The issue of maximum system power (current)

Hi bobber ,

According to the datasheet, this part is not designed for direct parallel operation, but might be paralleled using the LTC4370.

mike

Hi,mike 

thank you for response! i'm got it.

I'm also wondering, hasn't the customer never done this? Or is there any risk if you have experimental basis to do so? What are the specific risks?

Looking forward to a reply! Thanks!

bobber

Hi bobber ,

I cannot answer if customers have done this. I also can't answer the question about risks, but that load sharing part is a good one. Here is a good article regarding your particular use case. 

Is there a particular reason you are not using a directly parallelable contoller?

mike

Hi mike ,

i gor it! no worries,thank you for your replied!

Because this product comes from a few years ago, we want to try whether this parallel solution is feasible. The current demand changes require higher power, or do you have any recommended models here? It's best to be P2P!

Similar to laser pump drivers, do you have a better solution? I'm happy to discuss, thank you, thank you for your support!

bobber

Hi bobber ,

Sorry, don't understand P2P. Person to Person? Peak to Peak?

Anyway, ADI has hundreds of power supply solutions. From what little understanding I have of a laser diode is that you probably want a constant current source, like you would an LED driver. ADI has quite a few devices that have a current control loop in addition to the voltage control loop.

A few questions you would ask yourself:

Max current needed: 6A
Is that current in a pulse or continuous?
Vin and Vout?
Digital control?
Pulsed or not?
If so, what is duty cycle?
Protection?
Recovery?

Many LED drivers have a PWM feature, ostensibly for dimming, but maybe useful in your driver?

I would look here:

https://www.analog.com/en/product-category/led-driver-ic.html

And here:

https://www.analog.com/en/product-category/current-sources.html

Or, even here (subcategory of first one):

https://www.analog.com/en/product-category/led-flash-drivers.html

It can be a little daunting.

mike

Hi,mike

First of all,thank you for your detailed reply.

Sorry,i may not have made it clear. The p2p.....my meaning is pin to pin and need't modify the software.

Maybe the LTC1735's power is 1.5V x 15A?

Now we are using the LTC3310S,but the maximum current is 10A.I need  Synchronous Step-Down and the power is 30-35w,preferably compatible the LTC1735.

Vin is 5v ,Vout is 4-4.8V and the maximum current is 12-13A,the pump working operation at the QWC mode.

I will read through the materials you recommended carefully.Hopefully we can continue to communciate.Forgive me for clumsy english expressions.

thanke you!

bobber

Hi bobber ,

Huh, my cursory analysis suggests the LTC3310S might be the perfect solution, much better than the LTC1735, and you already have those? The LTC3310S an be directly paralleled for up to 40A operation (back of datasheet). Has 100% duty cycle operation for when output and input are the same: Extremely efficient in that situation.

OK, you are throwing out more jargon. :-) Assuming QWC mode is a pumped laser (oh man, haven't worked with lasers since I worked for a laser glass company in the late 80s). Parallel LTC3310Ss would be far superior to other solutions handling the pump (load) step.

What is the feature of the LTC1735 you like? Note that the load step response of paralleled LTC3350Ss will be very good as will be efficiency and thermal control. The more in parallel, the better.

There is also this article.

mike

Hi,mike

Sorry, I said the technical term....hhhh,the QCW is Quasi-Continuous Wave, QCW and CW is working opation mode .but it isn't important..

Back to the main topic,Our current products used LTC3310Ss, according to datasheet of LTC3310S,i got it that parallel schemes of LTC3310S.You are right！

The reason for asking about LTC1735,because our previous product used LTC1735,but we now have newer products used LTC3310S,emmmm,however, a parallel scheme was not adopted.The LTC3310S is enough for us to use.

As a side note, I previously worked in the automotive industry.My job is BMS(battery management system) hardware design,I am also in the process of learning about laser products now. It's a pleasure to communicate with you,we use a lot of ADI products, can we discuss other issues?

Thank you for your support!

Best regards!

Bobber

Hi bobber ,

Of course, good luck with your designs. QCW is interesting. I do believe the LTC3310S has become a popular driver for fiber lasers. Ah BMS, I was at Linear when the LTC680x battery stack monitors first came out…

Feel free to tag me in a question (type MStokowski ). I actually work with the LTspice team, monitoring the LTspice forum, but occasionally dip into the Power forum (since there's often a lot of overlap).

mike

Hi,mike

thank you very much!

It sounds like you are also an experienced engineer, and I am honored to communicate with you:)

Thank you for your support!

Best regards!

Bobber