Features

● Excellent sound quality

● Ultra -low distortion: 0.000022%

● [ 123] Low noise: 1.3NV/√Hz

● High speed:

conversion rate: 50V/μs

#872222 Gain bandwidth: 180MHz

●

Full differential architecture:

Balance input and output convert single -end input to a balanced differential output

[[[

123] ● Wide power range: ± 2.5V to ± 16V

● Turn off to save electricity

Application [ 123] ●

Audio ADC driver

●

Balance line drive

●

Balance receiver

] ● Active filter

● Preface

OPA1632 is a full differential amplifier, for driving high Performance audio modulus converter (ADC). It provides applications with the highest audio quality, very low noise and output -driven feature optimization. OPA1632's excellent 180MHz gain bandwidth and the rapid conversion rate of 50V/μs generate extremely low distortion. 1.3nv/√Hz's extremely low input noise further ensures the maximum signal ratio and dynamic range. The flexibility of the structure of the full differential architecture allows the single -end -to -full differential output conversion. Differential output can reduce the occurrence of occasional harmonics and minimize co -modular noise interference. OPA1632 has excellent performance when driving high -performance audio ADC (such as PCM1804). The closing function also enhances the flexibility of this amplifier.

OPA1632 has SO-8 packaging and thermal enhancement MSOP-8 PowerPad #63722; package. Related devices

Typical features

ta u003d+25 ° C, Vs u003d ± 15V, RL u003d 2K unless there is another explanation.

Application information FIG804 high -performance audio ADC differential output drive OPA1632.

OPA1632 usually uses a power supply voltage of ± 15V. If necessary, the relatively low input voltage of the ADC allows a lower power voltage amplitude. It can be used as low as ± 8V and has excellent performance. This reduces power consumption and heat up. The power supply should be connected parallel with 10 μF 器 capacitors and 0.1 μF ceramic capacitors to avoid possible oscillation and instability.

VCOM reference voltage output on PCM1804 ADC provides correct input co -mode reference voltage (2.5V). The VCOM voltage is buffered by the computing amplifier A2 and drives the output co -mode voltage pins of OPA1632. This makes the average output voltage of OPA1632 shift to 2.5V.

The signal gain of the circuit is usually about 0.25, which is compatible with the common audio line level. If necessary, you can adjust the gain by changing the values u200bu200bof R1 and R2. As shown in the figure, the feedback resistance value (R3 and R4) should be relatively low to obtain the best noise performance. R5, R6, and C3 provide ADC to provide input filters and charge fault memory. The value shown is generally satisfactory. Some adjustments to the value may help optimize the performance of different ADCs.

Maintaining accurate resistance on R1/R2 and R3/R4 is very important to achieve good differential signal balance. Use 1%resistance to obtain the highest performance. When connected to a single -end input (reverse input ground, as shown in Figure 1), the source impedance must be very low. Differential input sources must have good balance or low source impedance.

Capacitor C1, C2, and C3 should be cautious to obtain good distortion performance. The types of polystyrene, polypropylene, NPO ceramics and cloud mother are usually very good. Polyester and high -K ceramic types, such as Z5U, can cause deformation.

Note: (1) Signal supply to enable logic reference V See the shutdown function part.

Full Differential Player

Differential signal processing provides many performance advantages in high -speed analog signal processing systems, including anti -external co -model noise, inhibiting unclear non -linearity, and increasing dynamic range. The full differential amplifier not only as the main means to provide gain to the differential signal chain, but also provides a single -chip solution that converts the single -end signal into a differential signal, so as to achieve simple and high -performance processing.

The standard configuration of the device is shown in Figure 2. The function of a fully differential amplifier can be imagined as two inverters that share one incurable terminal (although the voltage is not necessarily fixed). For more information about the basic working principle of the full differential amplifier, please refer to the Texas Instrument Application Description Sloa054, a full differential amplifier.

The shutdown function

The shutdown (enabled) function of OPA1632 is related to the negative power of the operation amplifier. A effective logic (negative power supply above lt; 0.8V) is applied to the enable pin (pin 7) disable the amplifier output. The voltage on the pins 7 on the negative power supply above 2V is applied to the activation state of the amplifier, and the device is enabled. If the pin 7 keeps disconnect, the internal pull -up resistor will be enabled to use the device. The opening and closing time is about 2 μs.

When the amplifier is disabled, the static current is reduced to about 0.85mA. When disabled, the output level is not in a high impedance state. Therefore, the control function cannot be used to create a multi -way reuse switch function connected to multiple amplifiers.

Output co -mode voltage

Output co -mode voltage pins set OPA1632 DC output voltage. The voltage exerted from low impedance sources to VOCM tube feet can be used to directly set output co -mode voltage. For VOCM voltage at the middle power supply, do not connect to the VOCM pin.

According to the expected application, it is recommended to install an decoupling capacitor on the VOCM node to filter any high -frequency noise in the signal path that may be coupled to the signal path through the VOCM circuit. 0.1 μF or 1 μF capacitor is usually sufficient.

The output co -modular voltage allows the additional current to flow in the feedback resistance network. Because the current is provided by the output level of the amplifier, additional power consumption will be generated. For commonly used feedback resistance values, this current is easily provided by the amplifier. The additional internal power consumption generated by this current may be very important in some applications, and it may be required to use the MSOP PowerPad package to effectively control the heating.

PowerPad Design Note

OPA1632 is a hot enhanced PowerPad package series. These packaging is constructed with a lower -loading framework, and molds are installed on this framework (see Figure 3 [a] and Figure 3 [B]). This layout causes the lead frame to be exposed to the hot pad at the bottom of the packaging (see Figure 3 [C]). Because the thermal pad has a direct heat contact with the mold, it can obtain excellent thermal performance by providing a good heat path away from the hot pad.

PowerPad package allows assembly and thermal management at the same time in a manufacturing operation. During the surface of the surface (when welding), the thermal pads must be welded to the copper area below the packaging. By using the heat path in this copper area, the heat can be transmitted from the package to the ground layer or other heat dissipation devices. Always need to welded PowerPad to the printing circuit board (PCB), even in low -power applications. It provides necessary thermal connections and mechanical connections between the leading framework and PCB.

PowerPAD PCB layout Note

1. The hot pad must be connected to the most negative power voltage on the device V .

2. Prepare PCB with the top etched pattern, as shown in Figure 4. Both wires and hot pads should be etched.

3. Place five holes in the thermal pad area. The diameter of these holes should be 13 dense ears. Keep them very small, so that during the return welding process, the welded core of the hole will not become a problem.

4. You can place additional pores along any position of the hot plane outside the hot pad area.

These pores help dissipate the calories generated by the OPA1632 integrated circuit, which may be larger than the pores with a dense ear in the diameter of 13 dense in the diameter of the heat pad. They can be larger because they are not welded in the hot pad area, so the core suction is not a problem.

5. Connect all holes to the internal power board with the same negative electrode voltage as V.

6. When connecting these holes to the plane, do not use a typical abdomen or wheel spoke connection method. The network connection has a high thermal resistance connection, which helps to slow the heat transfer during the welding process. This makes it easier to weld the pores with a plane connection. However, in this application, in order to achieve the most effective heat transfer, low thermal resistance is required. Therefore, the holes under the OPA1632 PowerPad should be connected to the internal plane and a complete connection around the entire circle around the electroplated hole.

7. The top welded mask should expose five holes in the packaging terminal and the hot pad area. The welding mask at the bottom should cover five holes in the hot pad pad area. This prevents welded from pulling away from the hot pad area during the return welding.

8. Apply the tiny paste to the exposed thermal pad area and all IC terminals.

9. With these preparation steps, the integrated circuit is simply placed in an appropriate position, and as a standard surface paste component through welding back welding operation. This will cause the parts to be installed correctly.

Power consumption and heat dissipation consideration

OPA1632 has no heat shutdown protection. Be careful not to exceed the highest knot temperature. Excessive knot temperature will reduce performance or cause permanent damage. To obtain the best performance and reliability, ensure that the knot temperature does not exceed+125 ° C.

The thermal characteristics of the device are determined by the packaging and circuit board. The maximum power consumption of the given package can be calculated using the following formulas:

where:

PDMAX is the maximum power consumption of the amplifier (W).

Tmax is the absolute maximum knot temperature (℃).

TA is the ambient temperature (℃).

θja u003d θjc+θ CA.

θjc is from silicon to outsideThe thermal coefficient of the shell (℃ /w).

θca is the thermal coefficient (℃ /w) from the shell to the environmental air.

For a more critical system for heat dissipation, OPA1632 uses MSOP-8 with PowerPad.Compared with the traditional SO packaging, the thermal coefficient of MSOP PowerPad (DGN) packaging has increased significantly.Figure 5 describes the maximum power consumption level of these two packages.The data of the DGN software package assumes that the circuit board layout follows the PowerPad layout criteria.