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3

Analog Technologies

Evaluation Board for ATLS1A103D

ATLS1A103DEV1.0

The schematic is shown in Figure 7 below.

VPS 12

PGND 11

LDC 10

LDA 9

TMP O

8

LPGD

7

SDN

1

GND

2

2.5VR

3

LILM

4

LIS

5

LIO

6

U1

ATLS 1A103

1

SDN

1

GND

1

3

W1 22 K

1

3

W2 22 K

1

2.5VR

1

LILM

1

LIS

C1

1u F

LED

Green

1

LPGD

1

TMP O

1

LDA

1

PGND

1

VPS

SDN1

2.5VR

SDN

LILM

LIO

VPS

LDA

TMPO

LP GD

1

LIO

LIS1

LIS

1

2

R1 10 K

1

2

R5 10 0K

R4

25 0

1

2.5VR

1

LDC

LDC

1

GND

1

GND

VPS

SDN

2.5VR

LIS

LIO

LILM

1

2

TB 2

1

2

3

4

5

6

7

8

TB 1

TMP O

LP GD

AMMTR +

AMMTR -

LDA

LDC

1

2

3

4

5

6

7

8

TB3

1

LISSET

LISS ET

1

2

R3

10 0

1

Q

MMB T64 28

C2

1u F

VPS

1

2

D1

1

2

D3

1

2

D5

1

2

D2

1

2

D4

LDA

AMMTR +

AMMTR -

1

AMMTR +

1

AMMTR-

1

0

LDC

1

GND

LISS ET

S1 A

S1 B

S1 C

S1 D

S1 E

8

9

S1 G

7

10

S1 H

S1 F

Figure 7. Schematic of ATLS1A103DEV1.0

GETTING STARTED

1. Hook up the power supply. There are 2 solder pads in the

upper center area on the edge for connecting the power

supply voltages. The connection can be done by clipping or

soldering on the pads, or use the screws to lock in 2 wires

through the terminal block TB2, see Figure 1. Usually the

power supply is set to 5V. If the output maximum voltage is

for sure know to be always at low value, such as 2.5V, a

power supply of about having 1V higher voltage than the

maximum output voltage, i.e. 3.5V, can be used. When

using a lower voltage power supply, the power

consumption of the controller will get smaller, thus, the

controller will be working under lower temperature rise.

2. Check the voltage reference. Use a voltmeter to check the

voltage reference pin 2.5VR having an accurate 2.5V.

3. Turn on and off the controller. This can be done by either

turning off the power supply or turning off the shut-down

pin of the controller. To do the latter, turn the switch S1H

to its upper position to turn off the controller, which shorts

circuit the shutdown pin SDNG to the ground, or turn the

switch S1H to its lower position to turn on the controller, at

this time, this pin is pulled high, 4.6V.

4. Monitor the output current by using the LIO pin voltage.

Measuring the voltage of the LIO pin using a voltmeter

(measure between the LIO pin and the ground node) will

allow monitoring the output current. The relationship

between the LIO voltage and the output current is linear:

maximum current of the laser driver in the evaluation board,

LIO stands for the voltage at the LIO pin.

5. Monitoring the output current directly by using an

Ammeter. Comparing with the approach to measure current

by measuring the voltage of LIO pin as described above,

Measuring the output current directly by using an Ammeter

is not recommended when a real laser is connected, because

these potential problems:

A. The Ammeter brings in EMI (Electro-Magnetic

Interference) noise.

B. The Ammeter has voltage drop, which decreases the

maximum output voltage.

C. If the Ammeter is not connected well or there is an

intermittent disconnection at any portion of the

circuit, the real laser may be damaged permanently.

If the user really needs to do it in this way, this is the

procedure to do so:

A. Use the terminal block on the right side, the 3rd and the

4th conductors, insert the Ammeter between AMMTR+

pin and AMMTR

− pin.

B. Turn the switch S1F to its lower off position, thus the

output current goes through the ammeter and can be

measured by reading Ammeter’s value.; when the

switch S1F is placed in the upper on position, the

ampere meter is shorted, thus, it does not measure the