Datasheet LT1193 (Analog Devices) - 10
| Hersteller | Analog Devices |
| Beschreibung | Video Difference Amplifier |
| Seiten / Seite | 12 / 10 — APPLICATIO S I FOR ATIO. Using the Shutdown Feature. Driving Capacitive … |
| Dateiformat / Größe | PDF / 448 Kb |
| Dokumentensprache | Englisch |
APPLICATIO S I FOR ATIO. Using the Shutdown Feature. Driving Capacitive Load. Output Shutdown. Murphy Circuits
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LT1193
U U W U APPLICATIO S I FOR ATIO
termination is preferred because reflected energy is ab- isolating the capacitance with 10Ω can be helpful. Precau- sorbed at each end of the cable. When using the double tions primarily have to do with driving large termination technique it is important to note that the signal capacitive loads. is attenuated by a factor of 2, or 6dB. The cable driver has Other precautions include: a – 3dB bandwidth of 80MHz while driving a 150Ω load. 1. Use a ground plane (see Design Note 50, High Fre-
Using the Shutdown Feature
quency Amplifier Evaluation Board). The LT1193 has a unique feature that allows the amplifier 2. Do not use high source impedances. The input capaci- to be shut down for conserving power or for multiplexing tance of 2pF, and RS = 10k for instance, will give an several amplifiers onto a common cable. The amplifier will 8MHz – 3dB bandwidth. shut down by taking Pin 5 to V–. In shutdown, the amplifier 3. PC board socket may reduce stability. dissipates 15mW while maintaining a true high impedance output state of 15kΩ in parallel with the feedback resis- 4. A feedback resistor of 1k or lower reduces the effects of tors. The amplifiers may be connected inverting, nonin- stray capacitance at the inverting input. (For instance, verting or differential for MUX applications. When the closed-loop gain of ±2 can use RFB = 300Ω and output is loaded with as little as 1kΩ from the amplifier’s RG = 300Ω.) feedback resistors, the amplifier shuts off in 200ns. This shutoff can be under the control of HC CMOS operating
Driving Capacitive Load
between 0V and – 5V.
Output Shutdown
tON = 300ns tOFF = 200ns LT1193 • TA14 AV = 2, IN DEMO BOARD, CL = 30pF, RFB = 1k, RG = 1k LT1193 • TA12
Driving Capacitive Load
1MHz SINE WAVE GATED OFF WITH SHUTDOWN PIN, AV = 3, RFB = 1k, RG = 500Ω The ability to maintain shutoff is shown on the curve Shutdown Supply Current vs Temperature in the Typical Performance Characteristics section. At very high el- evated temperatures it is important to hold the SHDN pin close to the negative supply to keep the supply current from increasing.
Murphy Circuits
There are several precautions the user should take when LT1193 • TA15 using the LT1193 in order to realize its full capability. AV = 2, IN DEMO BOARD, CL = 30pF Although the LT1193 can drive a 30pF in gains as low as␣ 2, WITH 10Ω ISOLATING RESISTOR 1193fb 10
U U W U APPLICATIO S I FOR ATIO
termination is preferred because reflected energy is ab- isolating the capacitance with 10Ω can be helpful. Precau- sorbed at each end of the cable. When using the double tions primarily have to do with driving large termination technique it is important to note that the signal capacitive loads. is attenuated by a factor of 2, or 6dB. The cable driver has Other precautions include: a – 3dB bandwidth of 80MHz while driving a 150Ω load. 1. Use a ground plane (see Design Note 50, High Fre-
Using the Shutdown Feature
quency Amplifier Evaluation Board). The LT1193 has a unique feature that allows the amplifier 2. Do not use high source impedances. The input capaci- to be shut down for conserving power or for multiplexing tance of 2pF, and RS = 10k for instance, will give an several amplifiers onto a common cable. The amplifier will 8MHz – 3dB bandwidth. shut down by taking Pin 5 to V–. In shutdown, the amplifier 3. PC board socket may reduce stability. dissipates 15mW while maintaining a true high impedance output state of 15kΩ in parallel with the feedback resis- 4. A feedback resistor of 1k or lower reduces the effects of tors. The amplifiers may be connected inverting, nonin- stray capacitance at the inverting input. (For instance, verting or differential for MUX applications. When the closed-loop gain of ±2 can use RFB = 300Ω and output is loaded with as little as 1kΩ from the amplifier’s RG = 300Ω.) feedback resistors, the amplifier shuts off in 200ns. This shutoff can be under the control of HC CMOS operating
Driving Capacitive Load
between 0V and – 5V.
Output Shutdown
tON = 300ns tOFF = 200ns LT1193 • TA14 AV = 2, IN DEMO BOARD, CL = 30pF, RFB = 1k, RG = 1k LT1193 • TA12
Driving Capacitive Load
1MHz SINE WAVE GATED OFF WITH SHUTDOWN PIN, AV = 3, RFB = 1k, RG = 500Ω The ability to maintain shutoff is shown on the curve Shutdown Supply Current vs Temperature in the Typical Performance Characteristics section. At very high el- evated temperatures it is important to hold the SHDN pin close to the negative supply to keep the supply current from increasing.
Murphy Circuits
There are several precautions the user should take when LT1193 • TA15 using the LT1193 in order to realize its full capability. AV = 2, IN DEMO BOARD, CL = 30pF Although the LT1193 can drive a 30pF in gains as low as␣ 2, WITH 10Ω ISOLATING RESISTOR 1193fb 10