Features

The ideal choice of current diversion applications; high-co-mode voltage range; -2 V to +65 V run; -25 V to +75 V living voltage; gain 20; width working temperature range range; ; -40 ° C to+125 ° C (level Y and WY); -40 ° C to+150 ° C (white); two-way operation; providing 8 lead SOIC; suitable for automobile applications; excellent communication performance; 15 Slightly/Celsius displacement drift; 30 ppm/℃ gain drift; 80 dB CMRR flow to 20 kHz.

Application

High-side current influenza input; motor control; gearbox control; diesel injection control; engine management; suspension control; vehicle dynamic control; DC-DC converter.

General description

AD8206 is a single -power differential amplifier, which is used to place differential voltage of the size when the voltage of the communist model is existed. The working input of the co-mode voltage is expanded from -2V to+65V. The typical single power supply voltage is 5V.

AD8206 is encapsulated by 8 -guide SOIC. The rated operating temperature of the Y-level and WY-level model is -40 ° C to+125 ° C. The rated operating temperature of the WH level is -40 ° C to+150 ° C.

The excellent DC overcurrent has minimized the error of the measurement circuit. Disposal drifts are usually less than 15 micro -volt/degrees Celsius, and gain drift is usually lower than 30 PPM/degree Celsius.

The output offset can be adjusted from 0.08 V to 4.7 V to use VREF1 and VREF2 pins to provide 5 V power. When VREF1 is connected to the V+pin and VREF2 is connected to the GND pin, the output is set to half -scale. Connecting the two pins to the GND will cause the output to be a single pole, starting from the ground. Connecting the two pipes to V+will cause the output to start with the single pole near V+. Other offsets can be obtained by applying external voltage to VREF1 and VREF2 pins.

Function box diagram

Pinged configuration and function description

OperationTheory

AD8206 is a single -power differential distribution large. With a unique structure, the difference current with the size of the size and the voltage of the differential size is accurately enlarged. It is provided in the form of 8 -guide SOIC packaging. In typical applications, the AD8206 measures the current by amplifying the voltage on the current diversion on the input terminal.

AD8206's gain is 20V/V, and accuracy is 1.2%. When the operating temperature range is -40 ° C to+125 ° C, the accuracy can be guaranteed. However, please note that the WH version of AD8206 stipulates that it works within the temperature range of -40 ° C to+150 ° C. The accuracy is 1.2%.

AD8206 works under a single power supply from 4.5 V to 10 V (absolute maximum value 12.5 V). The power supply is less than 2 milliang.

The high -precision fine -tuning of the internal resistor allows AD8206 to have a typical co -model suppression ratio, from DC to 20 kHz, which is better than 80 dB. The smallest co -model suppression ratio at work temperature is 76DB.

For one -way and two -way operation, the output offset can be adjusted from 0.08 V to 4.7 v (v 5 V).

AD8206 consists of two amplifiers (A1 and A2), a resistance network, a small voltage benchmark, and a bias circuit. Simplified schematic diagrams see Figure 16 (no offset circuit).

The previous input attenuation device of A1 consists of RA, RB, and RC. They reduce the co -mode voltage to match the input voltage range of A1. Two attenuers form a balanced bridge network. When the bridge is balanced, the differential voltage generated by the input end of the co -mode voltage at A1 is 0V. The input attenuation ratio is 1/16.7. The combination of RA, RB, and RC is about 200 kΩ ± 20%.

Through the voltage of 1 and 8 stitches at attenuation, even if the pin 1 and the pin 8 exceed the power supply or below the public (ground) voltage, the A1 amplifier input remains within the range of the power supply. The reference voltage of 250 millivoltors deviates from the ground. This allows the amplifier to work under the negative model.

The input network is also attenuation normal (differential) mode voltage. A1 amplifies at the attenuation signal 26. The input and output of the amplifier are differentiated to maximize the communication co -modular.

A2 converts the differential voltage of A1 into a single -end signal and provides further amplification. The income of the second stage is 12.86.

Reference to input VREF1 and VREF2 connect to the positive input of A2 through the resistor, which allows adjustment of the output offset anywhere within the scope of the output work. When the benchmark pin is used in parallel, the gain from the benchmark pin to the output end is 1V/V. When they are used to allocate the power, the gain is 0.5 V/V.

The ratio of resistors RA, RB, RC, RD and RF is adjustedThe whole is high accuracy to allow the co -model to suppress the ratio of more than 80dB. This is achieved by minimizing the resistance than 0.01%by laser fine -tuning resistance than 0.01%.

Total gain 20 is composed of input attenuation 1/16.7 multiplied by the first -level gain 26 and the second level of 12.86.

The output level is a Class with PNP pull -up crystal tube and a 300μA current receiver.

output offset adjustment

The output of AD8206 can be adjusted for one -way or two -way operation.

One -way operation

One -way operation allows AD8206 to measure the current in one direction. The basic mode of one -way operation is the ground reference output mode and V+reference output mode.

For one -way operation, when the differential input is 0V, the output can be set on orbit (close to the ground) or on -track (close to V+). When the correct polar difference input voltage is applied, the output moves to the right track. In this case, the full scale is about 250 millivolves. The polarity required for differential input depends on the output voltage settings. If the output is set on the right track, the input polarity needs to be negative before the output can be moved down. If the output is set to ground, the polarity is to move the output upward.

Flood reference output

When using AD8206 in this mode, both reference inputs are connected to the ground. Rail (see Figure 17).

V+reference output

When both reference pins are connected to the positive power supply, set this mode. When the diagnostic scheme is required to detect the amplifier and wiring before the load is powered on, this method is usually used (see Figure 18).

Two -way operation

The two -way operation allows AD8206 to measure the current in the two directions.

In this case, the output is set to anywhere within the output range.

Under normal circumstances, set it in the same range in the two directions to half -scale. However, in some cases, when the two -way current is asymmetric, it is set to the voltage outside the semi -standard degree.

Adjust the output by applying an application voltage to the reference input.

VREF1 and VREF2 are connected to the internal resistor connected to the internal offset node. There is no difference in operation between pins.

External reference output

When there is no differential input, connect the two tube feet together and connect it to a reference voltage To. InputWhen negative, relative to the input pin, the output is moved down from the reference voltage; when the input is positive, the output is moved up from the reference voltage, which is relative to the input pin.

Confession

By connecting one reference pin to V+, the other to the ground pins, when there is no differential input, the output setting is set to to Half of the power supply (see Figure 20). Its advantage is that external reference does not require external reference to offset the output of two -way current measurement. This will create a medium -scale offset that is proportional to the power supply, which means that if the power supply increases or decreases, the output is still half of the power supply. For example, if you supply 5.0V, the output is semi -standard or 2.5V. If the power supply increases by 10%(to 5.5V), the output is 2.75V.

Disassembling external reference

In this case, by connecting one VREF foot to the ground with another VREF tube to the benchmark, the external benchmark, the external benchmark Except 2, accuracy is about 0.5%(see Figure 21).

Application information

A typical application of AD8206 is to measure the current through the solenoid valve, so Essence Typical applications include hydraulic transmission control and diesel jet control.

Two typical circuit configurations are used for such applications.

High -voltage side current detection with a low -voltage switch

In this case, the PWM control switch is referenced. The inductive load (snail line tube) is connected to the power supply. Place a resistor splitter between the switch and the load (see Figure 22). One advantage of putting the shunting device on the high voltage side is that the entire current can be measured, including the recycling current, because when the switch is cut off, the shunt is still in the circuit. In addition, the diagnosis can be strengthened because the high -voltage side shifts can be detected by short -circuits on the ground.

In this circuit structure, when the switch is turned off, the co -mode voltage is moved down to a neat nearby. When the switch is turned on, the voltage on the inductive load causes the co -mode voltage and the diode is kept on a diode above the battery.

High -voltage side current detection with high -voltage side switches

This configuration possibility of the accidental start and over -corrosion of the solenoid valve to the minimum (see Figure 23). In this case, the switch and the downtale are on the high -voltage side. When the switch is cut off, this will remove the battery from the load to prevent the potential to be damaged by short circuits on the ground. At the same time, the recycling current is still allowed to be measured and diagnosed. Most of the time, disconnecting the power supply from the load can minimize the effects of the voltage difference between the load and the ground.

When the high -voltage side switch is used, when the switch is turned off, the battery voltage is connected to the load, so that the co -mode voltage is increased to the battery voltage.In this case, when the switch is cut, the voltage on the sensor load causes the co -mode voltage to be clawed by a diode in an underground diode.

Another typical application of AD8206 is part of the control circuit of the H bridge motor. In this case, the AD8206 is placed in the middle of the H bridge (see Figure 24) so that it can accurately measure the current in the two directions by using the spacing used on the motor. This is a better solution than the ground reference op amp, because in this type of application, grounding is usually not a stable reference voltage. This instability in the grounding reference causes the measurement of simple ground reference to inaccurate the measurement of the use of a simple ground. When the H bridge switch and the motor change the direction, the AD8206 measures the current in the two directions. The output configuration of the AD8206 is the external reference two -way mode, please refer to the output offset adjustment part.

The size of the shape

Automobile product