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Copyrights 2000-2022, Analog Technologies, Inc. All Rights Reserved. Updated on 1/24/2022 Email: staff@analogti.com/sales@analogti.com 1 Analog Technologies LDA1-CP1-D Dual Mode Laser Driver Figure 1. Physical Photo

FEATURES

High Efficiency: ≥90% Maximum Output Current: 2A No Heat Sink Required Current and Power Programming, Modulation & Monitoring Capabilities. Current Output Noise: 0.05% High Stability: 100ppm/°C Zero EMI Compact Size 100 % Lead (Pb)-free and RoHS Compliant

APPLICATIONS

DPSSL, EDFA, and instrumentation diode lasers.

DESCRIPTION

There are two versions: th e LDA1-CP1-D-SNI and the LDA1-CP1-D-SNO. The former one represents that the external signal synchronizes th e signal of the chip, and the latter one is that the signal of the chip synchronizes the external signal. The LDA1-CP1-D is an electronic module designed for driving diode lasers (P type) with well controlled and monitored driving current and output laser power. Its PWM (Pulse Width Modulation) output stage achieves ≥90% high power efficiency, elim inating the need for a heat sink. The output current and laser power can be set linearly by two separate input voltages and monitored linearly at the same time by two output voltages respectively. It comes with a high stability low noise 2.5V reference voltage which can be used for setting the output current and as voltage references for external ADCs and DACs. LDA1-CP1-D is packaged in a 6 sided metal enclosure, which blocks EMIs (Electro-Magnetic Interferences) to prevent the controller and other electronics from interfering each other. The LDA1-CP1-D physical photo is shown in Figure 1. Figure 2 is the actual size top view of the LDA1-CP1-D, which shows the pin names and locations. Its thickness is 4.6mm. The LDA1-CP1-D pin functions are shown in table 1. Warning: This module can only be soldered manually onto the PCB by a solder iron at < 310 °C (590 °F), it cannot go through the reflow or wave soldering processes. Figure 2. Pin Names and Locations of LDA1-CP1-D-SNO Figure 3. Internal Shut down Circuit Table 1. Pin Function Descriptions

1 SDNG Digital input

Figure 3 above. The diode is for shortening the shut down time. open drain output and pulled up by a 20k resistor to VPS.

Copyrights 2000-2022, Analog Technologies, Inc. All Rights Reserved. Updated on 1/24/2022 Email: staff@analogti.com/sales@analogti.com 2 Analog Technologies LDA1-CP1-D Dual Mode Laser Driver 3 P/CM Analog output Power/current mode indication. HI = power mode, LO = current mode. Low output impedance, capable of driving 20mA load. 4 GND Signal ground Signal ground pin. Connect ADC and DAC grounds to here. 5 2.5VREF Analog output Reference voltage. It is used by the internal DACs as the reference voltage. It can source 3mA max, with 5μVp-p noise @ 0.1 to 10Hz and 25ppm/°C stability max.

6 LIS Analog input

Laser current set-point voltage. 0V to 2.5V sets the output current from 0 to 2A linearly. The input impedance of this pin is 100k Ω. This pin can be set by an external analog signal source, such as the output of a closed-looped op-amp, POT, or DAC. 7 LIO Analog output Laser current output indication. 0V to 2.5V indicates the laser current of from 0A to 2A linearly.

8 LPS Analog input

Laser power set-point voltage. 0V to 2.5V sets the laser output power from 0 to the maximum value linearly. The input impedance of this pin is 100k Ω. This pin can be set by an external analog signal source, such as the output of a closed-looped op-amp, POT, or DAC.

9 GND Signal ground The same as Pin 4

10 LPO Analog output

Laser power output voltage. Low impedance output. This is the output of the TIA (Trans- Impedance Amplifier) for the photodiode in the laser. The trans-impedance is set by an external resister between LPO pin and PDC (pin 11). See the schematic in Figure 5 or Figure 6.

11 PDC Analog input

Photodiode cathode. This is the negative input of the TIA. See Pin 10 description and Figure 5 or Figure 6 for the usage of this pin. If the PD’s capacitance exceeds 10pF, put a capacitor of about the same value in parallel with R1 for compensation.

12 LDA Analog output

Laser diode anode. Connect it to the anode of the laser diode. 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. See Figure 5 or Figure 6. 13 PGND Power ground Power ground pin. Connect it directly to the la ser’s cathode which is also the case of the laser. See Figure 5 or Figure 6. 14 PGND Power ground Power ground pin. Connect it directly to power supply return rail. 15 VPS Power input Power supply voltage. The driver works from 3.0V to 6.0V.

16 SNO Digital output

Synchronization output. This pin outputs a square waveform with a 10k AC output impedance. Its duty cycle equals to LDA/VPS. Measuring this signal can help determine if the output stage is workin g stably. It can be used to synchronize another switch mode power driver such as for a TEC (Thermo-Elect ric Cooler) or a power supply so that the other drivers will not interfere with this laser driver by generating a low beating frequency. The default switching frequency is set at 500kHz. In case multiple LDA1-CP1 laser drivers are used within one system and powered by one power supply rail, it's better to use one of the drivers as the master sw itching frequency setter and the rest of the drivers as the slave driver which follows the master driver for setting the switching frequency. The master driver will be set at slightly higher frequency, 550kHz, the part number will become LDA1-CP1-D-M. The slave drivers will be of the normal laser driver with the default switching frequency of 500kHz and the default part number LDA1-CP1-D, see Figure 4.

17 SNI Digital input

Synchronization input. This pin is to be used by using an external digital signal to synchronize this laser controller's internal switching frequency of the output PWM power stage, to eliminate beating interferences caused by similar but different switching frequencies of multiple PWM power stages powered by the same power supply rail. This pin has a high DC impedance of > 100k and its AC impedance is of a capacitor of < 5 pF.

  1. Set LPS to the voltage generated at the LPO pin by

protection laser power level. power mode (up to the maximum rated current of 2.0A).

  1. Connect LIS to 2.5V reference pin.
  2. Set LPS to the voltage value which is generated at

current, the laser will be operating in constant current mode.

  1. Set LPS to the voltage value which is generated at

95% of the protection current. Figure 8. VLDA vs. Output Current Noise@0.1Hz~10Hz

Copyrights 2000-2022, Analog Technologies, Inc. All Rights Reserved. Updated on 1/24/2022 Email: staff@analogti.com/sales@analogti.com 7 Analog Technologies LDA1-CP1-D Dual Mode Laser Driver

ORDERING INFORMATION

Table 3. Part Number or laser controllers as the source signal for synchronizing their internal switching frequencies. Table 4. Prices

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