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The project engineering personnel faced with many challenges, one of them are for the medium power which develops unceasingly (each board <100W) the tabletop, the data communication and the telecommunication system provide the low voltage power distribution construction. The newest silicon product’s working voltage is marching into 1.0V~2.5V gradually the scope. In the computer and the telecommunication system, on each circuit wafer must realize the dc power source main line to isolate, but typical power source solution is mainly draws up a memo the output isolated-type dc/dc power source module by expensive many kinds to be composed. The cross many kinds of application domain’s system design personnel have the similar demand as well as to favor in use the dc/dc power source module the request. Mentioned frequently is to a thinner thickness, a smaller area, a higher efficiency and high efficiency density [1] and so on characteristic the demands. The new generation dc/dc power source module arises at the historic moment, is starting to march into the market to satisfy the above request. These pair of outputs and three output isolated-type module movement in the standard -48V bureau end power source, may provide 3W~100W the power. They are lowest including the output voltage reach 1.0V the module and the maximum output electric current reach 30The module. Size The system design personnel for realize the high performance signal processing electric circuit in a smaller space, faces the competition challenge is day by day intense. Advanced DSP and ASIC are helpful in provide this function, but the need more voltage low power source axle, and must have high accuracy sorting and the adjustment. Overall module number which needs through the reduced implementation electrical power system, the newest multi-output power source module has satisfied this request.
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| Many list output isolated-type module | the 33W efficiency outputs 3.3V/9A only | 89.0% | 3.7 | 42.38 US dollars | |
| the 20W list outputs 2.5V/8A | 75.0% | 3.06 | 38.52 US dollars | ||
| Grand total: | 77.6% | 9.82 | 119.42 US dollars | ||
| Single three output isolated-type module | 25A three output 3.3/2.5/1.8V | 87.0% | 5.41 | 96.64 US dollars |
The multi-output power source module provided has been possible to save the board level space the unique design choice. The distributional power source construction is seeping the telecommunication and the data communication market gradually. Speaking of needs to surpass three kind of different voltages the applications, the designers may use the multi-output module to provide the power source main line isolation, and may for each kind of loading point module power supply. This kind of disposition causes the designers not to need to worry again the use all list output module needs board level space.
Electrical specification
Sorting
Newest DSP, ASIC, FPGA and the microprocessor need many low voltages, and possible to request complicated and diversified Canada/power failure sorting. As a result of product going on the market time limit, numerous higher paraffin products (power source module is only this product module) outside the design does not have the time or the board level space constructs sets at the sorting electric circuit. Moreover, even if not the time and the board level space’s limit, they must consider the module cost increase. Is the choice uses compared with the simple solution may use the new internal sort multi-output power source module the system power source construction.
For example, such as Texas Instruments (TI) the PT4850 series’s three output module’s Canada characteristic can satisfy the microprocessor and the DSP chip set’s request. This module movement under the standard -48V input voltage, its fixed combination output current may reach 25A. The output voltage option uses in DSP or the ASIC essence low voltage output including one, as well as two use in I/O and other function extra supply voltage.
PT4850 has provided the best Canada order, may monitor the output voltage, and may when the short circuit and so on wrong situation appears provides all voltage track’s order closure. All three outputs carry on sorting in the interior in order to simultaneously add the electricity start.
When adds the electricity start, Vo1 at first climbs to approximately 0.8V, afterward Vo2 and Vo3 increase fast to and the Vo1 same voltage number. All three outputs then together increase, achieves up to its respective voltage until each. This module has the full-automatic adjustment output generally in 150ms. When closure, as a result of rectifier movable switch’s electric discharge effect, all output fast drop. The discharge time is 100 µ s generally, but acts according to the external load electric capacity to have a difference.
Efficiency
In low power application, even if the smallest dc/dc power source module also will possibly have several hundred milliwatt static losses. This solution loss mainly creates by the consumption power’s module, like the rectifier, exchanges the transistor and the transformer. If uses a part to provide needs two to three independences to group the work which originally the part does, then may reduce the consumption power module total quantity. As shown in Table 1, this raised 9.4% efficiencies.
Some newest multi-output module may in the sum total constant load electric current by 90% efficiency movement. Such high efficiency is exactly uses the MOSFET synchronous rectifier’s analysis situs by these to realize. This rectifier consumes electric quantity the Short base diode which uses the previous generation dc/dc power source module in consumes the electricity to be less.
Mutually constant voltage
The newest multi-output power source module uses the advanced electric circuit, eliminated mutually the constant voltage question, enhanced the output voltage ripple and the transient state is corresponding. According to the beforehand experience, will increase the output current in module any output to cause in other outputs the voltage change. TI PT4850 and the PT4820 series three output modules have solved this problem. The new generation power source module in isolates on the out-port which anti- bonds on each output to use the constant voltage control circuit. Through the appropriation magnetic coupling design, the control signal may carries on the transmission in module primary side and between the second-level end. Figure 5 had demonstrated outputs one (≤5mV), in outputs two loads to increase in the change of situation.
Transient state and ripple
PT4820 and the PT4850 series has the splendid transient response and characteristics and so on output voltage ripple performance. This module’s three logical voltage output is the independent control, this is helpful in may the transient response which compares favorably with the list output power source module (≤200 µ Sec) and the output voltage ripple (≤20mV).
Cost
The multi-output power source module no longer needs two or the more list output component, this reduced the cost. Table 1 has demonstrated power source same 25A three output modules and three list output module contrast.
In the distributional power source application, the designers (Figure 2) have substituted the high cost list output brick through the use single multi-output module and the non-isolated-type loading point module, thus has realized the cost saving. May also realize, because the multi-output module may also be able to implement in the less module situation, therefore further saved the cost (and board level space). For example, in certain applications, the multi-output module only requests a heat to insert pulls out the controller and the input decoupling condenser. On the contrary, these modules in the electrical power system must with each list output brick union use.
The product going on the market time is one kind of overhead costs, uses the multi-output power source module to be possible to reduce this cost. This kind of cost saving is mainly because the OEM manufacturer reduced resources and so on design, test and manufacture.
Fault management
The designers must determine how its electrical power system does carry on the response to the breakdown situation. The now multi-output power source module unified the advanced fault management function. These functions have included the pressure, the overflow and the short circuit protection, is helpful in the avoid damage designer’s electric circuit.
What the output overvoltage protection uses is may examine the output overvoltage situation unceasingly the circuitry. When the voltage surpasses the preinstall rank (preset level), the circuitry will close or clinches the power source to output, and causes the module to enter the fixed condition. In order to resume the normal operation, some modules must restart on own initiative. This may through eliminate switch’s input power source to obtain immediately realizes. In order to realize the breakdown automatic protection movement and the redundancy, the overvoltage protection circuitry is the independence in the module internal feedback loop.
Crosses the current protection to be possible to prevent the load to be wrong. In certain designs, once achieves the current limitation threshold value from the module load current, if the load attempts absorption more electric current again, will then cause the module constant voltage output voltage the drop. This module not because will continue to execute wrongly damages in any output load.
When the module each output’s combination current surpasses the current limitation threshold value (for example on any output pin has short circuit), will short-circuit the protection to close the module. This closure will force all outputs the output voltage simultaneously to drop to zero. After the closure, the module through will carry out the soft start in the fixed intervals time to add the electricity regular attempt restoration. If the load breakdown still existed, then the module will experience the continual electric current wrong, to close and to restart continually.
Flexibility
The voltage and the electric current output as well as the seal design’s flexibility is a multi-output power source module essential characteristic. Certain manufacturers may provide 24V (18V to 36V) and 48V (36V to 72V) two kind of inputs. It uses isolates the output the general construction to be possible completely to cause the system design personnel uses the module in pair or three output circuits, but will not create the situation which the excessively many lowest load requests or the constant voltage will degrade mutually.
Because the chip supplier develops component’s control voltage not necessarily to conform to the beforehand repetitive process, therefore the voltage and the electric current output aspect’s flexibility becomes day by day important. The numerous multi-output modules solve this problem by the independent control and the adjustable output voltage. In order to obtain the unique voltage, in certain module’s output may carry on the long-distance programming from the external voltage. In addition, such as Tyco Corporation’s CC025 and so on three output series module may also connects the adjustment pin through the use (trim pin) the non-essential resistance permit the output voltage setpoint adjustment.
The seal flexibility simplified the motherboard designers’ work. Many existing multi-output modules use the field standard the brick shape seal (brick type packaging) and the area specification, this has guaranteed the pin compatibility and the auxiliary source of goods. TI Excalibur™ innovation mold blocks and so on series use have the surface mounting, the vertical through hole and the parallel through hole seal style tin-plating thin steel plate copper box.
The multi-output power source module’s commercial usability has provided the extremely good flexibility for the designers. Table 2 had demonstrated some make the multi-output module field leading supplier. These modules save in the leading distributor place, may provides the extremely quick usability for the design qualifications authentication and the final time change.
Table 2, multi-output module manufacturer
| Manufacturer | Product type |
| Artesyn science and technology company | 15W to the 60W pair, three outputs |
| Astec | 20W to the 150W double output |
| Ericsson | 30W to the 110W pair, three outputs |
| APower-One | 2.5W to the 195W pair, three, four outputs |
| SynQor | 40W to the 60W double output |
| Texas Instruments | 3W to the 75W pair, three, four outputs |
| Tyco Power Systems | 25W to the 50W pair, three outputs |
Reliability
Has the highly reliable electrical power system design is the challenge which the system design personnel always want to face. From intrinsic, the use single multi-output module’s electrical power system’s reliability must be higher than all list output module. For example, a three output module may provide 1,108,303 hour fixed MTBF (902.3 FIT). With this comparison, provides the same output voltage and the electric current three list output module has achieved 984,736 MTBF (1015.5 FIT) fixed MTBF. The reason that the multi-output module has a higher reliability, is because in its construction uses overall module quantity are less.
Conclusion
Used the volume along with the industrial tidal current request designers to be smaller, the efficiency higher power source supply, the power source module manufacturer promotes has been possible to simplify the system design and the operation outputs the dc/dc power source module, responded the above tidal current. The newest multi-output module can through for the mixed logic application (such as DSP, ASIC and microprocessor and so on) provides the constant voltage low voltage output to cause the designers to profit. Compares with the first generation of product, the above module obviously enhanced has assigned in the area the function. In the certain circumstances, this small construction occupies the space is only the list output power source module 55%. Reduced module quantity may also reduce the cost, simultaneously raises the efficiency and the reliability. The built-in operation and the protection feature avoided have developed the exterior circuitry’s duty and the expense, thus has not only saved the board level space, moreover also greatly sped up the product above advancement.
Bibliography
Researcher [1] VDC techniques market, “AC/DC Exchange Power source, DC/DC Module As well as Telecommunication Rectifier’s Commercial market And Application”, pp 5,2001 years
