U.S. patent application number 10/207318 was filed with the patent office on 2002-12-12 for alternating current soft start circuit.
Invention is credited to Organvidez, Juan Humberto, Quintanar, Felix Clarence.
Application Number | 20020186573 10/207318 |
Document ID | / |
Family ID | 24191087 |
Filed Date | 2002-12-12 |
United States Patent
Application |
20020186573 |
Kind Code |
A1 |
Quintanar, Felix Clarence ;
et al. |
December 12, 2002 |
Alternating current soft start circuit
Abstract
An alternating current soft starting circuit comprising a power
level detecting circuit responsive in an alternating current source
and positioned to detect voltage changes by sensing frequency
changes and voltage null points; and a micro-controller responsive
to the power level detection circuit to monitor low power
conditions and high power conditions to limit inrush current during
high power condition from the alternating current source and to
slowly ramp up to high power on-state condition.
Inventors: |
Quintanar, Felix Clarence;
(Miami, FL) ; Organvidez, Juan Humberto; (Miami,
FL) |
Correspondence
Address: |
LOTT & FRIEDLAND, P.A.
P.O. BOX 141098
CORAL GABLES
FL
33114-1098
US
|
Family ID: |
24191087 |
Appl. No.: |
10/207318 |
Filed: |
July 29, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10207318 |
Jul 29, 2002 |
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09548961 |
Apr 13, 2000 |
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6448857 |
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Current U.S.
Class: |
363/49 |
Current CPC
Class: |
H03F 3/3074 20130101;
H03F 3/68 20130101; H03F 1/52 20130101 |
Class at
Publication: |
363/49 |
International
Class: |
H02M 001/00 |
Claims
We claim:
1. An alternating current soft starting circuit comprising: a power
level detecting circuit responsive in an alternating current source
and positioned to detect voltage changes by sensing frequency
changes and voltage null points; and a micro-controller responsive
to the power level detection circuit to monitor low power
conditions and high power conditions to limit inrush current during
high power condition from the alternating current source and to
slowly ramp up to high power on-state condition.
2. The alternating current soft start circuit of claim 1, wherein
said micro-controller includes wave analyzing means for analyzing
sinusoidal waves of the alternating current source detected by said
power level detecting circuit to determine a voltage null so that
the soft start function allows a power on-state to be initiated
just prior to a voltage null and to gradually ramp up to a the high
power on-state condition.
Description
CLAIM OF PRIORITY
[0001] This application is a divisional of U.S. patent application
Ser. No. 09/548,961, filed on Apr. 13, 2000.
FIELD OF THE INVENTION
[0002] The present invention relates to the stereo and audio
industries and, more particularly, to the field of audio amplifiers
for amplifying audio and related methods.
BACKGROUND OF THE INVENTION
[0003] Over the years, the stereo and audio industries have grown
dramatically. As additional capabilities of the various audio and
stereo equipment has advanced, a continual cost pressure of new
equipment from consumers and the increased worldwide competition
has forced prices to down over the years for audio and stereo
equipment. This audio and stereo equipment, for example, includes
audio amplifiers, power boosters, power supplies, receivers,
transmitters, radios, clocks, tuners, speakers, tape, compact disc,
and various players, and various other equipment as understood by
those skilled in the art.
[0004] In the power audio amplifier field, however, many
advancements have focused on improved techniques for generation of
high acoustic power and yet have high bandwidth and low distortion.
Also, improvements have been made in providing power or supplying
power to audio amplifiers. These power amplifiers conventionally
use two different power sources. One from a high voltage source and
another from a low voltage source. A switching transistor is often
used to change between the low and high voltage sources. The audio
signal applied to the speaker is detected, and when the level of
audio signal exceeds a preselected level, the switching transistor
is so turned as to supply power from the high voltage source. When
the level of the audio signal is below the preselected level, the
switching transistor is so turned as to supply power from the low
voltage source. High levels of power, especially for long periods
of time or in very high surges, can overheat and severely damage
the transistors and many of the other electronic components of
these audio amplifiers.
[0005] To address some of these problems, power amplifiers have
been developed with temperature controls which attempt to prevent
the transistors and other electronic components from overheating.
Examples of such power amplifiers can be seen in U.S. Pat. No.
5,818,301 by Higashiyama et al. titled "Power Amplifier Arrangement
Of A Plural Power Supply Switching Type" and U.S. Pat. No.
5,331,291 by D'Agostino et al. titled "Circuit And Method For
Adjusting The Bias Of An Amplifier Based Upon Load Current And
Operating Temperature." Such power amplifiers, however, fail to
take into account power surges which can arise, particularly in
start up, which can quickly damage the transistors and other
electronic components.
[0006] To address these power surge problems, circuits have been
developed which detect abnormal voltage levels and cut off portions
of a power amplifier circuit. An example of such a circuit can be
seen in U.S. Pat. No. 5,847,610 by Fujita titled "Protection
Circuit For An Audio Amplifier." Such power circuits do little to
address start up problems and do little to discriminate or
recognize true or false power surge problems.
SUMMARY OF THE INVENTION
[0007] With the foregoing in mind, the present invention
advantageously provides an audio amplifier controller for an audio
amplifier and associated methods which limits in-rush current
during start up and slowly ramps up to a high power and amplifier
state. The present invention also advantageously provides an audio
amplifier controller which in combination allows for soft start
capabilities, power discrimination capabilities, and thermal
monitoring capabilities to enhance protection for power audio
amplifiers during various power surge and temperature increasing
conditions. The present invention additionally advantageously
provides an audio amplifier controller which monitors the current
output of the amplifier to protect speakers or other devices by
disconnecting the load to the output circuits during high current
conditions and then continues to monitor the current output to
resume normal conditions if desirable. The present invention yet
also provides an audio amplifier controller for an audio amplifier
which protects the amplifier from going into and remaining in a
circuit protection mode by continuously monitoring for normal
current conditions. The present invention further advantageously
provides an audio amplifier having an audio controller and
associated methods which detects voltage level changes by frequency
changes and voltage nulls. The present invention still further
provides an alternating current soft start circuit which
advantageously limits inrush current and allows a slow ramp up of
power to a high power on-state by sensing frequency and voltage
nulls.
[0008] More particularly, the present invention provides an audio
amplifier power and temperature controller which preferably
includes power receiving means for receiving power from a power
source to an audio amplifier and power condition switching control
means responsive to the power receiving means for switching
components of an audio amplifier during a plurality of power
conditions. The power condition switching control means preferably
includes soft starting means responsive to the power receiving
means for limiting inrush current from the power receiving means
and for slowly ramping up to an audio amplifier on-state, thermal
status monitoring and controlling means for monitoring thermal
status of operating values of audio amplifier components and
responsively decreasing power to the audio amplifier components to
protect the audio amplifier components against damage caused by
excess heat and for responsively increasing power when the audio
amplifier components return to normal thermal operating conditions,
and output monitoring means for monitoring current output circuits
of the audio amplifier to protect an audio amplifier during a high
current condition when connected to the audio amplifier by
disconnecting a load to the current output circuits and
reconnecting the load to the current output circuits when normal
operating current conditions resume.
[0009] The present invention additionally includes a alternating
current ("AC") soft starting circuit which preferably has a power
level detecting circuit responsive to an alternating current source
and positioned to detect voltage changes by sensing frequency
changes and voltage null points and a micro-controller responsive
to the power level detection circuit to monitor low power
conditions and high power conditions to limit inrush current during
high power condition from the alternating current source and to
slowly ramp up to high power on-state condition. The AC soft start
circuit can also include the micro-controller having wave analyzing
means for analyzing sinusoidal waves of the alternating current
source detected by the power level detection circuit to determine a
voltage null so that the soft start function allows a power
on-state to be initiated just prior to a voltage null and to
gradually ramp up to a the high power on-state condition.
[0010] The present invention also includes methods of controlling
power to an audio amplifier. A method preferably includes receiving
power from a power source to an audio amplifier and switching
components of an audio amplifier during a plurality of power
conditions. The step of switching components preferably includes
limiting inrush current from the power source, slowly ramping up to
an audio amplifier on-state, monitoring thermal status of operating
values of audio amplifier components, responsively decreasing power
to the audio amplifier components to protect the audio amplifier
components against damage caused by excess heat, and responsively
increasing power when the audio amplifier components return to
normal thermal operating conditions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Some of the features, advantages, and benefits of the
present invention having been stated, others will become apparent
as the description proceeds when taken in conjunction with the
accompanying drawings in which:
[0012] FIG. 1 is a perspective view of an audio amplifier having an
audio amplifier controller with a soft start circuit according to
the present invention;
[0013] FIG. 2 is a schematic circuit diagram of an audio amplifier
controller according to a first embodiment of the present
invention;
[0014] FIGS. 3A-3D are schematic circuit diagrams of an audio
amplifier controller according to a second embodiment of the
present invention;
[0015] FIGS. 4A-4B are schematic flow diagrams of a method of
controlling an audio amplifier according to a first embodiment of
the present invention;
[0016] FIGS. 5A-5G are schematic flow diagrams of a method of
controlling an audio amplifier according to a second embodiment of
the present invention;
[0017] FIG. 6 is a graph of timing diagrams for methods of
controlling an audio amplifier according to the present invention;
and
[0018] FIG. 7 is a graph of amplitude versus time for methods of
controlling an audio amplifier according to the present
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0019] The present invention will now be described more fully
hereinafter with reference to the accompanying drawings which
illustrated preferred embodiments of the invention. This invention
may, however, be embodied in many different forms and should not be
construed as limited to the illustrated embodiments set forth
herein. Rather, these illustrated embodiments are provided so that
this disclosure will be thorough and complete, and will fully
convey the scope of the invention to those skilled in the art. Like
numbers refer to like elements throughout, and prime and/or double
prime notation are used to indicate similar elements in alternative
embodiments.
[0020] FIG. 1 illustrates a perspective view of a power audio
amplifier 10 having an audio amplifier power and temperature
controller 20 according to the present invention (see also FIGS.
3A-3D). The audio amplifier 10 includes a housing 11 with a display
15 and a plurality of light indicators D5, D6, D7 on a front panel
thereof and a plurality of vent openings 12 positioned in a top and
side panels thereof. As perhaps best shown in FIGS. 2-3D, the audio
amplifier power and temperature controller 20 preferably includes
power receiving means for receiving power from a power source to an
audio amplifier 10. The power receiving means is preferably
provided by a power receiving circuit which includes a plurality of
conductors P1, P2, P3, P4 positioned to receive power from a power
cord, e.g., from an alternating current ("AC"), a power supply,
and/or a power transformer as understood by those skilled in the
art. The power receiving circuit can also include a power switch
SW1 (preferably for the entire audio amplifier), or other power
ON/OFF sensing circuitry, and additional ON/OFF switch circuitry,
e.g., preferably resistors R4, R5 and diodes D8,D9, e.g., Schottky
diodes, in a resistor-diode network with +5 volts and ground as
illustrated (see FIG. 2). The power receiving circuit can also
include a plurality of fuses F1, F2 connected to the conductors, a
damping capacitor C9 connected to the conductors, and a main power
transformer Ti connected to one of the fuses F1 and one of the
conductors P3 for supplying power to the power condition switching
control circuit as described further herein.
[0021] The audio amplifier power and thermal controller also
preferably includes power condition switching control means
responsive to the power receiving means for switching components of
an audio amplifier during a plurality of power conditions. The
power condition switching control means is preferably provided by a
power condition switching control circuit which advantageously
switchingly controls power from the power receiving circuit to
other components of the audio amplifier, including any amplifying
transistors associated with the audio amplifier 10. The control
circuit is preferably responsive to power being switched on during
start up and power being supplied during continuous operation of
the amplifier 10. An example of such a power condition switching
control circuit is illustrated in FIG. 2. Another example is
illustrated in FIGS. 3A-3D in conjunction with an audio amplifier
circuit.
[0022] The power condition switching control circuit preferably
includes soft starting means, e.g., preferably provided by a soft
start circuit according to the present invention, responsive to the
power receiving circuit for limiting inrush current from the power
receiving circuit and for slowly ramping up to an audio amplifier
on-state. The soft starting circuit advantageously includes a power
level detection circuit to detect voltage changes by sensing
frequency changes and voltage null points and a micro-controller
U3, such as P1C16C505, responsive to the power level detection
circuit to monitor low power conditions and high power conditions.
Although particularly advantageous for amplifiers, and more
particularly audio power amplifiers, the soft start circuit can
also advantageously be used in other AC start up circuit
applications. The micro-controller U3, for example, preferably
includes wave analyzing means, e.g., a software program in the
micro-controller U3, for analyzing the sinusoidal waves, i.e., AC,
detected by the power level detection circuit to determine a
voltage null so that the soft start function allows the audio
amplifier to turn on just prior to a voltage null and to gradually
ramp up to a fully on-start or high power condition. By analyzing
the frequency of the waves, the wave analyzer, for example, can use
the elongation of the step function to indicate a higher
voltage.
[0023] As shown in FIG. 2, for example, the soft start circuit can
also include a voltage regulating circuit connected to a voltage
supply, e.g., +5 volts, which regulates input voltage to the soft
start circuit. The voltage regulating circuit can include a voltage
regulator U1 and one or more Zener or other diodes D1, D2 and
capacitors C4, C5, C6 connected to power and ground. A diode D1 can
also be used for isolation of the AC signal. A bridge rectifier BD1
connected to the power transformer T1, a capacitor C2 connected to
ground, and a capacitor Cl is positioned to rectify the voltage
from the power transformer T1. A plurality of resistors R12, R13, a
capacitor C7, and a diode D4, e.g., a Schottky diode, are also
connected to the capacitor C1 in a network arrangement as
illustrated and the +5 volts source, ground, and a pin (Pin 4) of
the micro-controller.
[0024] The power level detection circuit is preferably provided by
a power triac or other similar circuit which tracks or detects when
alternating current ("AC") power is low at the end of a cycle to
limit inverse current. An optocoupler or optoisolator U2 provides
optical isolation between the power receiving circuit and the
transistor Q1, as well as resistors R1, R3 to indicate power status
to the micro-controller U3 at a pin (Pin 3) thereof.
[0025] The micro-controller U3 of the soft starting circuit
receives an analog signal as an input to Pin 4. This signal is
processed in the micro-controller U3 without utilization of an
external or internal analog to digital converter ("ADC") as
understood by those skilled in the art. Instead, this is
accomplished by taking advantage of the characteristics of a
micro-controller, e.g., formed of silicon CMOS. As perhaps best
shown in FIGS. 2 and 6, the AC signal from the diode bridge
rectifier BD1 is delivered to Pin 4 in analog form. The software
programs embedded or stored in the micro-controller can be written
to allow the micro-controller to assign a digital value to each
timed portion of the input analog signal (timing is referenced to
the micro-controller internal clock as understood by those skilled
in the art). The software of the micro-controller can also be
written to accomplish frequency, amplitude, and input AC voltage
"null to null" timing based on a digital replica made of the analog
signal input at Pin 4. The software program is preferably written
in such a manner to be independent of micro-controller device
technology. In other words, gallium arsenide (GaAs), silicon
germanium (SiGe), or silicon carbide (SiC) based micro-controllers,
for example, will also function accurately in this circuit without
the use of external or internal ADC using such software
capabilities.
[0026] The power switching control circuit also preferably includes
thermal status monitoring and controlling means for monitoring
thermal status of operating values of audio amplifier components
and responsively decreasing power to the audio amplifier components
to protect the audio amplifier components against damage caused by
excess heat and for responsively increasing power when the audio
amplifier components return to normal thermal operating conditions.
The thermal status monitor and controlling means is preferably
provided by a thermal status monitoring and controlling circuit
which can be provided by the micro-controller U3 and software
programs stored or embedded therein, and as described further
herein with reference to FIGS. 4A-5G.
[0027] Output monitoring means of the power switching control
circuit is also provided for monitoring current output circuits of
the audio amplifier 10 to protect the amplifier during a high
current condition, e.g., transients or electro-static discharge,
when connected to the audio amplifier by disconnecting a load to
the current output circuits and reconnecting the load to the
current output circuits when normal operating current conditions
resume. The output monitoring means includes means for monitoring
the output current circuits to determine if full audio amplifier
shut down is desirable to protect the audio amplifier 10 and
speakers or other audio system components when connected thereto.
The output monitoring circuit, for example, can include a connector
J2 for connecting the power condition switching control circuit to
an input circuit of the power amplifier, and a resistor and diode
network, e.g., including R9, R10, R11, R14, and D3, connected to
the connector J2 and the micro-controller U3, as well as ground and
power, e.g., +5 volts. The micro-controller and software programs
embedded or stored therein also can form a portion of the output
current monitoring circuit as described with reference to FIGS.
4A-5G herein.
[0028] The power condition switching control means further includes
input power discriminating means responsive to the power receiving
means for discriminating between incoming audio component signals
to turn-on the audio amplifier 10 to the on-state and transient
line voltage to momentarily sense the signal but not activating the
audio amplifier 10 to the on-state. The input power discriminating
means is preferably provided by a power discriminating circuit. The
power condition switching control means also further includes
brown-out protecting means for protectively preventing the audio
amplifier 10 from going into and remaining in a circuit protection
or sleep mode by continuously monitoring the audio amplifier 10 for
normal current conditions and responsively resuming normal
amplifier operations when normal current conditions occur. The
brown-out protecting means is also provided by a brown-out
protecting circuit. Both the discriminating circuit and brown-out
detection circuit are preferably provided by the micro-controller
U3 and software programs stored therein, and as further described
with respect to FIGS. 4A-5G.
[0029] The audio amplifier power and thermal controller 20 can also
advantageously include visual feedback means responsive to the
power condition switching control means for providing visual
operating and error status feedback for diagnosing operating and
error status conditions. The visual feedback means includes
indicating means, e.g., preferably provided by a software program
in a micro-controller U3 and/or as a separate hardware circuitry,
e.g., resistors R6, R7, R8, for indicating at least one
predetermined visual signal and a plurality of light sources, e.g.,
light emitting diodes ("LEDs") D5, D6, D7, responsive to the
indicating means to visually display light representing the at
least one predetermined visual signal.
[0030] FIGS. 3A-3D illustrate an audio amplifier having another
embodiment of a power and thermal controller 20' of the present
invention. These figures illustrate the amplification on the left
and right channels in FIGS. 3A-3B (see also connection of FIG. 3D).
These amplification circuits are substantially the same for each
channel and are connected by a connector bridge JP10 and a resistor
R134. Each amplification circuit includes a switching or logic
circuits JP9, a plurality of transistors Q101-Q116, Q201-Q216, a
resistor, capacitor, and diode network having a plurality of
capacitors C101-C116, C201-C216, a plurality of resistors
R101-R133, R201-R233, and a plurality of diodes D101-D106,
D201-D206. These circuits serve primarily the amplification
function of the audio amplifier. The amplification circuits can
also include the circuits shown in FIG. 3B which are also
substantially similar and include logic or switching interface
circuits JP301, JP302, JP306, JP307, resistors R301-R304,
capacitors C304-C307, fuses F302-F305, and bridging circuits U301,
U302.
[0031] FIGS. 3C and 3D illustrate another embodiment of the power
condition switching control circuit 20'. This circuit 20' likewise
includes a main power transformer T307, a bridge rectifier U307, a
triac Q8, an optocoupler or optoisolator U3, a micro-controller U1,
and fuses F3, F307 similar to the first embodiment described above.
Logic or switching interface circuits JP8, JP303, JP304 are also
connected to the transformer T307 and to the triac Q8 and fuse F3.
The visual operating and error status feedback circuits are
provided by LEDs D302, D303, D304 and resistor or logic circuits
JP305, JP308 connected thereto. The output from the bridge
rectifier U307 likewise has diode D25, resistors R16, R41, and
capacitor C15 network connected to the bridge rectifier U307 and
Pin 6 of the micro-controller U1.
[0032] The thermal monitoring circuit is provided by portions of
the micro-controller U1 and the diode D3, D9, and resistor R11,
R35, R40 circuit and logic or switching interface circuits JP5,
JP6. The power receiving circuit can also include the ON/OFF switch
SW, the diodes D18, D19 and resistors R6, R100 connected thereto,
to Pin 2 of the micro-controller U1, and to the logic circuit JP3.
The logic or switching interface circuit JP3 also has resistors
R17, R18 connected thereto and to Pins 6 and 7 of the
micro-controller U1. The soft starting portion of the circuit also
has resistors R20, R33, transistor Q2, capacitor C14, and logic
circuit JP8 connected thereto as illustrated. Likewise, the circuit
also has a voltage regulating circuit which includes a voltage
regulator U304 and a diode D307 and a plurality of capacitors C307,
C308, C303, C302 connected thereto. A diode IN4007 also is
positioned to isolate an AC signal and is connected to the bridge
rectifier U307 as illustrated.
[0033] As perhaps best illustrated in FIGS. 3C-3D, the power
condition switching control circuit can also include an audio sense
circuit or connector for sensing audio at Pin 13 of the
micro-controller U1, resistor R2, and the logic circuit JP1. A 3-30
volt range function circuit is also provided at Pin 12 of the
micro-controller U1, resistor R3, and logic circuit JP1. An audio
detect circuit is provided connected to Pin 4 of the
micro-controller U1 and have a switching or logic circuit JP2
connected thereto. The audio detect circuit includes a transistor
Q7, a plurality of resistors R8, R9, R22, R26, R27, R28, R30, R47,
R48, R49, R50, a plurality of capacitors C1, C2, C6, C11, C12, and
a plurality of diodes D1, D2, D4, D5, D11, D12, D23, D24 connected
in a network. The audio detect circuit also includes a plurality of
amplifiers U5A, U5B, U5C in a stage arrangement as illustrated.
[0034] Also, a direct current or over current detect circuit is
provided connected to Pin 3 of the micro-controller U1 and has
transistors Q3, Q4 connected thereto. This detect circuit also has
a plurality of resistors R4, R15, R36, R39, R43, R44, a plurality
of diodes D6, D7, and a capacitor C7 connected thereto. Capacitor
C3 also illustrates a capacitor positioned to a ground connection.
The circuit also connects to a relay, or switch, RY1 to the speaker
output at logic or switching circuit JP7 and resistors R45, R46 and
capacitors C4, C5. The speaker circuit is also connected to Pin 9
of the micro-controller U1 and has a transistor Q6, a plurality of
resistors R19, R42 and a diode D10 connected thereto.
[0035] Further, the audio sense and 3-30 volt range function detect
circuits can have a circuit connected to the logic or switching
interface circuit JP1. This circuit includes a logic or switching
interface circuit JP4, a pair of fuses F1, F2, a pair of diodes
D14, D15, a plurality of capacitors C8, C9, C10, a resistor R29,
and a voltage regulator U4.
[0036] FIGS. 4A and 4B are schematic flow diagrams of portions of
the power condition switching control circuit illustrating the soft
start method or process of the present invention. The method 500
includes starting the process 501 by initialization 502 where the
power is off and no protection indication variables are required
internal to the micro-controller U3. The next step is to check
whether the power switch is turned on 503 (see Pin 2 of
micro-controller U3). If not, then a loop back to this step 503
continues. If the power switch is turned on, however, a
determination is made as to whether the power is low 504 (see Pin 4
of micro-controller U3) such as in a brown-out condition. The
threshold level, for example, can be 2 volts. If the power is low,
then a determination is made as to whether this was a false signal
or a power problem exists 505. If so, then initialization can
reoccur 502 or a determination made as to whether the power switch
is really on or still on 506. If the power switch is still on after
a selected lapsed time, a power low indication 507 can be made to a
user or technician so that the user or technician can check the
power status of power being supplied to the audio amplifier
controller and audio amplifier and the amplifier will not be turned
on.
[0037] If, on the other hand, the power is not low, e.g., below a
predetermined threshold, then the soft start process is started to
limit the inrush current 508. The controller monitors the soft
start process to make sure that a low power condition has not
arisen 509. If so, then a determination is made as to whether the
power is off 510. If there is a preliminary indication, then a time
period elapses to verify this determination (see B). The process
returns to verify that the power is still low 505 and that cycle
continues as described above.
[0038] If the power is not low (see D and FIG. 4B), however, then a
circuit protect process 511 is initiated to protect the output of
the output circuits (see Pin 10 of micro-controller U3) during high
current conditions. The protect signal is initiated and an LED,
e.g., D7 or D304, is turned on. If the protect signal is not
initiated for some reason, then a determination is made as to
whether the amplifier is active 512, e.g., to monitor whether the
amplifier is in a sleep mode or not. If the amplifier is active,
then an active indication process 513 is initiated, and a
determination as to whether the power switch is still on 515 is
made. If the amplifier is not active, then a no active indication
process is initiated, and a determination as to whether the power
switch is on 515 is also made.
[0039] If the protect signal is on, then a determination is made as
to whether the signal was noise 516 such as a longer transient
spike or a real power on signal. If it was noise (see C), then a
determination is made as to whether power is low 509 to verify this
determination, and the process 509 continues. If it was not noise,
then a determination is made as to whether the amplifier is damaged
517 is made. If not (see C), then a determination of whether power
is low now 509 is made. If the amplifier has been damaged, then a
damage signal or indication 518 is made, e.g., requesting that a
user or technician turn off the amplifier. The process would then
check to see if the power switch is still on 519. If so, the damage
indication would continue. If not, then the process returns to the
initialization 502 (see A and FIG. 4A).
[0040] FIGS. 5A through 5G illustrate an additional embodiment and
further aspects of a power condition switching control circuit.
These schematic flow diagrams of portions of the power condition
switching control circuit illustrate the methods and processes of
the structure as described above herein. The method or process 600
of the present invention preferably starts 601 by initialization
601 where the amplifier power indication is off and the amplifier
is mute. A determination is then made as whether the power switch
is on 603 or detected as being in an on position. If the switch is
not on, then a continuous wait to see if the switch is turned on
occurs. If the switch is on, then a determination of whether the
power is below a predetermined threshold or at an AC brown-out
level is made 604. If so, then a determination is made as to
whether the amplifier is off or mute 605 and whether an AC
brown-out is still occurring 606. If the amplifier is off or not
brown-out condition is detected, then initialization 602 reoccurs.
If the power switch is still on 607, then an indication of an AC
brown-out level 608 occurs.
[0041] If the power is not low or no brown-out condition is
detected, then power on indication 609 occurs. If the power switch
is not on or turned off 610, then initialization reoccurs 602. If
the power switch is still on 610, then a determination is made as
to whether an audio sense function is on 611. If the function is
not on, then a determination is made as to whether a 3-30 volt
range function is on 612. If the 3-30 volt range function is on,
then a determination is made as to whether the amplifier is active
613 (see FIG. 5B).
[0042] If the amplifier is active, then an AC brown out level
determination 621 is made, and the process as described above at
605 is repeated (see B of FIG. 5A). If the amplifier is not active,
then the soft start process is initiated by limiting the inrush
current 614 to slowly turn the amplifier on 615 or to an active
state with the amplifier mute function in an off-position. A
determination is then made as to whether the direct current or over
current signal 616 is on. If not, then a determination is made as
to whether a thermal signal is on 617. If not, then a determination
is made as to whether the power switch is still on 618. If not,
then initialization 602 reoccurs. If so, then whether the audio
sense function is on is determined 619. If not, the 3-30 volt range
function is reevaluated 620. If this function is not on, then a
brown-out level determination is made again 621 (see also B of FIG.
5A at 605).
[0043] If, on the other hand, the audio sense function is on 611
and 619, then a determination is made as to whether the amplifier
is active 622. If the amplifier is not active, then the amplifier
is off and/or amplifier mute may be on. A determination is made as
to whether the audio signal is on 625. If not, then a determination
is made as to whether the power switch is on 610 again (see C of
FIG. 5A). If the audio signal is on, however, then the soft start
process is initiated 626 to limit the inrush current and slowly
ramp up to an amplifier on-state with the amplifier mute in an off
position and the amplifier active 627. If the amplifier is active,
then a determination is made as to whether the audio signal is on
623, 628. If the audio signal is on, then a determination is made
as to whether the power switch is still on 629. If not, then
initialization 601 reoccurs. If so, however, then a determination
is made as to whether a direct current or over current signal is on
630. If not, then a determination is made about the thermal signal
631. If the thermal signal is not on, e.g., no overheat condition,
then a determination is made as to whether the 3-30 volt range
function of the amplifier is on 632. If not, then a determination
is made as to whether the audio sense function is on 633. If not,
the process of step 622 is repeated (see FIG. 5C). If so, then a
brown-out level is determined 634. If a brown-out condition is
detected, then the process returns to step 605 (see B of FIG. 5A).
If no brown-out condition is detected, then the process returns to
the audio signal on determination 628 and the process repeated.
[0044] If, however, the 3-30 volt range function is on 612, 620,
632 (see FIG. 5D), then a determination is made as to whether the
amplifier is active 635. If so, then the 3-30 volt range function
signal is determined to be on or not 636, 641. If the amplifier is
not active, then the amplifier is off and/or the amplifier mute is
on 637. Then a determination is made as to whether the 3-30 volt
signal is on 638. If not, then a determination is made again on
whether the power switch is on 610 (see FIG. 5A). If the signal is
on, however, then the soft start process to limit the inrush
current and slowly ramp the current up to an amplifier on-state 639
is initiated. The amplifier mute is then off and the amplifier is
active 640.
[0045] A determination is then made as to whether the 3-30 volt
range function signal is on 641. If not, then the process of step
635 is repeated. If this function signal is on, then a
determination is made again whether the power switch is still on
642. If not, then initiation 601 is repeated. If the power switch
is still on, then a direct current or over current signal
determination 643 is made. If this signal is not on, then a thermal
signal on condition is determined 644. If this signal is not on,
then an audio sense function signal is determined 645. If this is
on, then the process of step 622 (see E of FIG. 5C) is repeated. If
this audio sense function signal is not on, then the 3-30 volt
range function signal is determined 646. If this is on, then a
brown-out condition determination is repeated 647 (see B of FIG.
5A). If this brown-out level is not occurring, then the process of
step 641 is repeated.
[0046] Now, as set forth in FIG. 5C, if the audio signal is not on
628, then a determination is made as to whether a predetermined
time lapse or period, e.g., 3 minutes, occurs 648 (see FIG. 5E). If
it has occurred, then the process of step 622 (see E of FIG. 5C)
occurs. If this time period has not lapsed, then determinations are
made as to whether the power switch is on 649, whether the audio
signal is on 650, whether the thermal signal is on 651, whether the
direct current or over current signal is on 652, whether the 3-30
volt range function is on, whether the audio sense function is on
654, and whether a brown-out level occurs 655.
[0047] If the thermal signal is on 617, 631, 644, 651, then the
amplifier is turned off, muted, and deactivated 656 (see FIG. 5F).
Thermal protection is also indicated 657. The controller then
determines whether a brown out level exists 658. If not, then
determinations are made as to whether the power switch is on 659,
the thermal signal is on 660, or has a predetermined time period,
e.g., 12 seconds, passed 661. If the time period has not passed,
then the thermal protection indication continues 657 and the steps
are repeated. If the period has passed, then the amplifier is
turned on 662, and a determination of whether the thermal signal is
still on 663 is made. If so, then the process of step 656 is
repeated. If not, the direct current or over current signal on
condition is determined 664.
[0048] If the direct current or over current signal is on 616, 630,
643, 652, 664, then the amplifier is muted 665 (see FIG. 5G). The
same direct or over current signal condition is reevaluated 666. If
the signal is on, then the amplifier is off, muted, and deactivated
667 and an indication of general protection failure occurs 668. A
determination is made as to whether the power switch is still on
669, 670 repeatedly during this indication 668 or until
initialization 601 (FIG. 5A). If the direct or over current signal
is not on, however, then the indication is off for direct current
or over current protection 671, the amplifier is mute 672, and a
brown-out level can be determined 673. If the brown-out does not
exist, then a power switch on determination is made again 674. If
the power switch is on, then a determination is made as to whether
a preselected number, e.g., 5 times, of direct current or over
current arise 675. If such a condition did arise then the steps of
667 are repeated. If no condition did arise, then whether the
direct current or over current signal turn on is made again 676. If
the signal is not on, then initialization 601 occurs again. If it
is on, then the process of step 665 is repeated.
[0049] Additionally, the audio amplifier further includes
overvoltage and undervoltage detecting means which is preferably
provided by the interface to and the software within the
micro-controller U3. The signal is processed to the
micro-controller U3 without the need for an external analog to
digital converter ("ADC"). This is accomplished, as described above
herein as well, by taking advantage of the device characteristics
of the micro-controller, e.g., silicon complimentary metal oxide
semiconductor or CMOS. The alternating current signal from the
diode bridge rectifier circuit is delivered to pin 4 of the
micro-controller U3 in analog form. The software of
micro-controller, as understood by those skilled in the art, allows
the micro-controller to assign a digital value to each timed
portion of the input analog signal such as shown in the graph in
FIG. 7, e.g., about 120 volts and 80 volts. Timing is referenced to
an internal clock of the micro-controller. The software can
advantageously accomplish frequency, amplitude, and input voltage
"null to null" timing based on the digital replica made of the
analog signal input at pin 4. The software, however, is notably
independent of the micro-controller device technology. In other
words, GaAS, SiGe, SiC or other device technologies can be written
to take advantage of this digital replication technique as
well.
[0050] In essence, the software acts as a comparator to look at the
crest voltage from the rectifier. The phase of the voltage is first
measured and a look up table is positioned within the
micro-controller, e.g., as part of software or database memory, to
determine the time difference. If the crest voltage is below a
certain threshold or low, then the signal is a 0, and if the crest
voltage is above a certain threshold or high, then the signal is a
1.
[0051] As shown in FIG. 7, the shaded regions, t1 and t2,
illustrate the difference in time used by the micro-controller U3
at the point when the voltage crosses a preselected threshold as
described above. If the time is longer than t1 for about 120 volts
(or other selected voltage level), then an overvoltage condition
has been detected. If the time is shorter than t1 for about 120
volts (or other selected voltage), then an undervoltage condition
has been detected. The same is true for t2. This digital
replication or timing technique advantageously can, for example,
have an accuracy margin well within 0.1%, e.g., 0.01%. This also
advantageously provides flexibility to the designer and decreases
the cost and overhead for the amplifier.
[0052] FIGS. 1-7, and particularly FIGS. 4A-7, illustrate methods
of controlling power to an audio amplifier. A method preferably
includes receiving power from a power source to an audio amplifier
and switching components of an audio amplifier during a plurality
of power conditions. The step of switching components preferably
includes limiting inrush current from the power source, slowly
ramping up to an audio amplifier on-state, monitoring thermal
status of operating values of audio amplifier components,
responsively decreasing power to the audio amplifier components to
protect the audio amplifier components against damage caused by
excess heat, and responsively increasing power when the audio
amplifier components return to normal thermal operating
conditions.
[0053] The method can also advantageously include the step of
switching components of an audio amplifier further including
monitoring current output circuits of the audio amplifier to
protect the audio amplifier during a high current condition when
connected to the audio amplifier by disconnecting a load to the
current output circuits and reconnecting the load to the current
output circuits when normal operating current conditions resume,
discriminating between incoming audio component signals to turn-on
the audio amplifier to the on-state and transient line voltage to
momentarily sense the signal but not activating the audio amplifier
to the on-state, and protectively preventing the audio amplifier
from going into and remaining in a circuit protection mode by
continuously monitoring the audio amplifier for normal current
conditions and responsively resuming normal amplifier operations
when normal current conditions occur.
[0054] The method can additionally include the step of limiting
inrush current including detecting voltage changes by sensing
frequency changes and voltage null points and monitoring low power
conditions and high power conditions, and the step of monitoring
further including monitoring the output current circuits to
determine if full audio amplifier shut down is desirable to protect
the audio amplifier and other system components when connected
thereto. The method can further include providing visual operating
and error status feedback for enhancing diagnosis of operating and
error status conditions. The step of providing operating and error
status feedback can include indicating at least one predetermined
visual signal and displaying through a plurality of light sources
light representing the at least one predetermined visual
signal.
[0055] In the drawings and specification, there have been disclosed
a typical preferred embodiment of the invention, and although
specific terms are employed, the terms are used in a descriptive
sense only and not for purposes of limitation. The invention has
been described in considerable detail with specific reference to
these illustrated embodiments. It will be apparent, however, that
various modifications and changes can be made within the spirit and
scope of the invention as described in the foregoing specification
and as defined in the appended claims.
* * * * *