DBD-R2V1 Analog Technologies, Inc. Dual Mode Bi-directional Dual Input Laser Driver Main features: dual control mode, bi-directional output, dual input mode (analog & digital), high precision, high reliability, and small package. Part number: Maximum output current on LDA and LDC: Output voltage range on LDA: Output voltage range on LDC: Laser current and power control accuracy: Laser current control resolution: Laser power control resolution: Laser current & power digital control signal: Laser current set-point voltage: Laser power set-point voltage: Laser current and power indication voltage: Laser current indication absolute accuracy: Current output noise: Soft-start rise time: Power input DC voltage: Operation mode: Operating temperature: Module dimension: DBD-R2V1 200mA 0.8V 8V -0.8V -8V 14bit 48.8µA/step 0.024%/step TTL, serial 0 to 2.5V 0 to 2.5V 0 to 2.5V ±0.2% 0.1% RMS 0.1 S 4.75V to 5.25V CC (Constant Current) and CP (Constant Power) -20°C to +85°C 25.5mm × 20 mm × 4.5mm Pin Descriptions Pin 1 SD, shut down, digital input, positive logic, >2.3V = shut down, <0.5V = enable, normal threshold voltage = 1V. The input current is between −1µA and 1µA. It is pulled down by a 20K resistor to ground. Pin 2 CLGD, control loop good indication, digital output. The maximum output current is 10mA. A HI level indicates control loop locked. Pin 3 GND, signal ground pin. Connect ADC and DAC grounds to here. Pin 4 2.5V, reference voltage, analog output. It is used by the internal DACs as the reference voltage. It can source and sink 5mA current with a maximum 20ppm/°C stability max. Pin 5 LIS, laser current set-point voltage, analog input. 0V to 2.5V sets the output current from 0 to 200mA linearly. The input impedance of this pin is 20KΩ. This pin can be set by an external analog signal source, such as the output of a closed-loop op-amp, POT, or DAC, or set by the internal DAC B and leave LPS pin unconnected. The internal DAC is connected to the reference voltage 2.5V, so that its full scale is 2.5V. 5 5 0 E . W eddell D riv e , S u ite 4 , S u n n y v a le, C A 9 4 0 8 9 , U . S . A . Tel.: (4 0 8 ) 7 4 7 -9 7 6 0 , F a x : (4 0 8 ) 7 4 7 -9 7 7 0 , W eb: w w w . a n a l o g t e c h n o l o g i e s . c o m Copyright 2000 – 2003, Analog Technologies, Inc. All Rights Reserved. 1 Analog Technologies, Inc. DBD-R2V1 Pin 6 LIO, laser current output indication, analog output. 0V to 2.5V indicates the laser current of from 0 to 200mA linearly. Pin 7 LPS, laser power set-point voltage, analog input. 0V to 2.5V sets the laser output power from 0 to the maximum value linearly. The input impedance of this pin is 20KΩ. This pin can be set by an external analog signal source, such as the output of a closed-loop op-amp, POT, or DAC, or set by the internal DAC A and leave this LPS pin unconnected. The internal DAC is connected to the reference voltage 2.5V, so that its full scale is 2.5V. Pin 8 LPI, laser power feedback input, analog input. High impedance input. The (positive-going) output of an external power sense photodiode amplifier should be connected to this pin. Maximum power for a given laser diode should correspond to 2.5 V. Pin 9 LDA, laser diode anode, analog output. This pin is used to drive a laser of which the cathode is connected to the case and the case is connected to the ground. When using this pin, the laser anode needs to be connected to the ground. See Figure 1A. Pin 10 LDC, laser diode cathode, analog output. This pin is used to drive a laser of which the anode is connected to the case and the case is connected to the ground. When using this pin, the laser cathode needs to be connected to the ground. See Figure 1B. Pin 11 GND, ground. Connect laser anode or cathode to here. Pin 12 GND, ground. Connect power supply return rail to here. Pin 13 VPS, power supply, analog power input. The driver works at 5.0V. Pin 14 SCK, serial interface clock, high impedance digital input. See Linear Tech LTC1654 data sheet. Pin 15 SDI/MIND, serial data input/mode indication, digital input and output. The input impedance is 20KΩ. When used as an output, a HI (=VPS) indicates constant current mode operation and a LO (=GND) indicates constant power mode. When used as an input, is the data input to the serial interface DACs. See Linear Tech LTC1654 data sheet. Pin 16 CSLD, control/serial port/load, high impedance digital input. This pin is the DACs’ input for serial interface enable and load control. See Linear Tech LTC1654 data sheet. Mode Setting A. Set the driver to constant current mode without over power protection Under this mode, the laser is always operating at constant current mode. 1. Set LIS = 2.5V × Ilaser 4 200mA, where Ilaser is the set-point laser current. LIS can be set by the way described in the pin description section. 2. Set LPS to 2.5V reference and connect LPI pin to ground. LPS can be set by the way described in the pin description section. B. Set the driver to constant current mode with over power protection Under this mode, the laser is operating at the constant current mode unless the laser output power reaches the preset maximum power. When the laser output power reaches the protection power, the laser will be operating at a constant power mode. 5 5 0 E . W eddell D riv e , S u ite 4 , S u n n y v a le, C A 9 4 0 8 9 , U . S . A . Tel.: (4 0 8 ) 7 4 7 -9 7 6 0 , F a x : (4 0 8 ) 7 4 7 -9 7 7 0 , W eb: w w w . a n a l o g t e c h n o l o g i e s . c o m Copyright 2000 – 2003, Analog Technologies, Inc. All Rights Reserved. 2 Analog Technologies, Inc. DBD-R2V1 1. Set LIS = 2.5V × Iset 4 200mA, where Ilaser is a laser set-point current. LIS can be set by the way described in the pin description section. 2. Set LPS to a voltage value which will be generated at the LPI pin by the external TIA (TransImpedance Amplifier) when the laser is outputting the protection power. The TIA converts the current of the PD (Photo Diode) into a voltage which is fed into the LPI pin. The PD current is generated by the laser. LPS can be set by the way described in the pin description section. Make sure that the set-point laser current is at least 5% less than the current needed to generate the maximum laser power. C. Set the driver to constant power mode without over current protection Under this mode, the laser is operating at the constant power mode unless the laser current reaches 200mA. When the laser output power reaches 200mA, the laser will be operating at a constant current mode. 1. Connect LIS to 2.5V reference pin, or set LIS by the way described in the pin description section. 2. Set LPS to a voltage value which will be generated at the LPI pin by the external TIA (TransImpedance Amplifier) when the laser is outputting the set-point power. The TIA converts the current of the PD (Photo Diode) into a voltage which is fed into the LPI pin. The PD current is generated by the laser. LPS can be set by the way described in the pin description section. Make sure that the laser can output the set-point power by a current of less than 190mA. D. Set the driver to constant power mode with over current protection Under this mode, the laser is operating at the constant power mode unless the laser current reaches a predetermined protection current. When the laser reaches the protection current, the laser will be operating at a constant current mode. 1. Set LIS = 2.5V × Iprotect 4 200mA, where Iprotect is predetermined protection current. LIS can be set by the way described in the pin description section. 2. Set LPS to a voltage value which will be generated at the LPI pin by the external TIA (TransImpedance Amplifier) when the laser is outputting the set-point power. The TIA converts the current of the PD (Photo Diode) into a voltage which is fed into the LPI pin. The PD current is generated by the laser. LPS can be set by the way described in the pin description section. Make sure that the laser can output the set-point power by a current of less than 95% of the protection current. Mounting the High Precision Digital Input Laser Driver on PCB’s The high precision digital input laser drivers come in two types of packages: surface mount and through hole. The surface mount package has to be soldered manually, not by reflow oven. The through hole package can be mounted through a socket, soldered manually, or by wave soldering machine. 5 5 0 E . W eddell D riv e , S u ite 4 , S u n n y v a le, C A 9 4 0 8 9 , U . S . A . Tel.: (4 0 8 ) 7 4 7 -9 7 6 0 , F a x : (4 0 8 ) 7 4 7 -9 7 7 0 , W eb: w w w . a n a l o g t e c h n o l o g i e s . c o m Copyright 2000 – 2003, Analog Technologies, Inc. All Rights Reserved. 3 DBD-R2V1 Analog Technologies, Inc. DBD-R2V1 1 To micro-controller 2 To micro-controller 3 To signal GND 4 To ADC N/C 5 6 To ADC SD CSLD CLGD SDI/MIND GND SCK 2.5V VPS LIS GND LIO GND 7 N/C LPS R1 10K to 1M 2 1 8 LPI 15 To micro-controller 14 To micro-controller 13 +5V 12 To power supply GND 11 10 N/C 9 2 3 Laser 6 U1 4 Front_PD LDA To micro-controller 5V 7 D1 LDC 16 OPA350 Case Conductor Signal GND Signal GND Figure 1A Driving a Common Cathode Laser DBD-R2V1 1 To micro-controller 2 To micro-controller 3 To signal GND 4 To ADC N/C 6 To ADC R1 10K to 1M 2 1 N/C 7 8 CLGD CSLD SDI/MIND GND SCK 2.5V VPS LIS GND LIO GND LPS LDC LPI LDA 16 To micro-controller 15 To micro-controller 14 To micro-controller 13 +5V 12 To power supply GND 11 10 9 N/C 5V 7 D1 5 SD 2 3 6 U1 4 Front_PD OPA350 Signal GND Laser Case Conductor Signal GND Figure 1B Driving a Common Anode Laser 5 5 0 E . W eddell D riv e , S u ite 4 , S u n n y v a le, C A 9 4 0 8 9 , U . S . A . Tel.: (4 0 8 ) 7 4 7 -9 7 6 0 , F a x : (4 0 8 ) 7 4 7 -9 7 7 0 , W eb: w w w . a n a l o g t e c h n o l o g i e s . c o m Copyright 2000 – 2003, Analog Technologies, Inc. All Rights Reserved. 4 DBD-R2V1 Analog Technologies, Inc. Mechanical dimensions 1 SD CSLD 8 9 7 10 6 11 16 2.54mm SDI/MIND 15 GND SCK 14 5 12 4 2.5V VPS 13 4 13 5 LIS GND 12 3 14 6 LIO GND 11 2 15 16 LPS LDC 1 7 10 8 LPI LDA 9 2 CLGD 3 25.5mm 1.26mm Figure 2 Top View of DBD-R2V1-S 18mm 2.26mm 20mm 1.26mm Figure 3 Bottom View of DBD-R2V1-S 4.5mm 3mm 0.42mm 4.5mm Figure 4 End View of DBD-R2V1-S 18mm Figure 5 End View of DBD-R2V1-D 4.5mm 3mm 0.6mm 2.54mm Figure 6 Side View of DBD-R2V1-D 5 5 0 E . W eddell D riv e , S u ite 4 , S u n n y v a le, C A 9 4 0 8 9 , U . S . A . Tel.: (4 0 8 ) 7 4 7 -9 7 6 0 , F a x : (4 0 8 ) 7 4 7 -9 7 7 0 , W eb: w w w . a n a l o g t e c h n o l o g i e s . c o m Copyright 2000 – 2003, Analog Technologies, Inc. All Rights Reserved. 5 DBD-R2V1 Analog Technologies, Inc. 1 Solder Pad 16 2.54mm 2 15 3 14 4 13 5 12 6 11 7 10 26mm 1.35mm 8 Outline 9 17.5mm 2.9mm 21.5mm Figure 7 Recommended PCB Footprint for Surface Mount Package Ordering Guide Part Number Description DBD-R2V1-D High precision input laser driver Note DIP package DBD-R2V1-S High precision input laser driver SMT package 5 5 0 E . W eddell D riv e , S u ite 4 , S u n n y v a le, C A 9 4 0 8 9 , U . S . A . Tel.: (4 0 8 ) 7 4 7 -9 7 6 0 , F a x : (4 0 8 ) 7 4 7 -9 7 7 0 , W eb: w w w . a n a l o g t e c h n o l o g i e s . c o m Copyright 2000 – 2003, Analog Technologies, Inc. All Rights Reserved. 6