APA2065KI-TRL 查看數據表（PDF） - Anpec Electronics

零件编号

产品描述 (功能)

生产厂家

APA2065KI-TRL

Stereo 2.7-W Audio Power Amplifier (with DC_Volume Control)

Anpec Electronics 

APA2065

Application Descriptions

BTL Operation

The APA2065 output stage (power amplifier) has two

pairs of operational amplifiers internally, allowed for

different amplifier configurations.

OUT+

Volume Control

amplifier output

signal

OP1

RL

OUT-

Vbias

Circuit

OP2

Figure 1: APA2065 internal configuration

(each channel)

The power amplifier’s OP1 gain is setting by internal

unity-gain and input audio signal is come from internal

volume control amplifier, while the second amplifier

OP2 is internally fixed in a unity-gain, inverting

configuration. Figure 1 shows that the output of OP1

is connected to the input to OP2, which results in the

output signals of with both amplifiers with identical in

magnitude, but out of phase 180°. Consequently, the

differential gain for each channel is 2 x (Gain of SE

mode).

By driving the load differentially through outputs OUT+

and OUT-, an amplifier configuration commonly referred

to as bridged mode is established. BTL mode operation

is different from the classical single-ended SE amplifier

configuration where one side of its load is connected

to ground.

A BTL amplifier design has a few distinct advantages

over the SE configuration, as it provides differential

drive to the load, thus doubling the output swing for a

specified supply voltage.

Four times the output power same conditions. A BTL

configuration, such as the one used in APA2065, also

creates a second advantage over SE amplifiers. Since

the differential outputs, ROUT+, ROUT-, LOUT+, and

LOUT-, are biased at half-supply, no need DC voltage

exists across the load. This eliminates the need for an

output coupling capacitor which is required in a single

supply, SE configuration.

Single-Ended Operation

Consider the single-supply SE configuration shown

Application Circuit. A coupling capacitor is required to

block the DC offset voltage from reaching the load.

These capacitors can be quite large (approximately

33µF to 1000µF) so they tend to be expensive, occupy

valuable PCB area, and have the additional drawback

of limiting low-frequency performance of the system

(refer to the Output Coupling Capacitor). The rules

described still hold with the addition of the following

relationship:

1

Cbypass x 125kΩ

≤

1 << 1

RiCi RLCC

(1)

Output SE/BTL Operation

The ability of the APA2065 to easily switch between

BTL and SE modes is one of its most important costs

saving features. This feature eliminates the requirement

for an additional headphone amplifier in applications

where internal stereo speakers are driven in BTL mode

but external headphone or speakers must be

accommodated.

Internal to the APA2065, two separate amplifiers drive

OUT+ and OUT- (see Figure 1). The SE/BTL input

controls the operation of the follower amplifier that drives

LOUT- and ROUT-.

• When SE/BTL is held low, the OP2 is turn on and

the APA2065 is in the BTL mode.

Copyright © ANPEC Electronics Corp.

15

Rev. A.4 - Aug., 2005

www.anpec.com.tw

Share Link: