Recently, exceed large scale integration (the development spread of VLSI) technology became wide digital control uses range, be in especially the application of respect of component of power source electron. The number controls IC to have a variety of advantages, for instance naked a dimension is smaller, passive component amount fewer, cost is lower. Additional, digital control can use bus line of power source government (PMBus™) will finish a system to configure; Advanced control algorithm can improve performance; But process designing sex can realize application to optimize. Gain ground further and replace many imitate controller what manage as digital power source, it must maintain existing function backward compatibility, make module of digital power source and module of imitate power source all can be in thereby same a job in the system.

 

Voltage of average use output is adjusted in module of imitate power source, so final user can change the output voltage of power source module through exterior resistor. It has buildup flexibility, the standard module that allows to choose certain course is used in almost all applying, and no matter voltage asks how. The graph adjusts the typical configuration that outputs voltage in module of power source of imitate of 1 indication AGF600-48S30.

 

Output voltage can join through the change power source module is outputting end or the resistor that ground connection carries to undertake modulatory. Through join exterior resistor RUP makes RDOWN float empty, can upward adjustment outputs voltage (prep above is nominal output voltage) , perhaps pass join exterior resistor RDOWN makes RUP short circuit (resistance is 0) adjust downward (under nominal output voltage) .

 

Graph 1. Adjust the output voltage of AGF600-48S30 DC-DC converter

In imitate solution, the fiducial voltage of amplifier of changeable error of RUP and RDOWN. Error amplifier uses resistor voltage divider to feel measure output voltage, voltage divider passes those who lose amplifier of feedback join error to input end instead. Of the signal of drive of output voltage control of error amplifier occupy sky comparing, install output voltage then. Accordingly, output voltage is changed along with the change of fiducial voltage, and RUP or RDOWN can change fiducial voltage, then up or adjust output voltage downward.

 

Graph 2 those who show two kinds to be used extensively in module of imitate power source is pressure regulating means. The imitate controller in graph 2 (a) brings a foot to allow exterior resistor RDOWN to reduce error amplifier to input the voltage of end in phase, reduce output tension thereby. Exterior resistor RUP and series connection of resistor voltage divider join, can reduce the tension that brings to bear on to input end instead in error amplifier, increase output tension thereby. The imitate controller in graph 2 (b) does not offer the visit that is aimed at in-house and fiducial voltage, but can join amplifier of an exterior error and fiducial voltage source, so that be opposite,output voltage undertakes adjustment. Exterior amplifier outputs end and end of in-house amplifier output to be linked together, effectively bypass in-house error amplifier. Next, the identical circuit before fiducial voltage can be used undertakes configuration, undertake adjustment to module of two power source with same way thereby.

 

Graph 2. Use (A) contains the imitate controller that can configure in-house and fiducial voltage, or (the output voltage that B) contains the imitate controller that secures in-house and fiducial voltage to adjust module of imitate power source
 

To digital controller, all control functions all come true by digital logic. The graph shows the functional-block diagram of the ADP1051 of high number controller that is compositive PMBus interface 3 times. This parts of an apparatus suits power source of high density DC-DC to change very much, have 6 but modulation of width of process designing pulse (PWM) output, controallable develop of major efficient power source attacks. Additional, this parts of an apparatus still can control synchronous commutate (SR) , compositive 6 modulus converter (ADC) , can electric current of voltage of voltage of sampling imitate input, input electric current, output, output, temperature and other parameter. After changeover is data, send these signal undertake handling to digital kernel module. This parts of an apparatus uses agile condition machine framework, realize all function with hardware, offer stable and credible solution, but cannot design the function beyond through process designing implementation. All function — of parts of an apparatus includes to output voltage to adjust — to all be handled with digital means. To adjust output voltage, answer to send an order through PMBus interface, fiducial voltage is worth change number.

 

Graph 3. Functional-block diagram of digital controller ADP1051
 

The consideration is whole operating ring road, output voltage passes voltage voltage divider or operation amplifier shrinks put appropriate value, input VS+ to cite a base next. VS+ cites a base. ADC undertakes sampling to this voltage. The digital fiducial voltage that the output voltage that digital kernel knows digitlization is worth and installs through PMBus interface. Digital comparator and compensation filter the number fiducial voltage and the scale output voltage that detect have comparative, generation error signal in order to control PWM, processing means and imitate controller are same. Unfortunate is, digital comparator can use a number through PMBus only fiducial voltage. Fiducial voltage and digital compensation filter all use digital comparator, number only logistic n signal works, cannot use exterior and fiducial tension accordingly and bypass interior comparator and filter. Suffer the hardware configuration that be confined to secures this kind, backward the only way that compatible and existing imitate adjusts a function is to adjust the ADC that VS+ brings a foot to go up detects voltage. A kind of method is network of new configuration feedback.

 

Graph 4 in, RD1 and RD2 form — of standard feedback network a simple resistor voltage divider, can detect in ADC before outputting voltage, undertake modulatory to its. Detect voltage is:

 

 

Among them, VO is the actual output voltage of power source module. Use standard feedback network, output voltage to cannot be adjusted with imitate means. If the graph is shown 4 times, configure feedback network to be able to contrast afresh through adding the kind of RUP, RT0 and VTRIM exemple output voltage undertakes modulatory. Then, detect voltage is:

 

VS+ brings the regular job voltage on the foot to be 1 V. If VTRIM is 1 V to control and RT0 is ambitious at RD2, criterion but the part of the others branch of oversight circuit. Complex network uses as simple voltage divider, adjust RUP resistance, offer the character that is similar to imitate controller, realized the voltage upward adjustment in module of imitate power source.

 

Graph 4. ADP1051 can adjust feedback network
 

However, offer adjust ability to want downward more complex. The exact voltage that digital controller does not know to the system ought to be outputted is worth, because this its meeting trial and error is the biggest,degree reduces VVS+ and in-house number the error between fiducial voltage. VVS+ will follow in-house number from beginning to end of fiducial voltage change and change, its type cost is set for 1 V. 2 indication VO and VTRIM show equality linear relation. By the graph 2 knowable, the mechanism that adjusts output voltage downward is generation one expresses what to need to output voltage and nominal the error voltage of the difference that outputs voltage. Internal fiducial tension will be met first subtractive this error voltage, just can add the inphase end of error amplifier next. If be in of error amplifier input end to join identical voltage difference instead, criterion two circuit will have same output result. Accordingly, the output voltage that VTRIM ought to need with place and nominal the difference of voltage becomes scale, and rather than uses fixed value.

 

Graph the function that 5 medium circuit have compatible imitate to perhaps be down tone to press up. Two resistor voltage divider produces two fiducial tension, among them the output that a fiducial voltage represents to imitate controller needs is fiducial voltage, another shows in-house and fiducial tension. Use a voltage to follow implement the output that will avoid to need is fiducial voltage and follow-up circuit are affected each other. Use AD822 FET to input operation amplifier, output what what need fiducial voltage (V1) the in-house and fiducial voltage from imitate controller (the purify in V2) , the tension that gets needing is poor. The linear enlarge gain of this circuit ensured VTRIM is enough big, can produce an effect to VVS+ thereby.

 

Graph 5. Configure feedback network afresh, convenient undertake imitate output is adjusted
 

Graph 6. After the feedback network that uses new configuration, adjust ADP1051 to output the computational result of voltage: (A) is adjusted downward (B) upward adjustment
 

The target outputs voltage to adjust characteristic definition to refer to AGF600-48S30 data manual.

 

Express the 1 parameter in showing one group applies at network of new configuration feedback, use this group of parameter, can make its compatible voltage of module of imitate power source adjusts character.

 

Express 1. The graph shows the resistance of circuit 5 times

 

Use equality 2 with the watch 1 medium numerical value, calculable output voltage adjusts character. Graph curve of 6 indication results. The target is worth and the error between computational value arises by the feedback network that configures afresh. This error is dinky (nominal when output voltage is 30 V, this error value is not worth 0.1 V) , this states the output result of this circuit is favorable. It is OK to pass computation the method that test and verify deploys feedback network this kind to output voltage in order to adjust afresh, use a number for other for instance ADM1041A, ADP1046A, ADP1050 mixes the —— of controller of digital power source of fiducial voltage the —— such as ADP1053 backward compatible imitate controller offers train of thought, enhanced the flexibility of solution of digital power source.