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Analog Technologies

ATLS1A201D

Constant Current Laser Driver

Driving High Voltage Laser Diodes

Some laser diodes have high forward voltage, such as 7V,

while the laser driver ATLS1A201D has a maximum output

voltage of 4V. This section tells a way to drive such laser

diodes by using this laser driver.

The schematic is shown in Figure 7. Where Power Supply 1

is the power supply for the laser driver, Power Supply 2 is for

increasing the laser driver's maximum output voltage.

Please notice that the power on sequence has to be in this way:

turn on Power Supply 1, turn on Power Supply 2, then turn on

the laser driver by driving SDN (Shutdown) pin to logic high.

The sequence for turning off the laser circuit is: turn off the

SDN pin by pulling it down to the logic low, turn off Power

Supply 1, then, turn off Power Supply 2.

To make sure the circuit works ok: turn on the laser, measure

LDA voltage, it should be between 1V to 3V, at room

temperature, the ideal LDA voltage is around 2V.

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