DESCRIPTION

The LT1013 is the first precision dual op amp in the 8-pin industry standard configuration, upgrading the performance of such popular devices as the MC1458/ MC1558, LM158 and OP-221. The LT1013’s specifications are similar to (even somewhat better than) the LT1014’s. Both the LT1013 and LT1014 can be operated off a single 5V power supply: input common mode range includes ground; the output can also swing to within a few millivolts of ground. Crossover distortion, so apparent on previous single-supply designs, is eliminated. A full set of specifications is provided with ±15V and single 5V supplies.

 

FeaTures

Single Supply Operation Input Voltage Range Extends to Ground Output Swings to Ground While Sinking Current

Pin Compatible to 1458 and 324 with Precision Specs

Guaranteed Offset Voltage: 150µV Max

Guaranteed Low Drift: 2µV/°C Max

Guaranteed Offset Current: 0.8nA Max

Guaranteed High Gain  5mA Load Current: 1.5 Million Min 17mA Load Current: 0.8 Million Min

Guaranteed Low Supply Current: 500µA Max

Low Voltage Noise, 0.1Hz to 10Hz: 0.55µVP-P Low Current Noise—Better than 0P-07, 0.07pA/√Hz

 

Applications

Battery-Powered Precision Instrumentation Strain Gauge Signal Conditioners Thermocouple Amplifiers Instrumentation Amplifiers

4mA to 20mA Current Loop Transmitters

Multiple Limit Threshold Detection

Active Filters

Multiple Gain Blocks

 

Informations sur les applications

Single Supply Operation

The LT1013/LT1014 are fully specified for single supply  operation, i.e., when the negative supply is 0V. Input common mode range includes ground; the output swings within a few millivolts of ground. Single supply operation, however, can create special difficulties, both at the input and at the output. The LT1013/LT1014 have specific circuitry which addresses these problems. At the input, the driving signal can fall below 0V—inadvertently or on a transient basis. If the input is more than a few hundred millivolts below ground, two distinct problems can occur on previous single supply designs, such as the LM124, LM158, OP-20, OP-21, OP-220, OP-221, OP-420:

  1. When the input is more than a diode drop below ground, unlimited current will flow from the substrate (V– terminal) to the input. This can destroy the unit. On the LT1013/ LT1014, the 400Ω resistors, in series with the input (see Schematic Diagram), protect the devices even when the input is 5V below ground.
  2. b)When the input is more than 400mV below ground (at 25°C), the input stage saturates (transistors Q3 and Q4) and phase reversal occurs at the output. This can cause lock-up in servo systems. Due to a unique phase reversal protection circuitry (Q21, Q22, Q27, Q28), the LT1013/ LT1014’s outputs do not reverse, as illustrated below, even when the inputs are at –5V. There is one circumstance, however, under which the phase reversal protection circuitry does not function: when the other op amp on the LT1013, or one specific amplifier of the other three on the LT1014, is driven hard into negative saturation at the output. Phase reversal protection does not work on amplifier:

A when D’s output is in negative saturation. B’s and C’s outputs have no effect.

B when C’s output is in negative saturation. A’s and D’s outputs have no effect.

C when B’s output is in negative saturation. A’s and D’s outputs have no effect.

D when A’s output is negative saturation. B’s and C’s outputs have no effect.

At the output, the aforementioned single supply designs either cannot swing to within 600mV of ground (OP-20)  or cannot sink more than a few microamperes while swinging to ground (LM124, LM158). The LT1013/LT1014’s  all-NPN output stage maintains its low output resistance and high gain characteristics until the output is saturated. In dual supply operations, the output stage is crossover distortion-free.