iC-WK

2.4V CW LASER DIODE DRIVER

Rev A1, Page 1/12

FEATURES APPLICATIONS
° CW operation up to 60mA from 2.4..6V supply voltage ° Battery-powered LD modules
° Rapid soft start after power-on ° LD Pointers
° Simple power adjustment via the external resistor
° Control loop accuracy better than 1% with changes in
temperature, supply voltage and load current
° Integrated reverse polarity protection for the iC and laser
diode
° Strong suppression of transients with very small external
capacitors
° Integrated flyback path protects against transients PACKAGES
° Permanent shutdown with excessive temperature and
overcurrent (i.e. if the laser diode is damaged or the
feedback current path fails)
° Two feedback inputs permit all current LD types to be used
(M/P/N configurations)
° Modulation via the feedback inputs is possible
° Wide monitor current range from 10µA to 2.5mA
(MSOP8) SO8
° Extended temperature range available as an option

BLOCK DIAGRAM

+2.4..+5.5V 6 VCC LDA 7

CVCC CLDA

...47nF... ..1µF..

TRANSIENT
PROTECTION MDK 4
MD LD

MDA 5
-
+
VREF
0.5V
2
CI
1
D
LDK 8

R
NQ
iC-WK CI RM
200 ..50k
..100nF..
OVER CURRENT OVER TEMP.

1 GND 3
AGND
GND

suitable laser diode configurations: N, P, M

MD LD LD

MD LD MD

© 2000
iC-WK
2.4V CW LASER DIODE DRIVER
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DESCRIPTION
The iC-WK device is a driver for laser diodes in continuous wave operation which requires only four external
components. The broad power supply range of 2.4V to 6V and the integrated reverse battery protection allow
for battery operation with a minimum of two cells. A reversed battery connection destroys neither the iC nor
the laser diode.

The iC includes integrated circuitry protecting against destruction by ESD, excessive temperature and
overcurrent and a soft start which regulates the power and protects the laser diode when the power supply is
switched on. The iC also filters the laser diode power supply for transients.

The power supply is regulated and adapted for the laser diode used by an external resistor at MDA. The
monitor current acts as a reference and is regulated independent of the influence of temperature and supply
voltage (range: 10µA to 2.5mA). The capacitor at CI determines the recovery time constants and start-up time.

A second monitor input, pin MDK, allows the driver to be used for other types of laser diode configuration;
alternatively, it can be used as an analog modulation input (DC to a few kHz).

In the event of failure, such as overcurrent in the laser path with a lack of feedback, for example, a quick
power lockout is activated. The shutdown continues until power is reapplied, permitting a restart. The strain
on power packs and batteries is relieved and the laser class is retained even in the event of a disturbance.

PACKAGES SO8, MSOP8 to JEDEC Standard

PIN CONFIGURATION SO8 PIN FUNCTIONS
(top view) No. Name Function

1 GND Ground
2 CI Capacitance for Power Control
3 AGND Reference Ground for CI, RM
4 MDK Monitor Input 2
(MD Cathode, modulation)
5 MDA APC Setup, Monitor Input 1
(MD Anode)
6 VCC +2.4 .. +6V Supply Voltage
7 LDA Laser Supply (LD Anode)
8 LDK Driver Output (LD Cathode)

PIN CONFIGURATION MSOP8 (3mm)

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2.4V CW LASER DIODE DRIVER
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PACKAGE DIMENSIONS SOP8 (in mm)

Min. Max.
A 4.8 4.98
B 1.27 BSC
C 0.35 0.49
D 0.53 REF
E 3.81 3.99
F 5.8 6.2
G 0.1 0.25
H 1.1 1.65
I 1.35 1.75
J 0.19 0.25
K 45 DEG
L 0.41 1.27
M 0 DEG 8 DEG

PACKAGE DIMENSIONS MSOP8 (in mm)

Min. Max.
A 2.9 3.1
B 0.65 BSC
C 0.33
D 0.525
E 2.9 3.1
F 4.75 5.05
G 0.05 0.15
H 0.78 0.94
I 1.1
J 0.1
K 9 DEG 15 DEG
L 0.4 0.7
M 0 DEG 6 DEG
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2.4V CW LASER DIODE DRIVER
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ABSOLUTE MAXIMUM RATINGS

Beyond these values damage may occur; device operation is not guaranteed.
Item Symbol Parameter Conditions Fig. Unit
Min. Max.
G001 VCC Voltage at VCC -6 6 V
G002 I(VCC) Current in VCC -70 70 mA
G003 I(CI) Current in CI -10 10 mA
G004 I(LDA) Current in LDA -70 70 mA
G005 I(LDK) Current in LDK -70 70 mA
G006 I(MDA) Current in MDA -10 10 mA
G007 I(MDK) Current in MDK -10 10 mA
G008 I(AGMD) Current in AGND -10 10 mA
E001 Vd() ESD Susceptibility at all pins MIL-STD-883, Method 3015, HBM 2 kV
100pF discharged through 1.5kS
TG1 Tj Operating Junction Temperature -40 150 °C
TG2 Tj Storage Temperature Range -40 150 °C

THERMAL DATA

Operating Conditions: VCC= 2.4..5.5V

Item Symbol Parameter Conditions Fig. Unit
Min. Typ. Max.
T1 Ta Operating Ambient Temperature -25 85 °C
Range
(extended range on request)
T2 Rthja Thermal Resistance Chip / Ambient SO8 package, soldered on PCB, 140 K/W
no additional cooling areas

All voltages are referenced to ground unless otherwise noted.

All currents into the device pins are positive; all currents out of the device pins are negative.
iC-WK
2.4V CW LASER DIODE DRIVER
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ELECTRICAL CHARACTERISTICS

Operating Conditions: VCC= 2.4..5.5V, RM= 200S..50kS, Tj= -40..125°C unless otherwise noted
Item Symbol Parameter Conditions Tj Fig. Unit
°C Min. Typ. Max.
Total Device
001 VCC Permissible Supply Voltage 2.4 5.5 V
002 I(LDK) Permissible Laser Drive Current power control range 5 60 mA
003 Idc(VCC) Supply Current closed control loop, I(MDK)= 0, 5.5 mA
without load path RM= 200S, I(LDK)= 60mA
004 Ioff(VCC) Supply Current on Reset 2.4 5 mA
005 Ir(VCC) Reverse Supply Current RM= 50kS -6 -3 mA
006 ton() Turn-on Delay Ü
VCC: 0V 5V to 95% I(LDK);
I(LDK)= 60mA, CI= 47nF 70 µs
I(LDK)= 60mA, CI= 100nF 150 µs
E001 Vc()hi Clamp Voltage hi at I()= 10mA, other pins open 6 9 V
VCC, LDA, MDK
E002 Vc()hi Clamp Voltage hi at LDK V()< VCC+1V; I()= 10mA, 6 9 V
other pins open
E003 Vc()hi Clamp Voltage hi at MDA I()= 10mA, other pins open 1.4 4 V
E004 Vc()hi Clamp Voltage hi at CI I()= 10mA, other pins open 1.1 3.5 V
E005 Vc()lo Clamp Voltage lo at I()= -10mA, other pins open -9 V
VCC, LDA, MDK, MDA, CI
Reference and Monitor Inputs MDA, MDK, AGND
101 V(MDA) Reference Voltage at MDA closed control loop, 480 500 530 mV
V(LDK) >Vs(LDK)
102 dV(MDA) Reference Voltage Temperature see 101; 120 µV/°C
Drift at MDA
103 Ierr(MDA) Input Current in MDA closed control loop, -300 300 nA
I(MDK)= 0, I(LDK)= 20..60mA
104 dI(MDA) Input Current Temperature Drift see 103; -2 2 nA/°C
in MDA
105 APCerr Control Error RM= 10kS, Tj= 0..70°C 0.3 %
RM= 10kS, Tj= -25..85°C 1 %
106 dI(RM) Supply Voltage Suppression Ü
V(VCC): 2.4V 5.5V, -1 1 %
I(LDK)= 60mA
107 Rgnd() Resistor AGND-GND 3 S
301 Vf(MDK) Voltage at MDK Vf()= V(LDA) -V(MDK); 0.55 2 V
I(MDK)= 1µA..1mA
302 CR() Current Ratio I(MDA) / I(MDK) I(MDK)= 10µA..1mA 0.98 1.02
303 TC() Current Ratio Temperature -0.005 +0.005 %/°C
Coefficient I(MDA) / I(MDK)
Laser Drive LDA, LDK
201 Vs(LDK) Saturation Voltage at LDK I(LDK)= 40mA 300 mV
I(LDK)= 60mA 400 mV
202 dI(LD) Load Balancing Error I(LD)= 20mA, -1 1 %
Ü
I(LDK): 20mA 60mA
203 It(LDK) Overcurrent Threshold in LDK 60 130 300 mA
204 toff() Overcurrent Reset Delay lack of feedback:
I(RM)= 0 to I(LDK)= It(LDK);
I(LDK)= 20mA, CI= 47nF 85 µs
I(LDK)= 20mA, CI= 100nF 170 µs
I(LDK)= 60mA, CI= 47nF 60 µs
I(LDK)= 60mA, CI= 100nF 130 µs
iC-WK
2.4V CW LASER DIODE DRIVER
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ELECTRICAL CHARACTERISTICS

Operating Conditions: VCC= 2.4..5.5V, RM= 200S..50kS, Tj= -40..125°C unless otherwise noted
Item Symbol Parameter Conditions Tj Fig. Unit
°C Min. Typ. Max.
Laser Drive LDA, LDK (continued)
205 Vf() Diode Forward Voltage LDK-LDA I(LDK)< 60mA 1.1 V
206 Rvcc() Transient Protection Resistor VCC vs. LDA 3 S
Control Release Flip-Flop
401 VCCen Set Threshold for Enable -40 1.2 1.9 V
Flip-Flop 27 1.0 1.7 V
125 0.6 1.2 V
402 Toff Overtemperature Shutdown 125 150 °C
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2.4V CW LASER DIODE DRIVER
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DESCRIPTION OF FUNCTIONS

Turn-on behavior 5.0V

V(VCC)
After switching on the supply voltage the output stage
0V
remains disabled until the internal enabling flip-flop is
set by a sufficiently high voltage at LDA. 5.0V
V(LDA)
0V
A quick soft start occurs during phase I; the control
capacitor CI is loaded at an accelerated rate until the 200µA
-I(MDA)
output stage supplies current at LDK. An open-circuit
0µA
voltage at pin MDA is used to verify the external
resistance. 0.6V
V(MDA)
0V
Phase 2, the initialization process, begins when current
Phase I Phase II Phase III
starts to flow at LDK. This phase ends when the laser 2.0V
reaches its threshold current and the monitor current V(CI)
produced raises the potential at resistor RM. 0V

60mA
The transition to CW operation (phase 3) is gradual and I(LDK)
primarily influenced by the CI and RM components. CI is 0mA
0s 10µs 20µs 30µs 40µs 50µs
correctly dimensioned when the voltage overshoot at t
MDA is at a minimum. Fig. 1: Turn-on behaviour

Turn-off behavior 5.0V

iC-WK functions without a fixed undervoltage lockout, V(VCC)
0V
thus the laser diode forward voltage is the prime factor
determining the lowest possible supply voltage. 5.0V
V(LDA)
0V
If the voltage drops below this, the output stage is
forcibly saturated and the laser current falls. In this 200µA
instance iC-WK simultaneously discharges control -I(MDA)
0µA
capacitor CI so that no excessive laser diode currents
occur when the supply voltage again rises. 0.6V
V(MDA)
0V
Phase IV Phase V
Disruptions in operation 2.0V
The power control is shut down with excessive driver V(CI)
0V
temperature or when the laser current reaches the
overcurrent shutdown threshold, for example when the 60mA
feedback is interrupted. If the monitor diode or the I(LDK)
0mA
preset resistor RM fail the device is shutdown in less 100µs 150µs 200µs 250µs 300µs
than 0.25ms, provided that the supply voltage applied is t
high enough. Fig. 2: Turn-off behaviour
 iC-WK
2.4V CW LASER DIODE DRIVER
Rev A1, Page 8/12

APPLICATIONS INFORMATION

+VB +VB

C2 C2
100nF 100nF

C3 C3
100nF 100nF C1
C1
1µF 1µF

C4 C4
2.2nF 2.2nF

R1 R1
200 ...50k 200 ...50k

Fig. 3: circuit for N-type laser diodes (cathode MD to Fig. 4: circuit for P-type laser diodes (anode MD to
anode LD) cathode LD)

+VB

C2
100nF

C3
100nF C1
1µF

C4
2.2nF

R1
200 ...50k

Fig. 5: circuit for M-type laser diodes (common Fig. 6: using the second monitor input as a switching
cathode for LD and MD) input (N-type lasers)

+VB

C2
100nF
1 GND LDK 8
GND

J
I
2 CI LDA 7

C3 C1
100nF 1µF C4
2.2nF
+ -
3 AGND 6
VCC
0.5V

4 MDK MDA 5
iC-WK R1
200 ...50k

Fig. 7: using the second monitor input for modulation Fig. 8: using both monitor inputs to amplify the current
(N-type lasers) (N-type lasers)
 iC-WK
2.4V CW LASER DIODE DRIVER
Rev A1, Page 9/12
+VB
+6V
C2
C2 100nF
1 GND LDK 8 1 GND LDK 8
100nF
LED1

J J
I C3 I
2 CI LDA 7 100nF 2 CI LDA 7
C3 C1
100nF 1µF
+ - C1
C4 + - 100µF
3 AGND 6
VCC
2.2nF 3 AGND 6 C4
0.5V 2.2nF
VCC
0.5V
R1
200 ...50k
4 MDK MDA 5
iC-WK 4 MDK MDA 5
iC-WK R1
200 ...50k
ZD1 Q1
1.8V BD...
0V 1 GND LDK 8 C5 R2
100nF
GND 200 ...

2 CI
I
LDA 7
Fig. 10: circuitry for higher laser diode currents
C6
(60mA..4A) using an external power transistor
100nF
+ -
3 AGND 6
VCC
0.5V
+VB

C2
MDA
100nF
4 MDK 5
1 GND LDK 8
iC-WK R2
200 ...50k R2 LED1
GND 200 ...
J
I
2 CI LDA 7

Fig. 9: safety circuit with a second iC-WK monitoring + -

C1
100µF
the optical output power 3 AGND 6 C4
2.2nF
VCC
0.5V

4 MDK MDA 5
iC-WK R1
200 ...50k

Q1

C3
100nF

Fig. 11: circuitry for higher laser diode currents

(60mA..4A) using an external power MOSFET

Dimensions for external components

Component Range Comments

C1 100nF..1µF filter capacitor for the laser diode supply

C2 (0)..100µF optional, may be omitted if C1 offers sufficient filtering

C3 22nF..220nF selection depends on laser diode operated

ca. 100nF example: I(LDK) / I(MD)= 35mA / 0.25mA

C4 1nF..10nF optional, additional ESD protection capacitor

R1 200S..50kS selection depends on laser diode operated

ca. 2kS example: R1= V(MDA) / I(MD)= 0.5V / 0.25mA = 2kS
 iC-WK
2.4V CW LASER DIODE DRIVER
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DEMO BOARD

iC-WK comes with two Demo Boards (6.25mm x 20mm) for test purposes. The following figures show the
circuitry and the top and bottom of the test boards (layout are on a scale of 4:1).

+V
C2

n/a GND LDK 8

-V C

C4

J n/a
I
2 CI LDA 7 LA
C3 C1

100nF 1µF
+ -
3 AGND 6 PD
VCC
0.5V

4 MDK MDA 5
iC-WK R1
4.7k

P1
10k

Fig. 12: schematic diagram of demo board WK1D for P-/M-type laser diodes

Fig. 13: demo board WK1D (top side) Fig. 14: demo board WK1D (bottom side)
 iC-WK
2.4V CW LASER DIODE DRIVER
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+V
C2

n/a GND LDK 8

-V LK

C4

J n/a
I
2 CI LDA 7 C
C3 C1

100nF 1µF
+ -
3 AGND 6 PD
VCC
0.5V

4 MDK MDA 5
iC-WK R1
4.7k

P1
10k

Fig. 15: schematic diagram of demo board WK2D for N-type laser diodes

Fig. 16: demo board WK2D (top side) Fig. 17: demo board WK2D (bottom side)
 iC-WK
2.4V CW LASER DIODE DRIVER
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ORDERING INFORMATION

Type Package Order designation

iC-WK SO8 iC-WK SO8
MSOP8 iC-WK MSOP8

WK demo board for P-/M-type lasers WK1D DEMO

WK demo board for N-type lasers WK2D DEMO

For information about prices, terms of delivery, other packaging options etc., please contact:

iC-Haus GmbH Tel +49-6135-9292-0

Am Kuemmerling 18 Fax +49-6135-9292-192
D-55294 Bodenheim http://www.ichaus.com
GERMANY

This specification is for a newly developed product. iC-Haus therefore reserves the right to modify data without further notice. Please contact
us to ascertain the current data. The data specified is intended solely for the purpose of product description and is not to be deemed
guaranteed in a legal sense. Any claims for damage against us - regardless of the legal basis - are excluded unless we are guilty of
premeditation or gross negligence.
We do not assume any guarantee that the specified circuits or procedures are free of copyrights of third parties.
Copying - even as an excerpt - is only permitted with the approval of the publisher and precise reference to source.