Features

140MHz Bandwidth: AV u003d 2, RL u003d 150 1100V/μs conversion rate

Low cost

30mA output drive current [ 123]

0.01%Differential gain

0.01 ° Differential phase

High input impedance: 14m , 3pf

The range of power is wide: ± 2V to ± 15V

Shipping mode: IS LT; 250 μA low power current: IS u003d 10mA

Input a common mode in the range of power 1.5V

Output swing within the range of 0.8V [123 ]

Application

Video amplifier

Cable drive

RGB amplifier

Test equipment amplifier

Drive mixer 50 #8486 The buffer

Instructions

LT1227 is a wide -band wide and excellent video feature. Differential gains and phase, wide band wide, 30mA output drive current makes the LT1227 very suitable for cables in the video system. The shutdown function switches the device to high impedance and low current mode, allowing multiple devices to connect parallel and be selected. When the input amplitude increases, when 10MHz is 10MHz, the input and output isolation at the time of stopping is 70db to 10VP-P. Turn off the pins to connect to the open circuit or the leakage logic of the road, and only 4μs is required to enable or disable. LT1227 uses industry standard pins and the performance of many old products can be upgraded. For dual or quadruple versions, please refer to the introduction of the LT1229/1230 product introduction. LT1227 uses linear technology to manufacture patent complementary bipolar processes.

Major value

Power supply voltage ± 18 volts

Input current ± 15 mAh

output short -circuit duration (Note 1) continuous [ 123]

Work temperature range

LT1227C 0 ° C to 70 ° C

LT1227 meters –55 ° C to 125 ° C

Storage temperature range –65 ° –65 ° C to 150 ° C

Jacking temperature

Plastic packaging 150 degrees Celsius

Ceramic packaging 175 degrees Celsius

Lead temperature (welding, 10 seconds) 300 degrees Celsius [ 123]

Electric characteristics vcm u003d 0, ± 5V ≤VS ≤ ± 15V, pulse test, unless there is another instructions

Electric characteristics VCM u003d 0, ± 5V ≤VS ≤ ± 15V, pulse test, unless there is another instructions.

indicates the scope of standardized work temperature.

Note 1: Depending on the power supply, the radiator voltage may be required.

Note 2: LT1227's power current is negative temperature coefficient. For details, see the typical performance characteristic curve.

Note 3: When measuring IS, reduce the voltage of the needle 8 from 15V. When did you fall to less than 0.5mA and measure the needle 8 current.

Note 4: On the ± 10V output signal, the measurement return rate at ± 5V is working on the ± 15V power supply, RF u003d 2K, RG u003d 220 , RL u003d 400

Note 5: AC parameters perform 100%test packaging parts (suffix J and N) on ceramic and plastic impretions and perform sample test packaging parts (suffix) on each batch of SOs.

Note 6: NTSC composite video, the output level is 2V.

典型性能特征

[123 ] LT1227 is a very fast current feedback amplifier. Because it is a current feedback amplifier, the bandwidth maintains the voltage gain in a large range. This amplifier is designed to drive low impedance loads, such as good linear cables under high frequency. Feedback resistance selects the small signal bandwidth of the LT1227 from external feedback resistors and internal knot capacitors. Therefore, the bandwidth is the power supply voltage, the closed ring gain of the feedback resistor and the load resistance. The relationship between the characteristic bandwidth and the power supply voltage shows the heavy load (100 ) and the light load (1K). When the response of these curves is less than 0.5DB, the use line should be used as 0.5db to 5DB. The curve stops at the peak of the response exceeding 5DB. When the gain is 2, ON ± 15V provides a 1K feedback resistor, and the bandwidth of the light load exceeds 140MHz, but under the negative load, the bandwidth will be reduced to 120MHz. Because there is a slight resonance at the output level, the light load is improved, but its Q value decreases due to heavy load. This enhancement is only useful when the low -gain settlement; it cannot increase the bandwidth at gain. The enhancement at the increase in Unity is so effective that the feedback value resistance is very small. In a very high closed -loop gain, the bandwidth is limited to about 1GHz with the width of the bandwidth. The curve shows that when the closed -loop gain is 100, the bandwidth is 12MHz, only twice the income of only one tenth.

Reverse input capacitance

current feedback amplifier needsThe resistance feedback from the output to the inverter input is stable. Pay attention to minimize the output and inverter input. The reverse input to the ground capacitance will cause the frequency peak response (and overwhelming in the transient response), but it will not reduce the stability of the amplifier. The capacitance load is used as an appropriate feedback resistance value. The maximum capacitor load VS feedback resistance is used to select appropriate values. The display value is 5DB peak when the value of 2 is driven by 2. This is the worst case, a higher gain and heavier load in the amplifier. Alternatively, the output output of the A small resistor (10 to 20 ) can beolate the capacitance load from the amplifier with the amplifier. The advantage of this is that only when there is a capacitance load, the bandwidth of the amplifier will reduce the disadvantage is that gain is the function of the load.

Power supply

LT1227 will use a single power supply or split power supply ± 2V (total 4V) to ± 15V (total 30V). There is no need to use the equivalent division power supply, but the offset voltage inverter input bias current will also change. The offset voltage changes do not match the power supply of about 500 μV/V. The reverse bias current can change the loss of each voltage to 5.0 μA, but the general change is usually less than 0.5 μA/V. The conversion rate of the conversion rate current feedback amplifier is not independent of the amplifier gain configuration. The conversion rate is in the traditional operational amplifier. This is because the input and output levels have a transition rate limit. In the reversal mode, for higher gain in non -vertical mode, the signal amplitude between the input pin is small, and the entire conversion rate is output. The entire conversion rate of the gain of less than 10 under non -turning mode is limited by the input level. The input level conversion rate of LT1227 is about 125V/μs, which is set by internal current and capacitance. The output conversion rate is set by the feedback value setting resistance and internal capacitors. Use a 1K feedback resistor and ± 15V power supply at a different point, and the output conversion rate is usually 1100V/μs. The feedback resistance will reduce the conversion rate and reduce the power supply voltage, similar to the way of reducing bandwidth. The relationship between the maximum distorted output and the frequency will limit the conversion rate restrictions with various gain configurations associated with sine input.

Settlement time Feature curve display LT1227 amplifier is within 40ns to 55ns. In any case, at the final value, the final value The final output voltage value of 1 millival to 10 millivoltage within the 10mv range indicates that there is a slower heat contribution to the output and input level. The output is only 300 micro voltage per voltage changes per volt output change and input voltage below 1mV. Fortunately, the input heat tends to offset output heat. For this is the inferiority of the irreversible gain to 1 of the two configurations.

Close

LT1227 has a mode of high impedance, low power current controlled by the pin 8 control. Turn offIn the mode, the output looks like a 12PF capacitor and power current dropped to about 8 foot currents. This shutdown pin refers to the internal pull circuit inside the positive power supply (see simplified schematic diagram). Unplug the current from needle 8 to get the device into the shutdown mode. A simple compulsory method uses an open drainage pipe (collector) to the ground logic of the power cord 8. Because the pin refers to the positive power supply, the logic used should have a higher breakdown voltage instead of a positive power supply voltage. Without other circuits, as an internal JFET, the current of the pin 8 must be limited to about 100 μA. When the pin 8 is opened, the LT1227 work is normal.

Differential input signal switching

Differential input swing is limited to about ± 6V ESD protection device connected between the input end. When running normally, the voltage difference input pin is small, so this fixture has no effect; however, in the shutdown mode, the differential rotation can be the same as the input swing. Then set the maximum allowable input voltage to set the clamp voltage. Considering some margin, it is recommended to enter the signal that is smaller and greater than ± 5V when the device is closed. The offset adjustment pin 1 and 5 are used for bias zero. Small current to V+or ground will compensate the device. These pins are related to the positive power supply (see the simplified schematic diagram). If it is not used, it should be kept open. The offset adjustment mainly acts on the reversal input bias current. The connection to a 10K cans connected to No. 1 and 5 stitches to V+will make the bias current zero, but it will not have much effect on the offset voltage. From the output, the offset is VO #8773; AVVOS+(IIN-) radio frequency at a high gain (AV GT; 5), VOS items will dominate. In the VOS term, a 10K jar is used between the 1st and 5th needles from the wiper to the ground 150K resistor. It is used for 15V to connect the power supply, and 47K is used for 5V split power supply.

Typical application

Multi -road amplifier

The closing function can be effectively used to form a multi -path reuse amplifier. Display dual -channel versions, but you can add more inputs with appropriate logic. By configured each amplifier into a unit gain follower as the amplifier, it is closed when the amplifier is not loaded by the feedback network. 74C906 buffer's bright canal is used to connect 5V logic to the stop pin. The input of the feed that has never been selected to the output at -70db10 MMH. The differential voltage between the MUX input VIN1 is displayed in the VIN2 device in the input end of the shutdown. This voltage should be less than ± 5V to avoid opening the diode discussed before. If the input is sine, the DC level is zero, which means that the amplitude of each input should be less than 5VP-P. The output resistance of the off-cutting amplifier is kept unchanged until the output level exceeds about 6VP-P10MHz, and the maximum available output level is set. Without external devices, the switching time between the input is about 4 μs. Add a 10K pull -up power to V every time you shut down to V+Will shorten the switching time to 2 μs, but increase the positive power current by 1.5mA

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