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Analog Technologies
ALDD28V15A401
Digital High Voltage Constant Current 15A Laser Driver
Figure 2. Pin Names and Locations
Figure 2 is the top view of the ALDD28V15A401, which
also shows the pin names and locations. Its thickness is
17mm. The pin functions and specifications are described in
Table 1 below. Note that the metal case is internally
connected to ground.
Table 1.Pin Function Descriptions
Pin
#
Name Type
Description
1 LIO
Analog
Output
Laser Current Output indication. 0.1V to 4.096V indicates the laser current being from 0 to
15A linearly.
2 LIS
Analog
Input
Laser current low value setting voltage. There is a 10M
Ω
input resistor tied to GND. Setting
it from 0.1V to 4.096V will set the laser lower current from 0 to 15A linearly. The laser driver
will output the current set by this pin. The input bias current of this pin is < 0.1
μ
A.
3 4VR
Analog
Output
Voltage Reference 4.096V output. It can source and sink up to 10mA output current, with a
very low 5
μ
V
P-P
noise between 0.1 to 10Hz and < 6ppm/
°
C stability. Under Standby Mode,
this pin is still working.
4 GND
Signal
Ground
Signal Ground pin. Connect ADC and DAC grounds to here. When using POTs
(potentiometer) to set the output currents, connect the ground terminal of the POTs to here.
5 EN
Analog/Digital
Input
Standby and Shutdown Control. This pin has three states: between 0V
∼
0.3V, it shuts down
the entire laser driver; between 0.5V
∼
1.2V, it sets the laser driver to standby mode; between
1.5V
∼
28V, it sets the laser driver to operation mode. The input current on this pin is < 2µA.
6 LPGD
Digital
Output
Loop Good indication. When the laser driver's output current equals the set-point current
value, and there is no short nor open circuit at the output, this pin is pulled up high by an
internal 3k
Ω
resistor to an internal 5V power supply as shown in Figure 3; when the output
current is not equal to the set-point current, such as there is an open circuit at the output, or
the load has too high a resistance that even the output voltage reaches the power supply
voltage, the output current is still lower than the set-point value, this pin is pulled low by an
open drain MOSFET of which Rdson < 500
Ω
. When outputting the low value, the sinking
capability is < 0.5V at 1mA.
7 LDA
Analog
Output
Laser Diode Anode. Connect it to the laser diode anode terminal. The maximum current of
this pin can go up to 15A. When doing layout, do not use a thin and long PCB track,
otherwise, the inductance might be too high, and oscillation may occur.
8 LDC
Analog
Output
Laser Diode Cathode. Connect it to the laser diode cathode terminal. The current on this pin
can go up to 15A. Use thick and short PCB track for this pin to minimize the inductance to
avoid oscillation or ringing. This pin has a low voltage potential, when the output current is
15A, the potential is 30mV above PGND.
9 PGND
Power
Ground
Power ground pin. Connect this pin directly to power supply return path line, 0V. The
maximum current on this pin can go up to 15A.
10 VPS Power
Input
Power supply voltage. The driver works from V
VPS
= 12V ~27V. The maximum current can
go up to 15A.
