Features

Low offset voltage: 25 μV (maximum)

zero drift: 0.03μv/° C

#8226 ; Low noise: 8.8 nv/√Hz

-0.1-Hz to 10 Hz noise: 0.25 μVPP

Excellent DC accuracy:

-D power suppression Bi: 142 decibel

-CMRR: 146 DBS

-Bei ring gain: 136 db

gain bandwidth: 2 MHz

#8226; Static current: 475 μA (maximum)

Wide power supply range: ± 2 v to ± 18 v

Rail transit: Input included neat tracking

RFI filter input

miniature packaging

Application

] Response meal

Testing equipment

sensor application

temperature measurement

#8226; Electronic scale

Medical Device

Resistance temperature detector

123] Explanation

OPA2188 operational amplifier uses the TI patent automatic zero -adjustment technology to provide a low offset voltage (maximum 25 μV), and near zero drift with time and temperature. This miniature, high -precision, low static current exile provides high input impedance and rail -to -orbit output width within 15 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).

OPA2188 has MSOP-8 and SO-8 software packages. The device is stipulated at the temperature of -40 ° C to+105 ° C.

Zero Drift Combination amplifier

Typical features

vs u003d ± 18 v, vcm u003d Vs/2, roload u003d 10 kΩ, connect to vs/2, cl u003d 100 PF, unless there are other instructions.

Application information OPA2188 operation The amplifier combines precise offset and drift and excellent overall performance, making this device an ideal choice for many precision applications. The precision offset drift of only 0.085 μV per degree Celsius can provide stability throughout the temperature range. In addition, the device has the overall performance of high CMRR, PSRR and AOL. 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 characteristics OPA2188 stipulates that the working voltage is 4 volts to 36 volts (± 2 volts to ± 18 volts). Many specifications are suitable for -40 ° C to+105 ° C. The typical features are given significant parameters related to work voltage or temperature. Electromagnetic interference suppression OPA2188 uses integrated electromagnetic interference (EMI) filtering to reduce the effects of EMI interference from wireless communication and densely populated plates (with analog signal chain and digital components). EMI antipity can be improved through circuit design technology; OPAX188 benefits from these design improvements. Texas Instruments has developed an antipity of accurate measurement and quantitative operational amplifier on a broadband zone from 10 MM to 6 MM. Figure 39 shows the test results on OPA2188. For details, you can also find it in the application report. The EMI suppression ratio of the computing amplifier (SBOA128) can be downloaded from the TI website.

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

OPA2188 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. OPA2188 input 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 40.

The dynamic characteristics of capacity load and stability

OPA2188 have been optimized for a series of common operation conditions. Low -closed loop gain and high capacityThe binding of sexual loads reduces the phase margin of the amplifier and may cause the peak or oscillation of the gain. 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). Figures 41 and Figure 42 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. FIG. 43 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 generates a high -voltage pulse with a short duration. When it discharge through semiconductor devices, the pulse is converted into a short -time 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.

Application instance

Application examples of Figure 44 and Figure 45 only highlight the minority electricity that can use OPA2188road.

Note: (1), R5 provides positive change incentives to make the output linear.