Hi all, I’m currently designing a circuit using the LZ1-00UBN0 LED. To accurately determine the maximum frequency at which I can drive it, I need to know its rise and fall times. I’ve looked through the datasheet but haven’t found those specific values. Does anyone have this information or know where I could find it? Any help would be greatly appreciated!
anson_0920
Thank you for contacting DigiKey , I am not seeing the info you are requesting on the manufacturer web site , below is a link for contact for the manufacturer to request this info .
Thanks Craig
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Hi anson_0920,
I believe that the typical applications for the LZ1-00UBN0-00Ux don’t require particularly high switching rates, so that characteristic isn’t specifically tested.
There is, however, a clue one can glean from page 4 of the datasheet about a lower limit to its maximum switching frequency. The “Forward Current pulsed” spec is tested with a pulse-width of less than 10μs. This implies that it can switch at better than 100kHz, and likely somewhat faster than that.
From page 4 of the LZ1-00UBN0 datasheet:
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Multiple inquiries on this specific matter have been received in the past day. Please note that it’s the same group of people addressing matters on this side of the screen, and that multiple posts on the same topic will not achieve an expedited response.
As David mentions, devices of the type are not typically used for communications or similar applications where frequency response is an issue, and therefore the products are not characterized by the manufacturer in manners associated with such use.
When using a device in a manner other than generally intended, the most appropriate course of action is to acquire a sample (or several) and measure the characteristic(s) of interest oneself. This allows the conditions of measurement to be aligned with the intended use case, and an appropriate delegation of the burden of inquiry. Further, since the transfer function of a system incorporating the LED in question would also be dependent to some degree on the receiver/detection element chosen, characterization of the system as a whole may be advisable.
Regarding pulsed current ratings, these most directly speak to a device’s internal thermal properties; as time scales involved approach zero, so does heat transfer to the surrounding environment. The limiting factor then becomes the ability of the active region in the device to absorb thermal energy without being damaged. While the manufacturer’s choice to characterize this limitation at a ~10us time frame may offer some hint at transfer function characteristics, it’s a very tenuous inference to make.
Hi David, thank you for your response! Just to confirm, if 100kHz is possible, then 1kHz and 10kHz should be no problem, correct?
Hi anson_0920,
Pretty much any LED can handle 10kHz for PWM purposes. I assume that’s what you plan with such frequencies.
You mentioned PWM. Could I also use a sinusoidal current modulation at 10kHz, or is square wave PWM generally preferred/required?
Hi anson_0920,
PWM square waves are generally used because they are much easier to produce than sinusoidal current modulation schemes. That being said, I can think of no reason why you couldn’t use sinusoidal current modulation. And, depending on how the sinusoid was produced, it would likely result in lower noise, so that would be a bonus.
The one thing I can think of which might be worse would be that since, by definition, the current would only be at the peak value for a brief moment during the sine wave, you would not be able to get maximum output from your LED. That could mostly be corrected for if you could amplify and clip the wave or amplify and compress the wave to provide more time near the peak current value.
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