説明

The LT1014 is the first precision quad operational amplifier which directly upgrades designs in the industry standard 14-pin DIP LM324/LM348/OP-11/4156 pin configuration. It is no longer necessary to compromise specifications, while saving board space and cost, as compared to single operational amplifiers. The LT1014’s low offset voltage of 50µV, drift of 0.3µV/°C, offset current of 0.15nA, gain of 8 million, common mode rejection of 117dB and power supply rejection of 120dB qualify it as four truly precision operational amplifiers. Particularly important is the low offset voltage, since no offset null terminals are provided in the quad configuration. Although supply current is only 350µA per amplifier, a new output stage design sources and sinks in excess of 20mA of load current, while retaining high voltage gain.

 

特徴

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

 

アプリケーション

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

 

アプリケーション情報

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. a)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.

Comparator Applications

The single supply operation of the LT1013/LT1014 lends itself to its use as a precision comparator with TTL compatible output: In systems using both op amps and comparators, the LT1013/LT1014 can perform multiple duties; for example, on the LT1014, two of the devices can be used as op amps and the other two as comparators.