APA2011 datasheet(17/27 Pages) ANPEC

17 / 27 page

Rev. A.4 - Aug., 2013

www.anpec.com.tw

APA2011/2011A

Function Description (Cont.)

Figure 4. APA2011 Output Signal vs. Time

The output level excesses the AGC start point.

A to B is the attack time (32ms), but the Gain needs to

change at output signal zero crossing.

The output level is under the limit level.

D to E is release time (512ms), but the Gain needs to change

at output signal zero crossing..

When the APA2011/2011A senses the input signal ex-

cesses the start point of DRC/Non-clipping, it needs 32ms

to decrease the gain, this calls “Attack Time”. And if the

input signal is small than the threshold about 512ms, the

gain will be recovery, this time calls “ release time”.

The APA2011’s compress ratio is 2:1, it means when the

input signal has the 2dB change, the output signal will

change 1dB. Because most small form speakers have

only small dynamic range, the compress allows input

signal with large dynamic range to fit into a small speaker

with small dynamic rage.

And the APA2011A is just decrease the gain to avoid the

output signal clipping, and the maximum control is 15dB

gain.

Dynamic Range Control Function

Figure 3. APA2011 Auto Gain Control Function

The APA2011 provides the 15 steps Dynamic Range Con-

trol (DRC), and the range is from 15dB to 0dB, 1dB/step.

DRC provides continuous automatic gain adjustment to

the amplifier through an internal Programmable Gain

Amplifier (PGA). This feature enhances the perceived

audio loudness and prevents speaker damage from oc-

curring clipping at the same time.

The equations 1 & 2 are the method that set the maxi-

mum output power. If the R

1=40k Ω , the VDR is 4V.

Therefore, the maximum output power is 1.125W

L=4Ω), and the output voltage swing is limited at 3Vpp

(1.5Vp) [The limited voltage can be calculated by 4V(V

DR)-

2.5V(Internal Bypass Voltage)=1.5V]. The AGC start point

is 0.536V

PP (1.5Vp/5.6(AV)=0.268VP) at output, it means

when the output power excesses 0.036W, the AGC will

start work and decrease the gain by 1dB. If the input sig-

nal increase un-limit, the gain will be decreased until the

maximum gain attenuation (15dB).

Maximum Output Power

V=0dB

V=15dB

AGC Start Point

Power Limit

Attack Time and Release Time

Time

Limit Level

Time

Gain

Release

Time

Attack Time

Limit Level

Non-Clipping Function (APA2011A) (Cont.)

Note: *The setting value has 15% variation by IC process and

this equation only for WLCSP1.5x1.5-9 package, the TDFN3x3-8

package’s output power will less than the calculation.

Shutdown Operation

In order to reduce power consumption while not in use,

the APA2011/2011A contains a shutdown function to ex-

ternally turn off the amplifier bias circuitry. This shutdown

feature turns the amplifier off when logic low is placed on

the SD pin for APA2011/2011A. The trigger point between

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