ic-wkn 15V CW LASER DIODE DRIVER

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Lambert Caldwell
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1 Rev A1, Page 1/7 FEATURES Ë CW operation up to 300 ma from V supply voltage Ë Rapid soft start after power-on typical within 70 Ë Optimised for N-type laser diodes Ë Simple power adjustment via the external resistor Ë Control loop accuracy better than 1.5 % with changes in temperature, supply voltage and load current Ë Integrated reverse polarity protection for the ic and laser diode Ë Strong suppression of transients with very small external capacitors; integrated flyback path Ë Permanent shutdown with excessive temperature and overcurrent (i.e. if the laser diode is damaged or the feedback current path fails) Ë Two feedback inputs permit all current types to be used (M/P/N configurations) Ë Modulation via the feedback inputs is possible Ë Wide monitor current range from 2.5 µa to 6.25 ma APPLICATIONS Ë modules Ë Blue laser diodes PACKAGES SO8tp BLOCK DIAGRAM V 6 VCC A 7 CVCC CA..47 nf....1 µf.. TRANSIENT PROTECTION K 4 1 ic-wkn D - + VREF 0.5 V A CI K R NQ OVER CURRENT/ OVER TEMP. FEEDBACK MON. CI..100 nf.. RM kω CM 47 pf GND RGND 1 GND AGND Ω suitable laser diode configurations: N, P, M Copyright 2003, ic-haus

2 Rev A1, Page 2/7 DESCRIPTION ic-wkn is a driver for laser diodes in continuous wave operation with laser currents of up to 300 ma, which requires only four external components. The wide power supply range of up to 15 V allows for operation of blue laser diodes. The ic includes integrated circuitry protecting against destruction by ESD, excessive temperature and overcurrent plus a soft start of the regulator to protect the laser diode when the power supply is switched on. The ic also filters the laser diode power supply for transients. The regulator is adapted to the laser diode by an external resistor at A. The monitor current acts as a reference and is regulated independent of the influence of temperature and supply voltage (range: 2.5 µa to 6.25 ma). The capacitor at CI determines the control time constants and start-up time. A second monitor input, pin K, 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 persists 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. ic-wkn offers additional protection by means of spike detection at pin A. Should spikes or oscillation occur at pin A the power lockout is activated after a time-out. PACKAGES SO8tp to JEDEC Standard PIN CONFIGURATION SO8tp (top view) PIN FUNCTIONS No. Name Function 1 GND Ground 2 CI Capacitance for Power Control 3 AGND Reference Ground for CI, RM 4 K Monitor Input 2 ( Cathode, modulation) 5 A APC Setup, Monitor Input 1 ( Anode) 6 VCC V Supply Voltage 7 A Laser Supply ( Anode) 8 K Driver Output ( Cathode)

3 Rev A1, Page 3/7 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 V G002 I(VCC) Current in VCC ma G003 I(CI) Current in CI ma G004 I(A) Current in A ma G005 I(K) Current in K ma G006 I(A) Current in A ma G007 I(K) Current in K ma G008 I(AG) Current in AGND ma G009 I(GND) Current in GND ma E001 Vd() ESD Susceptibility at all pins MIL-STD-883, Method 3015, HBM 100 pf discharged through 1.5 kω 2 kv TG1 Tj Operating Junction Temperature C TG2 Tj Storage Temperature Range C THERMAL DATA Operating Conditions: VCC = V Item Symbol Parameter Conditions Fig. Unit Min. Typ. Max. T1 Ta Operating Ambient Temperature Range C T2 Rthja Thermal Resistance Chip/Ambient soldered to PCB, K/W no additional cooling areas 170 therm. pad soldered to approx. 2cm² cooling area 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.

4 Rev A1, Page 4/7 ELECTRICAL CHARACTERISTICS Operating Conditions: VCC = V, RM = 80 Ω..200 kω, Tj = C unless otherwise noted Item Symbol Parameter Conditions Tj Fig. Unit C Min. Typ. Max. Total Device 001 VCC Permissible Supply Voltage V 002 I(K)m Permissible Laser Drive Current power control range ma 003 Idc(VCC) Supply Current without load path closed control loop, I(K) = 0, I(K) = 290 ma ma 004 Ioff(VCC) Supply Current on Reset ma 005 Ir(VCC) Reverse Supply Current RM= 50 kω, VCC = -6 V -6 ma 006 ton() Turn-on Delay VCC: 0 5 V to 95 % I(K), I(K) = I(K)m; CI = 47 nf CI = 100 nf 007 Vc()hi Clamp Voltage hi at VCC, A I()= 10mA, other pins open V 008 Vc()hi Clamp Voltage hi at K V()< VCC + 1 V; I() = 10 ma, other pins open V 009 Vc()hi Clamp Voltage hi at K vs. A I()= 10mA, other pins open 8 1 V 010 Vc()hi Clamp Voltage hi at A, CI I() = 10 ma, other pins open V 011 Vc()lo Clamp Voltage lo at VCC, A, K, A, CI I() = -10 ma, other pins open -9 V Reference and Monitor Inputs A, K, AGND 101 V(A) Reference Voltage at A closed control loop, V(K) > Vs(K) mv 102 dv(a) Reference Voltage Temperature see µv/ C Drift at A 103 Ierr(A) Input Current in A closed control loop, I(K) = 0, I(K) = ma na 104 di(a) Input Current Temperature Drift in A see na/ C 105 APCerr Control Error RM = 10 kω, Tj = C RM = 10 kω, Tj = C 106 di(rm) Supply Voltage Suppression V(VCC): V, I(K) = 290 ma % % %/V 107 Rgnd() Resistor AGND-GND 3 Ω 301 Vf(K) Voltage at K Vf() = V(A) - V(K); V I(K) = 1 µa..1 ma 302 CR() Current Ratio I(A)/I(K) I(K) = 1 µa..1 ma I(K) = 1..6 ma 303 TC() Current Ratio Temperature Coefficient I(A)/I(K) Laser Driver A, K I(K) = 1 µa..1 ma I(K) = 1..6 ma 201 Vs(K) Saturation Voltage at K I(K) = 40 ma I(K) = 290 ma 202 di() Load Balancing Error I() = 20 ma, I(K): 20 ma 290 ma %/ C %/ C mv mv % 203 It(K) Overcurrent Threshold in K V(K) = V ma 203 It(K)m Maximum Overcurrent Threshold 1.2 A in K 204 toff() Overcurrent Reset Delay lack of feedback: I() = 0 bis I(K) = It(K); CI = 47 nf CI = 100 nf 205 Vf() Flyback Diode Forward Voltage K-A I(K) < 290 ma 1.3 V

5 Rev A1, Page 5/7 ELECTRICAL CHARACTERISTICS Operating Conditions: VCC = V, RM = 80 Ω..200 kω, Tj = C unless otherwise noted Item Symbol Parameter Conditions Tj Fig. Unit C Min. Typ. Max. 206 Rvcc() Transient Protection Resistor VCC to A 1.3 Ω 207 Vt(A) Shutdown Threshold at A t > V Control Release Flip-Flop 401 VCCen Set Threshold for Enable Flip-Flop Toff Overtemperature Shutdown C V

6 Rev A1, Page 6/7 DESCRIPTION OF FUNCTIONS Turn-on behaviour After switching the supply voltage on, the output stage remains disabled until the internal enabling flip-flop is set by a sufficiently high voltage at A. A quick soft start follows during phase I; the control capacitor CI is charged at an accelerated rate until the voltage at pin A reaches 1/3 of its nominal value. With V(A) > 1/3 V(A) nom phase II starts, the controlled start-up. The transition to CW operation (phase III) is gradual and primarily determined by the values of CI and RM. CI is properly dimensioned when the voltage overshoot at A is at a minimum. Turn-off behaviour ic-wkn works without a fixed undervoltage lockout, thus the laser diode forward voltage is the prime factor determining the lowest possible supply voltage. Fig. 1: Turn-on behaviour If the voltage drops below this value, the output stage is forcibly saturated and the laser current decreases. ic-wkn simultaneously discharges the control capacitor CI so that no excessive laser diode currents occur when the supply voltage rises again. Disruptions in operation The power control is shut down with excessive driver temperature or when the laser current reaches the overcurrent shutdown threshold, for example when the feedback is interrupted. If the monitor diode or the bias Fig. 2: Turn-off behaviour resistor RM fail, the device is shut down in less than 250, provided that the supply voltage applied is high enough. When modulating the laser current via pin K, excessive voltage occurring at pin A also may cause a shutdown. 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.

7 Rev A1, Page 7/7 APPLICATION NOTES Application notes on ic-wkn and data sheets of the demo board are available as separate documents. ORDERING INFORMATION Type Package Order designation ic-wkn WKN demo board SO8tp ic-wkn SO8tp WKN4D For information about prices, terms of delivery, other packaging options etc., please contact: ic-haus GmbH Tel Am Kuemmerling 18 Fax D Bodenheim GERMANY

ic-wkn 2.4V to 15V DC CW Laser Driver with High Laser Diode Driver Currents (IC Form)

ic-wkn 2.4V to 15V DC CW Laser Driver with High Laser Diode Driver Currents (IC Form) 2.4V to 15V DC CW Laser Driver with High Laser Diode Driver Currents (IC Form) 99-2-48 Rev 1 18/2/21 FEATURES CW operation up to 3 ma from 2.4 to 15 V supply voltage Rapid soft start after power-on typical