RTQ2104-QA is a peak current mode synchronous BUCK converter with AEC-Q100 Grade 1 certified, the operating voltage range is 3V-36V, which can be resistant to the 122V voltage impact caused by the throwing effect, the output voltage range is 0.8V-VIN, The load capacity is 3A, operates with a frequency of 2.1MHz and supports the frequency of operation mode to improve electromagnetic compatibility efficiency in the work, with minimal on-time on 60ns, and maintain the fixed frequency operation under high pressure reduction, support 100% The duty cycle's upper bridge is directly connected to the working mode, providing the model optional light load PSM or forces the PWM mode of operation, which is easy to perform timing design, and the power good output, which is a vehicle electronic product and high reliability industrial control. Ideal for products.
I have said so much, some people may think that RTQ2104-qa will be very complicated, but in fact, if standing on the user's position, RTQ2104-qa is very simple, this can be seen from the following schematic I saw it:
This is the two schematic provided by the specification, which may have an output capability of 12V / 3A and 5V / 3A, and the available models of the main peripheral components are also given example, and there is no special requiring readers can be used directly. The EN end in the two circuits is directly connected to the VIN input, and thus power is powered and output. If it is necessary to perform timing management, the EN side needs to add control signals. The PGOOD output also needs to add pull-up resistors to provide the correct status information, otherwise it is in the state uncertain floating state, because it belongs to the open drain output, IC There is no design to provide potentials to any design for the potential to determine.
The above figure shows that the package information and pin arrangement of RTQ2104-QA, the information of the Exposed PAD indicates that the bottom of the package is a exposed heat dissipation pad, and it is connected to the copper foil on the PCB to strengthen heat dissipation. Effects, in particular, it is recommended to direct heat to the other side of the PCB to improve heat dissipation. This Exposed PAD is integrating with GND PAD, and the PCB design is just a GND connection with 2 feet, and the LC circuit and input capacitance of the SW and VIN pin next to it are just pull back. Connected to this Exposed Pad, so that it has formed extremely short and thick way, a simple, performance-effective design immediately formed, as shown below:
This is a PCB layout provided in the specification, the best VIN / GND connection position in the figure is the left side of CIN1, the best output connection position is the left side of COUT2, the best sampling point of the feedback signal in Cout2 The lower end is left behind. Since this is the design of EVB, the board is all GND copper foil. In the actual application design, such paving the copper design is easy to think that there is a connection load, if it is true. Just disrupt the direction of the current, bringing some users who don't want, so specific design needs to have corresponding changes.
RTQ2104-QA specification provides a test result of a radio frequency radiation, as shown below:
I estimate that this result is tested on the PCB shown above, where the strongest part of the signal appears at 2.xmHz, and it is obviously not the strongest in a single frequency, this is because RTQ2104-QA uses the exhibition Frequency working mode results.
The maximum operating frequency of the modem audio broadcast is located at 1.8MHz. In order to avoid interference to the work of the modem radio on the car, the operating frequency of the RTQ2104-QA is set to 2.1MHz + 6% change range, this change is It is in progress so that the actual operating frequency becomes a narrowband of 2.226 MHz. Since the operating frequency is constantly changing, the energy of RF radiation will not accumulate in a frequency, thereby bringing the result of single-frequency point radiation power reduction, but the test data above is not about RF power, it is directly measured. It is an electric field voltage of the radio frequency radiation signal, which can be transformed with each other.
In the introduction of the article, there is no problem with soft start, but the RTQ2104-QA is soft and started. Its soft start time is 2ms, because it is internal design, users cannot regulate from the outside, but 2MS soft The start time is enough for general applications, and it is fully possible to avoid the startup process to bring a large current impact on the input. During the soft start, if the output is a pre-voltage offset, the PWM modulation system has no action before the feedback voltage of the internal soft start voltage exceeds the FB, so that the monotonicity of the startup process can be ensured.
In addition, as a car power conversion device that puts safety in the first place, RTQ2104-QA is in addition to the general various protection characteristics, it also has an adjacent pin short circuit does not cause a fire and other affordable design, paying attention to Security users can choose.
Reprinted from Richtektechnology.
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