APA2068 Anpec Electronics Coropration, APA2068 Datasheet - Page 21

• Manufacturer Part Number: APA2068
• Description: Stereo 2.6W Audio Power Amplifier (with DC_Volume Control)
• Manufacturer: Anpec Electronics Coropration

APA2068
Optimizing Depop Circuitry (Cont.)
constant can be relatively large. To reduce transients
in SE mode, an external 1k resistor can be placed in
parallel with the internal 10k resistor. The tradeoff
for using this resistor is an increase in quiescent current.
In the most cases, choosing a small value of Ci in the
range of 0.33 F to 1 F, Cb being equal to 4.7 F and
an external 1k resistor should be placed in parallel
with the internal 10k
virtually clickless and popless turn-on.
A high gain amplifier intensifies the problem as the
small delta in voltage is multiplied by the gain. So it
is advantageous to use low-gain configurations.
Shutdown Function
In order to reduce power consumption while not in use,
the APA2068 contains a shutdown pin to externally
turn off the amplifier bias circuitry. This shutdown
feature turns the amplifier off when a logic low is placed
on the SHUTDOWN pin. The trigger point between a
logic high and logic low level is typically 2.0V. It is
best to switch between ground and the supply V
provide maximum device performance.
By switching the SHUTDOWN pin to low, the amplifier
enters a low-current state, I
shutdown mode, except PC-BEEP detect circuit.
On normal operating, SHUTDOWN pin pull to high
level to keeping the IC out of the shutdown mode.
The SHUTDOWN pin should be tied to a definite
voltage to avoid unwanted state changes.
Mute Function
The APA2068 mutes the amplifier outputs when logic
high is applied to the MUTE pin. Applying logic low to
the MUTE pin returns the APA2068 to normal
operation. Prevent unanticipated mute behavior by
connecting the Mute pin to logic high or low. Do not
let the Mute pin float.
Copyright
Rev. A.2 - Jul., 2005
Application Descriptions (Cont.)
ANPEC Electronics Corp.
resistor should produce a
DD
<1 A. APA2068 is in
DD
to
21
Maximum Output Swing Clamping Function
(VolMax)
The APA2068 provide the maximum output swing
clamping function to protect the speaker.
the amplifier’ s output amplitude (Vo) is be limited at
Vo = Vdd –Vx. This function can effective to limited
the output power across the speaker, and avoid
damaging the speaker.
The maximum setting voltage of VolMax is Vdd/2, and
when this function is not used, place the VolMax
connect to GND.
BTL Amplifier Efficiency
An easy-to-use equation to calculate efficiency starts
out as being equal to the ratio of power from the power
supply to the power delivered to the load.
The following equations are the basis for calculating
amplifier efficiency.
Where :
Efficiency of a BTL configuration :
Table 1 calculates efficiencies for four different output
power levels.
Note that the efficiency of the amplifier is quite low for
lower power levels and rises sharply as power to the
When input a non-zero voltage (Vx) to VolMax pin,
Efficiency =
P
V
P
P
P
P
ORMS
SUP
O
SUP
O
O
=
=
= V
=
(
V
V
=
V
ORMS
ORMS
DD
2R
P
xV
V
x I
2
L
P
P
P
DDAVG
R
R
) / (V
P
SUP
O
L
L
V
V
ORMS
ORMS
DD
= V
x
DD
2V
R
x 2V
P
L
) =
=
=
R
P
L
www.anpec.com.tw
4V
V
V
2R
2R
P
P
V
DD
P
V
V
L
L
P
P
(10)
(9)
(11)
(12)