apa3010 Anpec Electronics Corporation, apa3010 Datasheet - Page 11

• Manufacturer Part Number: apa3010
• Description: 3w Mono Low-voltage Audio Power Amplifier
• Manufacturer: Anpec Electronics Corporation

Effective Bypass Capacitor, C
As other power amplifiers, proper supply bypassing is
critical for low noise performance and high power supply
rejection.
The capacitors located on both the bypass and power
supply pins should be as close to the device as possible.
The effect of a larger bypass capacitor will improve PSRR
due to increased supply stability. Typical applications em-
ploy a 5V regulator with 1.0 F and a 0.1 F bypass capaci-
tor as supply filtering. This does not eliminate the need
for bypassing the supply nodes of the APA3010/1. The
selection of bypass capacitors, especially C
pendent upon desired PSRR requirements, click and pop
performance.
To avoid the start-up pop noise occurred, the bypass volt-
age should rise slower than the input bias voltage and the
relationship shown in equation (4) should be maintained.
The bypass capacitor is fed thru from a 125k
inside the amplifier and the 40k
sistance of (R
to 10 F ceramic or tantalum low-ESR capacitors are rec-
ommended for the best THD and noise performance.
The bypass capacitance also effects to the start-up time.
It is determined in the following equation :
Power Supply Decoupling, C
The APA3010/1 is a high-performance CMOS audio am-
plifier that requires adequate power supply decoupling
to ensure the output total harmonic distortion (THD) is as
low as possible. Power supply decoupling also prevents
the oscillations being caused by long lead length be-
tween the amplifier and the speaker. The optimum
decoupling is achieved by using two different types of
capacitors that target on different types of noise on the
power supply leads.
For higher frequency transients, spikes, or digital hash
on the line, a good low equivalent-series-resistance(ESR)
ceramic capacitor, typically 0.1 F placed as close as pos-
sible to the device V
frequency noise signals, a large aluminum electrolytic
Copyright
Rev. A.6 - Jun., 2009
Application Information (Cont.)
APA3010/1
C
Tstart up = 5 x (C
B
x 125k
ANPEC Electronics Corp.
1
i
+ R
f
). Bypass capacitor, C
DD
lead works best. For filtering lower-
B
x 125k )
<<
40k
S
B
1
is maximum input re-
x C
i
B
, values of 3.3 F
B
, is thus de-
resistor
(4)
(5)
11
capacitor of 10 F or greater placed near the audio power
amplifier is recommended.
Optimizing Depop Circuitry
Circuitry has been included in the APA3010/1 to minimize
the amount of popping noise at power-up and when com-
ing out of shutdown mode. Popping occurs whenever a
voltage step is applied to the speaker. In order to elimi-
nate clicks and pops, all capacitors must be fully dis-
charged before turn-on. Rapid on/off switching of the de-
vice or the shutdown function will cause the click and pop
circuitry.
The value of C
Effective Bypass Capacitance) The bypass voltage ramp
up should be slower than input bias voltage. Although the
bypass pin current source cannot be modified, the size of
C
amount of clicks and pops. By increasing the value of C
turn-on pop can be reduced. However, the tradeoff for
using a larger bypass capacitor is to increase the turn-on
time for this device. There is a linear relationship be-
tween the size of C
A high gain amplifier intensifies the problem as the small
delta in voltage is multiplied by the gain. Therefore, it is
advantageous to use low-gain configurations.
Shutdown Function
In order to reduce power consumption while not in use,
the APA3010/1 contain a SHUTDOWN pin to externally
turn off the amplifier bias circuitry. This shutdown feature
turns the amplifier off when a logic high (APA3011 held
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 the ground and the supply V
to provide maximum device performance.
By switching the SHUTDOWN pin to high, the amplifier
enters a low-current state, I
down mode. On normal operating, the SHUTDOWN pin
pulls to a low level to keep the IC out of the shutdown
mode. The SHUTDOWN pin should be tied to a definite
voltage to avoid unwanted state change.
BTL Amplifier Efficiency
An easy-to-use equation to calculate efficiency starts out
as being equal to the ratio of power from the power sup-
ply to the power delivered to the load.
B
can be changed to alter the device turn-on time and the
i
will also affect turn-on pops. (Refer to
B
and the turn-on time.
DD
< 0.1 A. APA3010 is in shut-
www.anpec.com.tw
DD
B
,