4

http://www.elm-tech.com

Rev.1.0

7 -

5

2

1

LD

MD

4

3

R1

power

adjust

D1

D2

0.1~10�F

C1

Fig.1

5

2

1

AMD

GND

IREF

VCC

ALD

0.1~10�F

LD

MD

4

3

R1

power

adjust

D1

D2

C1

R4

voltage shift for MD

Fig.2

■Appliation circuits

LDMs are used in many LD applications. A LDM contain a laser diode and a monitor diode in one package.

These two diodes are optically connected inside the package. The monitor diode is a PN diode generates photo

current to measure photo power from the LD.

ELM186CxA can drive 4 kinds of laser diode modules(LDMs) having different polarity pins.

Each ELM186CxA can drive only corresponding polarity of laser diodes(LD) and monitor diodes(MD). Table1

shows ELM186CxA and laser diode modules (LDM) combinations.

LD anode driving applications

ELM186C1A and C2A are used when LD anode is driven. ALD is NPN emitter follower output. LD anode

driving application only requires a resister for output power definition. Only a noise absorbing capacitor at VCC

is recommended.

Operation voltage is 5V or higher because it is necessary to have the sum of IC operation voltage and to LD

forward voltage. LD anode drive has advantages on heat dissipation and fewer RC parts. The cases of LD mod-

ules can be directly grounded in Fig.1 for good heat dissipation.

ELM186C2A needs to have a compensation capacitor and a resistor at KMD pin for stable operation in Fig.3

and Fig4.

LD anode driving application circuits Fig.1, Fig.2, Fig.3, Fig.4.

No.

Laser diode module pins

Parts number of ELM186CxA

1

: LD anode, common, MD anode

ELM186C1A(Fig.2) or ELM186C3A(Fig.6)

2

: LD anode, common, MD cathode

ELM186C2A(Fig.4) or ELM186C4A(Fig.8)

3

: LD cathode, common, MD anode

ELM186C1A(Fig.1) or ELM186C3A(Fig.5)

4

: LD cathode, common, MD cathode ELM186C2A(Fig.3) or ELM186C4A(Fig.7)

5

: Other LDM without a common pin

All ELM186CxA

Table 1 :

LD

MD

LD

MD

LD

MD

LD

MD

LD

MD