Features

Unit gain bandwidth: 250MHz

Broadband: 100MHz GBW

High conversion rate: 150V/ s Low noise: 6.5nv/ √Hz [123 [123 ]

I/O

High -output current: gt; 100ma

Outstanding video performance:

Differential gain: 0.02%, difference: 0.09: 0.09 0.1DB gain flatness: 40MHz

Low input bias current: 3Pa

Static current: 4.9ma

Hot turnover

Power range: 2.5VV To 5.5V

Shut off IQ LT; 6 A micro and PowerPad #63722; software package

Application

Video processing

Ultrasonic

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123] Optical network, adjustable laser

Optical diode cross -blocking large device

Active filter

High -speed integralor

Model converter input buffer input buffer Device

digital modular converter output amplifier

barcode scanner

Communication

Instructions

OPA357 series high -speed voltage feedback CMOS operational amplifier amplifier It is designed for videos and other broadband applications. They are stable in unit gain and can drive large current output. Differential gain is 0.02%, and the differential phase is 0.09 °. The static current of each channel is only 4.9mA.

OPA357 series operations amplifiers are optimized and can run on a single power or dual power supply at a single power or dual power supply of up to 2.5V (± 1.25V) and up to 5.5V (± 2.75V). The input range of the co -model exceeds the range of power. The output width is within the range of 100mv and supports the wide dynamic range.

For applications that require 100 mA-continuous output current, a single SO-8 power board version can be provided.

A single version (OPA357) is encapsulated by micro SOT23-6 and SO-8 PowerPad. Dual version (OPA2357) is provided in the MSOP-10 software package.

The characteristic of the dual version is a complete independent circuit to reduce the bruises and avoid interaction. All these are specified within the extended 40 ° C to+125 ° C temperature range.

OPAX357 related products

Point configuration

Note: (1), SOT23-6's pin 1 is determined by adjusting the direction of the packaging mark, as shown in the figure.

(2), NC indicates that there is no internal connection.

(3), the power board should be connected to V-or left to float.

Typical features

Unless otherwise explained, in TA u003d+25 ° C, vs u003d 5V, g u003d+1, RF u003d 0 , RL u003d 1K And connected to VS/2.

Application information [123 ]

OPA357 is a CMOS, I/O, high -speed, voltage feedback computing amplifier, designed for video, high -speed and other applications. It has a single or dual operation amplifier.

The amplifier has a conversion rate of 100MHz gain bandwidth and 150V/μs, but the unit gain is stable and can be used as a+1V/V voltage follower.

Working voltage

The power range of OPA357 is+2.7V to+5.5V (± 1.35V to ± 2.75V). However, the range of power voltage is+2.5V to+5.5V (± 1.25V to ± 2.75V). The power supply voltage higher than 7.5V (absolute maximum value) will permanently damage the amplifier.

See the typical feature part of this data table with the parameters of the power supply voltage or temperature change.

Enable function

The enable function of OPA357 is implemented using a Schmitt trigger. Use the TTL high-voltage level (reference V-) to the enable pin to enable the amplifier. Instead, the TTL low voltage level (refer to V ) will disable the amplifier, and reduce its power current from 4.9mA to only 3.4 μA per amplifier. Each channel has an independent enabled pin (double version), which provides the greatest design flexibility. For portable battery operation applications, this function can be used to greatly reduce the average current, thereby extending the battery life.

enable input can be modeled as a CMOS input door with a pull -up resistance of 100K The pin should be connected to an effective high or low voltage or driver, not the left.

The enable time is 100ns, and the disable time is only 30ns. This allows OPA357 to work as a door control amplifier, or replicate it on the public output bus. When disabled, the output assumes a high impedance state.

Rail -to -track input

The input co -mode voltage range specified in OPA357 exceeds 100mV of the power rail. This is achieved through a complementary input level. A N -channel input difference is paired with the P channel, as shown in Figure 1. The N-channel is effective for input voltage near the track, usually higher than the positive power supply (V+)-1.2V to 100MV, and the P-channel is to approximately from 100 millivolal to about (V+ 1.2V below the negative electrode power supply (V+ 1.2V ) The input is opened. There is a small transition area, usually (V+) -1.5V to (V+)-0.9V, two of which are opened. The 600 millivolo transition zone can change ± 500 millivolves with the process. Therefore, at the low-end, the range of the transition zone (both input levels open) is (V+)-2.0V to (V+)-1.5V, high-end reaches (V+ 0.9V to (V+)- 0.4V.

Dual -folding the common source code of the two input pairs of the signal and providing differential signals to the AB output level.

[ 123] Rail -to -rail transfers

AB output stage adopts a common source transistor to achieve rail transfers. For high impedance loads ( gt; 200 ), the output voltage swing is usually 100 mm from the power rail 100mm Fu. When the load is 10 can achieve useful output swing while maintaining the high -opening gain. See the typical characteristic curve of the output voltage and the output current. 123] The output level of OPA357 can provide a continuous output current of ± 100mA, and it still provides about 2.7V output swing on the 5V power supply, as shown in Figure 2. In order to achieve the maximum reliability, it is not recommended to run more than ± 100mA continuous consecutive consecutive consecutive DC current. Refer to the characteristic curve of the typical output voltage swing and output current. In order to provide continuous output current greater than ± 100mA, OPA357 can run parallel, as shown in Figure 3. OPA357 will provide up to 200mA with up to 200mA Peak current, which corresponds to a typical short -circuit current. Therefore, a hot shutdown circuit is provided to protect the high knot temperature of OPA357 from danger. At 160 ° C, the protective circuit will turn off the amplifier. By the time below 140 ° C, normal work will be resumed.

Video

OPA357 output level that can drive standards can drive standard 75 Video cables, as shown in Figure 4. Through the reverse end transmission line, it will not display the capacitance load to the drive. 75 the cable will not be displayed as a capacitor; it only provides 150 #to OPA357 output 150 # 8486; resistance load.

OPA357 can be used as a amplifier of the RGB graphics signal. The voltage of the signal is zero under the flat black electricity, and the signal is offset and communicated. See Figure 5.

Broadband video multi -road reuse

A common application of video speed amplifier is to connect multiple amplifiers together, and then from several possible possible Which one is selected in the video input to enter a line. This simple wired or video multi -way relics can be easily implemented using OPA357; see Figure 6.

Drive Simulation-Digital Converter

OPA357 series operational amplifier provides a stable time of 60 nan seconds to 0.01%, making it a high-speed sampling A driver A. /D converter and good choice of reference circuits. The OPA357 series provides an effective method to buffer the input capacitance of the A/D converter and the injecting the charge generated, and at the same time provides a signal gain.

OPA357 driving the A/D converter is shown in Figure 7. When the OPA357 is in a inverted configuration, the capacitors on the feedback can be used to filter the high -frequency noise in the filter signal; see Figure 7.

Rongtability load and stability

OPA357 series operational amplifier can drive various capacitance loads. However, under certain conditions, all operational amplifiers may become unstable. The configuration, gain, and load value of the operation amplifier are only a few factors to consider when determining the stability. The computing amplifier of the unit gain structure is most likely to be affected by the capacitor load. The output resistance of the capacitance load and the calculation amplifier and any additional load resistance react, and a pole is generated in the small signal response to reduce the phase margin. For details, please refer to the typical characteristic curve frequency response of various CLs.

OPA357's topological structure enhances its ability to drive capacitance loads. At the unit gain, these computing amplifiers perform well with large capacitor loads. For details, please refer to the recommended typical characteristic curve RS VS capacitance load and frequency response VS capacitance load.

A method of capacitive load driving in the improvement unit gain configuration is to connect a resistor of 10 to 20 #8486 at the output end, as shown in Figure 8. This significantly reduces the bell phenomenon when the large capacitance load is #63719; However, if there is a resistor load and a capacitor load, RS will generate a divisioner. This will introduce DC errors at the output end and slightly reduce the output swing. This error may be irrelevant. For example, in the case of RL u003d 10K and RS u003d 20 output only about 0.2%of errors.

Broadband spanPlotea

Broad band width, low input bias current, low input voltage and current noise make OPA357 an ideal broadband optical diode interoperability of low -voltage single power applications. Low -voltage noise is important because the optical diode capacitance increases the effective noise gain of the circuit at high frequency.

As shown in Figure 9, the key element of cross -resistance design is the expected diode capacitance (including the parasitic input co -mode and differential input capacitance of the OPA357 (2+2) PF) (RF) and OPA357 (100MHz) gain bandwidth (GBP). After setting these 3 variables, you can set the feedback capacitor value (CF) to control the frequency response.

In order to obtain the largest flat second -order Bartvos frequency response, the feedback pole should be set to:

Typical typical The parasitic capacitance of the surface sticker is about 0.2pf, which must be deducted from the calculated feedback capacitor value.

Bandwidth calculation formula is as follows:

For higher cross -resistance bandwidth, you can use high -speed CMOS OPA355 (200MHz GBW) or OPA655 (400MHzGBW).

PCB layout

OPA357 should adopt a good high -frequency printing circuit board (PCB) layout technology. A large number of ground layers, short and direct signal trajectories, and appropriate bypass electrical containers located in V+pins will ensure clean and stable operation. Large -area copper also provides a method of calorie during normal runtime.

The socket is definitely not recommended to use it with any high -speed amplifier.

10NF ceramic side electric container is the minimum recommendation value; when the driver is driven with a low resistance load, it may be beneficial to add 1 μF or larger electric container. Providing sufficient bypass capacitors is essential for achieving very low harmonic and distortion of interoperability.

Power loss

In addition to the conventional SOT23-6 and MSOP-10, the single and dual versions of OPA357 also have a SO-8 power board. SO-8 PowerPad is the standard size SO-8 package. The naked lead frame of the packaging bottom is directly welded to the PCB to generate extremely low thermal resistance. This will greatly enhance the power consumption capacity of OPA357 and eliminate the bulky radiator and plugs used in hot packaging. This package can easily install the standard PCB assembly technology. Note: Since SO-8 PowerPad is compatible with the standard SO-8 packaging, OPA357 can directly replace the calculation amplifier in the existing socket. It is recommended to welded PowerPad to PCB, even if it is a low -power application.This provides necessary thermal connections and mechanical connections for the lead frame of the lead framework and PCB.

For the resistance load, the maximum power consumption occurs at the DC output voltage of half of the power supply voltage. The loss of the exchange signal is lower. Application announcement AB-039 (SBOA022), the power amplifier stress and power processing limit, explains how to calculate or measure the power consumption of abnormal signals and loads.

Any trend of starting the heat protection circuit indicates that the power consumption is too large or insufficient heat dissipation. For reliable operation, the highest knot temperature should be limited at 150 ° C. In order to estimate the safety of the full design, please increase the ambient temperature until the thermal protection is triggered at 160 ° C. Thermal protection should be triggered above 35 ° C above the maximum expected environmental conditions.

PowerPad thermal enhancement package

OPA357 uses so8powerPad packaging, which is a standard -enhanced standard size IC packaging, which aims to eliminate bulky heat sinks and plugs used in traditional heat packaging. This package can easily install the standard PCB assembly technology.

The design of PowerPad packaging makes the lead frame mold pad (or hot pad) exposed to the bottom of the IC, as shown in Figure 10. This provides a very low thermal resistance (JC) path between the mold and the outside of the packaging. The thermal pad at the bottom of the integrated circuit is directly welded to the PCB and uses PCB as a heat sink. In addition, the electroplated hole (over -perforated) provides a low thermal heating runner on the back of the PCB.

PowerPad assembly process

1. The power board must be connected to the maximum negative power supply voltage of the device. In the application of a single power supply, the voltage will be grounded. The voltage will be grounded in the split power supply application.

2. Prepare PCB with the top etched pattern, as shown in Figure 11. According to the specific assembly process requirements, the specific ground design may be different. Both wires and thermal pads should be etched.

3. Place a recommended number of electroplating pores (or heating holes) in the hot pad area. The diameter of these holes should be 13 dense ears. They remain very small, so that during the return welding, it is not a problem with the welded core of the hole. The minimum recommended hole of the SO-8powerPad package is 5, as shown in Figure 11.

4. Suggestions (but not required) Put a small amount of extra holes under the package and outside the hot pad area. These holes provide additional thermal channels between copper thermal pads and ground floors. They may be bigger because they are not in areas that need welding, so core suction is not a problem. As shown in Figure 11.

5. Connect all holes (including holes in the hot pad area and outside the pad area) to internal ground plane or other internal copper planes (for single power supply), and connect to V Upper (for divisionSinic power application).

6. When arranging these holes, do not use a typical Webor Spoke Via connection method, as shown in Figure 12.The network connection has a high thermal resistance connection, which helps to slow the heat transfer during the welding process.This makes welding more easily with holes with ground plane.However, in this application, low thermal resistance is the most effective heat transfer requirement.Therefore, the holes under the PowerPad component should be connected to the internal ground plane and a complete connection around the entire electroplated hole.

7. The welding mask at the top should expose the pads and the thermal pads area.The hot pad area should be exposed with 13 dense ears.The large holes outside the thermal pad can be covered with welding molding.

8. Apply hot welding balm on all exposed pad areas and all pads.

9. With these preparation steps, PowerPad ICIS can simply place it in place, and complete the welding back welding operation like any standard surface installation component.This will cause the parts to be installed correctly.