Abstract:
A system may comprise a DC-to-DC converter, a load coupled to and receiving an operating voltage from the converter and an output adjust circuit coupled to the converter and the load. The output adjust circuit may receive a first voltage from the load, generate a second voltage indicative both of the first voltage and of an offset signal, and provide the second voltage to the converter. The DC-to-DC converter may control the operating voltage using the second voltage.

Description:
BACKGROUND  
         [0001]    Active electrical components generally require electrical power to operate. As an example, a computer may include a battery for its power or receive electrical power from an alternating current (AC) wall outlet. Regardless of the power source, the computer&#39;s individual electrical components generally require electrical power in a particular form. Typically, that form includes direct current (DC) voltage. The AC wall outlet may supply 120 volts of AC (i.e., time varying) voltage to the computer. The computer may include a power supply which, among other things, may perform the function of converting the incoming 120 VAC power to one or more suitable DC voltages (e.g., 5 VDC, 3.3 VDC, etc.). Even if the computer operates from a battery, which produces DC voltage, the battery&#39;s DC voltage may still have to be converted to a different voltage level for the particular needs of the computer&#39;s electrical devices.  
           [0002]    DC-to-DC converters may be employed to convert a DC voltage from one level to another. Such converters may be used in numerous of applications, not the least of which include computers. DC-to-DC converters typically are fabricated as pre-packaged modules which can, for example, be mated with a circuit board in an electronic system. In general, a DC-to-DC converter receives an input DC voltage and generates an output DC voltage at a predefined voltage level. The converter may include other input pins having signals that enable the converter to maintain its output voltage at the rated level. Such input pins may include “sense” inputs which may be connected to the load to which the converter is connected. The converter may also include a “trim” pin which may be used, with circuitry external to the converter module, to tune the output voltage of the converter to account for voltage losses between the converter and the load connected to the converter. The trim input generally provides a system designer some degree of control over the converter&#39;s output voltage.  
           [0003]    A manufacturer of DC-to-DC converters may provide trim inputs on its converter modules, but may require the trim inputs to be used differently than for other manufacturer&#39;s modules. That is, a particular external circuit may need to be connected to the trim input of one manufacturer&#39;s converter, while a different external circuit may need to be connected to the trim input of another manufacturer&#39;s converter. The customization required to implement trim inputs of disparate converter modules places a burden on the designer of the system in which the converter is to operate.  
         BRIEF SUMMARY  
         [0004]    The present disclosure includes methods and systems that may address the problem noted above. In some embodiments, a system may comprise a DC-to-DC converter, a load coupled to and receiving an operating voltage from the converter and an output adjust circuit coupled to the converter and the load. The output adjust circuit may receive a first voltage from the load, generate a second voltage indicative both of the first voltage and of an offset signal, and provide the second voltage to the converter. The DC-to-DC converter may control the operating voltage using the second voltage. As such, the output adjust circuit, which may be usable in conjunction with a wide range of converters, may be used to control the operation of the DC-to-DC converter, thereby avoiding the necessity to have to provide circuitry external to the converter that is customized to the particular design of the converter. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    For a detailed description of the embodiments of the invention, reference will now be made to the accompanying drawings in which:  
         [0006]    [0006]FIG. 1 shows a system in which an output adjust circuit may be used in conjunction with a DC-to-DC converter in accordance with exemplary embodiments;  
         [0007]    [0007]FIG. 2 shows the output adjust circuit in greater detail in accordance with various embodiments of the invention; and  
         [0008]    [0008]FIG. 3 shows an embodiment usable to generate an offset inject current to be used with the output adjust circuit of FIGS. 1 and 2. 
     
    
     NOTATION AND NOMENCLATURE  
       [0009]    Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ”. Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections.  
       DETAILED DESCRIPTION  
       [0010]    The following discussion is directed to various embodiments of the invention. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims, unless otherwise specified. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment.  
         [0011]    Referring now to FIG. 1, a system  100  is shown as comprising a DC-to-DC converter module  102 , a load  104  and an output adjust circuit  106 . Although only one each of a converter module  102 , load  104  and output adjust circuit  106  is shown in FIG. 1, in other embodiments any number of converters  102 , loads  104  and output adjust circuits  106  may be included. In general, the DC-to-DC converter  102  receives an input DC voltage and generates an output DC voltage across the V+ and V− terminals of the converter. The V+ and V− terminals of the converter  102  may be connected to corresponding V+ and V− terminals of the load  104 . The load  104  may comprise one or more electrical components such as, and without limitation, a microprocessor in a computer. The load  104  thus may comprise a single component or a plurality of components coupled together to form a functional system.  
         [0012]    Both the converter  102  and load  104  may include sense pins S+ and S− as shown in FIG. 1. The S− terminals may be connected together and grounded if desired. The S+ terminal of the load  104  may connect to an S+ in  input terminal of the output adjust circuit  106 . A S+ out  output terminal from the output adjust circuit  106  may connect to the S+ terminal of the converter  102 . Further, an offset inject current or voltage may be provided to the output adjust circuit  106 . The operation of the output adjust circuit  106  will be explained below.  
         [0013]    Referring still to FIG. 1, the sense voltage, S+, from the load  104  generally is provided to the DC-to-DC converter  102  through the output adjust circuit  106 . Based on the magnitude of the offset inject current, the output adjust circuit  106  may cause the sense voltage from the load to be altered as provided to the converter  102  via the S+ out  output. The output adjust circuit  106  thus permits the converter&#39;s output voltage (across its V+ and V− terminals) to be adjusted as desired based on the offset inject signal. It should be noted that the DC-to-DC converter  102  may include a trim terminal (TRIM), or equivalent, but, as explained below, the TRIM input can be used, but need not be used if desired.  
         [0014]    In some embodiments, such as in FIG. 1, the DC-to-DC converter  102  may comprise a “module.” The term module is meant to refer to a pre-packaged electronic unit that performs a function. The module  102 , for example, may comprise a mechanical housing that contains various electrical components coupled together to convert an incoming DC voltage to an output DC voltage. The converter&#39;s housing may be sealed to prevent contamination from effecting the components contained therein. By including the output adjust circuit  106  and providing a mechanism by which to influence the sense voltage from the load (i.e., the offset inject current), the output adjust circuit may be usable to control the output voltage of the converter module  102 . The output adjust circuit  106  thus may be usable in conjunction with virtually any DC-to-DC converter module. The embodiment shown in FIG. 1 avoids the necessity of a custom circuit to connect to the TRIM input terminal of the converter  102 .  
         [0015]    [0015]FIG. 2 shows an exemplary implementation of the output adjust circuit  106 . As shown, the circuit  106  may include resistors R 1 -R 5  and an operational amplifier (op amp)  110  configured as a non-inverting amplifier. The S+ sense voltage from the load  104  may be connected to resistor R 1 . Resistors R 1  and R 4  may be connected in series with node  115  connected to the non-inverting input terminal (+)  112  of the op amp  110 . As such, resistors R 1  and R 4  may form a voltage divider network in which the voltage at node  115  may be approximately equal to the sense voltage (S+) times the ratio of resistor R 4  to the sum of R 1  and R 4 . That is,  
       Node115voltage   =       S   +          (     R4     R1   +   R4       )                             
 
         [0016]    In some embodiments, resistors R 1  and R 4  may be the same, or approximately the same, value of resistance and, in that case, the node  115  voltage is approximately to one half of the load&#39;s sense voltage S+.  
         [0017]    Resistors R 2  and R 5  may define the gain of the non-inverting amplifier generally to be:  
       Gain   =       R2   +   R5     R5                           
 
         [0018]    In some embodiments resistors R 2  and R 5  may be selected to be equal or approximately equal. As such, the resulting gain of the amplifier will be approximately equal to 2. Moreover, with the voltage divider network of resistors R 1  and R 4  reducing the sense voltage by a factor of 2 (at node  115 ), and the amplifier circuit providing a gain of 2, all else being equal, the resulting output voltage from op amp  110  (which is provided to the S+ input of the converter module  102 ) may be approximately equal to the sense voltage from the load  104 .  
         [0019]    Through resistor R 3 , an offset inject DC current (or voltage) can be injected. This current results in the output signal (S+) from op amp  110  to change—a higher offset inject current results in a smaller output op amp output voltage. As such, the sense input (S+) to the converter  102  can be adjusted through the output adjust circuit as desired. This permits a system designer (or other person) to monitor the behavior of a load  104  and adjust the offset inject current to achieve the most desirable load behavior.  
         [0020]    The offset inject current may be generated through any of a variety of mechanisms. FIG. 3 shows an electronic system  150  coupled to a digital-to-analog converter (DAC)  152 . The DAC  152  may generate the offset inject signal based on information generated by, and received from, the electronic system  150 . The electronic system  150  may comprise the load  104  or may comprise separate logic altogether. The electronic system  150  may comprise, for example, a computer system. A person may control a value in the electronic system  150  to correspond to a particular offset inject current. After observing the behavior of the load  104 , the person may adjust the value in the electronic system. This action may comprise incrementing or decrementing the value or otherwise selecting a new value as desired. A digital signal  151  indicative of the user-selected value may be provided to the DAC  152 . The DAC  152  may convert the input digital signal  151  to, an analog signal (i.e., the offset inject current). In other embodiments, a digital potentiometer may be used to generate the offset inject current.  
         [0021]    The output adjust circuit  106  described herein can be used with a DC-to-DC converter module in any of numerous applications including, but not limited to computer systems, consumer electronics (e.g., DVD players, digital cameras, etc.) and, in general, any electrical system employing DC-to-DC converters. The output adjust circuit  106  may be usable to tune the output voltage from a DC-to-DC converter module without regard to any module or manufacturer-specific trim (or equivalent) application details. The circuit  106  thus permits considerable flexibility to the system designer.  
         [0022]    The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.