Features

Low offset voltage: 75 μV (maximum)

#8226 ; Low noise: 10 nv/√Hz

Very low 1/f noise

Excellent DC accuracy:

Width voltage range: ± 2 v

Rail transmission: Input included neat

low bias current: 250 PA (typical value)

RFI filter input

miniature packaging

Electronic scale

Medical Device

Resistance hot detector

precision active source Filter

Instructions

OPA2180 and OPA4180 operational amplifier use zero drift technology, while providing low offset voltage (75 μV), and nearly zero drift with time and temperature. These miniature, high -precision, low static current exilers provide high input impedance and rail -to -orbit output width within 18 millivolo. The input co -modular range includes negative. A single power or dual power supply can be used in the range of +4.0 V to +36 V (± 2 V to ± 18 v).

Double versions are provided in MSOP-8 and SO-8 software packages. Quad provides SO-14 and TSSOP-14 packaging. All models work at a temperature of -40 ° C to+105 ° C.

vs u003d ± 18 v, vcm u003d vs/2, RLOAD u003d 10 kΩ, connected to VS/2, CL u003d 100 PF, unless otherwise explained.123]

Application information OPAX180 series operation amplifier will be precise The combination of migration and drift and excellent overall performance makes it an ideal choice for many precision applications. The precision offset drift is only 0.085 μV/° C, which can provide stability throughout the temperature range. In addition, the Airr and PSRR of the device are very good. Like all amplifiers, the application of noise or high -impedance power supply requires the deserted off -coupled capacitors close to the device pin. In most cases, 0.1-μF capacitors are enough. Working features The operating voltage of the OPAX180 series amplifier is 4 to 36 v (± 2 v to ± 18 v). Many specifications are suitable for -40 ° C to+105 ° C. The typical features are given significant parameters related to work voltage or temperature.

Total plane layout guide

In order to obtain the best equipment operation performance, it is recommended to use a good printing circuit board (PCB) layout method. The low loss of 0.1-μF bypass power container should be connected between each power supply foot and ground, and as close to the device as much as possible. Single -width capacitors from V+to the ground are suitable for single power applications.

Phase protection

OPAX180 series has internal phase reversal protection. When the input is driven by its linear co -modular range, many operational amplifiers will have phase reversal. This situation is the most common in non -switching circuits. When the input is driven to the co -mode voltage range that exceeds the specified specified, the output reverse into the opposite track. The input of OPAX180 can prevent the phase reversal when the co -mode voltage is too high. Instead, the output is limited to the appropriate track. This performance is shown in Figure 26.

The dynamic characteristics of capacity load and stability

OPAX180 have been optimized for a series of common operation conditions. Low -closed loop gain and high -capacity loadThe combination of the amplifier is reduced, and the peak or oscillation of the gain may be caused. Therefore, the heavier capacitance load must be isolated from the output. The easiest way to achieve this isolation is to connect a small resistance in series at the output end (for example, ROUT is equal to 50Ω). Figure 27 and Figure 28 show the relationship diagram of the small signal super -adjustment and capacitance load of several ROUT values. In addition, for the detailed information about analytical technology and application circuits, please refer to the application report, feedback the DEFINEOPAPC PERFORMANCE (SBOA015), you can download it from the TI website.

Excessive electrical stress

Designers often ask the capacity of the computing amplifier to withstand excessive electrical stability. These problems are often concentrated on the device input, but may involve the power supply voltage pins and even output pins. Each different pins function has the electrical stability limit determined by the voltage breakdown characteristics of a specific semiconductor manufacturing process and a specific circuit connected to the pin. In addition, internal electrostatic discharge (ESD) is protected in these circuits to prevent an ESD incident that occurs before and in the process of product assembly.

These ESD protection diode also provides input -drive protection in the circuit. As long as the current is limited to 10 mAh, as described as absolutely maximum rated values. Figure 29 shows how to add a series input resistance to the driver input to limit the input current. The increased resistance generates thermal noise at the amplifier input terminal, and its value should be kept at the minimum value in the application of sensitivity to noise.

The ESD event will generate a short -lasting high -voltage pulse. When it discharge through semiconductor devices, the pulse is converted into a short duration and large current pulse. The ESD protective circuit design is used to provide a current circulation around the core of the computing amplifier to prevent it from being damaged. The energy absorbed by the protective circuit was subsequently lost in the form of heat.

When the operational amplifier is connected to the circuit, the ESD protection component will maintain a non -activity state and will not participate in the operation of the application circuit. However, when the external voltage exceeds the operating voltage range of the given pin, this may occur. If this happens, there are risks that some internal ESD protection circuits may be biased and transmitted. Any current is generated by electrostatic discharge units, which rarely involves an absorption device.

If the power absorption current is uncertain, you can add an external Qina diode to the power pins. The Qina voltage must be selected so that the diode will not be turned on during the normal operation.

However, its Qina voltage should be low enough to guide the Qina diode when the power pins start to rise to the level of the safe working power supply level.