIN.

Graph 5. Have 4 in-house switch rise – step-down converter

Component of most power source management is to use afore-mentioned 4 converter frameworks among them a kind.

Use interior or external MOSFET?

Need electricity of very big switch (be like > 10A) application, can use normally external switch MOSFET, and cooperate use step-down controller or step up controller. Means of this kind of configuration is the power converter that is used in output power to exceed 25W normally.

Output electric current > the step-down application of 25A uses heterogeneous more step-down controller, the phasic phase that differs namely shares same electric current. Provide the circuit of voltage of very tall switch, for example in the applied circuit from power supply of AC line voltage, the controller that can use normally is to use exterior, be able to bear or endure high-pressured MOSFET.

What LED driver adjusts is stable output electric current, is not stable output voltage, because specific light outputs LED,be complete will decide by electric current. Of LED of most tall brightness to voltage be 3? 3.5V; And the amount of the LED in be being strung together according to inputting voltage and LED, converter can be step-down, step up or rise – step-down.

LCD is in a poor light the system needs the LED with many drive, because this meeting is used,string together to how model LED driver. Certain the framework that can use linear LED driver from driver of line type LED. Most LED driver still includes to move smooth function, so that can control output electric current, keep abreast of and control the smooth output of LED.

Graph 6. LED drive is main circuit

Protect a function

Security and dependability are power source is supplied implement require special attention. Most converter includes to protect a function, make its can cross the circumstance with working big or exorbitant temperature to fall in load, supply power supply implement shut surely.

Power switch can use course of control power source to whether put through at circuit. Its are basic circuit is shown 7 times like the graph.

Graph 7. The power switch of function of tie-in and different protection

Supply implement power source of monitoring IC meeting monitoring is pressed too or owe the case that press. Graph the 8 power source monitor that show a pattern diagnose power source to owe the case that press.

Graph 8. IC of power source monitoring diagnoses power source to owe control state

Batteries charger IC can offer correct charging current and voltage in the light of specific batteries in application.

Graph 9. The basic circuit of linear batteries charger

AC / DC stimulates type controller to be used at needing to turn AC line voltage to be the application of the power source voltage of a stability, segregation instead. The graph is shown 10 times turn over the power source that stimulate type basically for.

Graph 10. Basic AC/DC stimulates type power source instead

The trend of power source management

Blue tooth of low power comsumption, Wi-Fi 6 and net of beehive content couplet brought join sex for equipment of network of couplet of content of low power comsumption. But, power source management needs efficient chip not just, the electric energy that comes from batteries or power source also must undertake adjust and allocation, if equipment by can charge batteries power supply, need to charge sometimes. This is meant, no matter how the processor in wireless chip, radio and memory are efficient, if power source manages a system to did not undertake enough optimizing, can affect battery life.

Compose builds system of efficient power source management had been a formidable task originally, and should come true at the same time compact model the design has challenge sex more. The space of products of a lot of content couplet network is finite, but solution of traditional power source government is comprised by many chip normally, for example charger of manostat, batteries, coulombmeter, exterior watchdog and hard restoration device, these metropolises take up valuable space.

Does Nordic manage IC through NPM series power source? (PMIC) solved power source management to be in efficiency and space the difficult problem of two respects. This series is newest the NPM1300 that roll out has high accuracy coulombmeter, but accurate measure n of batteries the rest, prolonged the battery life of equipment of content couplet network.

Article origin: Electronic project special

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