công cụ tìm kiếm bảng dữ liệu linh kiện điện tử
  Vietnamese  ▼
ALLDATASHEET.VN

X  

LM4668 bảng dữ liệu(PDF) 8 Page - National Semiconductor (TI)

[Old version datasheet] Texas Instruments acquired National semiconductor.
tên linh kiện LM4668
Giải thích chi tiết về linh kiện  10W High-Efficiency Mono BTL Audio Power Amplifier
Download  14 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
nhà sản xuất  NSC [National Semiconductor (TI)]
Trang chủ  http://www.national.com
Logo NSC - National Semiconductor (TI)

LM4668 bảng dữ liệu(HTML) 8 Page - National Semiconductor (TI)

Back Button LM4668 Datasheet HTML 4Page - National Semiconductor (TI) LM4668 Datasheet HTML 5Page - National Semiconductor (TI) LM4668 Datasheet HTML 6Page - National Semiconductor (TI) LM4668 Datasheet HTML 7Page - National Semiconductor (TI) LM4668 Datasheet HTML 8Page - National Semiconductor (TI) LM4668 Datasheet HTML 9Page - National Semiconductor (TI) LM4668 Datasheet HTML 10Page - National Semiconductor (TI) LM4668 Datasheet HTML 11Page - National Semiconductor (TI) LM4668 Datasheet HTML 12Page - National Semiconductor (TI) Next Button
Zoom Inzoom in Zoom Outzoom out
 8 / 14 page
background image
General Features
SYSTEM FUNCTIONAL INFORMATION
Modulation Technique
Unlike typical Class D amplifiers that use single-ended com-
parators to generate a pulse-width modulated switching
waveform and RC timing circuits to set the switching fre-
quency, the LM4668 uses a balanced differential floating
modulator. Oscillation is a result of injecting complimentary
currents onto the respective plates of a floating, on-die ca-
pacitor. The value of the floating capacitor and value of the
components in the modulator’s feedback network and sets
the nominal switching frequency at 450kHz. Modulation re-
sults from imbalances in the injected currents. The amount
of current imbalance is directly proportional to the applied
input signal’s magnitude and frequency.
Using a balanced, floating modulator produces a Class D
amplifier that is immune to common mode noise sources
such as substrate noise. This noise occurs because of the
high frequency, high current switching in the amplifier’s out-
put stage. The LM4668 is immune to this type of noise
because the modulator, the components that set its switch-
ing frequency, and even the load all float with respect to
ground.
The balanced modulator’s pulse width modulated output
drives the gates of the LM4668’s H-bridge configured output
power MOSFETs. The pulse-train present at the power
MOSFETs’ output is applied to an LC low pass filter that
removes the 450kHz energy component. The filter’s output
signal, which is applied to the driven load, is an amplified
replica of the audio input signal.
Shutdown Function
The LM4668’s active-low shutdown function allows the user
to place the amplifier in a shutdown mode while the system
power supply remains active. Activating shutdown deacti-
vates the output switching waveform and minimizes the
quiescent current. Applying logic 0 (GND) to pin 8 enables
the shutdown function. Applying logic 1 (4V
≤ V
LOGIC
≤ V
DD)
to pin 8 disables the shutdown function and restores full
amplifier operation.
Under Voltage Protection
The under voltage protection disables the output driver sec-
tion of the LM4668 while the supply voltage is below 8V. This
condition may occur as power is first applied or during low
line conditions, changes in load resistance, or when power
supply sag occurs. The under voltage protection ensures
that all of the LM4668’s power MOSFETs are off. This action
eliminates shoot-through current and minimizes output tran-
sients during turn-on and turn-off. The under voltage protec-
tion gives the digital logic time to stabilize into known states,
further minimizing turn output transients.
Turn-On Time
The LM4668 has an internal timer that determines the am-
plifier’s turn-on time. After power is first applied or the part
returns from shutdown, the nominal turn-on time is 600ms.
This delay allows all externally applied capacitors to charge
to a final value of V
DD/2. Further, during turn-on, the outputs
are muted. This minimizes output transients that may occur
while the part settles into is quiescent operating mode.
Output Stage Fault Detection And Protection
The output stage MOSFETs are protected against output
conditions that could otherwise compromise their operational
status. An onboard fault detection circuit continuously moni-
tors the signal on each output MOSFET’s gate and com-
pares it against the respective drain voltage. When a condi-
tion is detected that violates a MOSFET’s Safe Operating
Area (SOA), the drive signal is disconnected from the output
MOSFETs’ gates. The fault detect circuit maintains this pro-
tective condition for approximately 600ms, at which time the
drive signal is reconnected. If the fault condition is no longer
present, normal operation resumes.
If the fault condition remains, however, the drive signal is
again disconnected.
Thermal Protection
The LM4668 has thermal shutdown circuitry that monitors
the die temperature. Once the LM4668 die temperature
reaches 170˚C, the LM4668 disables the output switching
waveform and remains disabled until the die temperature
falls below 140˚C (typ).
Over-Modulation Protection
The LM4668’s over-modulation protection is a result of the
preamplifier’s (AMP1 and AMP2, Figure 1) inability to pro-
duce signal magnitudes that equal the power supply volt-
ages. Since the preamplifier’s output magnitude will always
be less than the supply voltage, the duty cycle of the ampli-
fier’s switching output will never reach zero. Peak modula-
tion is limited to a nominal 95%.
Application Hints
SUPPLY BYPASSING
Correct power supply bypassing has two important goals.
The first is to reduce noise on the power supply lines and
minimize deleterious effects that the noise may cause to the
amplifier’s operation. The second is to help stabilize an
unregulated power supply and to improve the supply’s tran-
sient response under heavy current demands. These two
goals require different capacitor value ranges. Therefore,
various types and values are recommended for supply by-
passing. For noise de-coupling, generally small ceramic ca-
pacitors (0.01µF to 0.1µF) are recommended. Larger value
(1µF to 10µF) tantalum capacitors are needed for the tran-
sient current demands. These two capacitors in parallel will
do an adequate job of removing most noise from the supply
rails and providing the necessary transient current. These
capacitors should be placed as close as possible to each
IC’s supply pin(s) using leads as short as possible.
The LM4668 has two V
DD pins: a power VDD (PVDD) and a
signal V
DD (SVDD). The parallel combination of the low value
ceramic (0.1µF) and high value tantalum (10µF) should be
used to bypass the PV
DD pin. A small value (0.1µF) ceramic
or tantalum can be used to bypass the SV
DD pin.
AMPLIFIER OUTPUT FILTERING
The LM4668 requires a lowpass filter connected between
the amplifier’s bridge output and the load. The second-order
LC output filter shown in Figure 1 creates the lowpass re-
sponse that is necessary to attenuate signal energy at the
amplifier’s switching frequency. It also serves to suppress
EMI. Together, the output filter’s 0.27µF capacitors and the
recommended minimum inductor value of 27µH produce a
www.national.com
8


Số phần tương tự - LM4668

nhà sản xuấttên linh kiệnbảng dữ liệuGiải thích chi tiết về linh kiện
logo
National Semiconductor ...
LM4663 NSC-LM4663 Datasheet
606Kb / 10P
   2 Watt Stereo Class D Audio Power Amplifier with Stereo Headphone Amplifier
LM4663MT NSC-LM4663MT Datasheet
606Kb / 10P
   2 Watt Stereo Class D Audio Power Amplifier with Stereo Headphone Amplifier
LM4664 NSC-LM4664 Datasheet
550Kb / 14P
   Filterless High Efficiency 1.1W Switching Audio Amplifier
LM4665 NSC-LM4665 Datasheet
1,018Kb / 18P
   Filterless High Efficiency 1W Switching Audio Amplifier
logo
Texas Instruments
LM4665 TI1-LM4665 Datasheet
1Mb / 28P
[Old version datasheet]   LM4665 Filterless High Efficiency 1W Switching Audio Amplifier
More results

Mô tả tương tự - LM4668

nhà sản xuấttên linh kiệnbảng dữ liệuGiải thích chi tiết về linh kiện
logo
National Semiconductor ...
LM4680 NSC-LM4680 Datasheet
754Kb / 11P
   10W High-Efficiency Mono BTL Audio Power Amplifier
logo
Sanyo Semicon Device
LA4919N SANYO-LA4919N Datasheet
79Kb / 6P
   Monolithic Linear IC Two-Channel 10W BTL High-Efficiency TV Audio Output Power Amplifier
logo
NXP Semiconductors
TDA7052 PHILIPS-TDA7052 Datasheet
44Kb / 8P
   1 W BTL mono audio amplifier
July 1994
logo
Integral Corp.
ILA7056SH INTEGRAL-ILA7056SH Datasheet
24Kb / 3P
   3 W Mono BTL Audio Output Amplifier
logo
KODENSHI_AUK CORP.
KKA7056 KODENSHI-KKA7056 Datasheet
100Kb / 3P
   3 W Mono BTL Audio Output Amplifier
logo
National Semiconductor ...
LM4950 NSC-LM4950 Datasheet
1Mb / 25P
   7.5W Mono-BTL or 3.1W Stereo Audio Power Amplifier
logo
Panasonic Semiconductor
AN7161NFP PANASONIC-AN7161NFP Datasheet
225Kb / 4P
   BTL High Audio Power Amplifier
logo
NTE Electronics
NTE7052 NTE-NTE7052 Datasheet
26Kb / 3P
   Integrated Circuit Mono BTL Audio Amplifier, 3W
logo
NXP Semiconductors
TDA7056 PHILIPS-TDA7056 Datasheet
47Kb / 8P
   3 W mono BTL audio output amplifier
May 1992
logo
NTE Electronics
NTE7051 NTE-NTE7051 Datasheet
20Kb / 2P
   Integrated Circuit 1W BTL Mono Audio Amplifier
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14


bảng dữ liệu tải về

Go To PDF Page


Link URL




Chính sách bảo mật
ALLDATASHEET.VN
Cho đến nay ALLDATASHEET có giúp ích cho doanh nghiệp của bạn hay không?  [ DONATE ] 

Alldatasheet là   |   Quảng cáo   |   Liên lạc với chúng tôi   |   Chính sách bảo mật   |   Trao đổi link   |   Tìm kiếm theo nhà sản xuất
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com