Feature

● Ultra -low offset voltage: 10 μV

● Ultra -low drift: ± 0.1 μV/° C

123] ● High -co -model suppression: 140db

● High power suppression: 130db

● Low bias current: maximum 1NA

● The power supply range is wide: ± 2V to ± 18V

● Low static current: 800 μA/amplifier

● Single, double and four versions

● Replace OP-07, OP-77, OP-177 [123 [123 ]

Application

● Sensor amplifier

● Bridge amplifier

● Temperature measurement

● Resistance amplifier

● Precision Points

● Battery power supply instrument

● Test equipment

Instructions

OPA277 series precision computing amplifier replaced the industry standard OP-177. They provide improved noise, wider output voltage swing, and twice the speed of static current. Features include ultra -low -imbalance voltage and drift, low bias current, high -co -model suppression, and high power suppression. Single, double and four versions have the same specifications to achieve the maximum design flexibility.

The OPA277 series operator works in the range of ± 2V to ± 18V with excellent performance. Different from most of the operational amplifiers specified at a power supply voltage, the OPA277 series is designed for practical applications; there is a single limit within the range of the power supply range of ± 5V to ± 15V. When the amplifier swings to the specified limit, it can still maintain high performance. Because the initial offset voltage (maximum ± 20 μV) is very low, user adjustment is usually not required. However, a single version (OPA277) provides external decoration for special applications.

OPA277 operational amplifier is easy to use, and there is no phase reversal and overload problem found in other computing amplifiers. They are stable in unit gain and provide good dynamic performance under extensive load conditions. The characteristics of the dual and four -way versions are completely independent circuits to reduce the interaction of string disturbance and freedom, even at speeding or overload.

single (OPA277) and double (OPA2277) versions include DIP-8, SO-8 and DFN-8 (4mm x 4mm) packages. Quad (OPA4277) uses DIP-14 and SO-14 surface installation components. All devices are completely stipulated between -40 ° C to+85 ° C, and run at -55 ° C to+125 ° C.

Pipe instructions

Typical features

TA u003d+25 ° C, vs u003d ± 15V, RL u003d 2K There are explanations.

Application information OPA277 series is the unit gain stable, there is no no The unexpected output phase reverses, making it easy to use in widespread application. In the application of noise or high impedance power supply, decoupling capacitors that are close to the device pins may be needed. In most cases, 0.1 μF capacitors are enough.

The OPA277 series has very low offset voltage and drift. In order to achieve the best performance, the circuit layout and mechanical conditions should be optimized. The bias voltage and drift can be reduced by the small thermal potential of the input end of the amplifier. The connection of heterogeneous metals will generate thermal power, which reduces the final performance of the OPA277 series. By ensuring that the thermal power of the two inputs is equal, these thermal potential can be eliminated.

keep the thermal quality connected to the two input terminals is similar.

The thermal source should stay away from the key input circuit as much as possible.

Shielding the computing amplifier and input circuit to prevent it from the impact of airflows such as cooling fans.

Working voltage

OPA277 series operator works in the range of ± 2V to ± 18V voltage range, with excellent performance. Different from most of the operational amplifiers specified at a power supply voltage, the OPA277 series is designed for practical applications; there is a single limit within the range of the power supply range of ± 5V to ± 15V. This makes customers working under VS u003d ± 10V voltage have the same reliable performance as customers using ± 15V power supply. In addition, the key parameters are within the specified temperature range, that is, -40 ° C to+85 ° C. In the entire operating voltage range (± 2V to ± 18V), most of the performance remains unchanged. The typical performance curve shows parameters with significant changes in operating voltage or temperature.

Adjustment of offset voltage

OPA277 series is a very low offset voltage and drift of laser fine -tuning, so most circuits will not require external adjustment. However, the bias voltage is fine -tuned on the pin 1 and 8. As shown in Figure 1, the offset voltage can be adjusted by the connection potential meter. This adjustment can only be used to make the operational amplifier's offset to zero. This adjustment is not used in other places in the compensation system, because this may cause additional temperature drift.

Input protection

The input of the OPA277 series is 1K Series input resistors and diode clamps protection. The input can withstand the ± 30V differential input without damage. Of course, when the input terminal is excessively driven, the diode will be transmitted. This may interfere with the rotation of the unit gain of the follower, but it will not damage the operational amplifier.

Input bias current eliminates

The input -level base current of the OPA277 series is over an equal and opposite offset circuit for internal compensation. The input bias current is the difference between the input -level base current and the difference to the anti -current current. The remaining input bias current can be positive or negative.

When the bias current is eliminated in this way, the amplitude of the input bias current and the input bias current is roughly the same. Therefore, there is no need to use bias current to eliminate the resistor like other computing amplifiers (Figure 2). The increase in resistance to eliminate the input bias current error may actually increase the bias voltage and noise.

OPA277 series uses 8 -lead DFN (also known as SON). This is a QFN package, only There are contacts on both sides of the package. This lead -free, closer to the chip size packaging to maximize the space of the circuit board, and enhances thermal characteristics and electrical characteristics through a bare pad.

DFN packaging volume is small, the wiring area is small, the thermal performance is improved, the power performance is improved, and the pins are consistent with other commonly used packaging (such as SO and MSOP). In addition, there is no external lead to eliminate the problem of bending.

DFN packaging can be easily installed with standard printing circuit board (PCB) assembly technology. See application description, QFN/SON PCB attachment (SLUA271) and application reports, QUAD FLATPACK No Drawing Logic encapsulation (SCBA017).

The exposed lead frame mold pad at the bottom of the packaging should be connected to V -.

Layout Guide

The leading frame mold pad should be welded on the PCB hot pad. The mechanical drawings at the end of this data table list the physical dimensions of packaging and pads.

In temperature circulation, keys, packaging cutting, and similar board tests, welded exposed pads have significantly improved board -level reliability. Even in low -power applications, bare pads must be welded to PCB to provide structural integrity and long -term reliability.