IS31AP2036
Integrated Silicon Solution, Inc. – www.issi.com
Rev. D, 02/03/2016
11
APPLICATION INFORMATION
The IS31AP2036 is a Class-K audio power amplifier
with high efficiency and automatic gain control. It
drives up to 2.0W (10% THD+N) into an 8 speaker
from a 4.2V V
CC
supply.
The IS31AP2036 integrates advanced high efficiency
charge pump and whole power amplifier efficiency can
be up to 75%. The output power will be maintained in
0.8W, 1.0W and 1.2W.
The IS31AP2036 provides low cost, space saving
solution for portable equipments which need audio
output with higher power by boosting up supply voltage.
Its external components just include a few capacitors
and resistors (no inductor).
CONSTANT OUTPUT POWER
The output power will fall down by the drop of supply
voltage and decrease audio volume. IS31AP2036
provides advanced AGC function to maintain the
output power stable within 3.3V~4.35V supply voltage.
Even voltage of battery falls down in mobile application;
IS31AP2036 can still provide high-quality audio. There
are four operation modes for IS31AP2036 and three of
these have AGC function with output power as 1.2W,
1W and 0.8W.
AGC Function
This is the function to control the output in order to
obtain a maximum output level without distortion when
an excessive input is applied which would otherwise
cause clipping at the differential signal output. That is,
with the traditional AGC function, lowers the gain of the
digital amplifier to an appropriate value so as not to
cause clipping at the differential signal output (Figure
21).
Figure 21 AGC Function
IS31AP2036 adopts advanced AGC function which
maintains constant output power without signal
distortion when the supply voltage falling down (Figure
22, 23).
Figure 22 Traditional AGC Function
Figure 23 IS31AP2036 Advanced AGC Function
Attack and Release Time
The attack time is a time interval that gains falls down
with a big signal input enough. And the release time is
a time from target attenuation to no AGC attenuation.
Attack Time Release Time
Figure 24 Attack and Release Time
K-CHARGEPUMP
IS31AP2036 adopts advanced K-CHARGEPUMP
techniques, which increases high efficiency and drive
power with 750kHz operation frequency and integrates
soft-start, over current and over voltage control circuit
to guarantee stable operation.
Soft-Start
To limit inrush current in charge pump start procedure,
the K-CHARGEPUMP adopts soft-start function. The
soft-start time is 0.7ms and limits the supply current
within 350mA.
Over Voltage Protection
K-CHARGEPUMP output voltage, PV
CC
is V
CC
of 1.5
times to provide high voltage for internal power
amplifier. K-CHARGEPUMP integrates over voltage
protection function. PV
CC
is not times V
CC
when supply
voltage is over 3.8V. The OVP circuit will keep PV
CC
in
5.8V (Typ.).
V
CC
V
CC
No AGC, output has distortion AGC, output has no distortion
No AGC, V
CC
falls down, output has distortion AGC, output has no distortion
V
CC
Traditional AGC, V
CC
falls down, output signal has no
distortion, but output power decreases
Constant
output power
Advanced AGC, output signal has no distortion,
output power keeps constant
V
CC
