Features

Outstanding video performance

Internal gain: 6DB

2 pole constant constructor

arcting correction

reduce the size of the coupling electric container size

The input range includes ground

DC coupling input

Integrated integration The level converter

DC coupling output (1)

no output capacitor

Rail -to -rail infusion

Low static current: 6mA

]

Single power supply: 2.7V to 3.3V

SC70-6 Packaging: 2.0mm x 2.1mm [123 123 [123 ]

(1), internal circuits prevent output saturation, even if the 0V synchronization prompt level of the 0V of the video signal is entered. Application

Digital camera

Phone

[ 123]

The set -top box video filter Related low -voltage video amplifier

Instructions

OPA360 high -speed amplifier is for 3V portable video application is optimized. It is specifically designed to be compatible with digital modulus (DAC) that is embedded in video processors, such as the digital media processor series of Texas Instruments. The input common modular range includes GND, which allows video DAC to couple to OPA360.

Standard video load (150 ) output at the ground end of the ground is swinging between 25 millivolves and 300 millivolttile to V+. Internal level offset circuits prevent output and 0V input saturation, thereby preventing synchronous pulse waves in ordinary video circuits. Therefore, OPA360 is very suitable for DC coupling of video load. If the communication coupling is the first choice, the OPA360 provides a vertical correction function, which can significantly reduce the infusionDimensions of coupled packet containers.

OPA360 sets up resistance (G u003d 2) and 2 polar video DAC reconstruction filters through integrated depression correction, internal gain, and 2 polar video DAC reconstruction filters, which is optimized for space -sensitive applications.

In the shutdown mode, the static current dropped to lt; 5μA, significantly reduced power consumption and extend the battery life.

OPA360 has 2 mm x 2.1 mm SC70-6 miniature packaging.

pin configuration

(1). To determine, as shown in the figure.

Typical features: vs u003d 3.3V

TA u003d+25 ° C and RL u003d 150

Application information

OPA360 video amplifier optimized for portable video applications:

Internal gain setting resistance (g u003d 2) reduces the number of external components required in the video circuit.

Use 2 pole filter for DAC signal reconstruction.

The vertical correction function can reduce the size of the output coupling container without affecting performance.

OPA360 uses internal level conversion circuits to avoid synchronous pulse wave waves and allow DC coupling output.

The shutdown function can reduce the static current to less than 5μA, which is essential for portable applications such as digital cameras (DSC) and photo mobile phones.

OPA360 interface digital media processor (DM320/270, DSC25). It has optimized the requirements of digital cameras and mobile phone/camera design.

Working voltage

OPA360 is completely specified in the temperature range of 40 ° C to+85 ° C from 2.7V to 3.3V. The typical feature shows the parameters of significantly changes with the working voltage or temperature.

Power insertion should be bypass with 100NF ceramic capacitors.

The input voltage

The input consensus range of the OPA360 series is expanded from GND to (V+ 1.5V). Due to internal gain, the input voltage range required for the output within the effective range will be limited.

Enter overvoltage protection

All OPA360 pins are used for electrostatic protection with internal ESD protection diode connected to the power supply. If the current is limited to 10mA, these diode will provide input -driven protection.

Enable/close

OPA360 has a closed function, which can disable output and reduce static current to less than 5μA. This feature is especially useful for portable video applications (such as digital cameras and camera phones), because these devices are rarely connected to TV or other video devices.

Enable the logic input voltage refer to the OPA360 GND pin. The logic level used to enable the grain to enable the operational amplifier high. Effective logic high level is defined as higher than GND ≥ 1.6V. Low effective logic is defined as higher than GND ≤ 0.8V. If the pins are not connected, the internal pull circuit will be enabled to use the amplifier. The effective logic high threshold (minimum 1.6V) and the effective logic low threshold (maximum 0.8V) of the effective logic high threshold (minimum 1.6V).

Internal 2 pole filter

OPA360 filter is a Sallen-Key topology with a 9MHz cut-off frequency. This makes the video signal pass without any visible distortion, as shown in Figure 3 to 5. The video data collection card is embedded in the digital media processor embedded in Texas instruments with a sample frequency of 27MHz. At this frequency, the attenuation is usually 21DB, which effectively attenuates the sampling alias.

Filter characteristics are different from the signal source impedance. The source impedance is greater than 500 it will reduce the performance of the filter. For the current output video DAC, the grounding resistance is usually used to generate voltage output, and then applies to OPA360 input (see Figure 1). TI's digital media processor, such as DM270 or DM320, usually uses a 200 resistance to convert current output signals. This 200Ω source impedance does not reduce video performance.

The capacitor connected to the resistor (Figure 1) generate an additional filter pole, which provides additional resistance attenuation. Without affecting the capacitor 28MHz frequency belt attenuation, a ceramic capacitor at about 28PF is provided attenuation.

Video Performance

Industry standard video test mode includes:

Multiple emergencies of different test frequencies to check the basics Frequency response.

Multi -pulse pulse pulses modulated in different frequencies, which are used to test the comprehensive measurement of the amplitude of the video baseband and group delay error.

color-brightness (CCIR17) -The test vibrationA amplitude, phase, and some distortion.

50Hz, 1/2 black 1/2 white screen test signal test signal swinging in the worst case required for the amplifier. The performance of these test signals is displayed.

FIG. 2 shows the test circuit of Figure 3 to 13 and FIG. (Note: 1 and 2 indicate the bid in the measuring point diagram corresponding to the waveform as 1 and 2.)

The frequency response of OPA360

Frequency response measurement assessment assessment evaluation The video system can uniformly transmit the ability of different frequency signal components without affecting their respective amplitude. Figure 3 shows the multi -pulse test mode; Figure 4 shows multiple pulses. The top waveform in these figures shows a complete test mode. The middle and bottom waveforms are more detailed views of the key part of the complete waveform. The middle waveform represents the input signal of the video generator; the waveform at the bottom is the OPA360 output to the line.

The color of the color and brightness (or the relative color level) is the change of the color and brightness component of the video signal at different frequencies. The common test mode is the pulse in the test mode CCir17, as shown in Figure 5. As shown in Figure 3 and Figure 4, the top waveform displays the complete test mode; the middle and bottom waveforms are a more detailed view of the key part of the complete waveform. The middle waveform represents the input signal of the video generator. Essence

The gain error usually shows the attenuation or peak of the color information. This is displayed in the picture as incorrect color saturation. Delay distortion can cause blurred or bleeding, especially the edge of objects in the picture. It may also lead to poor reproduction of sharp light transition.

All waveforms in FIG. 3 to Figure 5 uses the depression correction characteristics of OPA360. Figure 3 to 5 shows that OPA360 does not cause visible distortion or gain changes in the frequency range of the entire video.

Internal level conversion

Common videos in many embedded digital media processors (such as TMS320DM270 and new OMAP2420 processor) of. Generally, the minimum point of the synchronous pulse output of these video DACs corresponds to 0V. For 0V input, the output of the general single power supply amplifier is saturated under the voltage greater than 0V. This effect will cut the tip of the synchronous pulse to reduce the integrity of the video signal. OPA360 uses internal level conversion circuits to avoid cutting waves. The input signal usually moves about 60 millivolves. This is completely within the linear output voltage range of OPA360, standard 150 video load. Figure 6 shows the function of the level converter.

When the output and video load DC coupling of OPA360, the level offset function is particularly useful. However, it is also helpful when using depression correction. The offset helps to move the video signal near the track, so even a small 33μF coupling capacitor, the output far exceeds the saturation limit of the OPA360. Figure 7 shows the output width of the OPA360. Under the 3.0V power supply, it has 22 μF calibration capacitors and 33 μF output coupling capacitors. The test signal is a 50 Hz signal, which is used to generate 1/2 black 1/2 white screen. This video mode is one of the most difficult models, because it is the worst signal of signal swing. This worst signal is extremely impossible to appear in normal operation. Any other signal has a lower swing range. Please note that in Figure 7, the white parts and black parts of the video signal were not tailored.

output swing to GND (synchronous pulse)

FIG Slightly negative voltage. Even if the output synchronizes is 8mV, the output does not show the cutting wave of synchronous pulses.

Arc Dynamic Correction

The depression correction provides excellent video performance through two small output coupling electric containers. It eliminates the traditional, large 220 μF output capacitor. The traditional 220μF circuit (Figure 9A) generates a single low frequency pole ( 3dB frequency) at 5Hz. If this capacitor is much smaller, excessive phase shifts in the critical range of 50 to 100Hz will generate field tilt, which will interfere with the correct recovery of synchronous signals in the TV receiver.

OPA360 Arc Dynamic Correction Circuit (Figure 9b, see Figure 14) generate an amplitude response in the 20Hz area. The peak (a few of the decibels) of this small part provides compensation for phase response within the critical range of 50 Hz to 100 Hz, which greatly reduces the magnetic field tilt. Please note that there are two obvious and lower -cost capacitors.

In order to obtain good performance, 22 μF depression correction and 47 μF coupling capacitor can be used. Figures 10 and 11 show the comparison of standard video circuits with 220 μF coupling containers and OPA360 corrected with depression.

FIG. 10 shows that the 22μF/47μF combination only causes 50Hz, 1/2 black 1/2 white video signal slightly larger. The quality of the video is decreased.

Using 22μF/67μF combination can achieve a field tilt equivalent-See Figure 11. The capacitors value of these capacitors has not improved significantly by capacitors that are optimized than 22 μF. The smaller arc correction electric container will lead to higher tilt.

The power supply voltage and coupling capacitance

The output voltage switch is a function of the coupling electrical capacity. The value of the curved correction capacitor will only have a small impact. The smaller the coupling capacitor, the larger the output swing. Therefore, in order to adapt to large signal swings in order to use very small coupling capacitors (22 μF and 33 μF), higher power voltage may be required.

As shown in Figure 7, the output of the 33μF coupling container is very close to the saturation limit of 3V power supply. With the change of time and temperature, the value of the capacitor may change slightly, which in turn is forcing the output to reach saturation. Figure 12 and 13 use 50 Hz, 1/2 black 1/2 white screen test signal as the worst case analysis, indicating that the 3V power supply can be used together with a coupled electric container with a coupling of as low as 47 μF.

DC coupling output

Due to the internal level offset, OPA360 can also be coupled to the video load. As shown in Figure 15, there is no need to use AC coupling capacitors on the output end. This is especially important in portable video applications limited by the motherboard space.

DC coupling output configuration also shows the best video performance. Line 16 is not allowed to be allowed to tilt or the power cord that is not allowed to be used. In this mode, the OPA360 will not have a limited limit at a safe running signal at 2.5V voltage.

The disadvantage of DC coupling output is that it uses higher power currents.