APA2176 Просмотр технического описания (PDF) - Anpec Electronics

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APA2176

270mW Stereo Cap-Free Headphone Driver

Anpec Electronics 

APA2176/2176A

Function Description

VOUT

Conventional Headphone amplifier

VOUT

VDD

VDD/2

GND

VDD

voltage PVDD to provide maximum device performance.

By switching the both RSD and LSD pins to low level, the

amplifier enters a low-consumption current circum-

stance, with charge pump disabled, and very small I for

DD

the APA2176/2176A. The charge pump is enabled once

either RSD or LSD pin is pulled to high. In normal

operating, the APA2176/2176A’s RSD and LSD pins

should be pulled to high level to keep the IC out of the

shutdown mode. The RSD and LSD pins should be tied

to a definite voltage to avoid unwanted mode changing.

GND

VSS

Cap-free Headphone amplifier

Figure 1. Cap-Free Operation

The APA2176/2176A is a stereo, fixed gain, cap-free head-

phone driver. The gain is set by internal resistors, input

resistors (Ri), and feedback resistors (Rf) with -1.5V/V

(See Typical Application Circuit).

The APA2176/2176A’s headphone drivers use a charge

pump to invert the positive power supply (PV ) to nega-

DD

tive power supply (CVSS), see figure1. The headphone

drivers operate at this bipolar power supply (VDD and VSS)

and the outputs reference refers to the ground. This fea-

ture eliminates the output capacitors which are used in

conventional single-ended headphone amplifiers. Com-

pared with the single power supply amplifiers, the power

supply voltage is almost double.

Shutdown Function

In order to reduce power consumption, the APA2176/2176A

contain two shutdown signal input pins (LSD for left chan-

nel and RSD for right channel) to allow respective shut-

down which turns off the bias current of the amplifier.

This shutdown feature turns the amplifier off when logic

low is placed on the RSD or LSD pin for the APA2176/

2176A. The trigger point between a logic high and logic

low level is typically 0.6PVDD and 0.3PVDD. It is highly rec-

ommended to switch between ground and the supply

Copyright © ANPEC Electronics Corp.

18

Rev. A.7 - Jan., 2013

www.anpec.com.tw

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