Abstract:
A method for calculating a voltage spike value includes: predefining calculating requirements; inputting parameter values; analyzing whether inputted parameter values match with the calculating requirements; establishing a computing formula for calculating the voltage spike value if the inputted parameter values match with the calculating requirements; and calculating the voltage spike value by utilizing the inputted parameter values and the computing formula. A related system is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to systems and methods for analyzing voltage spikes, and more particularly to a system and method for calculating a voltage spike value. 
   2. Description of Related Art 
   Voltage regulation modules (VRM) are commonly employed in various electronic products, especially in portable devices, to provide a stable supply voltage. It is well known that a VRM transient occurs when a current of the VRM is momentarily switched from a first value to a second value. The VRM transient is an unstabilizing factor to the electronic products, especially the portable devices. If the VRM transient occurs, the VRM may not provide a stable supply voltage for a central processing unit (CPU) of an electronic product, further, filter capacitors electrically connected with the VRM may bring voltage spikes correspondingly. If the VRM is to be employed to the electronic product, attention needs to be paid to the VRM transient and the voltage spikes brought by the filter capacitors. 
   Unfortunately, there is no effective equipment/method to exactly calculate a value of the voltage spikes brought by the filter capacitors, and further to analyze whether the VRM is adaptive to the electronic product according to calculated voltage spike value. 
   What is needed, therefore, is a system and method that can be utilized to exactly calculate a value of the voltage spikes brought by the filter capacitors, so as to accurately analyze whether the VRM is adaptive to the electronic product according to calculated voltage spike value. 
   SUMMARY OF THE INVENTION 
   A system for calculating a voltage spike value in accordance with a preferred embodiment includes a storage unit, a data obtaining unit, an analyzing unit, and a data processing unit. The storage unit is configured for receiving calculating requirements. The data obtaining unit is configured for inputting parameter values. The analyzing unit is configured for analyzing whether inputted parameter values match with the calculating requirements. The data processing unit is configured for establishing a computing formula for calculating the voltage spike value if the inputted parameter values match with the calculating requirements, and for calculating the voltage spike value by utilizing the inputted parameter values and the computing formula. 
   A method for calculating a voltage spike value in accordance with a preferred embodiment includes the steps of: predefining calculating requirements; inputting parameter values; analyzing whether inputted parameter values match with the calculating requirements; establishing a computing formula for calculating the voltage spike value if the inputted parameter values match with the calculating requirements; and calculating the voltage spike value by utilizing the inputted parameter values and the computing formula. 
   Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic diagram of parasitic elements of a filter capacitor; 
       FIG. 2  is a schematic graph of a voltage spike brought by the filter capacitor of  FIG. 1 ; 
       FIG. 3  is a schematic diagram of a hardware configuration of a system for calculating a voltage spike value in accordance with a preferred embodiment; 
       FIG. 4  is a schematic diagram of a voltage spike analyzing circuit simulated by a data processing unit of the system of  FIG. 3 ; and 
       FIG. 5  is a flowchart of a method for calculating a voltage spike value in accordance with a preferred embodiment. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  is a schematic diagram of elements of a filter capacitor. The elements of the filter capacitor includes a capacitance “C”, an equivalent series resistance (ESR), and an equivalent series inductance (ESL). “i C ” denotes the current flowing through the filter capacitor. 
     FIG. 2  is a schematic graph of a voltage spike brought by the filter capacitor of  FIG. 1  with respect to time “t”. The filter capacitor brings the voltage spike when a current of a voltage regulation module (VRM) that is electrically connected with the filter capacitor is momentarily switched from a high value to a low value. The graph of  FIG. 2  represents an example of voltage spike levels (indicated along voltage spike axis) of the parasitic elements with respect to time. The filter capacitor begins to bring the voltage spike with a first value “a 1 ” at an initial time “t 0 ”. During a power up time from the initial time t 0  to a first time “t 1 ”, the voltage spike increases proportionally and reaches its peak to a second value “a 2 ” at the first time “t 1 ”. After the power up time, the voltage spike suddenly reduces to a first level and steadily approaches and reaches a second level at a second time “t 2 ” at which the VRM supplies a stable electric power. The value of the voltage spike at the first level is a third value “a 3 ” and is in a range between the first value a 1  and the second value a 2 . 
   The capacitance “C” brings the part “Ct” of the voltage spike, the ESR brings the part “A” of the voltage spike, and the ESL brings the part “B” of the voltage spike. “ΔV ESR ” denotes the value of the part A, and “ΔV ESL ” denotes the value of the part B. At the second time t 1 , the voltage spike is almost brought by the ESR and the ESL, the voltage spike mainly includes the part A and the part B, the value of the voltage spike equals the sum of the value ΔV ESR  and the value ΔV ESL . At the third time t 2 , the voltage spike is almost brought by the capacitance C, the voltage spike mainly includes the part Ct. 
     FIG. 3  is a schematic diagram of a hardware configuration of a system for calculating a voltage spike value (hereinafter, “the system”) in accordance with a preferred embodiment. The system is configured (i.e., structured and arranged) for calculating the voltage spike value of voltage spikes brought by one or more filter capacitors that are electrically connected with a VRM. The system may include a calculating device  10 , and an input/output device  20  connected with the calculating device  10 . The input/output device  20  is for storing calculating requirements and a predefined password that are preconfigured by a user, for prompting a user interface for the user to input a password and parameter values, for analyzing whether inputted password matches with the predefined password, and for analyzing whether inputted parameter values match with the calculating requirements. The calculating device  10  is for calculating the voltage spike value of the voltage spikes brought by the filter capacitors according to the inputted parameter values. 
   Since the filter capacitors typically includes one or more bulk capacitors and one or more coupling capacitors, the inputted parameter values typically include a stable electric power value supplied by the VRM, a highest current (hereinafter, “i max ”) and a lowest current (hereinafter, “i min ”) of the VRM when a current of the VRM is momentarily switched from the highest current i max  to the lowest current i min , capacitance values of the bulk capacitors and the coupling capacitors, ESR values and ESL values of the bulk capacitors, ESR values and ESL values of the coupling capacitors, an amount of the bulk capacitors and an amount of the coupling capacitors, and a slew rate of the current of the VRM. 
   The input/output device  20  typically includes a data obtaining unit  201 , a data transmitting unit  203 , a storage unit  205 , a data display unit  204  connected with the data obtaining unit  201  and the data transmitting unit  203 , and an analyzing unit  202  connected with the data obtaining unit  201 , the data transmitting unit  203 , and the storage unit  205 . The calculating device  10  typically includes a data processing unit  102  that is connected with the data obtaining unit  201  and the data transmitting unit  203  of the input/output device  20 . 
   The data display unit  204  is configured for displaying data typically including a first message denoting that the inputted password is invalid, a second message denoting that the inputted parameter values are unacceptable, and the voltage spike value calculated by the data processing unit  102 . 
   The storage unit  205  is configured for receiving the predefined password and the calculating requirements. The calculating requirements typically include required parameter values for calculating the voltage spike value, and an acceptable range of each parameter value. 
   The data obtaining unit  201  is configured for prompting the user interface for the user to input the password and the parameter values, for obtaining calculated voltage spike value from the data processing unit  102 , and for transmitting obtained voltage spike value to the data display unit  204 . 
   The analyzing unit  202  is configured for analyzing whether the inputted password matches with the predefined password by comparing the inputted password with the predefined password, and for analyzing whether the inputted parameter values match with the calculating requirements. 
   The data transmitting unit  203  is configured for transmitting the first message to the data display unit  204  if the inputted password does not match with the predefined password, for transmitting the second message to the data display unit  204  if the inputted parameter values do not match with the calculating requirements, and for transmitting the inputted parameter values to the data processing unit  102  if the inputted parameter values match with the predefined calculating requirements. 
   The data processing unit  102  is configured for simulating a voltage spike analyzing circuit according to configuration information of the filter capacitors, for establishing a computing formula for calculating the voltage spike value according to the voltage spike analyzing circuit, and for calculating the voltage spike value by utilizing the inputted parameter values and the computing formula. In the preferred embodiment, the data processing unit  102  establishes the computing formula according to the voltage spike analyzing circuit by utilizing Laplace transform technique. 
     FIG. 4  is a schematic diagram of the voltage spike analyzing circuit simulated by the data processing unit  102 . All bulk capacitors are simulated with a first equivalent capacitor, and all coupling capacitors are simulated with a second equivalent capacitor. “ESL 1 ” denotes a value of an ESL of the first equivalent capacitor, “ESR 1 ” denotes a value of an ESR of the first equivalent capacitor, “C 1 ” denotes a capacitance value of a capacitance C of the first equivalent capacitor, and “i 1 (t)” denotes a current flowing through the first equivalent capacitor. “ESL 2 ” denotes a value of an ESL of the second equivalent capacitor, “ESR 2 ” denotes a value of an ESR of the second equivalent capacitor, “C 2 ” denotes a capacitance value of a capacitance C of the second equivalent capacitor, and “i 2 (t)” denotes a current flowing through the second equivalent capacitor. “i 0 (t)” denotes a result current of the voltage spike analyzing circuit. The current i 0 (t), the current i 1 (t) and the current i 2 (t) are all dependent variables determined by the independent time variable “t”, and the current i 0 (t) equals the sum of the current i 1 (t) and the current i 2 (t). 
     FIG. 5  is a flowchart of a method for calculating a voltage spike value in accordance with a preferred embodiment. The system of  FIG. 3  may be used to calculate the voltage spike value of the voltage spikes brought by the filter capacitors, when the current of the VRM is momentarily switched from the highest current i max  to the lowest current i min . 
   In step S 29 , the data obtaining unit  201  prompts the user interface for the user to input the password. In step S 30 , the analyzing unit  202  analyzes whether the inputted password matches with the predefined password stored in the storage unit  205 , by comparing the inputted password with the predefined password. If the inputted password does not match with the predefined password, in step S 31 , the data transmitting unit  203  transmits the first message to the data display unit  204 . 
   Otherwise, if the inputted password matches with the predefined password, in step S 32 , the data obtaining unit  201  prompts the user interface for the user to input the parameter values. In step S 33 , the analyzing unit  202  analyzes whether the inputted parameter values match with the calculating requirements stored in the storage unit  205 . If the inputted parameter values do not match with the predefined calculating requirements, in step S 34 , the data transmitting unit  203  transmits the second message to the data display unit  204 . 
   Otherwise, if the inputted parameter values match with the calculating requirements, in step S 35 , the data transmitting unit  203  transmits the inputted parameter values to the data processing unit  102 . The data processing unit  102  simulates the voltage spike analyzing circuit according to configuration information of the filter capacitors, and establishes the computing formula for calculating the voltage spike value according to the voltage spike analyzing circuit by utilizing Laplace transform technique. 
   In the preferred embodiment, the data processing unit  102  gets a current formula of the current i 2 (t) by inversing Laplace transform, and establishes the computing formula shown as follow: ΔV=ΔV 1 +ΔV 2 . “ΔV 1 ” denotes a value of the voltage spike brought by the first equivalent capacitor, “ΔV 2 ” denotes a value of the voltage spike brought by the second equivalent capacitor, “ΔV” denotes the voltage spike value to be calculated. The current formula of the current i 2 (t) is shown as follow: 
                 i   2     ⁡     (   t   )       =         (       ESL   ⁢           ⁢     1   ·     t   2         +     ESR   ⁢           ⁢     1   ·   t       +     1     C   ⁢           ⁢   1         )     ·     SR     t   2               (       ESL   ⁢           ⁢   1     +     ESL   ⁢           ⁢   2       )     ·     t   2       +       (       ESR   ⁢           ⁢   1     +     ESR   ⁢           ⁢   2       )     ·     t   ⁡     (       1     C   ⁢           ⁢   1       +     1     C   ⁢           ⁢   2         )               ,         
the formula of the ΔV 1  is shown as follow:
 
               Δ   ⁢           ⁢     V   1       =             i   1     ⁡     (   t   )       ·   ESR     ⁢           ⁢   1     +     ESL   ⁢           ⁢     1   ·         i   1     ⁡     (   t   )       t         +       1     C   ⁢           ⁢   1       ·   SR   ·       t   2     2           ,         
the formula of the ΔV 2  is shown as follow:
 
               Δ   ⁢           ⁢     V   2       =             i   2     ⁡     (   t   )       ·   ESR     ⁢           ⁢   2     +     ESL   ⁢           ⁢     2   ·         i   2     ⁡     (   t   )       t         +       1     C   ⁢           ⁢   2       ·   SR   ·       t   2     2           ,         
the current formula of the current i 1 (t) is shown as follow: i 1 (t)=i 0 (t)−i 2 (t), and the formula of the time variable t is shown as follow:
 
           t   =     Δ   ⁢           ⁢       i   0     /     SR   .               
“SR” denotes the slew rate of the current of the VRM been switched, “Δi 0 ” denotes an absolute value of the current of the VRM been switched. The formula of the absolute value Δi 0  is shown as follow: Δi 0 =i max −i min .
 
   In step S 36 , the data processing unit  102  calculates the voltage spike value ΔV by utilizing the inputted parameter values and the computing formula. The data obtaining unit  201  obtains calculated voltage spike value from the data processing unit  102 , and transmits obtained voltage spike value to the data display unit  204 . 
   It should be emphasized that the above-described embodiments of the preferred embodiments, particularly, any “preferred” embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described preferred embodiment(s) without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the above-described preferred embodiment(s) and protected by the following claims.