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PDF AA4838 Data sheet ( Hoja de datos )
| Número de pieza | AA4838 | |
| Descripción | AUDIO POWER AMPLIFIER | |
| Fabricantes | Agamem Microelectronic | |
| Logotipo |  |
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AA4838Agamem Microelectronics Inc.
PRELIMINARY
AUDIO POWER AMPLIFIER
■ DESCRIPTION
The AA4838 is a monolithic integrated circuit that provides DC volume control, and stereo
bridged audio power amplifiers capable of producing 2W into 4Ωwith less than 1.0% THD or
2.2W into 3 Ω with less than 1.0% THD. The audio integrated circuits were designed
specifically to provide high quality audio while requiring a minimum amount of external
components. The AA4838 incorporates a DC volume control, stereo bridged audio power
amplifiers and a selectable gain or bass boost, making it optimally suited for multimedia
monitors, portable radios, and desktop and portable computer applications. The AA4838
features an externally controlled, low-power consumption shutdown mode, and both a power
amplifier and headphone mute for maximum system flexibility and performance.
■ FEATURES
• DC volume control interface.
• System beep detects.
• Stereo switchable bridged/single-ended power amplifiers
• Selectable internal/external gain or bass boost
• “Click and pop” suppression circuitry
• Thermal shutdown protection circuitry
■ APPLICATIONS
• Portable and desktop computers
• Multimedia monitors
• Portable radios, PDAs, and portable TVs
©Copyright Agamem Microelectronics Inc.
1
www.agamem.com.tw 2008/8/26
AGAMEM MICROELECTRONICS INCOPERATION RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE
TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. AGAMEM DOES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCTS OR CIRCUIT DESRIBED HEREIN; NEITHER
DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
1 page  
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AA4838Agamem Microelectronics Inc.
PRELIMINARY
AUDIO POWER AMPLIFIER
■ ELECTRICAL CHARACTERISTICS FOR VOLUME ATTENUATORS
The following specifications apply for VDD = 5V unless otherwise noted. Limits apply for TA = 25˚C
PARAMETER
Attenuator
Range
Mute
Attenuation
SYMBOL
CRANGE
AM
TEST CONDITION
Gain with VDCVOL = 5V, No
Load
Attenuation with VDCVOL
= 0V (BM & SE)
VMUTE = 5V, Bridged Mode
(BM)
VMUTE = 5V, Single-Ended
Mode (SE)
VALUE
MIN TYP MAX
UNIT
- - ±0.75 dB
-75 - - dB
-78 - - dB
-78 - - dB
■ ELECTRICAL CHARACTERISTICS FOR SINGLE-ENDED MODE OPERATION
The following specifications apply for VDD = 5V unless otherwise noted. Limits apply for TA = 25˚C
PARAMETER SYMBOL
TEST CONDITION
Output
Power
PO
Total
Harmonic
Distortion+
Noise
Power Supply
Rejection
Ratio
Signal to
Noise Ratio
Channel
Separation
THD+N
PSRR
SNR
XTALK
THD = 1.0%; f = 1kHz; RL =
32Ω
THD = 10%; f = 1 kHz; RL=
32Ω
VOUT = 1VRMS, f=1kHz, RL
= 10kΩ, AVD = 1
CB = 1.0 µF,f=120Hz,
VRIPPLE
=200mVrms
POUT =75 mW, RL = 32Ω,
A-Wtd Filter
f=1kHz, CB = 1.0 µF
VALUE
MIN TYP MAX
UNIT
- 85
- mW
- 95
- mW
- 0.065 -
%
- 58
-
- 102
- 65
-
-
dB
dB
dB
©Copyright Agamem Microelectronics Inc.
5
www.agamem.com.tw 2008/8/26
AGAMEM MICROELECTRONICS INCOPERATION RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE
TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. AGAMEM DOES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCTS OR CIRCUIT DESRIBED HEREIN; NEITHER
DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
5 Page 
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AA4838Agamem Microelectronics Inc.
PRELIMINARY
AUDIO POWER AMPLIFIER
capacitor, CB, between the BYPASS pin and ground improves the internal bias voltage’s
stability and the amplifier’s PSRR. The PSRR improvements increase as the BYPASS pin
capacitor value increases. Too large a capacitor, however, increases turn-on time and can
compromise the amplifier’s click and pop performance. The selection of bypass capacitor
values, especially CB, depends on desired PSRR requirements, click and pop performance
(as explained in the following section, Selecting Proper External Components), system cost,
and size constraints.
• SELECTING PROPER EXTERNAL COMPONENTS
Optimizing the AA4838’s performance requires properly selecting external components.
Though the AA4838 operates well when using external components with wide tolerances,
best performance is achieved by optimizing component values. The AA4838 is unity-gain
stable, giving a designer maximum design flexibility. The gain should be set to no more than a
given application requires. This allows the amplifier to achieve minimum THD+N and
maximum signal-to-noise ratio. These parameters are compromised as the closed-loop gain
increases. However, low gain circuits demand input signals with greater voltage swings to
achieve maximum output power. Fortunately, many signal sources such as audio CODECs
have outputs of 1VRMS (2.83VP-P). Please refer to the Audio Power Amplifier Design section
for more information on selecting the proper gain.
• INPUT CAPACITOR VALUE SELECTION
Amplifying the lowest audio frequencies requires a high value input coupling capacitor
(0.33µF in Figure 2), but high value capacitors can be expensive and may compromise space
efficiency in portable designs. In many cases, however, the speakers used in portable
systems, whether internal or external, have little ability to reproduce signals below 150Hz.
Applications using speakers with this limited frequency response reap little improvement by
using a large input capacitor. Besides effecting system cost and size, the input coupling
capacitor has an affect on the AA4838’s click and pop performance. When the supply voltage
is first applied, a transient (pop) is created as the charge on the input capacitor changes from
zero to a quiescent state. The magnitude of the pop is directly proportional to the input
capacitor’s size. Higher value capacitors need more time to reach a quiescent DC voltage
(usually VDD/2) when charged with a fixed current. The amplifier’s output charges the input
capacitor through the feedback resistor, Rf. Thus, pops can be minimized by selecting an
input capacitor value that is no higher than necessary to meet the desired −6dB frequency.
As shown in Figure 2, the input resistor (RIR, RIL = 20k) (and the input capacitor (CIR, CIL=
0.33µF) produce a −6dB high pass filter cutoff frequency that is found using Equation (7).
… (7)
As an example when using a speaker with a low frequency limit of 150Hz, the input coupling
capacitor, using Equation (7), is 0.053µF. The 0.33µF input coupling capacitor shown in
Figure 2 allows the AA4838 to drive a high efficiency, full range speaker whose response
©Copyright Agamem Microelectronics Inc.
11
www.agamem.com.tw 2008/8/26
AGAMEM MICROELECTRONICS INCOPERATION RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE
TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. AGAMEM DOES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCTS OR CIRCUIT DESRIBED HEREIN; NEITHER
DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet AA4838.PDF ] | |
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