Features

● High -output current:

8A continuous

10A peak value

● The power supply range is wide:

Single power supply source supply :+8V to+60V

Dual power supply: ± 4V to ± 30V

● The output voltage is large

● Complete protection:

Hot shutdown

Can be adjusted

● Output disable control

● Hot shutdown indicator

● High conversion rate: 9V/μs

] ● Control reference pins

● 11-leading power package

Application

● Valve, analog driver

● Synchronous, servo drive [ 123]

● Power supply

● Test equipment

● Sensor excitation

● Audio power amplifier

OPA549 is yes A low -cost, high -voltage/large current operational amplifier is an ideal choice to drive various loads. This laser fine -tuning single -chip integrated circuit provides excellent low -level signal accuracy and high output voltage and current.

OPA549 uses a single power supply or dual power supply to supply power to improve design flexibility. Enter the scope of the co -mode to below the negative power supply.

OPA549 has internal protection to prevent excessive temperature and current overload. In addition, OPA549 provides an accurate current limit for users to choose. Different from other designs, the ""power"" resistor is connected in series in the output current path, and the OPA549 sensing load is indirect. This allows the use of a resistor/potential meter to adjust the current limit from 0A to 10A, or use a voltage output or current output digital mode modular converter (DAC) for digital control.

Enable/status (E/S) pin provides two functions. It can be monitored to determine whether the device is in a heat shutdown state, and can force it to reduce it to disable the output level and effectively disconnect the load.

OPA549 uses 11 core power packs. Its copper tags can be easily installed on the radiator to obtain excellent thermal performance. The specified operating temperature range is -40 ° C to+85 ° C.

Wiring chart

Typical features

tcase u003d+25 ° C, vs u003d ± ± 30V, E/S pins open the road, unless there is another explanation.

Application information

FIG. 1 shows OPA549 as a basic non -conversion amplifier connection. OPA549 can be used for almost any computing amplifier configuration.

The power terminal should be bypass with low series resistance resistance. It is recommended to use parallel ceramics and 钽 technology shown in Figure 1. The power terminal should have low series impedance.

Make sure to connect two output pins (pin 1 and 2).

Power supply

OPA549 can work at a single power supply (+8V to+60V) or dual power supply (± 4V to ± 30V), with excellent performance. Without the entire working voltage range, most characteristics remain unchanged. The typical feature shows the parameters of significant changes with the working voltage. Some applications do not require equal positive and negative output voltage. The power supply voltage does not need to be equal. The minimum voltage between OPA549 can be 8V between the power supply and the voltage between the power supply is 60V. For example, you can set the positive power supply to 55V and the negative electrode power supply to -5V. Please ensure that the two V -pin (needle feet 5 and 7) are connected to the negative electrode power supply, and the two V+needle (needle foot 10 and 11) are connected to the positive electrode power supply. Package tab is connected to V -; but do not use TAB to transmit current.

Control reference (Ref) pin

OPA549 has a reference (REF) pin, and ILIM and E/S pins are referenced. Ref is just a reference point that users can access, which can be set to V-, Group or any reference for users. Ref cannot be set to below negative power or higher than (V+ -8V). If the smallest VS is used, the REF must be set to V -.

The adjustable current

OPA549 is accurate. The current limitation of the user -defined current can be set from 0A to 10A by controlling the input of the ILIM pins. Different from other designs, the power resistor that uses the OPA549 to connect with the output current path, which can induce the load indirect. This allows the current limit to set the current of 0 μA to 633 μA control signal. In contrast, other designs require a restricted resistance to process the entire output current (up to 10A in this case).

Although the design of OPA549 allows the output current to be as high as 10A, it is not recommended to continuously operate the device at this level. The maximum rated continuous current capacity is 8A. Continuously running OPA549 in the output current greater than 8A will reduce long -term reliability.

Operating OPA549 with a current limit of less than 1A will cause the current limit accuracy. The application of lower output current may be more suitable for OPA547 or OPA548.

Resistance control current limit

Simplified schematic diagram of internal circuits for setting current limit, see Figure 2A. Keep the ILIM pins open the programming output current to zero, and connect the ILIM directly to the REF programming maximum output current limit, usually 10A.

For OPA549, according to Formula 1, the easiest way to adjust the current limit is to use a resistor or potential meter connected between Ilim pins and REF:

Refer to Figure 2 to understand the common value.

CNC flow limit

Low -level control signal (0 μA to 633 μA) also allows digital control to limit current limits by setting current (ISET) or voltage (VSET). According to Formula 2, you can adjust the output current ILIM by changing the Iset:

FIG. 2B shows the circuit configuration to achieve this characteristic.

According to Formula 3, you can adjust the output current iLim by changing the VSET:

FIG. 11 demonstrates the circuit configuration to achieve this feature.

Enable/status (E/S) pin

ENable/Status pin provides two unique features: 1) reduce the output through mandatory pins to reduce the output Disable, 2) The heat shutdown instructions are achieved by monitoring the voltage level of the pins. One or two of these two functions can be used in applications. For normal operation (output enable), the E/S pins can be kept open or high -level driving (at least higher than Ref 2.4V). For noise applications, a small value capacitor may be connected between E/S pins and CREF.

Output disabled

In order to disable the output, the E/S pins were pulled to a low logic low (higher than the REF no more than 0.8V). Usually, the output is closed within 1 μs. To restore the output to the enable state, it should be disconnected (open) E/S pins or pull it to at least 2.4V higher than the reference voltage. It should be noted that the high level (output enable) drive E/S pins does not destroy the internal heat shutdown; however, it does prevents users from monitoring the heat shutdown state. Figure 3 shows an example of implementing this function.

This function not only saves electricity during the free period (static current drops to about 6mA), but also allows multi -way reuse in multi -channel applications. For the two OPA549 in the switch amplifier configuration, see Figure 12. The open/off state of the two amplifiers is controlled by the voltage on E/S. In these cases, the disabled device will show a 750pf load. The rotation speed exceeds 3V/μs will lead to the rapid increase in leakage current in the failure equipment.And additional loads will be generated. Under high temperature (125 ° C), the conversion threshold drops to about 2V/μs. The input signal must be restricted to avoid excessive reckles in multi -way reuse applications.

The heat shutdown status

OPA549 has a heat clearance circuit to protect the amplifier from being damaged. When the knot temperature reaches about 160 ° C, the thermal protection circuit will be disabled and allows the equipment to cool. When the knot temperature is cooled to about 140 ° C, the output circuit will be automatically enabled. According to the load and signal conditions, the thermal protection circuit can be turned on and closed. You can monitor the E/S pins to determine whether the device is in shutdown. During the normal operation, the voltage on the E/S pins is usually 3.5V higher than the reference value. Once the stop occurs, the voltage will drop to about 200mV higher than the reference value. Figure 4 shows an example of implementing this function.

External logic circuit or LED can be used to indicate whether the output is hot shutdown, see Figure 10.

Output disable and heat shutdown status

As mentioned earlier, the output of OPA549 can be disabled and the disabled state can be monitored at the same time. Figure 5 provides an example of connecting to the E/S tube.

Safe operating area

The stress on the output transistor is determined by the output voltage of the output current and the conductive output transistor vs --vo. The power consumption of the output transistor is equal to the output current and the voltage of the voltage of the conductive transistor, VS -VO. The safety working area (SOA curve, Figure 6) shows the allowable range of voltage and current.

With the increase of VS -VO, the safe output current decreases. The output short circuit is a very harsh situation for SOA. The short-circuit of the ground forced the entire power supply voltage (V+or V-) through the conductive transistor. Increasing the temperature of the shell will reduce the tolerance safe output current without active the heat clearance circuit of OPA549.

Power loss

Power consumption depends on power, signals and load conditions. For DC signals, the power consumption is equal to the output current multiplication to the voltage of the voltage of the transistor of the transistor. By using the required as much as possible to ensure the required output voltage, the power consumption can be minimized.

For the resistance load, the maximum power consumption occurs at the DC output voltage of half of the power supply voltage. The loss of the exchange signal is lower. The application announcement SBOA022 explains how to calculate or measure the power consumption of abnormal signals and loads.

Thermal protection

The power consumed in OPA549 will lead to an increased temperature. When the mold temperature reaches approximately 160 ° C, the internal heat off circuit is closed and the output is closed, and when the mold cools to 140 ° CSettled. According to the load and signal conditions, the thermal protection circuit can be turned on and closed. This limits the loss of the amplifier, but it may have adverse effects on the load.

Any trend of starting the heat protection circuit indicates that the power consumption is too large or insufficient heat dissipation. For reliable operation, the highest knot temperature should be limited at 125 ° C. In order to estimate the safety of the complete design (including the radiator), please increase the ambient temperature until trigger heating protection.

Use the load and signal conditions in the worst case. In order to obtain good reliability, thermal protection should trigger a temperature above the maximum expected environmental conditions above the application of 35 ° C. This will generate a 125 ° C knot temperature under the maximum expected environmental conditions.

OPA549 internal protection circuit design is used to prevent overload. This is not to replace proper heat dissipation. Continuously running OPA549 to enter the hot stop will reduce reliability.

The amplifier installation and heat dissipation

Most applications need a radiator to ensure that it will not exceed the maximum working knot temperature (125 ° C). In addition, in order to improve reliability, the temperature should be as low as possible. The knot temperature can be determined according to the following formulas:

Formula:

tj u003d knot temperature (° C)

ta u003d ambient temperature (° C)

pd u003d consumption power (w)

θjc u003d thermal resistance between the connector (° C/w)

θch u003d shell to heat dissipation to heat dissipation Thermal resistance of the device (° C/W)

θHa u003d Thermal resistance (° C/W)

θja u003d connecting thermal resistance (° C/W)

FIG. 7 shows the relationship between the maximum power consumption and environmental temperature when using and not using the radiator. As shown in Figure 7, at a given environmental temperature, the use of radiator can significantly improve the maximum power consumption.

The challenge of selecting the required heat sink is to determine the power consumed by OPA549. For DC output, the power consumption is the voltage of the load current multiply to conduct the voltage of the transmission of the transistor, PD u003d IL (VS -VO). Other loads are not so simple. See the SBOA022 application report to understand more information about calculating power consumption. Once you know the power consumption of the application, you can choose the appropriate radiator.

The radiator selection example-a 11-leading power compressed package consumes 10 watts. The expected maximum ambient temperature is 40 ° C. Find the appropriate heat sink to keep the knot temperature below 125 ° C (150 ° C minus 25 ° C's safety haunterness).

Combined with equations (4) and (5) to conclude:

Give TJ, TA, and PD. θjc is provided in the specification table, 1.4 ° C/W (DC). θch can be obtained from the radiator manufacturer. Its value depends on the size, area and materials used by the radiator. Semiconductor packaging types, installation screw torque, insulation materials (if.) Thermal connection compounds (if.) Also affect θch. For the installed 11 lead power zipper packaging, the typical θch is 0.5 ° C/W. Now we can solve the θha:

To keep the knot temperature below 125 ° C, the θHA of the selected radiator must be less than 6.6 ° C/W. In other words, the temperature rise of the radiator higher than the ambient temperature must be less than 66 ° C (6.6 ° C/w u0026#8226; 10W). For example, the temperature of the 10W heat alloy model 6396B is 56 ° C (θha u003d 56 ° C/10W u003d 5.6 ° C/W), which is lower than the 66 ° C required by this example. The water tank temperature of the 6399b heat alloy rises to 33 ° C (θha u003d 33 ° C/10W u003d 3.3 ° C/W), which is also lower than the 66 ° C example of this specification. Figure 7 shows the relationship between the power consumption and ambient temperature of the 11 -core power zipper package with the heat alloy 6396B and 6399B radiator.

Another variable to be considered is the natural convection and forced convection. Small fan forced wind and cold can significantly reduce θca (θCh+θha). Some radiator manufacturers provide the heat data boxes of these two radiator. The performance of thermal receiver is usually specified under the ideal conditions that may be difficult to achieve in practical applications.

As mentioned earlier, once the heat sink is selected, a complete design should be tested under the worst load and signal conditions to ensure proper heat protection. Any trend of starting the heat protection circuit may indicate insufficient heat dissipation.

The convex ears of the power zipper bag of the 11 line are connected to the negative electrode power supply V -electric connection. It is best to use Yunmu (or other film) insulators to isolate the convex ears of the 11 -line power zipper packet from the installation surface. In order to reduce the overall thermal resistance, it is best to isolate the entire radiator/OPA549 structure from the installation surface instead of using insulators between semiconductor and radiator.

Output level compensation

The common complicated load impedance in the application of power computing amplifier can lead to the output level instability. For normal operations, compensation circuits are usually not required. However, for difficulty loads or OPA549 under current restrictions, the R/C network may be required. Figure 8 shows an output R/C compensation network, which usually provides excellent stability.

When the drive large capacitance load (u0026 gt; 1000pf) or perceptual load (a load separated by a motor, through the long cable to the amplifier), the buffer circuit can also increase stability stability sex. Usually, 3 u0026#8486; to 10 u0026#8486; the resistor can be connected in series with 0.01 μF to 0.1 μF capacitors. Some loads may require some changes in the circuit value.

Output protection

The load that generates non -merit and electric momentum can return the load current to the amplifier, causing the output voltage to exceed the power supply voltage. From the output to the clamping diode of the power supply, this damage can be avoided, as shown in Figure 8. It is recommended to use the continuous rated value of 8A or larger Schottky rectifier diode.

Voltage source application

FIG. 9 illustrates how to use OPA549 to provide a precise voltage source resistor with only three external voltage. The first one is based on the required output current. The voltage generated on the ILIM pins is constant and stable at ultra -temperature. This voltage, VCL, is connected to the irreversible input of the computing amplifier for the voltage benchmark, so it does not require an external benchmark. Select the feedback resistance to gain VCL to the required output voltage level.

The programmable power supply

using OPA549 can easily build a programmable source/receiver power supply. The output voltage and output current are controlled by users. As shown in Figure 10, use the potential to adjust the output voltage and current, and Figure 11 uses DAC. Whether the OPA549 is connected to the E/S pins is in a hot shutdown state through the logic door.