Page 1 of9
`
`PHHJPS EXHIBIT 201
`
`WAC V. PHHJPS
`
`IPR2015-01292
`
`
`
`Page 1 of 9
`
`PHILIPS EXHIBIT 2010
`WAC v. PHILIPS
`IPR2015-01292
`
`

`
`CLOSING
`
`THE FEEDBACK
`
`LOOP
`
`by
`
`Lloyd
`
`H.
`
`Dixon,
`
`Jr
`
`Switching
`feedback
`and
`load
`the
`closed
`
`power
`systems
`regulation
`loop
`
`almost
`supplies
`to
`in
`order
`and
`dynamic
`be described
`
`can
`
`always
`achieve
`response.
`in
`terms
`
`use
`design
`
`closed-loop
`objectives
`in
`As shown
`these
`major
`
`negative
`for
`line
`Figure
`1,
`elements:
`
`of
`
`and
`Reference
`Error
`amplifier
`Pulse
`width
`Output
`power
`
`comparator
`and
`compensation
`modulator
`and
`power
`filter
`
`81
`
`( 5 ) :
`
`82(5):
`
`He(5):
`
`networks
`switching
`
`circuit
`
`Figure
`
`1.
`
`Control
`
`loop
`
`block
`
`diagram
`
`these
`Fortunately,
`analytical
`using
`simple
`the
`gain
`in
`only
`once
`use
`of
`a simplified
`Bode
`plots
`provide
`calculating
`the
`
`loop
`
`vs.
`version
`a simple
`gain
`
`systems
`closed-loop
`gain
`Unity
`techniques.
`characteristic,
`frequency
`Nyquist
`the
`of
`powerful
`and
`parameters
`(see
`
`control
`
`be stabilized
`can
`crossover
`occurs
`permitting
`the
`criterion.
`displaying
`B).
`
`and
`
`stability
`method
`of
`Appendix
`
`frequency,
`switching
`The
`modulator
`width
`pulse
`the
`are
`He(s),
`filter,
`the
`topology.
`circuit
`of
`choice
`characteristic
`define
`the
`is
`to
`compensation
`networks,
`closed
`loop
`gain-bandwidth
`load
`regulation
`and
`stability.
`
`task
`of
`the
`that
`good
`
`81(5),
`for
`
`characteristics
`gain-frequency
`the
`fc,
`circuit,
`82(5),
`power
`switching
`and
`application
`and
`predetermined
`by
`the
`the
`feedback
`The
`in
`closing
`error
`amplifier
`and
`will
`result
`the
`dynamic
`
`of
`and
`the
`loop
`related
`optimum
`line
`and
`
`in
`response,
`
`UNITRODE
`
`CORPORATION.
`
`5 FORBES ROAD.
`
`LEXINGTON,
`
`MA 02173.
`
`TEL
`
`(617) 861-6540
`
`.TWX
`
`(710) 326-6509
`
`.TELEX
`
`95-1064
`
`2-1
`
`
`
`Page 2 of 9
`
`

`
`CLOSED LOOP DESIGN PROCEDURE
`
`(1]
`
`loop
`
`Define
`
`the
`
`Goal:
`
`Make
`
`a Bode
`
`plot
`
`of
`
`the
`
`desired
`
`closed-
`
`characteristic
`
`that
`
`will
`
`achieve
`
`the
`
`best
`
`possible
`
`gain-
`
`bandwidth
`
`for
`
`good
`
`dynamic
`
`response,
`
`line
`
`and
`
`load
`
`regulation
`
`and
`
`stability.
`
`(2)
`method.
`pulse
`
`Control
`the
`Define
`a Bode
`plot
`Make
`modulator
`and
`
`width
`
`to Outgut
`of G2(s),
`power
`switch,
`
`Gain:
`the
`
`upon
`Decide
`gain
`characteristic
`and He(s),
`the
`
`the
`
`filter.
`
`control
`of
`the
`
`Design
`(3)
`plotted
`phase
`characteristic
`
`the
`
`Com~ensation
`(2)
`above
`in
`necessary
`to
`
`Network:
`from
`(1).
`attain
`the
`
`Subtract
`The
`result
`closed
`loop
`
`the
`
`gain(dB)
`is
`the
`objective.
`
`and
`G1(s)
`
`DEFINE
`
`THE GOAL
`
`Stabilit~
`crosses
`lag
`at
`addition
`feedback
`180
`degrees
`
`Criterion:
`unity
`(0 d8J
`the
`crossover
`the
`to
`systemJ.
`and
`
`the
`
`Referring
`only
`once,
`freq~ency,
`180
`normal
`other
`At
`system
`
`Figure
`system
`is
`less
`phase
`
`2,
`
`if
`
`is
`
`gain magnitude
`if
`the
`phase
`degrees
`(in
`the
`negative
`lag may
`exceed
`
`180
`of
`
`the
`stable
`than
`shift
`the
`phase
`stable.
`
`be
`
`to
`the
`fc,
`
`degree
`frequencies,
`will
`still
`
`is
`
`phase
`the
`by which
`amount
`the
`margin'
`'phase
`The
`degrees.
`than
`180
`is
`less
`fc,
`frequency,
`crossover
`gain
`is
`less
`than
`by which
`the
`the
`factor
`is
`margin'
`is
`180
`degrees.
`the
`phase
`lag
`frequency
`where
`at
`the
`fc
`is
`slightly
`less
`than
`180
`degrees
`lag
`at
`the
`will
`stable,
`but
`will
`exhibit
`be
`margin),
`and
`A phase
`margin
`of
`45 degrees
`overshoot
`good
`response
`little
`overshoot.
`
`only
`system
`ringing.
`with
`
`very
`
`at
`
`the
`lag
`'gain
`The
`(0 dB)
`unity
`phase
`the
`If
`phase
`(small
`condsiderable
`provides
`
`for
`
`BO
`
`60
`
`Nyquist's
`the
`permits
`180
`degrees
`fc where
`the
`
`stability
`lag
`phase
`at
`frequencies
`gain
`is
`greater
`
`criterion
`to
`exceed
`below
`than
`
`but
`
`0 dB,
`practice.
`conditionall~
`loop
`gain
`unstable.
`happens
`large
`large
`
`when
`signal
`step
`
`not
`is
`this
`system
`The
`but
`stable,
`it
`decreases
`exactly
`That
`is
`the
`system
`runs
`bounds,
`as
`changes
`in
`load.
`
`a good
`will
`be
`if
`the
`becomes
`what
`into
`with
`The
`
`system
`have
`
`will
`severe
`
`oscillate
`then
`underdamped
`ringing.
`
`or
`
`Short
`
`is
`It
`stability
`
`Cut
`
`easy
`
`Stabilization
`
`Method:
`
`achieve
`to
`using
`a
`
`good
`dominant
`
`by
`
`loop
`low
`
`PHASE
`
`40
`6AIN
`(~J
`20
`
`o
`
`-20
`
`o
`
`frequency
`
`pole
`
`to
`
`roll
`
`the
`
`loop
`
`-w
`
`gain
`
`Unity
`
`off
`
`at
`
`a
`
`very
`
`low
`
`frequency.
`
`gain
`
`cross
`
`over
`
`must
`
`occur
`
`substantially
`
`below
`
`the
`
`filter
`
`pole
`
`frequency
`
`to
`
`output
`
`avoid
`
`-100
`
`2-2
`
`UNITRODE
`
`CORPORATION.
`
`5 FORBES ROAD.
`
`LEXINGTON,
`
`MA 02173.
`
`TEL
`
`(617) 661-6540
`
`.TWX
`
`(710) 32&-6509
`
`.TELEX
`
`95-1064
`
`Frequency
`
`""
`
`+
`
`Figure
`
`
`
`Page 3 of 9
`
`

`
`the
`cut
`
`additonal
`stabilization
`
`lag
`phase
`method
`
`it
`is
`
`introduces.
`poor
`dynamic
`
`result
`The
`response.
`
`of
`
`this
`
`short
`
`Closed
`
`network
`
`Looc
`
`Objective:
`
`is
`
`to
`
`optimize
`
`The
`
`line
`
`goal
`
`in
`
`designing
`
`the
`
`stabilization
`
`and
`
`load
`
`regulation
`
`and
`
`dynamic
`
`response
`
`by
`
`providing
`
`high
`
`loop
`
`gain
`
`out
`
`to
`
`high
`
`frequencies.
`
`Phase
`
`lower
`
`Stability
`
`lag
`
`must
`
`not
`
`approach
`
`within
`
`45
`
`degrees
`
`of
`
`180
`
`at
`
`fc
`
`and
`
`all
`
`frequencies
`
`to
`
`avoid
`
`oscillations,
`
`ringing
`
`and
`
`instability.
`
`analysis
`
`must
`
`be made
`
`at
`
`circuit
`
`operating
`
`extremes.
`
`goal
`pole
`
`A practical
`net
`single
`low
`frequency
`at
`-20
`d8/decade
`High
`fc
`provides
`
`the
`for
`as
`shown
`provides
`with
`good
`
`loop
`closed
`2.
`in
`Figure
`good
`DC
`regulation.
`90 degree
`phase
`small
`signal
`dynamic
`
`characteristic
`The
`resulting
`Gain
`falls
`until
`response.
`
`lag
`
`is
`high
`off
`
`of
`
`a
`at
`
`that
`gain
`linearly
`above
`
`well
`
`fc.
`
`Freauenc~:
`Crossover
`Maximum
`information
`to
`transmit
`possible
`[which
`the
`sampling
`frequency
`unstable
`[2)
`The
`system
`becomes
`0.5.[1)
`cycle,
`D, greater
`than
`is maximally
`fast.
`[3) At
`fc
`
`may
`drive
`reduction
`
`to
`enough
`be high
`the
`error
`amplifier
`in
`
`fc.
`
`cause
`into
`
`theory
`Sampling
`[1)
`any
`frequency
`at
`the
`switching
`is
`when
`fc
`exceeds
`At
`fc =
`fs/[27rD),
`fs/[27rD)
`the
`error
`
`shows
`greater
`frequency,
`fs/[2~D)
`system
`amplifier
`
`not
`is
`it
`1/2
`than
`fs/2).
`duty
`with
`response
`gain
`
`amplified
`saturation,
`
`ripple
`output
`necessitating
`
`voltage
`a
`further
`
`to
`
`=
`
`the
`
`In
`
`the
`
`examples
`
`given
`
`in Appendix
`
`C,
`
`a crossover
`
`frequency
`
`fc =
`
`fs/4
`plane
`
`attempted,
`is
`zeros
`or
`
`but
`insufficient
`
`not
`
`always
`error
`
`attained
`amplifier
`
`of
`because
`gain-bandwidth.
`
`right-half-
`
`DEFINE THE CONTROL TO OUTPUT GAIN
`
`control
`The
`gain
`combined
`and
`switching
`PWM,
`switching
`the
`switching
`well
`before
`
`transfer
`or
`frequency
`plus
`
`gain,
`output
`to
`vs.
`and
`phase
`G2(sJ,
`circuit,
`and
`filter
`circuit
`supply.
`These
`power
`process
`of
`closing
`
`the
`
`is
`characteristic,
`the
`of
`characteristics
`He(sJ.
`output
`filter,
`the
`the
`design
`are
`fundamental
`to
`elements
`usually
`designed
`are
`the
`loop
`is
`started.
`
`the
`PWM
`The
`of
`
`know
`and
`
`the
`Because
`is
`necessary
`order
`to
`amplifier
`the
`equations
`combination.
`physical
`phase
`
`vs.
`
`is
`gain
`output
`to
`control
`the
`of
`plot
`a Bode
`to make
`remainder
`the
`design
`how
`to
`network.
`compensation
`for
`given
`in Appendix
`C
`These
`eq.uations
`translate
`parameters
`of
`the
`PWM and
`switching
`frequency
`for
`the
`Bode
`plots.
`
`part
`control
`of
`
`This
`each
`
`total
`the
`output
`to
`loop
`--the
`the
`is
`facilitated
`task
`PWM-switching
`the
`previously
`circuit
`
`of
`
`it
`in
`
`loop,
`gain
`error
`
`by
`
`topology
`defined
`gain
`
`and
`
`POWER
`SWITCH
`
`into
`
`Control
`of
`the
`great
`
`method:
`pulse
`effect
`
`of
`The mode
`width
`modulator
`upon
`performance
`
`the
`
`operation
`has
`
`v
`
`a
`of
`
`s 0-!
`
`system
`loop
`closed
`the
`the
`compensation
`of
`discussion
`considers
`that
`run
`fixed
`function
`the
`
`design
`the
`and
`This
`networks.
`only
`PWM methods
`frequency,
`which
`all
`basis
`of
`a comparator
`
`at
`on
`
`Vc Q-J
`
`rnmm
`~~~:1...
`
`Figure
`
`3
`
`UNITRODE
`
`CORPORATION.
`
`5 FORBES ROAD.
`
`LEXINGTON,
`
`MA 02173.
`
`TEL.
`
`(617) 861-6540
`
`.TWX
`
`(710) 32&-6509.
`
`TELEX 95-1064
`
`2-3
`
`
`
`Page 4 of 9
`
`

`
`3.
`
`Figure
`in
`shown
`as
`linear
`frequency
`fixed
`rectangular
`provides
`output
`transistors.
`switching
`power
`thereby
`conduction
`is
`between
`Vc and Vs.
`
`controlled
`
`A control
`sawtooth
`fixed
`The
`
`voltage,
`ramp
`voltage,
`frequency
`cycle
`duty
`according
`
`a
`
`is
`Vc,
`Vs.
`pulses
`of
`to
`
`to
`compared
`The
`comparator
`the
`which
`drive
`the
`power
`switch
`the
`relationship
`
`v.-
`
`v,t-
`
`v
`
`ramp
`4),
`as
`
`oldest,
`The
`Control:
`C~cle
`Dut~
`Direct
`implemented
`used method,
`commonly
`most
`sawtooth
`IC's.
`The
`in most
`control
`amplitude,
`[see
`Figure
`is
`constant
`circuit
`operates
`exactly
`and
`the
`Disadvantages
`are:
`[1)
`Provides
`above.
`feedforward
`to
`anticipate
`no
`voltage
`input
`voltage
`changes.
`of
`affects
`sudden
`input
`changes.
`to
`response
`susceptibility.
`Poor
`open
`audio
`requiring
`regulation,
`higher
`line
`specifications.
`to
`achieve
`gain
`regulators,
`continuous
`mode
`filter
`resonant
`pole
`phase
`Control
`filter
`to make
`
`two
`shift.
`poles
`
`[2)
`provides
`characteristic
`changes
`must
`a desired
`output
`
`the
`Slow
`Poor
`loop
`loop
`In
`no help
`with
`its
`propagate
`correction,
`
`~r1
`
`Figure
`
`4.
`
`in dealing
`sudden
`through
`
`the
`with
`180
`degree
`these
`two
`resulting
`in
`
`, ~
`
`,1
`
`I I
`
`~1
`
`~
`
`/
`
`/
`
`/.
`
`T7:ji-
`
`;1
`: J m
`
`Figure
`
`5.
`
`-L
`~
`
`rT
`
`poor
`
`dynamic
`
`response.
`
`Voltaae
`exactly
`
`Feedforward
`like
`direct
`
`Control:
`duty
`
`cycle
`
`Functions
`control
`
`above
`sawtooth
`but
`varies
`input
`vol
`
`with
`ramp
`in
`tage
`
`key
`one
`not
`is
`direct
`[see
`
`exception
`constant
`proportion
`Figure
`5).
`
`--the
`amplitude,
`to
`The
`
`the
`ef-
`
`of
`
`simple
`this
`fect
`Because
`dramatic.
`voltage,
`with
`input
`cycle
`the
`duty
`input
`voltage.
`
`varies
`Thus
`
`Vs
`if
`
`is
`
`modification
`varies
`is
`Vc
`inversely
`the
`volt-second
`
`directly
`constant
`with
`
`v
`02
`
`v-,
`
`v..-
`
`...
`
`VinD,
`
`remains
`product,
`change.
`any
`control
`very
`is
`regulation
`duty
`direct
`lems
`of
`above
`are
`corrected.
`mostly
`to
`achieve
`generation
`control
`
`good,
`cycle
`
`without
`constant
`loop
`line
`Open
`the
`prob-
`and
`control
`in
`[1)
`Much
`less
`closed
`dynamic
`response.
`good
`IC with
`voltage
`feedforward
`
`is
`gain
`loop
`The UC184O
`capability.
`
`required,
`is
`a
`third
`
`Current
`
`UC1846
`
`Mode
`
`Control:
`
`This
`
`newest
`
`control
`
`method,
`
`embodied
`
`in
`
`the
`
`IC,
`
`also
`
`controls
`
`the
`
`duty
`
`cycle
`
`by
`
`comparing
`
`the
`
`control
`
`frequency
`
`sawtooth
`
`ramp.
`
`In
`
`this
`
`case,
`
`the
`
`voltage
`
`to
`
`a
`
`fixed
`
`ramp
`
`voltage
`
`is
`
`not
`
`derived
`
`artificially
`
`from
`
`a
`
`ramp
`
`generator,
`
`but
`
`is
`
`provided
`
`directly
`
`from
`
`the
`
`power
`
`switching
`
`circuit
`
`inductor
`
`current
`
`waveform
`
`through
`
`a current
`
`sampling
`
`resistor
`
`(Figure
`
`6).
`
`Thus
`
`the
`
`inductor
`
`current
`
`ramp
`
`is
`
`fed
`
`back
`
`to
`
`the
`
`comparator,
`
`formin~
`
`a second,
`
`inner
`
`control
`
`loop.
`
`The
`
`control
`
`control
`
`voltage
`
`voltage
`
`control
`
`out
`
`of
`
`the
`
`error
`
`amplifier
`
`is
`
`derived
`
`from
`
`the
`
`output
`
`compared
`
`to
`
`a voltage
`
`reference,
`
`as
`
`before,
`
`but
`
`now
`
`the
`
`voltage
`
`programs
`
`the
`
`inductor
`
`current
`
`via
`
`the
`
`inner
`
`loop
`
`and
`
`no
`
`longer
`
`controls
`
`the
`
`duty
`
`cycle
`
`directly.
`
`UNITROOE CORPORATION.
`
`5 FORBES ROAO .LEXINGTON, MA 02173. TEL. (617) 861-6540. TWX (710) 326-6509. TELEX 95-1064
`
`2-4
`
`
`
`Page 5 of 9
`
`

`
`Vcc
`
`t
`
`~
`
`J:
`
`1
`
`~ ~
`
`Reference
`-
`Error
`amplIfier PWM
`
`~
`
`k
`
`~.~
`
`comoareto,
`
`R
`
`a
`
`Letch
`
`J1..:
`
`Clock
`\I-."
`
`I'
`, ,
`
`, ,
`
`I
`
`, ,
`
`\1-
`
`~
`
`U
`
`U
`
`Latch
`output -J
`
`n
`
`n
`
`LJ
`
`n
`
`LJ
`
`L
`
`L
`
`Figure
`
`6.
`
`of
`results
`The
`All
`profound.
`di rect
`of
`the
`trol
`method
`
`this
`of
`duty
`(1)
`and
`
`are
`method
`the
`problems
`cycl
`e con-
`(2)
`above
`
`to
`
`voltage
`
`loop
`
`current
`with
`corrected
`are
`In
`addition
`control.
`mode
`feedforward
`the
`having
`instanta-
`with
`characteristic
`to
`response
`neous
`open
`mode
`current
`input
`changes,
`induc-
`the
`control
`eliminates
`this
`because
`tor
`pole,
`filter
`loop.
`inner
`the
`pole
`inside
`is
`second
`pole
`two
`This
`reduces
`not
`easy
`is
`which
`order
`filter
`a single
`pole
`to
`to
`compensate
`capacitor)
`first
`(the
`filter
`which
`permits
`order
`filter,
`simpl er
`compensation
`networks.
`
`Current
`switching
`required
`Appendix
`upon
`the
`sation,
`
`circuits
`benefit
`
`control
`mode
`circuits
`at
`for
`stability
`A.
`Power
`transformer
`reflected
`load
`current
`but
`the
`amount
`is
`rather
`
`from
`duty
`
`with
`used
`slope
`cycles
`magnetizing
`acts
`to
`variable
`
`mode
`continuous
`and
`compensation,
`50%.
`greater
`than
`superimposed
`current
`slope
`compen-
`provide
`some
`and
`indeterminate.
`
`power
`it
`
`is
`Ref.
`
`DESIGN THE COMPENSATION NETWORK
`
`The
`overall
`sought
`
`control
`closed
`in
`the
`
`to
`
`gain
`output
`loop
`objective
`error
`amplifier
`
`characteristic
`roughly
`with
`
`its
`
`from
`subtracted
`the
`characteristic
`defines
`compensation
`network.
`
`the
`
`In
`
`the
`
`up
`
`general,
`(1)
`where
`phase
`
`procedure
`the
`the
`zeros
`in
`Put
`occur
`excess
`poles
`shift
`has
`an adequate
`
`involves:
`compensation
`in
`the
`margin
`
`network
`control
`(45
`
`near
`output
`to
`degrees)
`
`frequencies
`gain
`so
`that
`to
`the
`cross-
`
`over
`(2)
`where
`output
`teristic
`If
`(3)
`regulation
`pair
`at
`(4)
`In
`
`it
`
`frequency.
`compensation
`the
`in
`Put
`poles
`right-half-plane
`and
`ESR
`zeros
`these
`Otherwise
`gain.
`from
`prevent
`and
`gain
`frequency
`low
`zeros
`because
`of
`to
`boost
`frequency
`low
`complex
`situations,
`
`zeros
`falling
`is
`added
`gain.
`a certain
`
`too
`in
`
`network
`zeros
`will
`off
`
`frequencies
`the
`control
`the
`gain
`charac-
`
`in
`the
`
`near
`occur
`flatten
`as
`desired.
`to
`obtain
`(1),
`add
`
`low
`step
`
`desired
`a pole-zero
`
`amount
`
`of
`
`juggling
`
`with
`
`to
`
`DC
`
`trial
`
`solutions
`
`is
`
`inevitable.
`
`are
`
`handle
`will
`that
`circuits
`Two
`Circuits:
`ComDensation
`A. These
`given
`in Appendix
`sation
`requirements
`C.
`problems
`in Appendix
`example
`applied
`to
`the
`tapalagy/cantral
`method
`combination
`power
`switching
`essentially
`characteristic
`the
`the
`use
`of
`no
`input
`capacitor,
`avoid
`which
`has
`behavior
`that
`invariably
`results
`circuits
`
`flat
`
`to
`with
`
`the
`
`poor
`like
`
`Try
`
`of
`
`compen-
`most
`are
`circuits
`the
`use
`to
`allows
`that
`A-1
`circuit
`signal
`large
`A-2
`because
`
`of
`
`abnormal
`
`voltage
`
`levels
`
`that
`
`appear
`
`on
`
`the
`
`input
`
`capacitor,
`
`Ci.
`
`UNITRODE
`
`CORPORATION.
`
`5 FORBES ROAD.
`
`LEXINGTON,
`
`MA 02173.
`
`TEL.
`
`(617) 861-6540
`
`.TWX
`
`(710) 326-6509
`
`.TELEX
`
`95-1064
`
`2-5
`
`~
`
`
`
`Page 6 of 9
`
`

`
`Determine
`DC
`regulation
`but
`this
`is
`gain
`of
`the
`variables.
`
`Closed
`of
`often
`system
`
`Reaulation:
`Loop
`system
`the
`awkward
`often
`
`using
`of
`and
`changes
`
`to
`
`is
`It
`classical
`questionable
`as a
`function
`
`possible
`closed
`value,
`of
`
`calculate
`loop
`analysis,
`because
`input
`and
`
`the
`load
`
`the
`
`DC
`(1)
`
`is
`
`of
`
`direct
`that
`
`to
`
`of
`
`the
`calculate
`and more
`simpler
`It
`is:
`really
`it
`signal
`problem
`large
`the
`combination
`method
`the
`topology/control
`equation
`Vc,
`voltage,
`DC control
`to
`calculate
`the
`examples)
`under
`level
`at
`the
`desired
`the
`output
`voltage
`maintain
`must
`The
`extreme
`Vc swing
`load
`conditons.
`line
`and
`system
`ramp
`amplitude
`or
`the
`the
`sawtooth
`less
`than
`desired
`range
`conditions.
`over
`the
`have
`control
`extreme
`Vc swing
`by
`the
`low
`frequency
`gain
`of
`circuit.
`(3)
`The
`result
`is
`the
`output
`error
`provide
`the
`desired
`Vc
`control
`swing,
`which
`percentage
`of
`the
`nominal
`output
`voltage.
`
`regulation
`Use
`1a
`(Eq.
`required
`extremes
`of
`course
`will
`not
`(2)
`Divide
`E/A
`compensation
`the
`voltage
`required
`can
`be expressed
`
`the
`in
`
`as
`DC
`the
`to
`of
`be
`even
`the
`
`to
`as a
`
`Insufficient
`not
`enough
`alternatives
`or
`(2)
`back
`
`for
`
`on
`
`Gain-bandwidth:
`the
`desired
`other
`than:
`down
`the
`
`gain-bandwidth
`amplifier
`the
`If
`there
`are
`scheme,
`compensation
`IC with
`a better
`amplifier,
`(1)
`use
`an
`crossover
`frequency.
`
`is
`some
`
`One alternative
`gain
`because
`feedforward,
`current
`
`mode
`
`is
`line
`and
`control.
`
`use
`to
`regulation
`the
`two
`
`a control
`problems
`filter
`
`pole
`
`requires
`that
`method
`eliminated
`are
`characteristic
`
`is
`
`less
`with
`gone
`
`loop
`input
`with
`
`ramp
`when
`Also,
`such
`as
`independently,
`output
`gain-bandwidth
`correspondingly
`output
`range
`range,
`and
`
`the
`
`is
`error
`
`input
`comparator
`the
`at
`slope
`greater
`or UC1846,
`in
`the UC1840
`the
`ramp
`by
`reducing
`is achieved
`voltage.
`cycle
`clamp
`the
`duty
`reducing
`control
`with
`a smaller
`now
`controlled
`amplifier
`gain-bandwidth
`requirement
`
`set
`be
`can
`to
`control
`and
`slope
`full
`The
`voltage
`reduced.
`
`is
`
`Control
`highest
`requirement
`
`output
`to
`available
`of
`
`gain-bandwidth
`output
`voltage.
`the
`error
`amplifier.
`
`EXAMPLES OF CLOSING THE LOOP
`
`also
`is
`This
`
`increased
`reduces
`
`the
`
`sensing
`by
`gain-bandwidth
`
`the
`
`Examples
`operated
`modes,
`voltage
`
`out
`
`worked
`are
`in discontinuous
`and
`using
`three
`feedforward
`and
`
`most
`for
`C
`in Appendix
`as continuous
`as well
`control
`methods:
`direct
`current
`mode
`control.
`
`basic
`inductor
`duty
`cycle
`
`topologies
`current
`control,
`
`given,
`10:1
`
`the
`In
`current
`direct
`assumed
`actual
`ratio,
`the
`
`examples
`of
`range
`comparison.
`to
`be
`transformed
`primary
`side
`voltages,
`if
`used,
`are
`not
`visible.
`basis
`for
`feedback
`voltage
`
`is
`All
`
`input
`an
`assumed
`elements
`level
`to
`the
`currents
`The
`sensing.
`
`load
`and
`2:1
`range
`voltage
`to
`permit
`and
`for
`consistency
`circuit
`are
`power
`of
`the
`output,
`and
`a 12 volt
`and
`transformer
`turns
`volt
`output
`used
`
`of
`
`of
`
`12
`
`is
`
`as
`
`UNITRODE
`
`CORPORATION.
`
`5 FORBES ROAD.
`
`LEXINGTON.
`
`MA 02173.
`
`TEL.
`
`(617) 861-6540
`
`.TWX
`
`(710) 326-6509
`
`.TELEX
`
`95-1064
`
`2-6
`
`
`
`Page 7 of 9
`
`

`
`MISCELLANEOUS POINTS
`
`EMI
`
`Filter
`
`Resonance:
`
`When
`
`an
`
`input
`
`EMI
`
`filter
`
`is
`
`used,
`
`make
`
`sure
`
`its
`
`near
`
`resonance
`
`is
`
`well
`
`damped
`
`the
`
`resonant
`
`frequency
`
`and
`
`of
`
`its
`
`the
`
`resonant
`
`output
`
`frequency
`
`is
`
`not
`
`filter,
`
`or
`
`severe
`
`interaction
`
`will
`
`result.
`
`Modulator
`
`Phase
`
`laq:
`
`The
`
`vast
`
`majority
`
`of
`
`PWM
`
`control
`
`chips
`
`use
`
`a
`
`wherein
`
`the
`
`simple
`
`output
`
`the
`
`This
`
`comparator
`
`method
`
`of
`
`determining
`
`pulse
`
`width,
`
`pulse
`
`is
`
`terminated
`
`according
`
`to
`
`the
`
`instantaneous
`
`value
`
`of
`
`feedback
`
`control
`
`voltage
`
`at
`
`the
`
`moment
`
`of
`
`pulse
`
`termination.
`
`"naturally
`
`sampled"
`
`method
`
`of
`
`pulse
`
`width
`
`modulation
`
`ideally
`
`results
`
`in
`
`~
`
`~hase
`
`.!..9..9. jJ1
`
`Ji.!lg
`
`modulator
`
`..§1l.!:! jJ1
`
`Ji.!lg
`
`converter
`
`time
`
`in
`
`the
`
`comparator
`cause
`
`delays
`a phase
`lag
`
`DOWer
`and
`
`switchinq
`storage
`
`~.(2Jln
`delays
`
`practice,
`power
`
`however,
`switch
`will
`
`directly
`
`proportional
`
`to
`
`the
`
`delay
`
`time,
`
`td,
`
`and
`
`signal
`
`frequency,
`
`f,
`
`according
`
`to
`
`the
`
`relationship:
`
`+m = 360 td/T
`
`= 360 td
`
`f
`
`This
`
`gain
`loop
`
`additional
`
`crossover
`instability.
`
`phase
`
`lag
`
`reduces
`
`the
`
`phase
`
`margin
`
`at
`
`the
`
`unity
`
`frequency
`For
`
`and
`example,
`
`may
`
`therefore
`at
`a
`crossover
`
`contribute
`frequency
`
`to
`
`control
`of
`
`a
`
`switching
`
`frequency
`
`greater
`
`than
`
`50kHz,
`
`25
`
`a
`
`kHz,
`
`consistent
`
`with
`
`storage
`
`additional
`
`amount.
`
`time
`
`of
`
`1 microsecond
`
`in
`
`the
`
`power
`
`phase
`
`lag
`
`of
`
`9 degrees,
`
`reducing
`
`switch
`
`phase
`
`will
`
`cause
`
`an
`
`margin
`
`by
`
`that
`
`REFERENCES
`
`[1)
`Crossover
`04.16,
`
`J.
`
`R. Wood,
`Frequency
`March
`1983.
`
`"Taking
`in Closed
`
`of
`Account
`Loop Design,"
`
`Resistance
`Output
`POWERCON
`10,
`
`and
`pp. D4.1-
`
`R. D. Middlebrook,
`(2)
`Converter
`Feedback
`
`Loops,"
`
`"Predicting
`POWERCON
`
`Phase
`Modulator
`8,
`pp. H4.1-H4.6,
`
`Lag
`April
`
`in PWM
`1981.
`
`UNITRODE
`
`CORPORATION.
`
`5 FORBES ROAD.
`
`LEXINGTON,
`
`MA 02173.
`
`TEL.
`
`(617) 861-6540.
`
`TWX
`
`(710) 32&-6509
`
`.TELEX
`
`95-1064
`
`2-7
`
`
`
`Page 8 of 9
`
`

`
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`
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`
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`
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`
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`
`Copyright  2001, Texas Instruments Incorporated
`
`
`
`Page 9 of 9