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Comments by Claire
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New D24V150Fx 15A step-down voltage regulator family — our highest-power regulators yet!
- 9 December 2020Hi, John.
The soft-start circuit uses a capacitor to time how quickly to let the output voltage rise during startup. If you email us, I can send you a picture that shows where the soft-start capacitor is on the board.
-Claire
New adjustable voltage regulators with multi-turn fine adjustment
- 20 November 2020Hi, Ludovic.
Yes, a switch can be used to ground the EN line and put the regulator in low-power sleep mode. It is fine to adjust the output of the regulator while it is on. I am not sure I understand your question about offering an external potentiometer. You could remove and replace the on-board potentiometer. If the replacement potentiometer is not soldered directly to the board, I recommend keeping the connections as short as possible to minimize any issues.
-Claire
New products: G2 High-Power Motor Driver 18v25 and 24v21 (and price drops for other G2 drivers)
- 17 November 2020Hi, Terry.
As shown in the table in the Pinout section of each driver's product page, both the DIR and PWM pins are internally pulled low.
-Claire
New Product: 5V, 5A Step-Down Voltage Regulator D24V50F5
- 12 October 2020The D24V50F5 regulator could handle the possible 3A draw of the RPi 4B without additional cooling assuming room temperatures in free air. If you also want to power the motor driver and motors from the regulator, you might need something more powerful. It will depend on your input voltage and total load. If you want help determining if the D24V50F5 will work or selecting a different regulator, I recommend posting details about your system on our forum.
-Claire
New products: D36V50Fx Step-Down Voltage Regulators
- 2 October 2020The output of the D36V50F5 has one electrolytic capacitor with 10mohm ESR and several ceramic capacitors (which as you mentioned likely have an ESR up to 1mohm) all connected in parallel, so the total output ESR should be a bit less than 10mohms. Given that and a worst case of 2-4 amps of inductor ripple current the output ripple should be under 50mV.
I have been using output ripple a bit sloppily in these comments, and what I meant is the total peak to peak output variations which includes noise from the rest of the circuit and environment. This total figure is what I expect to be 100-150mV and that is why I expect extra capacitance to help, though the actual output ripple will probably stay basically the same. We only have a few step-down regulators capable of outputting 5A; D24V150F5, D36V50F5, D24V50F5, and D24V90F5. As mentioned in the other comment we do not have the output ripple or noise well characterized, but I do not expect the other two to be much better than 100mV total output fluctuation.
The electrolytic capacitor used on the D36V50Fx input is rated for 50V, which is the maximum voltage we list for that regulator. Note that that is not a recommended nominal operating point. Also, we did test at 50V and the performance data (like maximum continuous output current) for 50V that is given on the D36V50Fx product pages was drawn from that testing. It is the end system user's responsibility to ensure that the input voltage does not exceed the limit, and a safe operating margin will depend on the details of each application.
As for the input ripple current, the danger there is in making the capacitor too hot for too long and reducing its lifetime. The input capacitor used on the D36V50Fx regulators does have a fairly high ESR, but in testing in a variety of operating points, it did not get unusually hot. We have used the same capacitor on the inputs of several regulators with comparable current capabilities and have sold thousands of units over almost a decade and have not had complaints about short lifespan or units that seems to suddenly stop working after prolonged use, so we think it gives us a good balance of cost, size, and performance.
-Claire
New products: D36V50Fx Step-Down Voltage Regulators
- 21 September 2020Hi.
What comments on the D24V90F5 regulator's ripple are you referring to? Our D36V28F and D36V5Fx families operate in power save mode and we generally expect the output ripple to be as high as 100-150mV. They are fairly noisy for our regulators. That is not quite at the 1% mark, but you could add additional capacitance to the output to reduce it. We do not share specifics about the components used on these boards, but if your purpose in asking about the output capacitors is to see about replacing them to get lower ripple, adding large capacitors to the output would be much more effective.
The 4% accuracy specification is separate and refers to the typical output voltage which takes into account tolerances in various components on the board. We do not think of 4% as "so poor", but that specification is there partly because we are not interested in specifying (guaranteeing) these any tighter. What do you think is a normal or reasonable accuracy?
By the way, I am not sure where 880kHz is from, but as we list in the features section of the D36V28Fx and D36V50F regulator pages, they switch at around 500kHz.
-Claire
New version of the Zumo Shield for Arduino - now with full IMU!
- 24 August 2020Hi, Eduardo.
The IMU on the shield is powered from the 3.3V line of the Arduino, so it is separated from the motor voltage by a regulator. That should provide some isolation from noise on the motors, and in general we expect it to be good enough to do balancing with the Zumo. The Arduino library for our Zumo 32U4 robot includes a balancing example that you might be interested in.
If that did not answer your question or you would like help troubleshooting, our forum is a better place for an in depth discussion.
-Claire
New product: FEETECH FS90R Micro Continuous Rotation Servo
- 28 July 2020HI.
4.8V to 6V is the normal voltage range for standard RC servos including the FS90R. We do not carry a version of the FS90R servo with feedback. The only continuous rotation servo we carry with feedback is the Parallax Feedback 360° High-Speed Servo. Note that Parallax servo has an operating voltage range of 5.8V to 8.4V.
Depending on your application, you might also consider a brushed DC motor with an encoder. Some of our micro metal gearmotors are similar in torque and speed to the FS90R.
-Claire
Servo control interface in detail
- 8 May 2019Hi, Osvaldo.
It does not seem unusual for any electronics (especially a system involving a motor) to draw a spike of current on startup. We do not have any particular suggestions for reducing it, but you could power your servos in separate banks from two or three separate regulators. We generally recommend budgeting about 1A per standard size servo when selecting a supply, and you should try to use switching regulators rather than linear ones such as the 7805. Unfortunately, it is not common for servo manufacturers to share details about the control systems inside their servos.
-Claire
Electrical characteristics of servos and introduction to the servo control interface
- 5 March 2019Most RC receivers that are able to power servos do so by directly connecting the servos to your battery, so the receiver is mostly irrelevant to your question. You should just make sure the battery voltage and capacity are in line with the specifications of your sound system.
-Claire