Datasheet LT1259, LT1260 (Analog Devices) - 8

LT1259/LT1260
U U W U APPLICATIO S I FOR ATIO
The input slew rate of the LT1259/LT1260 is approxi- looks like a 4.4pF capacitor in parallel with a 75k resistor, mately 270V/µs and is set by internal currents and capaci- excluding feedback resistor effects. These amplifiers are tances. The output slew rate is set by the value of the designed to operate with open drain logic: the EN pins have feedback resistors and internal capacitances. At a gain of internal pullups and the amplifiers draw zero current when 10 with at 1k feedback resistor and ±15V supplies, the these pins are high. To activate an amplifier, its EN pin is output slew rate is typically 1600V/µs. Larger feedback pulled to ground (or at least 2V below the positive supply). resistors will reduce the slew rate as will lower supply The enable pin current is approximately 60µA when voltages, similar to the way the bandwidth is reduced. activated. Input referred switching transients with no input signal applied are only 35mV positive and 80mV The graph of Maximum Undistorted Output vs Frequency negative with R relates the slew rate limitations to sinusoidal input for L = 100Ω. various gains.
Output Switching Transient Large-Signal Transient Response, AV = 2
EN OUTPUT V LT1259/LT1260 • AI03 S = ± 5V RF = RG = 1.6k VIN = 0V RL = 100Ω V LT1259/LT1260 • AI01 S = ±15V RL = 400Ω The enable/disable times are very fast when driven from RF = RG = 1.6k standard 5V logic. The amplifier enables in about 100ns
Large-Signal Transient Response, AV = 10
(50% point to 50% point) while operating on ±5V sup- plies. Likewise the disable time is approximately 40ns (50% point to 50% point) or 75ns to 90% of the final value. The output decay time is set by the output capaci- tance and load resistor.
Amplifier Enable Time, AV = 10
OUTPUT V LT1259/LT1260 • AI02 EN S = ±15V RG = 110Ω RF = 1k RL = 400Ω
Enable/Disable
The LT1259/LT1260 amplifiers have a unique high imped- ance, zero supply current mode which is controlled by V LT1259/LT1260 • AI04 R R independent EN pins. When disabled, an amplifier output S = ±5V F = 1k L = 150Ω VIN = 0.1V RG = 110Ω 8