High current power amplifier PA04 and its application
1 Overview
PA04 APEX launched the United States as a power FET op amp, it has a high voltage (200V), output current (20A), high conversion rate (50V/μs), low distortion characteristics.
PA04 is very flexible to use. Sleep mode to protect the amplifier in standby operation or load protection allows low quiescent current. Its enhanced voltage input (VBOOST) to allow operation on the small signal section of the work at a higher voltage without the need for higher output current; PA04 precision sensor technology with four-limiting manner, without the need to consider Output line Connect mm internal or external coherent European-level resistance.
PA04 with 12-pin dual inline (DIP) packages, sealing, and insulation inside each other. The pin arrangement shown in Figure 1.
High current power amplifier PA04 and its application
The pin functions are as follows:
1 foot (-INPUT): the negative input terminal;
2 foot (+ INPUT): positive input;
3 feet, 4 feet (COMP): a phase compensation;
5 feet (-VBOOST): Negative enhanced voltage input;
6 feet (OUTPUT): negative power supply;
7 feet (-Supply): output;
8 foot (+ Supply): positive power supply;
9 foot (+ VBOOST): positive reinforcement voltage input;
10 feet, 11 feet (CURRENT, LIMIT): limit feedback input;
12 feet: hibernation control side.
When not using enhanced voltage input can be 5 feet, 6 feet and 8 feet, 9 feet were short.
2 Work
PA04 for the high current power amplifier. Because of its relatively large output current, which in ordinary settings, and use many different power amplifiers. Here on the working principle of PA04 and its external circuit in the application of issues needing attention and introduced the principles to do something.
2.1-limiting and current limiting resistor
PA04 pin 10 and pin 11 for the current feedback input connection circuit shown in Figure 2, the figure, the pin 11 and the amplifier output directly connected to pin 10 and limiting resistor connection. The benefits of such connections can bypass any other parasitic resistance. Limiting resistor must be connected to the position shown in Figure 2. Its size can be calculated by:
RCL = 0.76/ILIMIT
High current power amplifier PA04 and its application
2.2 Sleep works
Work in sleep mode, PA04 pin 12 and pin 9 connected, the internal amplifier to stop working, then the amplifier will be in hibernation. Sleeping approximately 3mA of current flow through the pin 12. Sleep mode when not in use, should pin 12 floating.
High current power amplifier PA04 and its application
There are many dormant circuit, shown in Figure 3 is a sleep circuit. Left logic circuits for the differential mode input signal, using transistor conduction and cut-off characteristics can be realized pin 9 and pin 12 is disconnected or connection control.
2.3 Enhanced input
PA04 pin 5 and pin 9 to enhance the voltage input (VBOOST) feet, with increased voltage input pin of the amplifier For most of the work in the high pressure with little in the high current state. Therefore, + VBOOST pin (pin 9) and-VBOOST pin (pin 5) is generally connected to the amplifier's small signal circuit, + Vs (pin 8) and-Vs (pin 6) was connected to a large current output. When the required output voltage is close to the power supply voltage (ie, lowering the pressure drop), can be applied in VBOOST pin 5V voltage (VBOOST = VS +5) to make the small-signal driving the output transistor saturation, while it can also improve the output voltage fluctuations. If you do not need to improve the output voltage fluctuations, + VBOOST pin and + Vs pin,-VBOOST pin and-Vs pin must be connected together, and VBOOST pin voltage must not be lower than the Vs pin voltage.
VBOOST = VS and VBOOST = VS +5 floating when the output voltage and output current relationship shown in Figure 4.
High current power amplifier PA04 and its application
2.4 Phase Compensation
PA04 phase compensation can be an external compensation capacitor and the compensation resistor to achieve. External compensation capacitor and the compensation resistor connected between pin 3 and pin 4, in Figure 5.
High current power amplifier PA04 and its application
The values of Rc and Cc can determine the size of the overall gain, shown in Table 1.
Table 1 Resistance of compensation and compensation capacitor value
Gain Rc Cc
1 470pF 120Ω
> 3 220pF 120Ω
≥ 10 100pF 120Ω
3 Typical Application
Figure 6 is designed to use PA04 sonar transducer drive circuit. Part of the circuit's signal source provided by the ultrasonic drive. Using PA04 high power-bandwidth and high output voltage performance of the circuit and through the icons match the transformer to drive the regulation of sonar transducers. The system load circuit for the resistive circuit. But when the control logic should be in hibernation off the op amp.
High current power amplifier PA04 and its application
4 Conclusion
PA04 with its small size, power-frequency bandwidth, output power and other characteristics of the motor drive, sonar transducers, programmable control power so on are widely used. As the device is FET devices, the impact is very sensitive to static electricity, so when in use and storage should pay attention to anti-static, so as not to damage the device.