Features

1LMH6570 is a high -performance simulation device 500 MHz, 500 MVPP, 3 dB bandwidth, AV u003d 2 is a multi -way reused device with professional -level video optimization 400 MHz, 2VPP 2VPP , 3 DB bandwidth, AV u003d 2 and other high -fidelity, high bandwidth simulation 8 NS channel switching time applications. The output amplifier selects a sel -based 10 MHz buffer input signal from the two options. LMH6570 at 0.02%, 0.05 ° differential gain, differential phase 2-VPP output signal level. Multimedia and high school applications for 150 MHz HD TV (HDTV), 0.1 DB gain flatness can benefit from the V/μS conversion rate of the 0.1-DB bandwidth of 150 MHz and the conversion rate of 2200 V/μS-LMH6570. Wide -power supply voltage range: 6 V (± 3 V) to 12 V (± 6 V), LMH6570 supports composite video applications 68 DB HD2@5 MHz, 0.02%and 0.05 ° Differential gain gain and phase driver video appear The wrong NTSC and NTPAL signals

84 DB HD3@5 MM

A single -ending 75Ω load. 80 mAh linear

The current drive video output that can be used for multiple applications.

Video router LMH6570 gain from external feedback and

multiple input video monitor gain setting resistance to maximize the flexibility.

Instrument/testing equipment LMH6570 can be used for 8 -needle SOIC

The frequency distribution package in the receiver.

Multi -channel A/D drive

Painting video switch in the painting

Electric characteristics ± 5V

vs u003d ± 5 v, RL u003d 100Ω, RF u003d 576 , AV u003d 2 V/V, TJ u003d 25 ° C, unless there are other regulations.

(1) The value of the electrical meter is only applicable to the factory testing conditions at the specified temperature. Factory test conditions cause limited self -heating of the equipment, so that TJ u003d TA. In the electrical meter, the parameter performance specifications are specified in the internal heating conditions of TJ gt; TA. For information about the temperature drop of this device, see the heat information. The minimum/maximum rated value is based on product testing, characteristics and simulation. Test a single parameter according to the instructions.

(2) In the working temperature range of 100 ° C, the number of statistical relationships is used to ensure more than 25%of the mass control (SQC) method.

(3) Typical numbers are the mostPossible parameter specifications.

(4) Design guarantee parameters.

(5) The rotation rate is the average value of the rising and down and down edges.

(6) Disposal with a certain temperature changes determined by total temperature changes with parameters at extreme temperatures.

(7) The current is the current entering the device

Electric characteristics ± 5V (continued)

vs u003d ± 5 v, rl u003d 100Ω, RF u003d 576 , AV u003d 2 V/V, TJ u003d 25 ° C, unless there are other regulations.

(8) The maximum output current (iOUT) is determined by the power consumption limit of the device (the knot temperature cannot be allowed to exceed 150 ° C). For details, see power consumption. The short -circuit status should be limited to 5 seconds or shorter.

Typical performance features

vs u003d ± 5 v, RL u003d 100 , AV u003d 2, RF u003d RG u003d 576 unless there are other regulations.

Application information

The LMH6570 is a high -speed 2: 1 simulation multi -way relics, which is optimized for very high speed and low distortion. With the optional gain and excellent communication performance, the LMH6570 is very suitable for switching high -resolution and demonstration of video signals. LMH6570 has no internal grounding reference. Both configurations are possible for a single or dividend, but all logic functions are referenced to the intermediate supply point. This LMH6570 has very high channel switching and disable time. When disabled, the LMH6570 output is possible to expand MUX expansion through multiple devices. See the extension of the multi -way reuse. This LMH6570 SEL defaults to low logic (IN0 activation). The default state of the SD pin is also low (the device has been enabled). If the default state is needed, both tube feet can be kept floating.

Video performance

LMH6570 is designed in a variety of formats, such as HD TV and high -resolution VGA. The rear end load will get the best performance. The back terminal reduces the reflection from the transmission line and effectively blocks the transmission line and other parasitic capacitors from the amplifier output stage. Figure 25 shows the configuration of a typical driver 75Ω cable. The output buffer is configured to the gain to 2, so the termination of the load after use will make the net gain to 1.

Typical application (continued)

LMH6570 with current feedback output buffer, its gainDetermine the resistor (RG) from external feedback (RF) and gain settings. For current feedback amplifiers, the closed -loop frequency response is a function of radio frequency. In order to gain 2 V/V, it is recommended that the RF value is 576 For other income, see Figure 26. Generally, reducing Radio frequency to respond and extend the bandwidth of the peak frequency from the recommended value. At the same time, increasing the RF value will make the frequency response faster attenuation. Reducing the RF value to the recommended value will cause over pumping, ringing and final oscillation. Because all applications are slightly different, it is necessary to conduct some experiments to find the best RF circuit under a given condition. For more information, please refer to the current feedback circuit gain analysis and performance enhancement. The application description OA-13 (SNOA366) describes the response of the current feedback amplifier between the relationship between the current and closed frequency frequency. The impedance of needle 8 is about 20 This makes the gain with a good bandwidth when the gain is as high as 10V/V. When used with gains over 10V/V, LMH6570 will show a ""gain bandwidth product"" similar to typical voltage feedback amplifiers. The gain exceeding 10 V/V Consider Choose a high -performance video amplifier like LMH6720 to provide additional gain.

Typical application (continued)

Multi -path reuse extension

You can use multiple LMH6570 devices to expand the number of inputs used for output.

FIG. 27 shows 4: 1 MUX using two LMH6570 devices.

In this application, the output stability may be longer than the LMH6570 switch specification (~ 20 ns), when switching between two separate LMH6570 devices. The switch time limit factor occurs at LMH6570, and the other uses SD (shutdown) pins to open. The time required for the output stability time from the first LMH6570 to enter the high impedance state plus the second LMH6570 output to consume the remaining output charge of the first device (the ability to limit the second device by the output current) and reach the final voltage to reach the final voltage The time required.

Typical application (continued)

Although Figure 27 MUX expansion benefits more isolation, stems from the parasitic load that has not selected channels on the selection channel, and each multi -way reusrator is performed by each multi -way reuseder The separate routing on the output, but the configuration does not generate the fastest conversion between a single LMH6570 device. Quickly transition between the LMH6570 device, and the configuration of FIG. 28 can be used for the LMH6570 output pins.

Typical application (continued)

FIG. 29 shows a typical conversion waveform, and the SD tube feet are displayed. The switch stabilizes within a time of less than 145 nan seconds.

If in the final application, make sure that no two inputs presented to the output at the same time are important optional shutdown time blocks, you can add a delay of a driving pin. Figure 30 shows a possible way for this delay circuit. The delayed circuit shown will delay H to L's shutdown conversion (R1 but will not delay the transition of L to H. Compared with R1, R2 should be kept smaller to reduce the shutdown voltage, so that the shutdown delay is small or there is no delay. .

Typical application (continued)

Close the tube foot to enter the high impedance state, several LMH6570 devices can be connected together to form a larger larger Enter MUX. However, due to the unexplained device. The circuit in FIG. 31 shows how to compensate this effect. For the 8: 1 MUX function as shown in Figure 31, the gain error is about 0.7%or 0.06db . In the circuit in FIG. 31, the resistance ratio has been adjusted to compensate for this gain error. By adjusting the gain of each multi -road reuse circuit, it can be reduced to the tolerance of the resistor used (1%in this example). [123 123). ]

Note

When performing this operation, it is not recommended to use EN pins to disable the LMH6570 multiplex reinstalizer extension. When disabled, if the selected input and chip output More than about 2 volts, the device will begin to enter a soft faulty country. This will be displayed as a reduction in the input and output isolation. The signal of the output drive amplifier input will be leaked to the inverse input and then outputs it by feedback resistance. The worst case is the worst case. It is the voltage of the inverter input of the input buffer in the input buffer of the activity in the input class of 1 non -reverse input. This solution is to use the shutdown mode for multi -road replica.

Other applications

LMH6570 can support double antenna receivers with two physical separation antennas. When monitoring is detected, the signal strength of the active antenna and switch to another antenna are a simple method to achieve spatial diversity. This method increases the average signal intensity of about 3dB, and is the expensive method of the smallest combination signal.

Typical application (continued)

Drive capacitance load

The capacitance output load application will benefit from the use of series output resistance pathways. Figure 32 Display the output of the amplifier under the capacitor load using a series of output resistance rout. The load of 5 to 120 PF of the capacitance is the most critical, which will cause ringing, frequency response to peak and possible oscillations. FIG. 33 gives the recommendation value to select the series output resistors to reduce the capacitance load. The value of the recommended value in this chart response to the peak of 0.5 dB or lower. This generates a good compromise between stable time and bandwidth. Suitable for the maximum frequency response is that when the required, some peaks can be accommodatedForbearance, ROUT's value can be slightly reduced on the basis of the proposed value.

ESD protection

The electrostatic discharge on all LM6570 pins is protected. LMH6570 will survive human models and 200V machine model events at 2000-V. Under normal operation, the ESD diode cannot afford the performance of the circuit performance. However, in some cases, static discharge diode will be obvious. If the LMH6570 is driven by the device, the ESD diode will be turned on. The flowing current passes through the ESD diode, either leaves the chip through the power pins or flows through the device. Therefore, a large signal is applied to the input foot to power the chip. The use of shutdown mode is one of the ways to save electricity and prevent accidents.

Power suggestion

Power consumption

LMH6570 has achieved maximum speed and performance optimization packaging under the small size and size of the standard SOIC. In order to ensure the maximum output driver and maximum performance, the heat shutdown is not provided. Therefore, the most important thing is to ensure that the total power does not exceed TJMAX dissipation. Determine the maximum power consumption of LMH6570 according to the following steps:

1. Calculate static (empty) power: pamp u003d ICC*(comparison),

vs u003d v+-v-negative electrode

2. Calculating the balance of the output level consumption: PD (RMS) u003d the average square root (vs-vout*iOut)

VOUT and IOUT are the voltage that pass

] The current and VS of the external load are the total power supply voltage

3. Calculate the total RMS power: PT u003d PAMP+PD (3)

LMH6570 packaged at a given temperature to disperse energy consumption at a given temperature. The maximum power can be used below: PMAX u003d (150 ° – TAMB)/Rθja

tamb u003d ambient temperature (° C)

rθja u003d given packaging from the thermal resistance from the end to the environment ( ° C/W)

For SOIC packaging, RθJA is 150 ° C/W

layout

layout guide

Except the grounding and power layer near the input and output pin. For long signal paths, the controlling impedance line should be used and both ends of the impedance matching components. The barrier capacitors should be as close to the device as possible. Each bypass capacitors are applied to the ground. The larger electrolytic bypass container can be placed in a smaller and smaller ceramic capacitor should be placed as close to the device as much as possible. In Figure 25, the capacitors between V+and V-are optional, but it is recommended for the best secondary harmonic distortion. Another way to improve performance is to use it for each power supply0.01 μF and 0.1 μF ceramic capacitors bypass.