AS1702V-T

AS1702V-T Datasheet


AS1702 - AS1705

Part Datasheet
AS1702V-T AS1702V-T AS1702V-T (pdf)
Related Parts Information
AS1702-T AS1702-T AS1702-T
AS1702V AS1702V AS1702V
AS1702 AS1702 AS1702
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Datasheet

AS1702 - AS1705
1.8W Single-Channel Audio Power Amplifiers
1 General Description

The AS1702 - AS1705 are single-channel differential audio poweramplifiers designed to drive 4 and 8Ω loads. The integrated gain circuitry of these amplifiers and their small size make them ideal for to 5V-powered portable audio devices.

The differential input design improves noise rejection and provides common-mode rejection. A bridge-tied load BTL design minimizes external component count, while providing high-fidelity audio power amplification.

The devices deliver 1.8W continuous average power per channel to a 4Ω load with less than 1% total harmonic distortion plus noise , while operating from a single to 5V supply.

For reduced component designs, the devices are available with different gain levels as shown in Table

Table Standard Products

Model

Gain

AS1702

Adjustable via external components

AS1703

AV = 0dB

AS1704

AV = 3dB

AS1705

AV = 6dB

Integrated shutdown circuitry disables the bias generator and amplifiers, and reduces quiescent current consumption to less than 100nA. The shutdown input can be set active-high or active-low. All devices contain click-and-pop suppression circuitry that reduces audible clicks and pops during power-up and shutdown.

The AS1702 - AS1705 are pin compatible with the LM4895 and the MAX9718A/B/C/D. The devices are available in a 10-pin MSOP package and a 10-pin DFN package.

Figure Simplified Block Diagram
2 Key Features
2.7V to 5.5V VCC Single-Supply Operation

THD+N 1.8W into 4Ω at 1% per Channel

Differential Input

Adjustable Gain Option AS1702

Internal Fixed Gain to Reduce External Component Count AS1703, AS1704, AS1705
<100nA Low-Power Shutdown Mode

Click and Pop Suppression

Pin-Compatible to National Semiconductor LM4895 AS1705 and Maxim MAX9718A/B/C/D

Operating Temperature Range -40 to +85ºC

Package Types - 10-pin MSOP - 10-pin DFN
3 Applications

The devices are ideal as audio front-ends for battery powered audio devices such as MP3 and CD players, mobile phones, PDAs, portable DVD players, and any other hand-held battery-powered device.

Single Supply 2.7V to 5.5V
9 VCC
4 IN+
2 IN-
1 SHDN
3 SHDM
Each device has either adjustable or fixed gains 0dB, 3dB, 6dB see Ordering Information on page

Bias

The devices operate from a single to 5.5V supply and contain an internally generated, common-mode bias voltage of:

VCC 2
referenced to ground. Bias provides click-and-pop suppression and sets the DC bias level for the audio outputs. Select the value of the bias bypass capacitor as described in Section BIAS Capacitor on page

Note Do not connect external loads to BIAS as this can adversely affect overall device performance.

Shutdown Mode

All devices implement a 100nA, low-power shutdown circuit which reduces quiescent current consumption. As shutdown mode commences, the bias circuitry is automatically disabled, the device outputs go high impedance, and bias is driven to GND. The SHDM input controls the polarity of SHDN:

Drive SHDM high for an active-low SHDN input.

Drive SHDM low for an active-high SHDN input.

Table Shutdown Mode Selection Configurations

SHDM 0 1

SHDN 0 1 0 1

Mode Shutdown Mode Enabled Normal Operation Enabled Normal Operation Enabled Shutdown Mode Enabled

Click-and-Pop Suppression

During power-up, the device common-mode bias voltage VBIAS see page 4 ramps to the DC bias point. When entering shutdown, the device outputs are driven high impedance to 100kΩ between both outputs minimizing the energy present in the audio band, thus preventing clicks and pops.
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AS1702 - AS1705

Datasheet - Application Information
9 Application Information

Figure AS1702 Typical Application Diagram
to 5.5V

Supply
10µF

CIN* RIN

Inverting 10µF 10kΩ

Differential Input

Non-Inverting

Differential Input CIN* RIN
10µF 10kΩ
* Optional

CBIAS 0.1µF
5 BIAS
1 SHDN
3 SHDM

RF 20kΩ

RF 20kΩ

AV = 2

Bias Generator

Shutdown Control

AS1702
The AS1703, AS1704, and AS1705 contain different internally-fixed gains see Ordering Information on page A fixed gain facilitates simplified designs, decreased footprint size, and elimination of external gain-setting resistors.

The fixed gain values are achieved using resistors R1 and R2 see Figure 31 on page

Adjustable Differential Gain AS1702

Gain-Setting Resistors The AS1702 uses external feedback resistors, RF and RIN Figure 33 , to set the gain of the device as:

AV = RF RIN
where AV is the desired voltage gain. For example, RIN = 10kΩ, RF = 20kΩ yields a gain of 2V/V, or 6dB.

Note RF can be either fixed or variable, allowing the gain to be controlled by software using a AS150x digital potentiometer. For more information on the AS1500 family of digital potentiometers, refer to the latest version of the AS150x data sheet, available from the austriamicrosystems website

Figure Setting the AS1702 Gain

RF 20kΩ

RF 20kΩ

Inverting Differential Input

Non-Inverting Differential Input

CIN* RIN 10µF 10kΩ

CIN* RIN 10µF 10kΩ
* Optional

CBIAS 0.1µF
2 IN-
4 IN+
5 BIAS

Bias Generator

AS1702
10 OUT+ 6 OUT-

Input Filter

The BTL inputs can be biased at voltages other than mid-supply. However, the integrated common-mode feedback circuit adjusts for input bias, ensuring the outputs are still biased at mid-supply. Input capacitors are not required if the common-mode input voltage VIC is within the range specified in Table 4 and Table
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AS1702 - AS1705

Datasheet - Application Information

Input capacitor CIN if used , in conjunction with RIN, forms a high-pass filter that removes the DC bias from an incoming signal. The AC coupling capacitor allows the amplifier to bias the signal to an optimum DC level. Assuming zero-source impedance, the -3dB point of the high-pass filter is given by:
f-3dB =

Setting f-3dB too high affects the low-frequency response of the amplifier. Capacitors with dielectrics that have low-voltage coefficients such as tantalum or aluminum electrolytic should be used, since capacitors with high-voltage coefficients, such as ceramics, can increase distortion at low frequencies. BIAS Capacitor BIAS is the output of the internally generated VCC/2 bias voltage. The BIAS bypass capacitor, CBIAS, improves PSRR and THD+N by reducing power supply noise and other noise sources at the common-mode bias node, and also generates the click- and pop-less DC bias waveform for the amplifiers. Bypass BIAS with a 0.1µF capacitor to GND. Larger values of CBIAS up to 1µF improve PSRR, but increase tON/tOFF times. For example, a 1µF CBIAS capacitor increases tON/tOFF by 10 and improves PSRR by 20dB at 1kHz .

Note Do not connect external loads to BIAS.

Supply Bypassing Proper power supply bypassing connect a 10µF ceramic capacitor CBIAS from VCC to GND will ensure low-noise, low-distortion performance of the device. Additional bulk capacitance can be added as required.

Note Place CBIAS as close to the device as possible.

Layout and Grounding Considerations

Well designed PC board layout is essential for optimizing device performance. Use large traces for the power supply inputs and amplifier outputs to minimize losses due to parasitic trace resistance and route heat away from the device. Good grounding improves audio performance and prevents digital switching noise from coupling onto the audio signal.
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AS1702 - AS1705

Datasheet - Package Drawings and Markings
10 Package Drawings and Markings

Figure 10-pin DFN Marking

Table Packaging Code YYWWQZZ
Datasheet - Ordering Information
11 Ordering Information

The devices are available as the standard products shown in Table
Table Ordering Information

Odering Code

Marking

AS1702-T

AS1702

AS1703-T

AS1703

AS1704-T AS1705-T

AS1704

AS1702V-T
1702

AS1703V-T
1703

AS1704V-T
1704

AS1705V-T
1705

Description 1.8W Single-Channel Audio Power Amplifiers 1.8W Single-Channel Audio Power Amplifiers 1.8W Single-Channel Audio Power Amplifiers 1.8W Single-Channel Audio Power Amplifiers 1.8W Single-Channel Audio Power Amplifiers 1.8W Single-Channel Audio Power Amplifiers 1.8W Single-Channel Audio Power Amplifiers 1.8W Single-Channel Audio Power Amplifiers

Gain Adjustable Av =0dB Av =3dB Av =6dB Adjustable Av =0dB Av =3dB Av =6dB

Delivery Form Tape and Reel Tape and Reel Tape and Reel Tape and Reel Tape and Reel Tape and Reel Tape and Reel Tape and Reel

Package 10-pin MSOP
10-pin DFN

Note All products are RoHS compliant. Buy our products or get free samples online at ICdirect:

Technical Support is found at

For further information and requests, please contact us or find your local distributor at
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AS1702 - AS1705

Datasheet

Copyrights

Copyright 1997-2011, austriamicrosystems AG, Tobelbaderstrasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. All products and companies mentioned are trademarks or registered trademarks of their respective companies.

Disclaimer

Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment are specifically not recommended without additional processing by austriamicrosystems AG for each application. For shipments of less than 100 parts the manufacturing flow might show deviations from the standard production flow, such as test flow or test location. The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However, austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of austriamicrosystems AG rendering of technical or other services.

Contact Information

Headquarters austriamicrosystems AG Tobelbaderstrasse 30 A-8141 Unterpremstaetten, Austria Tel +43 0 3136 500 0 Fax +43 0 3136 525 01

For Sales Offices, Distributors and Representatives, please visit:
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Datasheet ID: AS1702V-T 519651