Feature description

2 Ina149 is a precise unit gain poor

Common -mode voltage range: ± 75 v High input co -module large device

] The minimum co-mode suppression ratio: 90 decibels, the voltage range is -40 ° C to+125 ° C. It is a single-chip device

DC specifications: including a precision operational amplifier and an integrated thin piece-to maximum offset voltage: 1100 μV film resistance network. INA149 can accurately measure the small differential voltage in the following circumstances -maximum offset voltage drift: 15 μV/℃

The common mode signal is as high as ± 275 V. INA149 -Maximum gain error: 0.02%Input Activated co -mode protection -maximum gain error drift: 10 ppm/℃ or up to 500 V motion overload. - Maximum gain non -linearity: In many applications, 0.001%FSR, where does not include current isolation needs, INA149 can replace the isolation amplifier. AC performance: This ability can eliminate expensive independent input -bandwidth: 500 kHz

Power supply and related ripples, noise, and -typical conversion rate: 5 v/μs static current. Excellent 0.0005%non -linearity

Wide power supply range: ± 2.0V to ± 18V and 500kHz bandwidth of INA149 is better than those traditional isolation amplifiers. -Maximum static current: 900 μA-output turn on ± 15-V power supply:? 3.5 v INA149 and INA117 and INA148 high -co -modal electricity amplifiers

Input protection: and provide better performance on two devices. -Co-Model: ± 500 V INA149 can be used in SOIC-8 packaging-Differential: The operating temperature range specified in the extension industry is -40 ° C to+125 ° C.

Application

High -voltage current influenza

Battery voltage monitoring

Power current monitor Circuit

This integrated circuit may be damaged by electrostatic discharge. Texas instruments recommend that all integrated circuits proper prevention measures. Not observing the correct operation and installation program may cause damage. The range of ESD damage drops from fine performance to the device completely fails. The precision setting circuit is easy to damage, because the changes in very small parameters may cause the device to not comply with its announcement.

Absolutely maximum rated value (1)

exceeded the temperature range of the free air air, unless otherwise explained.

(1) more than these rated valuesStress may cause permanent damage. Long -term exposure to absolute maximum conditions decreases low equipment reliability. These are the specified stress -rated values, and the specified on the function of the device's functions under these or any other conditions is not implicit.

(2) Refa and Refb are clamping the diode on the power rail. The signal applied to these pins should be limited to 10 mAh or less than the power rail.

Electric characteristics: V+ +15 V and V- -1 15 V When RL 2 KΩ ground is ground, VCM Refa Refb ground, unless otherwise explained.

Typical features

When TA +25 ° C, RL 2 kΩ ground, vs ± 15 v, unless there is another instructions [123 [123 ]

Typical features (continued)

When TA +25 ° C, RL 2 kΩ ground, vs ± 15 v, unless otherwise explained.

Basic situation

FIG. 43 shows the basic connection required for dual power operation. In applications with noise or high impedance power cords, the decoupled power container may need to be placed near the device pin. The output voltage is equal to the input voltage between the pin 2 and 3. The co -mode input voltage is rejected. Figure 44 shows the basic connection required for the operation of the single power supply.

Transmitting functions

Most applications use INA149 as a simple unit gain differential amplifier. The transmission function is in formula 1: VOUT (+in) - ( - in) (1) (1). However, some applications apply voltage to reference terminals (REFA and Refb). Complete transfer equation 2 gives a function: VOUT ( + in) - (--in) + 20 × Refa - 19 × Refb

The scope of the common mode The resistor division is achieved by high -precision segmentation signal. This resistor divide dealer enables positive input and negative input to internal operational amplifiers. This input range depends on the power voltage of INA149. Figure 2 and 3 can be used to determine the maximum co -modular range voltage of a specific power supply. The maximum co -mode range can also ensure that the negative input of the internal amplifier is within the 1.5 V range of the power supply voltage. If the voltage of the input end of the internal amplifier exceeds the power supply voltage, the internal ESD diode begins to conduct conduction current. This current must be limited to 10 mAh to ensure the maximum rated value that does not exceed the absolute device.

Common model suppression

The co -mode suppression (CMR) of INA149 depends on the input resistance network. The network is trimmed by the laser to match the accurate ratio. forKeeping higher CMR is important to have low source impedance to drive these two inputs. The 75Ω resistor connected in series with pins 2 or 3 will inhibit the co -mode inhibition ratio (CMRR) from 100 decibels (typical) to 74 decibels. The resistance to the reference pins will also reduce the CMR. The 4Ω resistor connected with needle 1 or 5 in series reduced the co -mode inhibition from 100 decibels to 74 decibels. Most applications do not need to be trimmed. Figure 45 shows the optional circuit bias voltage and coexistence suppression that can be used for trimming.

(1) OPA171 (a 36 volt, low power, RRO, general operation amplifier) can be used for this application.

Measurement current

INA149 can measure the current by the voltage on the sensor connected resistor RS. FIG. 46 shows INA149 for measuring the power supply current of the measured device. The sensor makes the input resistor of the INA149 unbalanced, thereby reducing its CMR. In addition, input the INA149 load resistance, leading to the voltage current conversion gain error error. These two errors are easy to correct. The CMR error can be corrected by adding a compensation resistor (RC), and the compensation resistance is equal to the value of RS, as shown in Figure 46. If the RS is less than 5Ω, the degeneration in CMR can be ignored, and the RC can be omitted. If RS is greater than about 1 kΩ, it may need to be trimmed to reach the RC to reach 90 DB CMR. This error is caused by Ina149 input impedance loss.

If the RS is greater than about 50Ω, the gain error is greater than 0.02%of the specification of INA149. This gain error can be corrected by adding a slightly increased RS value. The correction value (RS ') can pass RS #39; RS × 380 KΩ/(380 KΩ – S) (3) For example: for 1-V/MA transmission function, the nominal value of RS is not modified to 1 kΩ. A little larger value (RS #39; 1002.6Ω), compensate the gain error caused by compensation loading. RS #39; 380-KΩ terminal tolerance in the equation is 25%, so the sensing resistance may be fine-tuned than about 400Ω to obtain the gain accuracy higher than 0.02%.

Noise performance

The broadband noise performance of INA149 is mainly controlled by internal resistance networks. Johnson noise measurement value of heat or these resistors is about 550 nv/√Hz. Internal computing amplifiers actually help the frequency when the frequency is higher than 100 Hz. Many applications may be satisfied with all 500 kHz bandwidth less than in INA149. Using a low -pass filter at the output end in these cases can reduce noise. The bipolar filter shown in FIG. 47 limits the bandwidth to reduce noise. Because the frequency of 1/f noise angle of INA149 is about 100 Hz, the frequency of less than 100 Hz will not further reduce the noise. Different filtering frequencyThe component value is shown in Table 1.

(1) For most applications, OPA171 can be used as an operational amplifier. Used to directly drive the register (SAR) data converter one by one, OPA140 is a good choice.

Error budget analysis

The following error budget analysis proves that the small differential signal when measured when the high -co -modular voltage is measured. Figure 48 shows a typical current measurement application.

(1) For more information about RC, see the measurement current part

The maximum current of the diversion resistor (RS) is 1A, and it generates generate 10 V's full voltage voltage drop. The error source in all calculations is related to the full margin voltage. The co -mode voltage scheme is 265 V, and the temperature range is room temperature (+25 ° C) to+85 ° C. Table 2 shows the main source of error of INA149 and competitive devices.

If a smaller parallel resistor is used, the voltage drop is also small. A 1Ω parallel resistor will cause a voltage drop at a 1-V current at a current of 1-V. The error of the full marking voltage is 1808ppm when the full margin voltage is only 1V, and it becomes 18080 PPM (1.6%). This example shows that the main source of errors, even exceeding the temperature, comes from co -model suppression ratio equipment specifications. The co -mode error is 46%of the total error of INA149, which is the total error of the competitors.

Battery voltage monitor

INA149 can be used to measure the voltage of a single battery in the stack battery pack. Figure 49 shows examples of such applications.