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EUA2105 Schematic ( PDF Datasheet ) - Eutech Microelectronics

Teilenummer EUA2105
Beschreibung 5-W Stereo Class-D Audio Amplifier
Hersteller Eutech Microelectronics
Logo Eutech Microelectronics Logo 




Gesamt 16 Seiten
EUA2105 Datasheet, Funktion
EUA2105
5-W Stereo Class-D Audio Amplifier
with 64-Step DC Volume Control
DESCRIPTION
The EUA2105 is a high efficiency, 2 channel bridged-tied
load (BTL), class-D audio power amplifier. Operating from
a 12V power supply, EUA2105 is capable of delivering
5W/ channel of continuous output power to a 8load with
1% THD+N. The EUA2105 features a differential input
architecture offering improved noise immunity over a
single-ended (SE) input amplifier. Stereo speaker volume
is controlled with a dc voltage applied to the volume
control terminal offering a range of gain from -68dB to32
dB.
The EUA2105 also features short-circuit and thermal
protection preventing the device from being damaged
during a fault condition. The EUA2105 is available in
thermally efficient 28-pin TSSOP package.
FEATURES
z Wide Supply Voltage: 8V to 15V
z Unique Modulation Scheme Reduces EMI Emission
z 5W/ch into an 8Load From 12V Supply
z Efficient, Class-D Operation Eliminates Heatsinks
z 64-Step DC Volume Control From -68dB to 32dB
z Thermal and Short-Circuit Protection
z Integrated Click and Pop Suppression
z 28-pin TSSOP Package with Thermal Pad
z RoHS compliant and 100% lead(Pb)-free
APPLICATIONS
z LCD Monitors/TVs
z All-in-One PCs
Typical Application Circuit
DS2105 Ver1.1 Dec. 2009
Figure1.
1






EUA2105 Datasheet, Funktion
Block Diagram
EUA2105Tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com
DS2105 Ver1.1 Dec. 2009
Figure2.
6

6 Page









EUA2105 pdf, datenblatt
EUA2105Tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com
Application Information
Volume Control Operation
The VOLUME terminal controls the internal amplifier
gain. This pin is controlled with a dc voltage, which
should not exceed VREF. Table 1 lists the gain as
determined by the voltage on the VOLUME pin in
reference to the voltage on VREF.
If using a resistor divider to fix the gain of the amplifier,
the VREF terminal can be directly connected to VREG
and a resistor divider can be connected across VREF and
AGND. (See Figure 25 in the Application Information
Section). For fixed gain, calculate the resistor divider
values necessary to center the voltage between the two
percentage points given in the first column of Table 1.
If using a DAC to control the class-D gain, VREF and
AGND should be connected to the reference voltage for
the DAC and the GND terminal of the DAC, respectively.
For the DAC application, VREG would be left
unconnected to VREF. The reference voltage of the DAC
provides the reference to the internal gain circuitry
through the VREF input and any fluctuations in the DAC
output voltage will not affect the EUA2105 gain. The
percentages in the first column of Table 1 should be used
for setting the voltages of the DAC when the voltage on
the VOLUME terminal is increased. The percentages in
the second column should be used for the DAC voltages
when decreasing the voltage on the VOLUME terminal.
Two lookup tables should be used in software to control
the gain based on an increase or decrease in the desired
system volume.
If using an analog potentiometer to control the gain, it
should be connected between VREF and AGND. VREF
can be connected to VREG or an external voltage source,
if desired. The 3rd and 4th column in Table 1 should be
used to determine the point at which the gain changes
depending on the direction that the potentiometer is
turned. If the voltage on the center tap of the
potentiometer is increasing, the 3rd column in Table 1
should be referenced to determine the trip points. If the
voltage is decreasing, the trip points in the 4th column
should be referenced.
The trip point, where the gain actually changes, is
different depending on whether the voltage on the
VOLUME terminal is increasing or decreasing as a result
of hysteresis about each trip point. The hysteresis ensures
that the gain control is monotonic and does not oscillate
from one gain step to another. A pictorial representation
of the volume control can be found in Figure 22.
The timing of the volume control circuitry is controlled by
an internal 30-Hz clock. This clock determines the rate at
which the gain changes when adjusting the voltage on the
external volume control pins. The gain updates every
clock cycle (nominally 33 ms) to the next step until the
final desired gain is reached. For example, if the
EUA2105 is currently in the 0 dB gain step and the
VOLUME pin is adjusted for maximum gain at +32 dB,
the time required for the gain to reach +32 dB is 36 steps
x 33ms/step = 1.188 seconds.
Figure 22. DC Volume Control Operation
FADE Operation
The FADEB terminal is a logic input that controls the
operation of the volume control circuitry during
transitions to and from the shutdown state and during
power-up.
A logic low on this terminal places the amplifier in the
fade mode. During power-up or recovery from the
shutdown state (a logic high is applied to the
SHUTDOWN terminal), the volume is smoothly ramped
up from the mute state, -68 dB, to the desired volume
setting determined by the voltage on the volume control
terminal. Conversely, the volume is smoothly ramped
down from the current state to the mute state when a logic
low is applied to the SHUTDOWN terminal.
A logic high on this pin disables the volume fade effect
during transitions to and from the shutdown state and
during power-up. During power-up or recovery from the
shutdown state (a logic high is applied to the
SHUTDOWN terminal), the transition from the mute
state, -68 dB, to the desired volume setting is less than 1
ms. Conversely, the volume ramps down from current
state to the mute state within 1 ms when a logic low is
applied to the SHUTDOWN terminal.
SHUTDOWN Operation
The EUA2105 employs a shutdown mode of operation
designed to reduce supply current (ICC) to the absolute
minimum level during periods of nonuse for power
conservation. TheSHUTDOWN input terminal should be
held high (see specification table for trip point) during
normal operation when the amplifier is in use. Pulling
SHUTDOWN low causes the outputs to mute and the
amplifier to enter a low-current state. SHUTDOWN
should never be left unconnected, because amplifier
operation would be unpredictable. For the best power-off
pop performance, the amplifier should be placed in the
shutdown mode prior to removing the power supply
voltage.
DS2105 Ver1.1 Dec. 2009
12

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