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Analog Technologies

ATLS25A219GUI

32V 25A Constant Current Laser Driver

LASER

DIODES

ATLS25A219GUI

VPS

PGND

LDC 3

2

1

12V ~ 40V

POWER SUPPLY

4

LDA

Type-C

Mini

USB

Analog Circuit Setting

SBDN

Figure 11. Micro-Controller Based Application Schematic

Figure 10 shows a typical stand-alone application circuit.

Figure 11 shows a micro-controller based application

schematic.

Table 4 shows the relationship between Digital D1, D2, and

laser driver state. Refer to Figure 11.

Table 4.

Digital

Output

D1

Digital

Output

D2

Laser

Driver

State

0

0

Shutdown

0

1

Standby

1

0

Note

1

1

Operation

Note: For the input state D1=1 and D2=0, the controller's

state is depending on the output voltage at SBDN pin:

Digital signal V1 and V2 control the laser driver into Shutdown,

Standby or Operation mode. The starting up time delay is about

20mS and the shut down time is about 20µS.

It is worth mentioning that to achieve high speed and low

distortion digital modulation, one can use the LISL pin to set a

current that is a little lower than the threshold current of the laser

diode to turn off the laser beam, such as half of its value, use the

LISH pin to set the laser current when the laser diode is turned

on. In this way, the laser beam is turned on and off, while the

driver control loop is always kept on, so that the output stage is

always under control, not distortion is caused by turning on/off

the output stage.

When no modulation is needed, one can leave PCN unconnected;

LISL pin connects to GND, and use LISH to set the output

current.

In Figure 10, the LED is used to indicate laser diode status.

When LDGD pin is high, > 2V, the laser diode control loop is