Datasheet Ground Isolation Amplifier BA3121F General Description Key Specifications BA3121F is a ground isolation amplifier developed for car audio applications. This IC efficiently eliminates problems caused by wiring resistance and removes noise generated by other electrical devices used in automobiles. The external capacitor values required for this IC are so small that it allows for compact and reliable set design. Package Features Power Supply Voltage Range: 4V to 18V Quiescent Current: 9.0mA (Typ) High Common-mode Rejection Ratio(1kHz): 57dB (Typ) Low Noise: VNO = 3.5µVrms(Typ) Low Distortion: THD = 0.002% (Typ) Operation temperature range: -30°C to +85°C W(Typ) x D(Typ) x H(Max) Large Capacitors not Required High Common-mode Rejection Ratio Low Noise Low Distortion Two Channels Applications Car audio systems SOP8 5.00mm x 6.20mm x 1.71mm Typical Application Circuit ○Product structure：Silicon monolithic integrated circuit www.rohm.com © 2015 ROHM Co., Ltd. All rights reserved. TSZ22111・14・001 ○This product has no designed protection against radioactive rays 1/12 TSZ02201-0C2C0EZ00390-1-2 13.Nov.2015 Rev.001 BA3121F Block Diagram and Pin Configuration TOP VIEW VM1 VM2 Absolute Maximum Ratings (Ta = 25C) Parameter Power Supply Voltage Power Dissipation Operation Temperature Storage Temperature Symbol Limit Unit VCC Pd Topr Tstg 18 0.45 (Note 1) -30 to +85 -55 to +125 V W °C °C (Note 1) Reduced by 4.5mW in Ta of 1°C over 25°C . Caution: Operating the IC over the absolute maximum ratings may damage the IC. The damage can either be a short circuit between pins or an open circuit between pins and the internal circuitry. Therefore, it is important to consider circuit protection measures, such as adding a fuse, in case the IC is operated over the absolute maximum ratings. Recommended Operating Conditions (Ta = 25C) Parameter Symbol Min Typ Max Unit Power Supply Voltage VCC 4 12 18 V Electrical Characteristics (Unless otherwise noted, Ta = 25C, VCC = 12V, f = 1kHz, Rg = 1.8kΩ) Symbol Min Typ Max Unit Quiescent Current Output Noise Voltage IQ VNO 5.6 － 9.0 3.5 14.0 8.0 mA μVrms Voltage Gain GV -1.5 -0.04 +1.5 dB Maximum Output Voltage VOM 1.8 2.0 － Vrms Parameter THD － 0.002 0.02 ％ CMRR 41 57 - dB Common-made Voltage VCM 2.5 3.75 - Vrms Ripple Rejection Ratio RR 72 80 - dB Channel Separation CS - 82 - dB Slew Rate Input Resistance SR RIN 44 2.0 55 66 V/μS kΩ Total Harmonic Distortion Common-mode Rejection Ratio www.rohm.com © 2015 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 2/12 Conditions VIN＝0Vrms BPF＝20Hz-20kHz VOUT＝-10dBm, Rg＝0Ω THD＝0.1％, VCC＝8V VOUT＝0.7Vrms VCC＝8V,CMRR＝40dB fRR＝100Hz,VRR＝-10dBm, Rg＝0Ω VIN＝-10dBm, Rg＝1.8kΩ/OPEN TSZ02201-0C2C0EZ00390-1-2 13.Nov.2015 Rev.001 BA3121F Typical Performance Curves Quiescent Current : IQ (mA) Maximum Output Voltage : VOM (Vrms) VIN = 0Vrms Power Supply Voltage : VCC (V) Power Supply Voltage : VCC (V) Figure 1. Quiescent Current vs Power Supply Voltage Figure 2. Maximum Output Voltage vs Power Supply Voltage Voltage Gain : GV (dB) Output Noise Voltage : VNO (µVrms) THD=0.1% RL = 10kΩ f=1kHz Power Supply Voltage : VCC (V) Power Supply Voltage : VCC (V) Figure 4. Voltage Gain vs Power Supply Voltage Figure 3. Output Noise Voltage vs Power Supply Voltage www.rohm.com © 2015 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 3/12 TSZ02201-0C2C0EZ00390-1-2 13.Nov.2015 Rev.001 BA3121F Typical Performance Curves – continued Voltage Gain : GV (dB) Channel Separation : CS (dB) VCC = 12V VIN=-10dBm 10 20 50 100 200 500 1k 2k VCC=12V VIN = -10dBm Rg=1.8kΩ/Open RL=10kΩ 10 20 5k 10k 20k 50 100 200 500 1k 2k Frequency : f (Hz) Figure 6. Channel Separation vs Frequency VCC = 12V VRR=-10dBm Rg=0Ω RL=10kΩ 50 100 200 500 1k 2k Total Harmonic Distortion : THD (%) Ripple Rejection Ratio : RR (dB) Figure 5. Voltage Gain vs Frequency 10 20 VCC = 12V f=1kHz RL=10kΩ 5k 10k 20k Output Voltage : VOUT (Vrms) Frequency : f (Hz) Figure 8. Total Harmonic Distortion vs Output Voltage Figure 7. Ripple Rejection Ratio vs Frequency www.rohm.com © 2015 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 5k 10k 20k Frequency : f (Hz) 4/12 TSZ02201-0C2C0EZ00390-1-2 13.Nov.2015 Rev.001 BA3121F Common Mode Rejection Ratio : CMRR (dB) Typical Performance Curves – continued Total Harmonic Distortion : THD (%) VCC = 12V VOUT = 0.7Vrms RL= 10kΩ 10 20 50 100 200 500 1k 2k 5k 10k 20k Frequency : f (Hz) Common Mode Rejection Ratio : CMRR (dB) Figure 9. Total Harmonic Distortion vs Frequency VCC = 12V VN=-20dBm Rg=1.8kΩ (VM1, VM2)=(100µF, 47µF) (VM1, VM2)=(47µF, 22µF) (VM1, VM2)=(22µF, 10µF) 10 20 50 100 200 500 1k 2k 5k 10k 20k Frequency : f (Hz) Figure 10. Common Mode Rejection Ratio vs Frequency VCC = 8V f=1kHz Rg=1.8kΩ Input Noise Voltage : VCM (Vrms) Figure 11. Common Mode Rejection Ratio vs Input Noise Voltage www.rohm.com © 2015 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 5/12 TSZ02201-0C2C0EZ00390-1-2 13.Nov.2015 Rev.001 BA3121F Measurement Circuits BA3121F Figure 12 www.rohm.com © 2015 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 6/12 TSZ02201-0C2C0EZ00390-1-2 13.Nov.2015 Rev.001 BA3121F Application Information 1. Circuit Operation Figure 13. Flow of Noise in Car Audio Systems Car audio systems are grounded to the car body. For this reason, electrical noise generated by the car electrical system can enter the power amplifier input through the chassis and become audible. BA3121F utilizes the common-mode rejection characteristics of an operational amplifier to eliminate this noise. Without BA3121F noise enters the power amplifier inputs directly. With BA3121F, the CMRR of operational amplifiers 1-A and 2-A eliminates the noise. Principle of noise elimination: To obtain the output voltage (eO) Figure 14. The Principle of Noise Rejection R4 Vi e R3 R4 2 eO R2 R R2 e1 1 Vi R1 R1 ① ② With BA3121F, the elimination level of the noise is expressed as: CMRR = 20log (eO/eI)(eI = e1 = e2) Therefore, CMRR ≥ 41dB can be guaranteed. From ① and ② R2 R R2 R4 e1 1 e2 R1 R1 ( R3 R4 ) eO - R2 R R - R2 R3 e1 - e2 1 4 e2 R1 R1 ( R3 R4 ) Ideally, if R1R4 = R2R3, and e1 = e2, the noise voltage will be zero. However, due to resistor mismatch, difference in the noise voltages (e1 and e2), and tolerances in the operational amplifier, a noise voltage is generated. www.rohm.com © 2015 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 7/12 TSZ02201-0C2C0EZ00390-1-2 13.Nov.2015 Rev.001 BA3121F Operational Notes 1. Reverse Connection of Power Supply Connecting the power supply in reverse polarity can damage the IC. Take precautions against reverse polarity when connecting the power supply, such as mounting an external diode between the power supply and the IC’s power supply pins. 2. Power Supply Lines Design the PCB layout pattern to provide low impedance supply lines. Separate the ground and supply lines of the digital and analog blocks to prevent noise in the ground and supply lines of the digital block from affecting the analog block. Furthermore, connect a capacitor to ground at all power supply pins. Consider the effect of temperature and aging on the capacitance value when using electrolytic capacitors. 3. Ground Voltage Ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition. 4. Ground Wiring Pattern When using both small-signal and large-current ground traces, the two ground traces should be routed separately but connected to a single ground at the reference point of the application board to avoid fluctuations in the small-signal ground caused by large currents. Also ensure that the ground traces of external components do not cause variations on the ground voltage. The ground lines must be as short and thick as possible to reduce line impedance. 5. Thermal Consideration Should by any chance the power dissipation rating be exceeded the rise in temperature of the chip may result in deterioration of the properties of the chip. In case of exceeding this absolute maximum rating, increase the board size and copper area to prevent exceeding the Pd rating. 6. Recommended Operating Conditions These conditions represent a range within which the expected characteristics of the IC can be approximately obtained. The electrical characteristics are guaranteed under the conditions of each parameter. 7. Inrush Current When power is first supplied to the IC, it is possible that the internal logic may be unstable and inrush current may flow instantaneously due to the internal powering sequence and delays, especially if the IC has more than one power supply. Therefore, give special consideration to power coupling capacitance, power wiring, width of ground wiring, and routing of connections. 8. Operation Under Strong Electromagnetic Field Operating the IC in the presence of a strong electromagnetic field may cause the IC to malfunction. 9. Testing on Application Boards When testing the IC on an application board, connecting a capacitor directly to a low-impedance output pin may subject the IC to stress. Always discharge capacitors completely after each process or step. The IC’s power supply should always be turned off completely before connecting or removing it from the test setup during the inspection process. To prevent damage from static discharge, ground the IC during assembly and use similar precautions during transport and storage. 10. Inter-pin Short and Mounting Errors Ensure that the direction and position are correct when mounting the IC on the PCB. Incorrect mounting may result in damaging the IC. Avoid nearby pins being shorted to each other especially to ground, power supply and output pin. Inter-pin shorts could be due to many reasons such as metal particles, water droplets (in very humid environment) and unintentional solder bridge deposited in between pins during assembly to name a few. 11. Unused Input Pins Input pins of an IC are often connected to the gate of a MOS transistor. The gate has extremely high impedance and extremely low capacitance. If left unconnected, the electric field from the outside can easily charge it. The small charge acquired in this way is enough to produce a significant effect on the conduction through the transistor and cause unexpected operation of the IC. So unless otherwise specified, unused input pins should be connected to the power supply or ground line. www.rohm.com © 2015 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 8/12 TSZ02201-0C2C0EZ00390-1-2 13.Nov.2015 Rev.001 BA3121F Operational Notes – continued 12. Regarding the Input Pin of the IC This monolithic IC contains P+ isolation and P substrate layers between adjacent elements in order to keep them isolated. P-N junctions are formed at the intersection of the P layers with the N layers of other elements, creating a parasitic diode or transistor. For example (refer to figure below): When GND > Pin A and GND > Pin B, the P-N junction operates as a parasitic diode. When GND > Pin B, the P-N junction operates as a parasitic transistor. Parasitic diodes inevitably occur in the structure of the IC. The operation of parasitic diodes can result in mutual interference among circuits, operational faults, or physical damage. Therefore, conditions that cause these diodes to operate, such as applying a voltage lower than the GND voltage to an input pin (and thus to the P substrate) should be avoided. Resistor Transistor (NPN) Pin A Pin B C E Pin A N P+ P N N P+ N Pin B B N Parasitic Elements P+ N P N P+ B N C E Parasitic Elements P Substrate P Substrate GND GND Parasitic Elements GND Parasitic Elements GND N Region close-by Figure 15. Example of monolithic IC structure 13. The capacitors of Pin2 (VM1), and Pin 6 (VM2) should maintain the ratio of 2:1 for ripple rejection characteristics. Maintaining this ratio will prevent the significant decrease on ripple rejection even if the capacitance is reduced to half. 14. Setting the capacitor value to twice or half will make CMRR +6dB or -6dB respectively (Figure 10) in the low frequency range. www.rohm.com © 2015 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 9/12 TSZ02201-0C2C0EZ00390-1-2 13.Nov.2015 Rev.001 BA3121F Ordering Information B A 3 1 2 1 F - E2 Package F: SOP8 Part Number Packaging and forming specification E2: Embossed tape and reel Marking Diagram SOP8 (TOP VIEW) Part Number Marking 3 1 2 1 LOT Number 1PIN MARK www.rohm.com © 2015 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 10/12 TSZ02201-0C2C0EZ00390-1-2 13.Nov.2015 Rev.001 BA3121F Physical Dimension, Tape and Reel Information Package Name SOP8 (Max 5.35 (include.BURR)) (UNIT : mm) PKG : SOP8 Drawing No. : EX112-5001-1 www.rohm.com © 2015 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 11/12 TSZ02201-0C2C0EZ00390-1-2 13.Nov.2015 Rev.001 BA3121F Revision History Date Revision 13.Nov.2015 001 Changes New Release www.rohm.com © 2015 ROHM Co., Ltd. All rights reserved. TSZ22111・15・001 12/12 TSZ02201-0C2C0EZ00390-1-2 13.Nov.2015 Rev.001 Datasheet Notice Precaution on using ROHM Products 1. Our Products are designed and manufactured for application in ordinary electronic equipments (such as AV equipment, OA equipment, telecommunication equipment, home electronic appliances, amusement equipment, etc.). If you (Note 1) , transport intend to use our Products in devices requiring extremely high reliability (such as medical equipment equipment, traffic equipment, aircraft/spacecraft, nuclear power controllers, fuel controllers, car equipment including car accessories, safety devices, etc.) and whose malfunction or failure may cause loss of human life, bodily injury or serious damage to property (“Specific Applications”), please consult with the ROHM sales representative in advance. Unless otherwise agreed in writing by ROHM in advance, ROHM shall not be in any way responsible or liable for any damages, expenses or losses incurred by you or third parties arising from the use of any ROHM’s Products for Specific Applications. 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