Features

● The supply range is wide

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

- dual power supply: ± 4V to ± 30V

] ● High output current:

- 3A continuous

— 5A peak value

● Large output voltage swing

● Complete protection:

[[[

123] - Hot shutdown

- adjustable flow limit

● Output disable control

● Hot shutdown indicator

● High conversion rate: 10V/ μs

● Low static current

● Packaging:

— 7 lines to 220, zipper and direct lead

— 7-lead DDPAK surface installation [ 123]

Application

● Valve, actor driver

● Synchronous, servo drive

● Power supply

● Test equipment

● Sensor excitation

● Audio amplifier

Explanation

OPA548 is a low -cost, high voltage/large current transportation amplifier, which is an ideal that drives various loads choose. Laser fine -tuning single -chip integrated circuit provides excellent low -level signal accuracy and high output voltage and current.

OPA548 uses a single power supply or dual power supply to supply power to improve design flexibility. In the operation of a single power supply, the input co -mode range extends below the ground.

OPA548 has internal protection to prevent overheating and current overload. In addition, the design of OPA548 provides an accurate, current -selected current limit. Different from other designs, the ""power"" resistor is connected in series in the output current path, and the OPA548 indirect induction load. The current can be adjusted from the A/A potentiometer from A/A to the output limit.

Enable/status (E/S) pin provides two functions. The input on the pin not only makes the output level unable to effectively disconnect the load, but also reduce static current to save power. You can monitor the E/S pins output to determine whether the OPA548 is in a hot shutdown state.

OPA548 has an industrial standard 7-staggered and direct-lead to-220 packaging, and a 7-lead DDPAK surface installation plastic power supply packaging. Copper or radiator circuit boards are easy to install. It is specified at the extended industrial temperature range (-40 ° C to+85 ° C). SPICE macro model can be used for design and analysis.

Typical features

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

Application information [123 ] FIG. 1 shows OPA548 as a basic non -conversion amplifier connection. OPA548 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 the technologies shown in Figure 7, and the type of ceramics and crickets is used at the same time. In addition, we recommend using 0.01 μF capacitors between V+and V-, as close to OPA548 as much as possible. The power terminal should have low series impedance.

Power supply

OPA548 works under the 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 characteristic curve shows parameters with 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 the OPA548 can be 8V between the power supply and the maximum voltage between the power supply is 60V. For example, the positive power supply can be set to 55V, and the negative power supply is set to -5V, and vice versa.

adjustable flow limit

OPA548 has an accurate current limit by user selection. By controlling the input of the ILIM pin, the current limit is set to 5A from 0A. Different from other designs, OPA548 uses the power resistor with the output current road series, it indirectly perceive the load. This allows a control signal with 0 μA to 330 μA to set the current limit. Instead, other designs require a restricted resistance to process the entire output current (5A in this case).

For OPA548, the easiest way to adjust the current limit is to use a resistor or potential meter connected between ILIM pins and V-according to Formula 1:

Low -level control signals (0 μA to 330 μA) also allowed digital control to limit current limits.

Simplified schematic diagrams for internal circuits for setting current limit, see Figure 3. Keep the ILIM pins open, program the output current to zero, and connect iLim directly to V -programming maximum output current limit, usually 5A.

The safety operation 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 through the conductive transistorThe voltage of the tube, vs -vo. The safety working area (SOA curve, Figure 2) 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 safety output current without active the heat clearance circuit of OPA548. To learn more about SOA, see the application announcement SBOA022.

The amplifier installation

FIG. 4 provides a recommended welded footprint for To-220 and DDPAK power packages. The wiring films of the two battery packs are connected to the negative electrode power V-electricity. It is best to use Yunmu (or other film) insulators to isolate the convex ears packaged to the TO-220 with its installation surface (see Figure 5). In order to reduce the overall thermal resistance, it is best to isolate the entire radiator/OPA548 structure from the installation surface instead of using insulators between semiconductor and radiator.

In order to obtain the best thermal performance, the label of the DDPAK surface sticker should be welded directly to the copper area of u200bu200bthe circuit board. Increased copper area can improve heat dissipation. See Figure 6 from the typical thermal resistance (function as a copper area) from the surrounding.

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 OPA548 will cause the knot temperature to rise. OPA548 has a thermal turnover circuit to protect the amplifier from being damaged. When the knot temperature reaches about 160 ° C, the thermal protection circuit will be disabled and the equipment will cool down. When the knot temperature cools to about 140 ° C, the output circuit is enabled again. 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 the maximum of the applicationIt is expected to have a temperature above 35 ° C or more. This will generate a 125 ° C knot temperature under the maximum expected environmental conditions.

OPA548 internal protection circuit design is used to prevent overload. Sinking is inappropriate. Continuously running OPA548 to enter the hot stop will reduce reliability.

Heating

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:

tj u003d knot temperature (° C)

ta u003d ambient temperature (° C)

] Pd u003d consumption power (w)

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

θch u003d the thermal resistance of the shell to the radiator (° C/W )

θha u003d thermal resistance (° C/w)

θja u003d connecting thermal resistance to air (° C/w)

Figure 7 Display display The relationship between the maximum power consumption and environmental temperature when using and not using the radiator. As shown in the figure, at a given environmental temperature, using a radiator can significantly improve the maximum power consumption.

The difficulty of selecting the required heat sink is to determine the power consumed by OPA548. For the DC output of pure resistance load, power loss is the voltage generated by the load current by conducting the voltage generated by the transmission output transistor, PD u003d IL (vs -vo). Other loads are not so simple. Please refer to the application announcement SBOA022 to learn more about calculating power consumption. Once you know the power consumption of the application, you can choose the appropriate radiator.

A radiator selection example

The power consumption of the encapsulated packaging of to-220 is 5W. 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 (1) and (2):

Give TJ, TA, and PD. θjc is provided in the specification table, 2.5 ° 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. TO-220 The typical θch installed packaging is 1 ° C/W. Now we can solve θha:

To keep the knot temperature below 125 ° C, the θHA of the selected radiator must be less than 14 ° C/W.In other words, the temperature rise of the radiator higher than the ambient temperature must be less than 67.5 ° C (13.5 ° C/w u0026#8226; 5W). For example, a 5W heat alloy with a model of 6030B is 66 ° C than the ambient temperature (θha u003d 66 ℃/5W u003d 13.2 ℃/w), which is lower than the 67.5 ℃ required by this example. Figure 7 shows the relationship between the power consumption and ambient temperature with the TO-220 package with 6030B heat sink.

Another variable to be considered is the natural convection and forced convection. Small fan forced wind and cold can significantly reduce θca (θCh+θha). The radiator manufacturer provides hot data for these two situations. For more information on the requirements for determining the radiator, see the application announcement SBOA021.

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.

Enable/Status (E/S) pin

ENable/Status pin provides two functions: forced the pins, disable the output level, or monitor E/S, so as to use it to monitor E/S, so as to use it to monitor E/S, so as to monitor E/S, so as to monitor E/S, so as to monitor E/s, so as to monitor E/S, so as to monitor E/S, so as to monitor E/S, so as to monitor E/S, so as to monitor E/S, so as to monitor E/S. Determine whether the OPA548 is in a hot shutdown state. One or two of these functions can use a single power or dual power supply on the same device. For normal operation (output opening), the E/S pins can be kept or pulled up (at least 2.4V above track). Noise applications may need to be connected to small value capacitors between E/S pins and V-.

A unique feature of the output

OPA548 is its output disable capability. This function not only saves power during the idle period (static current drops to about 6mA), but also allows multiple reuses in low frequency (F u0026 LT; 20KHz) and multi -channel applications. Signals greater than 20kHz may cause leakage current of the following devices to increase shutdown. FIG. 18 shows the two OPA548 in the switch amplifier configuration. The open/off state of the two amplifiers is controlled by the voltage on the E/S pins.

In order to disable the output, the E/S pin was pulled down and did not exceed 0.8V above the negative guide rail. Usually, the output is closed within 1 μs. Figure 8 provides examples of how to use a single power supply to implement this function. Figure 9 gives a dual -power application circuit. To restore the output to the enable state, it should be disconnected (open) E/S pins or pull it to at least (v-)+2.4V. It should be noted that the E/S pins (output enabled) will not be disabled in internal heat shutdown.

The heat shutdown status When the mold temperature reaches about 160 ° C, the internal heat shutdown circuit is closed and the output is turned off. When the mold cools to 140 ° to 140 ° Reset when C. You can monitor the E/S pins to determine whether to shut down. During the normal operation, the voltage on the E/S pins is usually higher than the negative rear rail 3.5V. Once a shutdown occurs,The voltage drops to about 350mV above the negative.

FIG. 10 gives an example of monitoring and shutdown in a single power application. Figure 11 provides a dual -power circuit. External logic circuits or LEDs can be used to indicate whether the output has been hotly shut down, see Figure 16.

Output disable and heat shutdown status

As mentioned earlier, OPA548 output can be disabled, and the disable state can be monitored at the same time. Figure 12 and 13 provide examples of connecting E/S pins when using single power and dual power supply.

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, if the current is required to drive the current to the network 548, the current may be introduced into the network 548. FIG. 14 shows the output series R/C compensation (buffer) network, which usually provides excellent stability.

When a large -driven capacitance load (u0026 gt; 1000PF) or perceptual load (a load separated by a motor, a load separated by a long cable to the amplifier), the buffer circuit can also improve stability. Usually, 3 u0026#8486; to 10 u0026#8486; with 0.01 μF to 0.1 μF. Some loads may require some changes in the circuit value.

Output protection

The load that generates non -merit and electric momentum will 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 14. It is recommended to use the continuous rated value of 5A or larger Schottky rectifier diode.

Voltage source application

Figure 15 illustrates how to use OPA548 to provide an accurate voltage source with only three external resistors. First, select RCL of RCL according to the expected 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.

programmable power supply

using OPA548 can easily build a programmable source/receiver power supply. The output voltage and output current are controlled by users. As shown in Figure 16, the output voltage and current were used to use the potential meter, and FICS 17 uses DAC. LED instructions OPA548 connected to the E/S pins are in a hot shutdown state through the logic door.