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2

Analog Technologies

ATLS3A202D

Constant Current Laser Driver

switch mode power supplies, laser drivers, TEC controllers, etc. If other default

switching frequency is needed, please contact us, it can be specified from 300Hz to

700Hz.

3, 7

GND

Signal Ground

Signal ground pin. Connect POT (potentiometer), ADCs and DACs grounds to here.

4

2.5VR

Analog Output

Reference voltage. It can source 3mA max., with ＜5

and ＜25ppm/

°C (max.) stability.

5

LIS

Analog Input

Laser current setting voltage. There is an input resistor of 10M tied to GND on this

port. Setting it from 0V to 2.5V will set the laser current from 0A to 3A linearly.

6

LIO

Analog Output

Laser current output indication. 0V to 2.5V indicates the laser current being from 0A to

3A linearly.

8

LDGD

Digital Output

Laser diode good indication. When this pin is high, >2V, the control loop is working

properly. When this pin is low, <0.3V, the laser diode is bad, or there is a short or open

circuit at the laser diode.

9

LDA

Analog Output

Laser diode anode. Connect it to the anode of the laser diode.

10

LDC

Analog Output

Laser diode cathode. Connect it to the cathode of the laser diode.

11

PGND

Power Ground

Power ground pin. Connect this pin directly to power supply return terminal.

12

VPS

Power Input

SPECIFICATIONS

°C)

Parameter

Value

Unit

Laser driver efficiency

≥90

%

Maximum output current

3

A

Current output noise

4.37

@0.1Hz-

10Hz

Stability

±100

ppm/

°C

Laser current control signal level

0 ~ 2.5

V

Control accuracy

±0.2

%

Laser current indication signal level

0 ~ 2.5

V

Indication accuracy

±0.2

%

Output reference voltage

2.5

V

Power supply voltage range

3.0 ~ 5.5

V

Operating case temperature

−40 ~ 125

°C

Rise times of small signal

70

µS

Fall times of small signal

70

µS

Rise times of large signal

352

µS

Fall times of large signal

184

µS

OPERATION PRINCIPLE

The block diagram of the driver is shown in Figure 3. The shut

down control circuit accepts signals from 3 sources: external

shut down, over current and over temperature signals. When

one of these signals is activated, the driver is shut down. Only

when all these 3 signals go up, the soft start circuit starts

enabling the low noise driver.

It comes with a laser diode status indication circuit. When

LDGD pin is high, >2V, the control loop is working properly.

When this pin is low, <0.3V, the laser diode is bad, or there is a

short or open circuit at the laser diode.

The high stability low noise 2.5V voltage reference can be used

for setting the output current by setting the voltage on this LIS

pin, and also be used for the external ADCs and/or DACs as

voltage references.

An internal soft start circuit allows a slow start up and a quick

shut down for the laser control loop.

The current measurement circuit monitors the output current

and sets the current indication voltage on the LIO pin. The over

current protection circuit shuts down the driver upon detecting

the output current exceeds the pre-set value.