ST1CC40DR - Free wheel diode

i_mohiddin2003 · ‎2016-07-05

Posted on July 06, 2016 at 01:53

I have been looking for the best buck converter for my project that is to use as constant current source for 1.6Watt laser diode.

While surfing the STmicroelectronics website I got many options for the same. In which I happened to choose the above mentioned IC.

While using the software from the website for the design, for my surprise the software gave me the schematic diagram for my required inputs.

But the problem was, I have not seen any free wheel diode in the schematic. I dont know any buck converter exists without any free wheel diode along with the inductor.

My inputs are 7.4v~8.4v and the diode forward voltage is 4.7v. and the constant current required is 1.8A.

Please clarify my doubt. Thanking you sir,

#st1cc40dr

Patrizia BELLITTO · ‎2016-07-06

Posted on July 06, 2016 at 09:50

Hello,

ST1CC40DR is a synchronous rectifier, i.e., the low side switch is embedded inside the device.

If you prefer, there are other ICs that, for your specifications, allow to create a LED driver application with the external switch diode, as LED5000 or LED6000.

You can have a complete view using the eDesignSuite module where you can filter and select the right device according your specs:

/analogsimulator/flex_app/bin/smps_app_LED_spec.html?msg=%7b%22action%22:%22new_design%22%7d

Best regards,

Patrizia Bellitto

eDesignSuite developers team

i_mohiddin2003 · ‎2016-07-07

Posted on July 07, 2016 at 16:07

Dear Sir,

Thank you for the quick reply. I have checked LED5000, while doing the design using the software it is not allowing me to go below 50% inductor ripple. I want almost no ripple on the laser diode. Laser diodes are very sensitive on current.

Where as ST1CC40DR allows me 10% ripple on inductor current. Can i use synchronous rectifier buck converter for highter currents like 2 to 3 amps instead non-synchronous buck converters?

Best Regards,

Imran Mohammad

Patrizia BELLITTO · ‎2016-07-14

Posted on July 14, 2016 at 15:37

Dear Sir,

in attachment the answer from our application engineer, Paolo Scaramuccia

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Attachments :

led5000.docx : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006HzDL&d=%2Fa%2F0X0000000bIU%2Fge11URBEDhXlAPxRNDXH4uSTjcJTSgFQuJTMNPdl8Ew&asPdf=false