ONET1101L: ONET1101L

Rocky Isa

Part Number: ONET1101L
Other Parts Discussed in Thread: ONET4291VA

I Need to find a Laser driver that can output a low current. should be able to send out a current of around 5-20 mA as well as have a data rate of 1Gbps, I am having trouble reading the data sheets. Am i correct in understanding that the Bias Current would be the output current for the laser diode? This is for a Lidar TOF application i am working on.

over 5 years ago

0 Sriharsha Kota Pavan over 5 years ago

TI__Intellectual 1715 points

Hi Rocky,

Which type of Laser diode/TOSA are you using in your application?

We have specific laser driver devices for each of the DML, VCSEL or EML TOSA based applications at 1Gbps. I can recommend the best solution if you can specify your optics type and any other target specs you're looking for.

The Bias current is a DC output from the drivers to bias the Laser diode, while the MOD+/- are the modulation outputs used for modulating the laser.

Thanks,

Sri

0 Rocky Isa over 5 years ago in reply to Sriharsha Kota Pavan

Prodigy 150 points

Yes, the laser diode we are planning on using is a VCSEL, specifically, HFE6192-761. One target is trying to get the output current of the laser driver to the test current of the diode, which in HFE6192-761 is 6.5 mA. so if im not mistaken, the Bias current, which is DC, would be for Continuous wave, while the modulation current would be for pulsed lasers? In our application, we need a pulse width of under 10 ns. As we are making a product, we would want the power consumption to be at a minimum, so this is one of the reason why we want a low current, as the other reason is for safety reasons, we need to keep it at a class 1 laser. Thank you for your time.

0 Sriharsha Kota Pavan over 5 years ago in reply to Rocky Isa

TI__Intellectual 1715 points

Hi Rocky,

For a VCSEL-based application, please check out our ONET4291VA, the 4-Gbps capable VCSEL driver that can support data rates below 1-Gbps. The input to the driver (through DIN+/- pins) must be a modulating signal with the desired pulse width. The DC bias current output (BIAS pin) from the ONET4291VA is used to bias the VCSEL diode at the required optical average power output, while the modulation current output (MOD+/- pins) is to modulate the VCSEL around the bias point.

Hope this helps, please let me know for further questions.

Thanks,
Sri

0 Rocky Isa over 5 years ago in reply to Sriharsha Kota Pavan

Prodigy 150 points

What do you mean by the input to the driver must be a modulating signal with the desired pulse width? also, the DC current bias is to bias the diode at the required optical average power output. so under the specifications of the laser diode, the optical power is listed at 6 mW. The job of the DC bias current is to simply send out a current to start the laser diode into emitting at a power of 6 mW? is that correct?

0 Sriharsha Kota Pavan over 5 years ago in reply to Rocky Isa

TI__Intellectual 1715 points

Hi Rocky,

The input to the DIN+/- pins of the ONET4291VA must be the data signal at your desired speed. The ONET4291VA is just a driver that converts this into a modulation current with a peak-peak amplitude that is digitally tuned into the driver. Please read the datasheet of the driver for further details.

Your understanding about the DC current bias is correct.

Thanks,
Sri

0 Rocky Isa over 5 years ago in reply to Sriharsha Kota Pavan

Prodigy 150 points

A modulating current is for pulsing considerations, correct? And our desired speed would be our data rate or is our desired speed something else?

0 Sriharsha Kota Pavan over 5 years ago in reply to Rocky Isa

TI__Intellectual 1715 points

Yes, that is correct.
The desired speed would be your data rate.

0 Rocky Isa over 5 years ago in reply to Sriharsha Kota Pavan

Prodigy 150 points

Let me see if i got it. D+/D- is the voltage change from the input. as it passes through the driver, it will modulate it into a current(mod+/-). From the modulating current, it will either pulse(at mod+) or not pulse(mod-). Is that correct?