VT5376 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'VT5376' PDF : 24 Pages View PDF
Laser
6
Laser
VT5376
6.1
Direct laser drive and calibration
The sensor includes a 7-bit DAC and an output current source.
The DAC value must be set using two I2C commands after power-up (default is MIN =
3.4mA, with Rbin = 12KΩ).
To allow VCSEL output power measurements to be done, the user can set the laser out
(normally strobed during operation) to be continuously on using an I2C command. This
feature is optional and is designed to offer maximum flexibility.
Alternatively, the Idac maximum (up to 13 mA) and minimum values can be changed by
adjusting the Rbin value (for example, with Rbin = 24 KΩ, Idac max = 5 mA and Idac min =
1.7 mA).
Idac max is set by the formula:
Idac (max) = 120/Rbin (result in mA, Rbin in KΩ)
No external driver is required, just a FET power switch controlled by LASER_NEN signal.
Figure 8. Application schematics using Laser or LED (driven with internal DAC or external
current source)
Laser system driven by internal DAC LED system driven by internal DAC LED system driven with external drive
laser_selected = 1
VTOP
laser_selected = 0
led_dac_driven = 1
VTOP
laser_select = 0
led_dac_driven = 0
36X trk_led (active high)
VTOP
LASER_NEN
LASER_NEN
LASER_NEN
LED
LASER_OUT
laser
LASER_OUT
LED
LASER_OUT
RBIN
VD5376
RBIN
VD5376
RBIN
VD5376
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Doc ID 13939 Rev 4
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