LT1195 UUWUAPPLICATIO S I FOR ATIOOutput ShutdownSingle 5V Video Amplifier VIN 10µF 5V 5V 1k 3 + 7 1000µF 6 75Ω LT1195 2 R1 – 4 RFB 3k 10k 75Ω RG 1k 1k 1195 AI05 R2 100µF 2k 1MHz SINE WAVE GATED OFF WITH SHUTDOWN PIN AV = 1, RL = 1k 1195 AI04 Video Multiburst at Pin 6 of AmplifierDetecting Pulses The front page shows a circuit for detecting very fast pulses. In this open-loop design, the detector diode is D1 3V and a level shifting or compensating diode is D2. A load resistor RL is connected to –5V, and an identical bias 2V resistor RB is used to bias the compensating diode. Equal value resistors ensure that the diode drops are equal. A very fast pulse will exceed the amplifier slew rate and 1V cause a long overload recovery time. Some amount of dV/dt limiting on the input can help this overload condi- 0V tion, however too much will delay the response. Also 1195 AI06 shown is the response to a 4VP-P input that is 150ns wide. The maximum output slew rate in the photo is 30V/µs. This rate is set by the 30mA current limit driving 1000pF. Vector Plot of Standard Color BurstOperation on Single 5V Supply The LT1195 has been optimized for a single 5V supply. This circuit amplifies standard composite video (1VP-P including sync) by 2 and drives a double-terminated 75Ω cable. Resistors R1 and R2 bias the amplifier at 2V, allowing the sync pulses to stay within the common mode range of the amplifier. Large coupling capacitors are required to pass the low frequency sidebands of the composite signal. A multiburst response and vector plot standard color burst are shown. 1195 AI07 1195fa 9
