特瑞仕代理商泰德兰就变换器DC-DC和稳压器LDO详细区别、原理、特征分析
2018-04-19 13:33:16
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特瑞仕代理商泰德兰就变换器DC-DC和稳压器LDO详细区别、原理、特征分析。

What is the difference between DC/DC and LDO?

DC/DC和LDO的区别是什么?


DC/DC converters are generally composed of control chips, pole coils, diodes, transistors, and capacitors. DC/DC converter is a voltage converter that effectively outputs a fixed voltage after switching input voltage. DC/DC converters are divided into three types: boost DC/DC converters, step-down DC/DC converters, and uplift DC/DC converters. Three types of control can be used according to requirements. PWM has high efficiency and good output voltage ripple and noise. The PFM control model has the advantages of low power consumption even when used for a long time, especially for small loads. PWM/PFM switching small load is implemented by PFM control and automatically converted to PWM control during heavy load. Currently, dc-dc converters are widely used in mobile phones, MP3 players, digital cameras, portable media players and other products.

DC/DC转换器一般由控制芯片,电杆线圈,二极管,三极管,电容构成。DC/DC转换器为转变输入电压后有效输出固定电压的电压转换器。DC/DC转换器分为三类:升压型DC/DC转换器、降压型DC/DC转换器以及升降压型DC/DC转换器。根据需求可采用三类控制。PWM控制型效率高并具有良好的输出电压纹波和噪声。PFM控制型即使长时间使用,尤其小负载时具有耗电小的优点。PWM/PFM转换型小负载时实行PFM控制,且在重负载时自动转换到PWM控制。目前DC-DC转换器广泛应用于手机、MP3、数码相机、便携式媒体播放器等产品中。

LDO outline principle:

LDO简述原理:

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The main reason that linear regulators can achieve these characteristics is that the internal adjustment tube adopts P channel field effect tube rather than the PNP transistor in normal linear regulators. The field effect tube of P channel does not need the base current drive, so the power current of the device itself is greatly reduced. On the other hand, in the structure of PNP tube, in order to prevent PNP transistor from entering the saturated state to reduce the output capacity, it is necessary to guarantee the large input and output pressure difference. The pressure difference of the P channel field effect tube is approximately equal to the product of the output current and its conduction resistance, and the differential pressure difference of the small conduction resistance is very low. LDO is the best choice when the input voltage and output voltage are close to the system, which can be very efficient. So the lithium ion battery voltage is converted into a "is chosen mostly 3 v voltage applications, although there is no use ten percent of the battery finally discharge energy, but they can still in the low noise structure provides a longer battery life.

线性稳压器能够实现这些特性的主要原因在于内部调整管采用了P沟道场效应管,而不是通常线性稳压器中的PNP晶体管。P沟道的场效应管不需要基极电流驱动,所以大大降低了器件本身的电源电流;另一方面,在采用PNP管的结构中,为了防止PNP晶体管进入饱和状态降低输出能力,必须保证较大的输入输出压差;而P沟道场效应管的压差大致等于输出电流与其导通电阻的乘积,极小的导通电阻使其压差非常低。当系统中输入电压和输出电压接近时,LDO是最好的选择,可达到很高的效率。所以在将锂离子电池电压转换为3V电压的应用中大多选用LDO,尽管电池最后放电能量的百分之十没有使用,但是LDO仍然能够在低噪声结构中提供较长的电池寿命。


Portable electronic devices either by ac mains power supply after rectification (or ac adapter), or by the battery power supply, work process, supply voltage will change in large scope. For example, the voltage of a single lithium ion battery is 4.2V, and the voltage after discharge is 2.3V, and the range is very large. The output voltage of all kinds of rectifier is not only affected by the change of the electric voltage, but also affected by the load change. To ensure that the power supply voltage is stable, almost all electronic devices are powered by a voltage regulator. Small precision electronic equipment also requires very clean power (no ripple, no noise), so as not to affect the normal work of electronic equipment. In order to meet the requirements of the precision electronic equipment, the linear regulator should be added to the input end of the power supply to ensure the constant power supply voltage and realize active noise filtering.

便携电子设备不管是由交流市电经过整流(或交流适配器)后供电,还是由蓄电池组供电,工作过程中,电源电压都将在很大范围内变化。比如单体锂离子电池充足电时的电压为4.2V,放完电后的电压为2.3V,变化范围很大。各种整流器的输出电压不仅受市电电压变化的影响,还受负载变化的影响。为了保证供电电压稳定不变,几乎所有的电子设备都采用稳压器供电。小型精密电子设备还要求电源非常干净(无纹波、无噪声),以免影响电子设备正常工作。为了满足精密电子设备的要求,应在电源的输入端加入线性稳压器,以保证电源电压恒定和实现有源噪声滤波。

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LDO: is the abbreviation of lowdropoutvoltageregulator, rectifier)

LDO:是lowdropoutvoltageregulator的缩写,整流器)


Low pressure differential linear voltage stabilizer, hence the name, is a linear voltage regulator, can only be used in the application of reducing pressure. The output voltage must be less than the input voltage.

低压差线性稳压器,故名思意,为线性的稳压器,仅能使用在降压应用中。也就是输出电压必需小于输入电压。


Advantages: good stability, quick load response. The output ripple is small.

优点:稳定性好,负载响应快。输出纹波小。


Disadvantages: low efficiency, the input and output voltage difference cannot be too large. The load cannot be too large, the maximum LDO is 5A (but there are still many restrictions on the output of 5A).

缺点:效率低,输入输出的电压差不能太大。负载不能太大,目前最大的LDO为5A(但要保证5A的输出还有很多的限制条件)


DC/DC: DC voltage to DC voltage. Strictly speaking, LDO is also a kind of DC/DC, but current DC/DC multi-finger switching power supply.

DC/DC:直流电压转直流电压。严格来讲,LDO也是DC/DC的一种,但目前DC/DC多指开关电源。



There are many kinds of topology, such as BUCK, BOOST, etc.

具有很多种拓朴结构,如BUCK,BOOST,等。


Advantages: high efficiency, wide input voltage range.

优点:效率高,输入电压范围较宽。


Disadvantages: the load response is worse than the LDO, and the output ripple is larger than LDO.

缺点:负载响应比LDO差,输出纹波比LDO大。


I. basic principles of LDO.

一、LDO的基本原理

LDO,DC-DC,MOSFETs,TVS,AC-DC,电压检测器,POWER IC,IGBT,MOS,负载开关,TOREX,茂捷,AOS,松木代理商_深圳市泰德兰电子有限公司

Low dropout linear regulators (they) of the basic circuit as shown in figure 1-1, the circuit is changed from series tube VT (PNP transistor, note: actual applications, the commonly used here is p-channel field-effect tube), sampling resistor R1 and R2, comparative amplifier composed of A.

低压差线性稳压器(LDO)的基本电路如图1-1所示,该电路由串联调整管VT(PNP晶体管,注:实际应用中,此处常用的是P沟道场效应管)、取样电阻R1和R2、比较放大器A组成。


Figure 1-1 basic circuit of low voltage differential linear regulator.

图1-1低压差线性稳压器基本电路


Uin on sampling voltage comparator of A phase input, and added to the reference voltage at the inverting input Uref (Uout * / R2 (R1 + R2)), compared the difference. After amplified by the amplifier A Uout = (U + - U -) * A note A multiples, to compare the amplifier) control series adjustment of the pressure drop, and stable output voltage.

取样电压Uin加在比较器A的同相输入端,与加在反相输入端的基准电压Uref(Uout*R2/(R1+R2))相比较,两者的差值经放大器A放大后.Uout=(U+-U-)*A注A為比較放大器的倍數,)控制串联调整管的压降,从而稳定输出电压。


When the output voltage Uout reduce Uref benchmark voltage and Uin sampling voltage differential value increases, more amplifier output drive current increase, series adjustment of pipe pressure drop is reduced, so that the output voltage increases.

当输出电压Uout降低时,基准电压Uref与取样电压Uin的差值增加,比较放大器输出的驱动电流增加,串联调整管压降减小,从而使输出电压升高。



In contrast, if the output voltage Uout exceeds the required set value, the output voltage is reduced by reducing the front drive current of the amplifier output. During the power supply process, the output voltage correction is continuously carried out, and the adjustment time is limited only by the comparison amplifier and output transistor circuit reaction speed.

相反,若输出电压Uout超过所需要的设定值,比较放大器输出的前驱动电流减小,从而使输出电压降低。供电过程中,输出电压校正连续进行,调整时间只受比较放大器和输出晶体管回路反应速度的限制


Should note that the actual linear regulators should also has many other functions, such as load, short circuit protection, over voltage cut-off overheating shut off, reverse connect protection, etc., and also can use MOSFET series adjustment of pipe.

应当说明,实际的线性稳压器还应当具有许多其它的功能,比如负载短路保护、过压关断、过热关断、反接保护等,而且串联调整管也可以采用MOSFET。


DC-DC,(简述原理)

Dc-dc, (brief principle)


其实内部是先把DC直流电源转变为交流电电源AC。通常是一种自激震荡电路,所以外面需要电感等分立元件。

In fact, the DC DC power supply is converted to AC power supply. It is usually a self-oscillating circuit, so it requires discrete components such as inductance.

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然后在输出端再通过积分滤波,又回到DC电源。由于产生AC电源,所以可以很轻松的进行升压跟降压。两次转换,必然会产生损耗,这就是大家都在努力研究的如何提高DC-DC效率的问题。

Then at the output end through the integral filter, back to DC power. Because of the AC power generation, it can be very easy to carry on the lift and reduce pressure. Two transformations will inevitably result in loss, which is the problem that everyone is trying to study to improve the efficiency of dc-dc.


    对比:

Contrast:

1、DCtoDC包括boost(升压)、buck(降压)、Boost/buck(升/降压)和反相结构,具有高效率、高输出电流、低静态电流等特点,随着集成度的提高,许多新型DC-DC转换器的外围电路仅需电感和滤波电容;但该类电源控制器的输出纹波和开关噪声较大、成本相对较高。

1, DCtoDC including boost (boost), buck (step-down), boost/buck (l/step-down) and reverse phase structure, with high efficiency, high output current, low static current characteristics, with the improvement of integration, the periphery of the many new DC - DC converter circuit only inductor and filter capacitor; However, the output ripple and switching noise of this kind of power controller are large and relatively high.


2、LDO:低压差线性稳压器的突出优点是具有最低的成本,最低的噪声和最低的静态电流。它的外围器件也很少,通常只有一两个旁路电容。新型LDO可达到以下指标:30μV输出噪声、60dBPSRR、6μA静态电流及100mV的压差。

2. LDO: the outstanding advantage of low voltage differential linear regulators is the lowest cost, lowest noise and lowest static current. Its peripheral devices are also small, usually with only one or two bypass capacitors. The new LDO can achieve the following indexes: 30 mu V output noise, 60dBPSRR, 6 mu A static current and 100mV pressure difference.

                              


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