BA3121, BA3121F, BA3121N Datasheet. Www.s Manuals.com. Rohm
User Manual: Datasheets BA3121, BA3121F, BA3121N.
Open the PDF directly: View PDF 
.
Page Count: 10
| Download | |
| Open PDF In Browser | View PDF |
Audio ICs Ground isolation amplifier BA3121 / BA3121F / BA3121N The BA3121,BA3121F and BA3121N are ground isolation amplifiers developed for use in car audio applications. These ICs efficiently eliminate problems caused by wiring resistance, and remove noise generated by the electrical devices used in automobiles. The capacitance values of the external capacitors required for the ICs are small to allow compact and reliable set design. Applications Car audio systems Features 1) Large capacitors not required 2) High common-mode rejection ratio (57dB typ. at f = 1kHz). 3) Low noise (VNO = 3.5µVrms Typ.). 4) Low distortion (THD = 0.002% Typ.). 5) Two channels. Absolute maximum ratings (Ta = 25C) Recommended operating conditions (Ta = 25C) 717 Audio ICs Block diagrams 718 BA3121 / BA3121F / BA3121N Audio ICs BA3121 / BA3121F / BA3121N Electrical characteristics (unless otherwise noted, Ta = 25C, VCC = 12V, f = 1kHz, Rg = 1.8kΩ) 719 Audio ICs Measurement circuits 720 BA3121 / BA3121F / BA3121N Audio ICs BA3121 / BA3121F / BA3121N FCircuit operation Car-audio systems are earthed to the car body, and for this reason, electrical noise generated by the car electrics can enter the power amplifier input via the chassis, and become audible. The BA3121 makes use of the common-mode rejection characteristics of an operational amplifier to eliminate this noise. Without the BA3121 noise enters the power amplifier input directly, when used, the CMMR of operational amplifiers 1-A and 2-A eliminates the noise. Principles of noise elimination: To obtain the output voltage (eO) Vi = R4 (R3R4) eO = R2 e1 R1 S e2 1 R1R2 R1 S Vi 2 From 1 and 2 eO = R1R2 R2 e1 R1 R1 S eO = R2 R1 R1R4R2R3 S e2 R1 (R3R4) S (e1e2) R4 (R3R4) S e2 Ideally, if R1R4 = R2R3, and e1 = e2, the noise voltage will become zero. However, due to mismatching between the resistors, difference in the noise voltages (e1 and e2), and tolerances in the operational amplifier, a noise voltage does result. With the BA3121, the elimination level of the noise is expressed as: CMMR = 20log (eO / ei) (ei = e1 = e2) Therefore, CMRR 41dB can be guaranteed. FOperation notes (1) Maintain a ratio of 2: 1 for the values of the capacitors connected to pin 2 (Vm1) and pin 6 (Vm2) to keep the ripple rejection ratio stable. If this ratio is maintained, the ripple rejection ratio will not vary significantly even if the capacitance values are halved. (2) If the value of the capacitor connected to pin 2 (Vm1) in the example is doubled, the bass-region CMMR will be +6dB, and if it is halved, it will be 6dB (see Fig. 16). 721 Audio ICs Application example 722 BA3121 / BA3121F / BA3121N Audio ICs BA3121 / BA3121F / BA3121N Electrical characteristics curves 723 Audio ICs 724 BA3121 / BA3121F / BA3121N Audio ICs BA3121 / BA3121F / BA3121N External dimensions (Units: mm) 725 www.s-manuals.com
Source Exif Data:
File Type : PDF File Type Extension : pdf MIME Type : application/pdf PDF Version : 1.6 Linearized : No XMP Toolkit : Adobe XMP Core 4.0-c316 44.253921, Sun Oct 01 2006 17:14:39 Producer : Acrobat Distiller 3.01 for Windows Modify Date : 2013:03:10 14:09:02+02:00 Create Date : 1999:01:18 09:09:51Z Creator Tool : Interleaf, Inc. Metadata Date : 2013:03:10 14:09:02+02:00 Document ID : uuid:69bffcdb-b6c6-4d97-9715-929a3cd03121 Instance ID : uuid:f1b290b5-5533-4621-acab-56e9ac83dae1 Format : application/pdf Title : BA3121, BA3121F, BA3121N - Datasheet. www.s-manuals.com. Description : Creator : Subject : BA3121, BA3121F, BA3121N - Datasheet. www.s-manuals.com. Has XFA : No Page Count : 10 Keywords : BA3121, BA3121F, BA3121N - Datasheet. www.s-manuals.com.EXIF Metadata provided by EXIF.tools