Datasheet LT1077 (Analog Devices) - 10
| Manufacturer | Analog Devices |
| Description | Micropower, Single Supply, Precision Op Amp |
| Pages / Page | 16 / 10 — APPLICATIO S I FOR ATIO. Gain 100 Amplifier. Voltage Follower |
| File Format / Size | PDF / 309 Kb |
| Document Language | English |
APPLICATIO S I FOR ATIO. Gain 100 Amplifier. Voltage Follower
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LT1077
U U W U APPLICATIO S I FOR ATIO
resistors.) When the output is high the pull-down resistor Single supply operation can also create difficulties at the draws 80µA which dominates the micropower current input. The driving signal can fall below 0V—inadvertently budget. This situation is much worse in the gain of one or on a transient basis. If the input is more than a few circuit with V–=0V. At 100V common mode, the output has hundred millivolts below ground, two distinct problems to sink 2µA. At a minimum output voltage of 20mV can occur on previous single supply designs, such as the competing devices require a 10k pull-down resistor. As LM124, LM158, OP-20, OP-21, OP-220, OP-221, OP-420 the output now swings to 10V, this resistor draws 1mA of (a and b), OP-90/290/490 (b only): current. a) When the input is more than a diode drop below Since the output of the LT1077 cannot go exactly to ground, unlimited current will flow from the substrate ground, but can only approach ground to within a few (V – terminal) to the input (this can destroy the unit). On the millivolts, care should be exercised to ensure that the LT1077, resistors in series with the input protect the output is not saturated. For example, a 1mV input signal device even when the input is 5V below ground. will cause the amplifier to set up in its linear region in the b) When the input is more than 400mV below ground gain 100 configuration shown below; however, it is not (at 25°C), the input stage saturates and phase reversal enough to make the amplifier function properly in the occurs at the output (this can cause lock-up in servo voltage follower mode. systems). Due to a unique phase reversal protection circuitry, the LT1077’s output does not reverse, as
Gain 100 Amplifier Voltage Follower
illustrated below, even when the input is at – 1.0V. 5V 5V R 99R – – OUTPUT 100mV SATURATED ≈ 3.5mV 1mV + 1mV + LT1077 • AI01
Voltage Follower with Input Exceeding the Negative Common Mode Range (VS = 5V, 0V)
4V 4V 4V 2V 2V 2V 0 0 0 6V 1ms/DIV OP-90 1ms/DIV LT1077 1ms/DIV P-P INPUT –1.0 TO 5.0V EXHIBITS OUTPUT NO PHASE REVERSAL PHASE REVERSAL 1077fa 10
U U W U APPLICATIO S I FOR ATIO
resistors.) When the output is high the pull-down resistor Single supply operation can also create difficulties at the draws 80µA which dominates the micropower current input. The driving signal can fall below 0V—inadvertently budget. This situation is much worse in the gain of one or on a transient basis. If the input is more than a few circuit with V–=0V. At 100V common mode, the output has hundred millivolts below ground, two distinct problems to sink 2µA. At a minimum output voltage of 20mV can occur on previous single supply designs, such as the competing devices require a 10k pull-down resistor. As LM124, LM158, OP-20, OP-21, OP-220, OP-221, OP-420 the output now swings to 10V, this resistor draws 1mA of (a and b), OP-90/290/490 (b only): current. a) When the input is more than a diode drop below Since the output of the LT1077 cannot go exactly to ground, unlimited current will flow from the substrate ground, but can only approach ground to within a few (V – terminal) to the input (this can destroy the unit). On the millivolts, care should be exercised to ensure that the LT1077, resistors in series with the input protect the output is not saturated. For example, a 1mV input signal device even when the input is 5V below ground. will cause the amplifier to set up in its linear region in the b) When the input is more than 400mV below ground gain 100 configuration shown below; however, it is not (at 25°C), the input stage saturates and phase reversal enough to make the amplifier function properly in the occurs at the output (this can cause lock-up in servo voltage follower mode. systems). Due to a unique phase reversal protection circuitry, the LT1077’s output does not reverse, as
Gain 100 Amplifier Voltage Follower
illustrated below, even when the input is at – 1.0V. 5V 5V R 99R – – OUTPUT 100mV SATURATED ≈ 3.5mV 1mV + 1mV + LT1077 • AI01
Voltage Follower with Input Exceeding the Negative Common Mode Range (VS = 5V, 0V)
4V 4V 4V 2V 2V 2V 0 0 0 6V 1ms/DIV OP-90 1ms/DIV LT1077 1ms/DIV P-P INPUT –1.0 TO 5.0V EXHIBITS OUTPUT NO PHASE REVERSAL PHASE REVERSAL 1077fa 10
