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A high-efficiency high-current DC power supply design and production

In Electronic Infomation Category: A | on April 26,2011

Many electronic fans in DIY, often need a large output current, DC power supply with excellent performance, and DS90CF581MTD datasheet and hope that this DC power supply can also quite easy to change at any time according to their needs the size of the output voltage . This article describes the use of MP1593 made a DC-DC power supply, this DC-DC power supply size is small, but it can provide up to 2A or 3A of output current, and DS90CF581MTD price and its performance is very good, can DIY electronics enthusiasts to meet the time requirements in, the following principles and DS90CF581MTD suppliers and practical aspects of making some of the issues to make a detailed introduction.

1, MP1593 Introduction to the structure and working principle

MP1593 companies in the United States MPS (Monolithic PowerSystems, Inc) to develop and produce a step-down (Step-down) DC-DC devices, it uses a small 8 pin SOP package, the volume is very small, only 5mm 4mm 1.5 mm size. The IC allows the input voltage range from 4.75 ~ 28V, output current up to 3A, the highest efficiency of up to 95%. Typical data of the IC is: when the input 12V, output 5V, and the current of 2.5A, its efficiency is 90%. In such a high voltage difference, the high current case, the IC to work 24 hours straight and need not install any cooler, we can see the power consumption is very small. In addition, the integrated peripheral circuits are very simple and very easy to apply. MP1593

Figure 1 is a typical part of the internal circuit and external applications schematic.

Figure 1 MP1593 typical application circuit and the external part of the internal schematic diagram

The IC works are summarized below.

Input voltage Vin from the end into the integrated circuit pin 2, then if the pin 7 (Enable) terminal plus high (+5 V or so), the IC is activated into working condition. Time Ton (conduction time), the input voltage through the conduction of the MOS V1 tube end from the ICs pin 3 output, plus the left side of the inductor L1, the voltage through the composition of L1 and capacitor C5 to the load RL filter circuit power , while the electric energy stored on the inductor L1. In the time Toff (off time), MOS tube V1 is in the off state, then, in the energy storage device to generate the self-inductance of the inductor L1 voltage is negative the right is left, so added to the voltage on the diode D1 is forward biased set voltage, resulting in diode conduction, therefore, the inductor L1 and diode D1 and the load RL to form a discharge circuit, the inductor L1 to the load of power on the RL store release, in order to provide the required power load RL. Circuit waveforms, such as points (Figure 2) shows.

circuit of Figure 2 plot the points The regulator output voltage Vout

control process are summarized below. Resistors R1 and R2

voltage divider circuit composed of the output voltage Vout from the end of the sampling voltage out, then pin 5 to the end of the error voltage amplifier IC Y3 internal inverting input, and the IC internal settings of the Canadian side in the same phase 1.22V reference voltage comparison, so that the error voltage amplifier output voltage Ua Y3 produce a corresponding change in the voltage Ua is sent to IC internal current comparators inverting input Y2; the other hand, IC internal resistance R the output circuit through the current sampling, to obtain a sample voltage. The voltage through the current sense amplifier to amplify Y1 obtained by the voltage Ub, the voltage is sent to the current comparators inverting input Y2. These two voltages Ua and Ub together determine the current comparator Y2 the size of the output voltage Uc, and Uc is the voltage of the internal logic IC input control signal. Through the control logic circuit to change the MOS tube V1, the relative length of time off, change the inductor L1 is charged and discharged on the length of time that the Ton (turn-on time) and Toff (off-time) the relative length of thus changing the average voltage on the inductor size, that is, change the size of the output voltage Vout, and ultimately the output voltage Vout of the regulator control. The regulation process is essentially a feedback control process. Regulators from the control process described above, we see that: as long as the external resistors R1 and R2 change in the ratio of the voltage can change the size of sample, which also changes the size of the output voltage Vout, in fact, the circuit is by adjusting the ratio of resistors R1 and R2 to achieve the size of the output voltage Vout regulation.

MP1593 features of the pin definitions in Table 1.

Table 1 MP1593 functional description of each pin

2, MP1593, and some of the practical application of circuit design features

IC design using Fengyun the practical application of +5 V power supply circuit shown in Figure 3.

Figure 3 +5 V power supply of useful applications

On this circuit, there are several points as follows:

1). Here in the resistors, capacitors and other components are based on SMD components. The benefits of using chip-type components: First, the volume of the entire circuit can be very small, the second is to make a very compact arrangement of the components in order to avoid long cable between the components caused by the introduction of external interference to make the circuit work instability.

2). Capacitor C4, C5 can not use electrolytic capacitors, which must be multi-layer ceramic dielectric chip capacitors (MLCC capacitor that is), it is best to type with X7R or X5R type of chip capacitors, because the capacitor filter better, to ensure that the output voltage Vout of the ripple voltage small.

3). C2 must be X7R type of chip capacitors, but also as close to the MP1593, made from the input to ensure that the introduction of high frequency interference is minimized.

4). D1 must be greater than 3A forward current of the Schottky diode (Schottky barrier diode) to ensure that when the internal MOS IC tube V1 off, the inductor L1 can be provided quickly enough to the load current .

5). R3, R4, R5 must be in error is 1% of the chip resistors, to ensure the accuracy of the output voltage Vout. R4, R5 in series is also more convenient to adjust the Vout, to achieve the desired accuracy requirements.

6). L1 shaped by wire-wound chip inductors, the rated current of 2A or above must be met.

7). Resistors R1, R2 voltage divider circuit composed of series voltage separation of about 5V from the 12V voltage to pin 7 of about end as the start signal of the circuit. Circuit, all components used in the model specifications shown in Table 2.

Table 2 List of Electronic Components

3, Conclusion Design of the integrated circuit MP1593

DC power, the following points worth noting:

1). If the output voltage but not the +5 V +3.3 V, +1.8 V or other output voltage, then the application in the design MP1593 circuit, (Figure 3) the parameters of certain components is necessary adjustments, such as: L1, D1, C6, R3, R4, R5, R6 both the output voltage of the need to re-select the appropriate parameters.

How to choose parameters? MPS can refer to the IC MP1593 company press release the latest version of the file specifications: MP1593 DatasheetRev 2.0. Pdf.

2). In the PCB layout, you must pay attention to the arrangement of ground methods.

General requirements to enter the part of the ground and the output part of the ground at one point were summarized after each interconnect, and the location as close to the MP1593 summary of the pin 4 (GND) terminal.

3). In the PCB wiring, L1, D1, C3 must be connected at one point and end with the MP1593s pin3 connected line segments to be as short as possible, thicker.

4). In the PCB wiring, L1, D1, C4 these components in the PCB, the area enclosed by a small number as possible, in fact, is to ask these few components as possible in a mutually arranged close to these. Some measures are more than

designed to make practical application of the circuit with excellent job stability, the output voltage ripple, output voltage accuracy, signal to noise ratio and so forth have received very good performance. In fact, I have used in the MP1593 portable DVD products designed to +5 V, +3.3 V, +1.8 V DC power circuit of three, the actual measured performance of the aircraft is very good, very small output voltage ripple , the measured SNR audio system has reached more than 90dB, the brightness of the video system to achieve a 60dB signal to noise ratio more than adequately proved that the circuit has good practicability.

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