Abstract:
An integrated circuit device provides a choice of external pins (connections) that may be user selectable for coupling an external filter/stabilization capacitor to an internal voltage regulator. However, connecting the output of a internal voltage regulator to an uncharged external filter/stabilization capacitor (or to a capacitor charged to a different voltage level than the internal regulation voltage) through a low impedance path can cause the regulator output voltage to sag/spike if the internal voltage regulator tries to charge/discharge the capacitor up/down to equilibrium with the regulator output voltage. To minimize this potential sag/spike, the voltage on the external filter/stabilization capacitor may be adjusted in a controlled manner to substantially the same voltage as the voltage on the output of the internal voltage regulator, and then the internal voltage regulator is operationally coupled through a low impedance to the external regulator filter/stabilization capacitor.

Description:
RELATED PATENT APPLICATION 
   This application claims priority to commonly owned U.S. Provisional Patent Application Ser. No. 60/916,052; filed May 4, 2007; entitled “User Selectable Pin for an Internal Regulator Filter/Stabilization Capacitor Connection,” by Richard Hull, Vivien Delport, Zacharias Marthinus Smit, Sean Steedman, Jerry Zdenek, Michael Charles and Ruan Lourens; which is hereby incorporated by reference herein for all purposes. 

   TECHNICAL FIELD 
   The present disclosure relates to integrated circuit devices having internal voltage regulators, and more particularly, to a user selectable external contact (pin) connection between an internal voltage regulator and an external filter/stabilization capacitor. In addition, preventing a current surge during voltage equalization between the internal voltage regulator and the external filter/stabilization capacitor is also accomplished. 
   BACKGROUND 
   Currently, most integrated circuit devices having an internal voltage regulator require an external regulator filter/stabilization capacitor to be used with the internal voltage regulator. Connection of the internal voltage regulator to an uncharged or overcharged external regulator filter/stabilization capacitor, e.g., during start-up or power interruption, may cause the output of the internal regulator to droop/spike and/or otherwise disrupt proper operation thereof. Flexibility in selection of which external connection (e.g., pin) of the integrated circuit device used for connection to the external regulator filter/stabilization capacitor is also very desirable. The ability to select which external connection (pin) that is used for connection to the external regulator filter/stabilization capacitor is especially advantageous for low pin-count integrated circuit devices where the external connections (e.g., pins) have multiple functions, since it is very difficult to know before hand and dedicate a specific fixed external connection for the external regulator filter/stabilization capacitor. 
   SUMMARY 
   Therefore there is a need to couple an external regulator filter/stabilization capacitor in a controlled manner so as not to disrupt the function of an internal voltage regulator of an integrated circuit device. There is also need to provide a convenient and flexible way of selecting an external connection, e.g., pin, of the integrated circuit device for coupling to the external regulator filter/stabilization capacitor. This is especially important when designing with low pin count integrated circuit packages and still be able to utilize one of those pin connections for an external regulator filter/stabilization capacitor when desired. 
   According to the teachings of this disclosure, an integrated circuit device, e.g. microprocessor, microcontroller, digital signal processor, application specific integrated circuit (ASIC), programmable logic array (PLA), etc., may provide a user selectable pin (external contention) of a plurality of pins on an integrated circuit device package to use for an external regulator filter/stabilization capacitor. This pin selection may occur during start-up of the integrated circuit device once power, e.g., Vdd, is applied thereto, and may be determined from pin allocation information stored in a nonvolatile memory of the integrated circuit device, e.g., fusible links, EEPROM, FLASH memory, etc. One of two conditions may exist during the pin selection process, for example, 1) pin selection is determined using only the power source voltage, Vdd, or 2) pin selection is determined using the internal voltage regulator voltage, e.g., with low voltage circuit logic). 
   If the internal voltage regulator voltage is not required in the pin selection process, the voltage regulator may be used to equalize the voltage (charge or discharge) the external filter capacitor without any special consideration regarding the stability of the internal voltage regulator before a voltage regulator ready acknowledgement is asserted. In this case, after the pin has been selected for the external capacitor the internal voltage regulator is coupled to the external capacitor for voltage equalization thereof, and finally once the voltage on the external capacitor is substantially the same value as the internal voltage regulator, then the internal voltage regulator is ready to power the low voltage circuits of the integrated circuit device. 
   However, if pin selection for the external capacitor is done with low voltage logic, e.g., low voltage nonvolatile memory, that requires a voltage from the internal voltage regulator then start-up of the integrated circuit device may require that initially the internal voltage regulator not be connected to the external capacitor. Connecting the output of the internal voltage regulator to an uncharged filter capacitor (or to a filter capacitor charged to a different voltage level than the internal regulation voltage) can cause the regulation voltage to sag/spike as it sources/absorbs charge to charge/discharge the capacitor up/down to the internal voltage regulator output voltage. Therefore, in order to minimize this sag/spike it is important to connect the capacitor to the internal voltage regulator output in a controlled manner. Processes for adjusting a voltage charge on the external regulator filter/stabilization capacitor to substantially the same voltage as the voltage from the internal voltage regulator, and then coupling the external regulator filter/stabilization capacitor to the internal voltage regulator in a controlled manner is further disclosed herein. 
   According to a specific example embodiment of this disclosure, an integrated circuit device having an internal voltage regulator and selectable external connections, wherein at least one of which is selected for coupling the internal voltage regulator to an external capacitor comprises: a voltage regulator; a plurality of external connections; and a first circuit for selecting a one of the plurality of external connections and coupling the voltage regulator to the selected one of the plurality of external connections, wherein the selected one of the plurality of external connections is coupled to an external capacitor. 
   According to another specific example embodiment of this disclosure, an integrated circuit device having an internal voltage regulator and selectable external connections, wherein at least one of which is selected for coupling the internal voltage regulator to an external capacitor comprises: a voltage regulator; a plurality of external connections; a first circuit for selecting a one of the plurality of external connections, the selected one of the plurality of external connections is coupled to an external capacitor having an unknown voltage thereon, wherein the first circuit adjusts the unknown voltage on the external capacitor through a high impedance path to a voltage substantially the same value as a voltage of the voltage regulator; and a second circuit for coupling the voltage regulator through a low impedance path to the selected one of the plurality of external connections when the voltage thereon is substantially the same value as the voltage of the voltage regulator. 
   According to yet another specific example embodiment of this disclosure, an integrated circuit device having an internal voltage regulator and selectable external connections, wherein at least one of which is selected for coupling the internal voltage regulator to an external capacitor comprises: a voltage regulator; a plurality of external connections; and a circuit for selecting a one of the plurality of external connections and adjusting a voltage thereon, the selected one of the plurality of external connections is coupled to an external capacitor having an unknown voltage, wherein the circuit adjusts the unknown voltage on the external capacitor through a high impedance path to a voltage substantially the same value as a voltage of the voltage regulator then couples the selected one of the plurality of external connections through a low impedance path to the voltage regulator. 
   According to still another specific example embodiment of this disclosure, a method for selecting an external connection for coupling an internal voltage regulator to an external capacitor comprises the steps of: providing a voltage regulator in an integrated circuit device; providing a plurality of external connections for the integrated circuit device; and selecting a one of the plurality of external connections for coupling to the voltage regulator, the selected one of the plurality of external connections being coupled to an external capacitor. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete understanding of the present disclosure may be acquired by referring to the following description taken in conjunction with the accompanying drawings wherein: 
       FIG. 1  is a schematic block diagram of an integrated circuit device having external pin connections that are selectable for coupling to digital and/or analog circuits, and to an external regulator filter/stabilization capacitor for use with an internal voltage regulator, according to teachings of this disclosure; 
       FIG. 2  is a more detailed schematic block diagram of the internal voltage regulator portion of the integrated circuit device of  FIG. 1  showing apparatus and methods of coupling an external regulator filter/stabilization capacitor to the internal voltage regulator in a controlled manner, according to teachings of this disclosure; 
       FIG. 3  is a schematic diagram of a portion of the integrated circuit device of  FIG. 2  showing a circuit for charging the external regulator filter/stabilization capacitor to a desired voltage then coupling the external regulator filter/stabilization capacitor to the internal voltage regulator in a controlled manner, according to a specific example embodiment of this disclosure; 
       FIG. 4  is a schematic diagram of a portion of the integrated circuit device of  FIG. 2  showing a circuit for discharging the external regulator filter/stabilization capacitor to a desired voltage then coupling the external regulator filter/stabilization capacitor to the internal voltage regulator in a controlled manner, according to another specific example embodiment of this disclosure; and 
       FIG. 5  is a schematic diagram of a portion of the integrated circuit device of  FIG. 2  showing a circuit for charging and discharging the external regulator filter/stabilization capacitor to a desired voltage then coupling the external regulator filter/stabilization capacitor to the internal voltage regulator in a controlled manner, according to yet another specific example embodiment of this disclosure. 
   

   While the present disclosure is susceptible to various modifications and alternative forms, specific example embodiments thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific example embodiments is not intended to limit the disclosure to the particular forms disclosed herein, but on the contrary, this disclosure is to cover all modifications and equivalents as defined by the appended claims. 
   DETAILED DESCRIPTION 
   Referring now to the drawing, the details of specific example embodiments are schematically illustrated. Like elements in the drawings will be represented by like numbers, and similar elements will be represented by like numbers with a different lower case letter suffix. 
   Referring to  FIG. 1 , depicted is a schematic block diagram of an integrated circuit device having external pin connections that are selectable for coupling to digital and/or analog circuits, and to an external regulator filter/stabilization capacitor for use with an internal voltage regulator. An integrated circuit device  102  may comprise digital circuits  104 , e.g., registers, memory, central processing units, counters, latches, timers, combinatorial logic, etc.; analog circuits  106 , e.g., analog-to-digital converters, digital-to-analog converters, etc.; and an internal voltage regulator  108 . 
   The integrated circuit device  102  may be packaged in an integrated circuit package (not shown) where the pins (external connections on the package) may be selectively coupled to designated ones of the digital circuits  104  and/or the analog circuits  106  of the integrated circuit device  102 . This is especially advantageous when designing with low pin count integrated circuit packages, however, integrated circuit packages of any pin count can benefit from the teachings of this disclosure. A plurality of switching and voltage equalization circuits  110  (three shown for demonstrative clarity) may be used to couple pins  116 ,  118  and  120  to selected ones of the digital circuits  104 , the analog circuits  106  and/or the internal voltage regulator  108  of the integrated circuit device  102 , according to a desired application thereof. It is contemplated and within the scope of this disclosure that the plurality of switching and voltage equalization circuits  110  may be one multi-input/output signal switching and voltage equalization circuit, e.g., cross point switch matrix with voltage equalization components. It is also contemplated and within the scope of this disclosure that the voltage equalization components may be associated with the internal voltage regulator, and the plurality of signal switching circuits remain independent therefrom. One having ordinary skill in the art of digital circuit design and having the benefit of the teachings of this disclosure would readily understand how to implement an optimal combination of signal switching and voltage equalization components when designing an integrated circuit device. 
   A power source voltage, Vdd, may be coupled to pin  122  and a power source common, Vss, may be coupled to pin  124 . The integrated circuit device  102  may be a mixed signal device, e.g., having both analog and digital circuits, and may also include a central processing unit (CPU), interface logic and memory, e.g., volatile and/or non-volatile memory. The integrated circuit device  102  may be, for example but limited to, microprocessor, microcontroller, digital signal processor, application specific integrated circuit (ASIC), programmable logic array (PLA), etc. 
   Referring to  FIG. 2 , depicted is a more detailed schematic block diagram of the internal voltage regulator portion of the integrated circuit device of  FIG. 1  showing apparatus and methods of coupling an external regulator filter/stabilization capacitor to the internal voltage regulator in a controlled manner, according to teachings of this disclosure. If external pin selection relies on logic requiring a voltage from the internal voltage regulator  108 , then directly coupling the external regulator filter/stabilization capacitor  230  with an unknown voltage charge to the output of the voltage regulator  108  may cause instability thereto, e.g., voltage undershoot or overshoot which is undesirable. Therefore it is preferable that before the external regulator filter/stabilization capacitor  230  is coupled to the output of the voltage regulator  108 , the voltage charge on the external regulator filter/stabilization capacitor  230  be substantially the same value as the regulated output voltage from the voltage regulator  108 . These steps are not needed if the external pin selection is determined by logic circuits not requiring voltage from the internal voltage regulator, then external regulator filter/stabilization capacitor  230  may be directly coupled through the external pin  118  to the voltage regulator  108  and the voltage on the external regulator filter/stabilization capacitor  230  be adjusted directly by the internal voltage regulator  108  through the low impedance path  243 . 
   Coupling the voltage regulator  108  to the external regulator filter/stabilization capacitor  230  may be accomplished in several ways. For example, if the external regulator filter/stabilization capacitor  230  has little or no voltage charge thereon, then a controlled voltage may be applied to the filter/stabilization capacitor  230  until a desired voltage value is reached. If the external regulator filter/stabilization capacitor  230  has a voltage charge greater than desired, then the external regulator filter/stabilization capacitor  230  may be discharged until the desired voltage value is reached. Once the desired voltage value has been reached, e.g., substantially the same voltage as the output of the voltage regulator  108 , the filter/stabilization capacitor  230  may be coupled to the output of the voltage regulator  108  without causing voltage instability thereto. 
   The switching and voltage equalization circuit  110   b  may be used to charge and/or discharge the external regulator filter/stabilization capacitor  230  while isolating the output of the voltage regulator  108  from the external regulator filter/stabilization capacitor  230  until it has reached the desired voltage value (substantially the same voltage as the output of the voltage regulator  108 ), as more fully disclosed herein. 
   Switches  246  and  248  are used to couple external pins to the digital circuits  104  or the analog circuits  106 , respectively. In the following explanations, the switches  246  and  248  remain open since external pin  118  is being used only for connection to the external regulator filter/stabilization capacitor  230 . If the external pin  118  or any other pin  116 ,  120 , etc., was being used for the digital circuits  104  or the analog circuits  106 , then switch  246  or  248 , respectively, would be closed and the other switches  234 ,  238 ,  240  and  244  would remain open. 
   Charging the external regulator filter/stabilization capacitor  230  to the desired voltage value, may be accomplished by closing switch  244  while switches  240 ,  238  and  234  remain open. The external regulator filter/stabilization capacitor  230  is thereby charged from the power source terminal  122 , Vdd, until reaching the desired voltage value. The high impedance path  242  limits the magnitude of current during this voltage charging operation. Once the external regulator filter/stabilization capacitor  230  has charged to the desired voltage value, switch  244  opens and switch  240  closes. When switch  240  is closed the external regulator filter/stabilization capacitor  230  is coupled to the output of the voltage regulator  108  through a low impedance path  243 . Thereafter the voltage regulator  108  can operate normally with the external regulator filter/stabilization capacitor  230 . 
   Discharging the external regulator filter/stabilization capacitor  230  to the desired voltage value may also be accomplished by closing switch  234  while switches  240 ,  238  and  244  remain open. The external regulator filter/stabilization capacitor  230  is thereby discharged into the power common terminal  124 , Vss, until reaching the desired voltage value. The high impedance path  232  limits the magnitude of current during this voltage discharging operation. Once the external regulator filter/stabilization capacitor  230  has discharged to the desired voltage value, switch  234  opens and switch  240  closes. When switch  240  closes the external regulator filter/stabilization capacitor  230  is coupled to the output of the voltage regulator  108  through the low impedance path  243 . Thereafter the voltage regulator  108  can operate normally with the external regulator filter/stabilization capacitor  230 . 
   Charging/discharging of the external regulator filter/stabilization capacitor  230  to the desired voltage value may also be accomplished by closing switch  238  while switches  240 ,  234  and  244  remain open. The external regulator filter/stabilization capacitor  230  is thereby charged/discharged by being coupled to the output of the voltage regulator  108  through a high impedance path  236  until reaching the desired voltage value. The high impedance path  236  limits the magnitude of current during this voltage charging/discharging operation. Once the external regulator filter/stabilization capacitor  230  has discharged/discharged to the desired voltage value, switch  238  opens and switch  240  closes. When switch  240  is closed the external regulator filter/stabilization capacitor  230  is coupled to the output of the voltage regulator  108  through the low impedance path  243 . Thereafter the voltage regulator  108  can operate normally with the external regulator filter/stabilization capacitor  230 . 
   Referring to  FIG. 3 , depicted is a schematic diagram of a portion of the integrated circuit device of  FIG. 2  showing a circuit for charging the external regulator filter/stabilization capacitor to a desired voltage then coupling the external regulator filter/stabilization capacitor to the internal voltage regulator in a controlled manner. The switches  244  and  240 , e.g., metal oxide semiconductor field effect transistors (MOSFETs), are used to couple the external regulator filter/stabilization capacitor  230  to the power source, Vdd, at pin  122  through a high impedance path  242  when switch  244  is closed and switch  240  is open, or to the output of the internal voltage regulator  108  when switch  244  is open and switch  240  is closed. Thus coupling together the external regulator filter/stabilization capacitor  230  and the output of the internal voltage regulator  108  through the low impedance path  243 . 
   This circuit may be effectively used when the voltage on the external regulator filter/stabilization capacitor  230  is less than the voltage on the output of the internal voltage regulator  108 . When switch  244  is closed and switch  240  is open, the lower voltage on the external regulator filter/stabilization capacitor  230  will charge to an equilibrium voltage, substantially the same value, e.g., within 50 to 100 millivolts, as the voltage at the output of the voltage regulator, at a current determined by the high impedance path  242 . Once the voltage on the external regulator filter/stabilization capacitor  230  is substantially the same value as (in equilibrium with) the voltage at the output of the voltage regulator  108 , switch  244  will open and switch  240  will close. Now the output of the voltage regulator  108  is coupled to the external regulator filter/stabilization capacitor  230  through the low impedance path  243 . The high impedance path  242  and the low impedance path  243  may be inherent in the design of the switches  244  and  240 , respectively, since the physical size of a MOSFET transistor switch determines the on resistance thereof. 
   A voltage comparator  348  may be used to control the switch  244  on when the voltage on the external regulator filter/stabilization capacitor  230  is less than the voltage at the output of the voltage regulator  108 . A voltage comparator  350  may be used to monitor the voltages at the output of the voltage regulator  108  and the external regulator filter/stabilization capacitor  230  so that when both voltages are substantially the same value, automatic control of the switches  244  and  240  occur as described hereinabove. NAND gates  352  and  554  are shown for illustrative purposes only, many other logic designs may be used with equal effect as would be known to those having ordinary skill in digital logic design and having the benefit of the teachings of this disclosure. The comparators  348  and  350  may have hysteresis built in and/or will latch to prevent output chatter when the input voltages are approaching substantially the same values. 
   The MOSFET switches  240 ,  244 ,  346  and  348  may be used for the multiplexer functions. An enable control line  356  may be included to enable/disable operation of this control circuit when the associated external connection (pin) it is not being used to couple the voltage regulator  108  to the external regulator filter/stabilization capacitor  230 , e.g., when the external pin  118  is used for a digital circuit  104  or an analog circuit  106 , by closing switch  346  or  348 , respectively. In that case, switch  346  will couple the digital circuit  104  to the external pin  118  when controlled by the control line  358 , and switch  348  will couple the analog circuit  106  to the external pin  118  when controlled by the control line  360 . 
   Referring to  FIG. 4 , depicted is a schematic diagram of a portion of the integrated circuit device of  FIG. 2  showing a circuit for discharging the external regulator filter/stabilization capacitor to a desired voltage then coupling the external regulator filter/stabilization capacitor to the internal voltage regulator in a controlled manner. The switches  234  and  240 , e.g., metal oxide semiconductor field effect transistors (MOSFETs), are used to couple the external regulator filter/stabilization capacitor  230  to the power source common (represented as common connection  250 ) through a high impedance path  232  when switch  234  is closed and switch  240  is open, or to the output of the internal voltage regulator  108  when switch  234  is open and switch  240  is closed. Thus coupling together the external regulator filter/stabilization capacitor  230  and the output of the internal voltage regulator  108  through the low impedance path  243 . 
   This circuit may be effectively used when the voltage on the external regulator filter/stabilization capacitor  230  is greater than the voltage on the output of the internal voltage regulator  108 . When switch  234  is closed and switch  240  is open, the higher voltage on the external regulator filter/stabilization capacitor  230  will discharge to an equilibrium voltage, substantially the same value as the voltage at the output of the voltage regulator, at a current determined by the high impedance path  232 . Once the voltage on the external regulator filter/stabilization capacitor  230  is substantially the same value, e.g., within 50 to 100 millivolts, as (in equilibrium with) the voltage at the output of the voltage regulator  108 , switch  234  will open and switch  240  will close. Now the output of the voltage regulator  108  is coupled to the external regulator filter/stabilization capacitor  230  through the low impedance path  243 . The high impedance path  232  and the low impedance path  243  may be inherent in the design of the switches  234  and  240 , respectively, since the physical size of a MOSFET transistor switch determines the on resistance thereof. 
   A voltage comparator  458  may be used to control the switch  234  on when the voltage on the external regulator filter/stabilization capacitor  230  is greater than the voltage at the output of the voltage regulator  108 . A voltage comparator  350  may be used to monitor the voltages at the output of the voltage regulator  108  and the external regulator filter/stabilization capacitor  230  so that when both voltages are substantially the same value, automatic control of the switches  234  and  240  occur as described hereinabove. NAND gates  352  and  454  are shown for illustrative purposes only, many other logic designs may be used with equal effect as would be known to those having ordinary skill in digital logic design and having the benefit of the teachings of this disclosure. The comparators  458  and  350  may have hysteresis built in and/or will latch to prevent output chatter when the input voltages are approaching substantially the same values. 
   The MOSFET switches  234 ,  240 ,  346  and  348  may be used for the multiplexer functions. An enable control line  456  may be included to enable/disable operation of this control circuit when the associated external connection (pin) it is not being used to couple the voltage regulator  108  to the external regulator filter/stabilization capacitor  230 , e.g., when the external pin  118  is used for a digital circuit  104  or an analog circuit  106 , by closing switch  346  or  348 , respectively. In that case, switch  346  will couple the digital circuit  104  to the external pin  118  when controlled by the control line  358 , and switch  348  will couple the analog circuit  106  to the external pin  118  when controlled by the control line  360 . 
   Referring to  FIG. 5 , depicted is a schematic diagram of a portion of the integrated circuit device of  FIG. 2  showing a circuit for charging and discharging the external regulator filter/stabilization capacitor to a desired voltage then coupling the external regulator filter/stabilization capacitor to the internal voltage regulator in a controlled manner. The switches  238  and  240 , e.g., metal oxide semiconductor field effect transistors (MOSFETs), are used to select either high impedance or low impedance paths between the output of the internal voltage regulator  108  and the external regulator filter/stabilization capacitor  230 . 
   When switch  238  is closed and switch  240  is open the output of the voltage regulator  108  is coupled through the high impedance path  236  and the external pin  118  to the external regulator filter/stabilization capacitor  230 . Whereby the voltage charge on the external regulator filter/stabilization capacitor  230  will be brought into equilibrium with the voltage at the output of the voltage regulator  108 . For example, when the voltage on the external regulator filter/stabilization capacitor  230  is less than the voltage at the output of the voltage regulator  108 , the external regulator filter/stabilization capacitor  230  will be charged to an equilibrium voltage at a current determined by the value of the high impedance path  236 . When the voltage on the external regulator filter/stabilization capacitor  230  is greater than the voltage at the output of the voltage regulator  108 , the external regulator filter/stabilization capacitor  230  will be discharged to an equilibrium voltage at a current determined by the value of the high impedance path  236 . 
   Once the voltage on the external regulator filter/stabilization capacitor  230  is substantially the same value as, e.g., within 50 to 100 millivolts, (in equilibrium with) the voltage at the output of the voltage regulator  108 , switch  238  will open and switch  240  will close. Now the output of the voltage regulator  108  is coupled to the external regulator filter/stabilization capacitor  230  through the low impedance path  243 . A voltage comparator  350  may be used to monitor the voltages at the output of the voltage regulator  108  and the external regulator filter/stabilization capacitor  230  so that when both voltages are substantially the same value, automatic control of the switches  238  and  240  occur as described hereinabove. NAND gate  352 , OR gate  354  and inverter  355  are shown for illustrative purposes only, many other logic designs may be used with equal effect as would be known to those having ordinary skill in digital logic design and having the benefit of the teachings of this disclosure. The comparator  350  may have hysteresis built in and/or will latch to prevent output chatter when the input voltages are approaching substantially the same values. 
   The MOSFET switches  238 ,  240 ,  346  and  348  may be used for the multiplexer functions. An enable control line  556  may be included to enable/disable operation of this control circuit when the associated external connection (pin) it is not being used to couple the voltage regulator  108  to the external regulator filter/stabilization capacitor  230 , e.g., when the external pin  118  is used for a digital circuit  104  or an analog circuit  106 , by closing switch  346  or  348 , respectively. In that case, switch  346  will couple the digital circuit  104  to the external pin  118  when controlled by the control line  358 , and switch  348  will couple the analog circuit  106  to the external pin  118  when controlled by the control line  360 . 
   It is contemplated and within the scope of this disclosure that the external pin selection may be performed with logic operating at external supply voltage, Vdd, without requiring controlled voltage equalization of an external regulator filter/stabilization capacitor. Then equalization of the external regulator filter/stabilization capacitor may be performed directly by the internal voltage regulator but before low voltage circuits of the integrated circuit device come on line needing a stable low voltage from the internal voltage regulator, e.g., before the internal voltage regulator indicated that it is ready to supply a stable voltage. 
   While embodiments of this disclosure have been depicted, described, and are defined by reference to example embodiments of the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and are not exhaustive of the scope of the disclosure.